2 This is a version (aka dlmalloc) of malloc/free/realloc written by
3 Doug Lea and released to the public domain, as explained at
4 http://creativecommons.org/publicdomain/zero/1.0/ Send questions,
5 comments, complaints, performance data, etc to dl@cs.oswego.edu
8 #include <vppinfra/dlmalloc.h>
10 /*------------------------------ internal #includes ---------------------- */
13 #pragma warning( disable : 4146 ) /* no "unsigned" warnings */
16 #include <stdio.h> /* for printing in malloc_stats */
17 #endif /* NO_MALLOC_STATS */
19 #include <errno.h> /* for MALLOC_FAILURE_ACTION */
20 #endif /* LACKS_ERRNO_H */
22 #if DLM_ABORT_ON_ASSERT_FAILURE
24 #define assert(x) if(!(x)) DLM_ABORT
25 #else /* DLM_ABORT_ON_ASSERT_FAILURE */
27 #endif /* DLM_ABORT_ON_ASSERT_FAILURE */
34 #if !defined(WIN32) && !defined(LACKS_TIME_H)
35 #include <time.h> /* for magic initialization */
37 #ifndef LACKS_STDLIB_H
38 #include <stdlib.h> /* for abort() */
39 #endif /* LACKS_STDLIB_H */
40 #ifndef LACKS_STRING_H
41 #include <string.h> /* for memset etc */
42 #endif /* LACKS_STRING_H */
44 #ifndef LACKS_STRINGS_H
45 #include <strings.h> /* for ffs */
46 #endif /* LACKS_STRINGS_H */
47 #endif /* USE_BUILTIN_FFS */
49 #ifndef LACKS_SYS_MMAN_H
50 /* On some versions of linux, mremap decl in mman.h needs __USE_GNU set */
51 #if (defined(linux) && !defined(__USE_GNU))
53 #include <sys/mman.h> /* for mmap */
56 #include <sys/mman.h> /* for mmap */
58 #endif /* LACKS_SYS_MMAN_H */
61 #endif /* LACKS_FCNTL_H */
62 #endif /* HAVE_MMAP */
63 #ifndef LACKS_UNISTD_H
64 #include <unistd.h> /* for sbrk, sysconf */
65 #else /* LACKS_UNISTD_H */
66 #if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
67 extern void* sbrk(ptrdiff_t);
68 #endif /* FreeBSD etc */
69 #endif /* LACKS_UNISTD_H */
71 /* Declarations for locking */
74 #if defined (__SVR4) && defined (__sun) /* solaris */
76 #elif !defined(LACKS_SCHED_H)
78 #endif /* solaris or LACKS_SCHED_H */
79 #if (defined(USE_RECURSIVE_LOCKS) && USE_RECURSIVE_LOCKS != 0) || !USE_SPIN_LOCKS
81 #endif /* USE_RECURSIVE_LOCKS ... */
82 #elif defined(_MSC_VER)
84 /* These are already defined on AMD64 builds */
87 #endif /* __cplusplus */
88 LONG __cdecl _InterlockedCompareExchange(LONG volatile *Dest, LONG Exchange, LONG Comp);
89 LONG __cdecl _InterlockedExchange(LONG volatile *Target, LONG Value);
92 #endif /* __cplusplus */
94 #pragma intrinsic (_InterlockedCompareExchange)
95 #pragma intrinsic (_InterlockedExchange)
96 #define interlockedcompareexchange _InterlockedCompareExchange
97 #define interlockedexchange _InterlockedExchange
98 #elif defined(WIN32) && defined(__GNUC__)
99 #define interlockedcompareexchange(a, b, c) __sync_val_compare_and_swap(a, c, b)
100 #define interlockedexchange __sync_lock_test_and_set
102 #else /* USE_LOCKS */
103 #endif /* USE_LOCKS */
106 #define LOCK_AT_FORK 0
109 /* Declarations for bit scanning on win32 */
110 #if defined(_MSC_VER) && _MSC_VER>=1300
111 #ifndef BitScanForward /* Try to avoid pulling in WinNT.h */
114 #endif /* __cplusplus */
115 unsigned char _BitScanForward(unsigned long *index, unsigned long mask);
116 unsigned char _BitScanReverse(unsigned long *index, unsigned long mask);
119 #endif /* __cplusplus */
121 #define BitScanForward _BitScanForward
122 #define BitScanReverse _BitScanReverse
123 #pragma intrinsic(_BitScanForward)
124 #pragma intrinsic(_BitScanReverse)
125 #endif /* BitScanForward */
126 #endif /* defined(_MSC_VER) && _MSC_VER>=1300 */
129 #ifndef malloc_getpagesize
130 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
131 # ifndef _SC_PAGE_SIZE
132 # define _SC_PAGE_SIZE _SC_PAGESIZE
135 # ifdef _SC_PAGE_SIZE
136 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
138 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
139 extern size_t getpagesize();
140 # define malloc_getpagesize getpagesize()
142 # ifdef WIN32 /* use supplied emulation of getpagesize */
143 # define malloc_getpagesize getpagesize()
145 # ifndef LACKS_SYS_PARAM_H
146 # include <sys/param.h>
148 # ifdef EXEC_PAGESIZE
149 # define malloc_getpagesize EXEC_PAGESIZE
153 # define malloc_getpagesize NBPG
155 # define malloc_getpagesize (NBPG * CLSIZE)
159 # define malloc_getpagesize NBPC
162 # define malloc_getpagesize PAGESIZE
163 # else /* just guess */
164 # define malloc_getpagesize ((size_t)4096U)
175 /* ------------------- size_t and alignment properties -------------------- */
177 /* The byte and bit size of a size_t */
178 #define SIZE_T_SIZE (sizeof(size_t))
179 #define SIZE_T_BITSIZE (sizeof(size_t) << 3)
181 /* Some constants coerced to size_t */
182 /* Annoying but necessary to avoid errors on some platforms */
183 #define SIZE_T_ZERO ((size_t)0)
184 #define SIZE_T_ONE ((size_t)1)
185 #define SIZE_T_TWO ((size_t)2)
186 #define SIZE_T_FOUR ((size_t)4)
187 #define TWO_SIZE_T_SIZES (SIZE_T_SIZE<<1)
188 #define FOUR_SIZE_T_SIZES (SIZE_T_SIZE<<2)
189 #define SIX_SIZE_T_SIZES (FOUR_SIZE_T_SIZES+TWO_SIZE_T_SIZES)
190 #define HALF_MAX_SIZE_T (MAX_SIZE_T / 2U)
192 /* The bit mask value corresponding to MALLOC_ALIGNMENT */
193 #define CHUNK_ALIGN_MASK (MALLOC_ALIGNMENT - SIZE_T_ONE)
195 /* True if address a has acceptable alignment */
196 #define is_aligned(A) (((size_t)((A)) & (CHUNK_ALIGN_MASK)) == 0)
198 /* the number of bytes to offset an address to align it */
199 #define align_offset(A)\
200 ((((size_t)(A) & CHUNK_ALIGN_MASK) == 0)? 0 :\
201 ((MALLOC_ALIGNMENT - ((size_t)(A) & CHUNK_ALIGN_MASK)) & CHUNK_ALIGN_MASK))
203 /* -------------------------- MMAP preliminaries ------------------------- */
206 If HAVE_MORECORE or HAVE_MMAP are false, we just define calls and
207 checks to fail so compiler optimizer can delete code rather than
208 using so many "#if"s.
212 /* MORECORE and MMAP must return MFAIL on failure */
213 #define MFAIL ((void*)(MAX_SIZE_T))
214 #define CMFAIL ((char*)(MFAIL)) /* defined for convenience */
219 #define MUNMAP_DEFAULT(a, s) munmap((a), (s))
220 #define MMAP_PROT (PROT_READ|PROT_WRITE)
221 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
222 #define MAP_ANONYMOUS MAP_ANON
223 #endif /* MAP_ANON */
225 #define MMAP_FLAGS (MAP_PRIVATE|MAP_ANONYMOUS)
226 #define MMAP_DEFAULT(s) mmap(0, (s), MMAP_PROT, MMAP_FLAGS, -1, 0)
227 #else /* MAP_ANONYMOUS */
229 Nearly all versions of mmap support MAP_ANONYMOUS, so the following
230 is unlikely to be needed, but is supplied just in case.
232 #define MMAP_FLAGS (MAP_PRIVATE)
233 static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */
234 #define MMAP_DEFAULT(s) ((dev_zero_fd < 0) ? \
235 (dev_zero_fd = open("/dev/zero", O_RDWR), \
236 mmap(0, (s), MMAP_PROT, MMAP_FLAGS, dev_zero_fd, 0)) : \
237 mmap(0, (s), MMAP_PROT, MMAP_FLAGS, dev_zero_fd, 0))
238 #endif /* MAP_ANONYMOUS */
240 #define DIRECT_MMAP_DEFAULT(s) MMAP_DEFAULT(s)
244 /* Win32 MMAP via VirtualAlloc */
245 static FORCEINLINE void* win32mmap(size_t size) {
246 void* ptr = VirtualAlloc(0, size, MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE);
247 return (ptr != 0)? ptr: MFAIL;
250 /* For direct MMAP, use MEM_TOP_DOWN to minimize interference */
251 static FORCEINLINE void* win32direct_mmap(size_t size) {
252 void* ptr = VirtualAlloc(0, size, MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN,
254 return (ptr != 0)? ptr: MFAIL;
257 /* This function supports releasing coalesed segments */
258 static FORCEINLINE int win32munmap(void* ptr, size_t size) {
259 MEMORY_BASIC_INFORMATION minfo;
260 char* cptr = (char*)ptr;
262 if (VirtualQuery(cptr, &minfo, sizeof(minfo)) == 0)
264 if (minfo.BaseAddress != cptr || minfo.AllocationBase != cptr ||
265 minfo.State != MEM_COMMIT || minfo.RegionSize > size)
267 if (VirtualFree(cptr, 0, MEM_RELEASE) == 0)
269 cptr += minfo.RegionSize;
270 size -= minfo.RegionSize;
275 #define MMAP_DEFAULT(s) win32mmap(s)
276 #define MUNMAP_DEFAULT(a, s) win32munmap((a), (s))
277 #define DIRECT_MMAP_DEFAULT(s) win32direct_mmap(s)
279 #endif /* HAVE_MMAP */
283 #define MREMAP_DEFAULT(addr, osz, nsz, mv) mremap((addr), (osz), (nsz), (mv))
285 #endif /* HAVE_MREMAP */
288 * Define CALL_MORECORE
292 #define CALL_MORECORE(S) MORECORE(S)
294 #define CALL_MORECORE(S) MORECORE_DEFAULT(S)
295 #endif /* MORECORE */
296 #else /* HAVE_MORECORE */
297 #define CALL_MORECORE(S) MFAIL
298 #endif /* HAVE_MORECORE */
301 * Define CALL_MMAP/CALL_MUNMAP/CALL_DIRECT_MMAP
304 #define USE_MMAP_BIT (SIZE_T_ONE)
307 #define CALL_MMAP(s) MMAP(s)
309 #define CALL_MMAP(s) MMAP_DEFAULT(s)
312 #define CALL_MUNMAP(a, s) MUNMAP((a), (s))
314 #define CALL_MUNMAP(a, s) MUNMAP_DEFAULT((a), (s))
317 #define CALL_DIRECT_MMAP(s) DIRECT_MMAP(s)
318 #else /* DIRECT_MMAP */
319 #define CALL_DIRECT_MMAP(s) DIRECT_MMAP_DEFAULT(s)
320 #endif /* DIRECT_MMAP */
321 #else /* HAVE_MMAP */
322 #define USE_MMAP_BIT (SIZE_T_ZERO)
324 #define MMAP(s) MFAIL
325 #define MUNMAP(a, s) (-1)
326 #define DIRECT_MMAP(s) MFAIL
327 #define CALL_DIRECT_MMAP(s) DIRECT_MMAP(s)
328 #define CALL_MMAP(s) MMAP(s)
329 #define CALL_MUNMAP(a, s) MUNMAP((a), (s))
330 #endif /* HAVE_MMAP */
335 #if HAVE_MMAP && HAVE_MREMAP
337 #define CALL_MREMAP(addr, osz, nsz, mv) MREMAP((addr), (osz), (nsz), (mv))
339 #define CALL_MREMAP(addr, osz, nsz, mv) MREMAP_DEFAULT((addr), (osz), (nsz), (mv))
341 #else /* HAVE_MMAP && HAVE_MREMAP */
342 #define CALL_MREMAP(addr, osz, nsz, mv) MFAIL
343 #endif /* HAVE_MMAP && HAVE_MREMAP */
345 /* mstate bit set if continguous morecore disabled or failed */
346 #define USE_NONCONTIGUOUS_BIT (4U)
348 /* mstate bit set if no expansion allowed */
349 #define USE_NOEXPAND_BIT (8U)
351 /* trace allocations if set */
352 #define USE_TRACE_BIT (16U)
354 /* segment bit set in create_mspace_with_base */
355 #define EXTERN_BIT (8U)
358 /* --------------------------- Lock preliminaries ------------------------ */
361 When locks are defined, there is one global lock, plus
364 The global lock_ensures that mparams.magic and other unique
365 mparams values are initialized only once. It also protects
366 sequences of calls to MORECORE. In many cases sys_alloc requires
367 two calls, that should not be interleaved with calls by other
368 threads. This does not protect against direct calls to MORECORE
369 by other threads not using this lock, so there is still code to
370 cope the best we can on interference.
372 Per-mspace locks surround calls to malloc, free, etc.
373 By default, locks are simple non-reentrant mutexes.
375 Because lock-protected regions generally have bounded times, it is
376 OK to use the supplied simple spinlocks. Spinlocks are likely to
377 improve performance for lightly contended applications, but worsen
378 performance under heavy contention.
380 If USE_LOCKS is > 1, the definitions of lock routines here are
381 bypassed, in which case you will need to define the type MLOCK_T,
382 and at least INITIAL_LOCK, DESTROY_LOCK, ACQUIRE_LOCK, RELEASE_LOCK
383 and TRY_LOCK. You must also declare a
384 static MLOCK_T malloc_global_mutex = { initialization values };.
389 #define USE_LOCK_BIT (0U)
390 #define INITIAL_LOCK(l) (0)
391 #define DESTROY_LOCK(l) (0)
392 #define ACQUIRE_MALLOC_GLOBAL_LOCK()
393 #define RELEASE_MALLOC_GLOBAL_LOCK()
397 /* ----------------------- User-defined locks ------------------------ */
398 /* Define your own lock implementation here */
399 /* #define INITIAL_LOCK(lk) ... */
400 /* #define DESTROY_LOCK(lk) ... */
401 /* #define ACQUIRE_LOCK(lk) ... */
402 /* #define RELEASE_LOCK(lk) ... */
403 /* #define TRY_LOCK(lk) ... */
404 /* static MLOCK_T malloc_global_mutex = ... */
408 /* First, define CAS_LOCK and CLEAR_LOCK on ints */
409 /* Note CAS_LOCK defined to return 0 on success */
411 #if defined(__GNUC__)&& (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1))
412 #define CAS_LOCK(sl) __sync_lock_test_and_set(sl, 1)
413 #define CLEAR_LOCK(sl) __sync_lock_release(sl)
415 #elif (defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)))
416 /* Custom spin locks for older gcc on x86 */
417 static FORCEINLINE int x86_cas_lock(int *sl) {
421 __asm__ __volatile__ ("lock; cmpxchgl %1, %2"
423 : "r" (val), "m" (*(sl)), "0"(cmp)
428 static FORCEINLINE void x86_clear_lock(int* sl) {
432 __asm__ __volatile__ ("lock; xchgl %0, %1"
434 : "m" (*(sl)), "0"(prev)
438 #define CAS_LOCK(sl) x86_cas_lock(sl)
439 #define CLEAR_LOCK(sl) x86_clear_lock(sl)
441 #else /* Win32 MSC */
442 #define CAS_LOCK(sl) interlockedexchange(sl, (LONG)1)
443 #define CLEAR_LOCK(sl) interlockedexchange (sl, (LONG)0)
445 #endif /* ... gcc spins locks ... */
447 /* How to yield for a spin lock */
448 #define SPINS_PER_YIELD 63
449 #if defined(_MSC_VER)
450 #define SLEEP_EX_DURATION 50 /* delay for yield/sleep */
451 #define SPIN_LOCK_YIELD SleepEx(SLEEP_EX_DURATION, FALSE)
452 #elif defined (__SVR4) && defined (__sun) /* solaris */
453 #define SPIN_LOCK_YIELD thr_yield();
454 #elif !defined(LACKS_SCHED_H)
455 #define SPIN_LOCK_YIELD sched_yield();
457 #define SPIN_LOCK_YIELD
458 #endif /* ... yield ... */
460 #if !defined(USE_RECURSIVE_LOCKS) || USE_RECURSIVE_LOCKS == 0
461 /* Plain spin locks use single word (embedded in malloc_states) */
462 static int spin_acquire_lock(int *sl) {
464 while (*(volatile int *)sl != 0 || CAS_LOCK(sl)) {
465 if ((++spins & SPINS_PER_YIELD) == 0) {
473 #define TRY_LOCK(sl) !CAS_LOCK(sl)
474 #define RELEASE_LOCK(sl) CLEAR_LOCK(sl)
475 #define ACQUIRE_LOCK(sl) (CAS_LOCK(sl)? spin_acquire_lock(sl) : 0)
476 #define INITIAL_LOCK(sl) (*sl = 0)
477 #define DESTROY_LOCK(sl) (0)
478 static MLOCK_T malloc_global_mutex = 0;
480 #else /* USE_RECURSIVE_LOCKS */
481 /* types for lock owners */
483 #define THREAD_ID_T DWORD
484 #define CURRENT_THREAD GetCurrentThreadId()
485 #define EQ_OWNER(X,Y) ((X) == (Y))
488 Note: the following assume that pthread_t is a type that can be
489 initialized to (casted) zero. If this is not the case, you will need to
490 somehow redefine these or not use spin locks.
492 #define THREAD_ID_T pthread_t
493 #define CURRENT_THREAD pthread_self()
494 #define EQ_OWNER(X,Y) pthread_equal(X, Y)
497 struct malloc_recursive_lock {
500 THREAD_ID_T threadid;
503 #define MLOCK_T struct malloc_recursive_lock
504 static MLOCK_T malloc_global_mutex = { 0, 0, (THREAD_ID_T)0};
506 static FORCEINLINE void recursive_release_lock(MLOCK_T *lk) {
513 static FORCEINLINE int recursive_acquire_lock(MLOCK_T *lk) {
514 THREAD_ID_T mythreadid = CURRENT_THREAD;
517 if (*((volatile int *)(&lk->sl)) == 0) {
518 if (!CAS_LOCK(&lk->sl)) {
519 lk->threadid = mythreadid;
524 else if (EQ_OWNER(lk->threadid, mythreadid)) {
528 if ((++spins & SPINS_PER_YIELD) == 0) {
534 static FORCEINLINE int recursive_try_lock(MLOCK_T *lk) {
535 THREAD_ID_T mythreadid = CURRENT_THREAD;
536 if (*((volatile int *)(&lk->sl)) == 0) {
537 if (!CAS_LOCK(&lk->sl)) {
538 lk->threadid = mythreadid;
543 else if (EQ_OWNER(lk->threadid, mythreadid)) {
550 #define RELEASE_LOCK(lk) recursive_release_lock(lk)
551 #define TRY_LOCK(lk) recursive_try_lock(lk)
552 #define ACQUIRE_LOCK(lk) recursive_acquire_lock(lk)
553 #define INITIAL_LOCK(lk) ((lk)->threadid = (THREAD_ID_T)0, (lk)->sl = 0, (lk)->c = 0)
554 #define DESTROY_LOCK(lk) (0)
555 #endif /* USE_RECURSIVE_LOCKS */
557 #elif defined(WIN32) /* Win32 critical sections */
558 #define MLOCK_T CRITICAL_SECTION
559 #define ACQUIRE_LOCK(lk) (EnterCriticalSection(lk), 0)
560 #define RELEASE_LOCK(lk) LeaveCriticalSection(lk)
561 #define TRY_LOCK(lk) TryEnterCriticalSection(lk)
562 #define INITIAL_LOCK(lk) (!InitializeCriticalSectionAndSpinCount((lk), 0x80000000|4000))
563 #define DESTROY_LOCK(lk) (DeleteCriticalSection(lk), 0)
564 #define NEED_GLOBAL_LOCK_INIT
566 static MLOCK_T malloc_global_mutex;
567 static volatile LONG malloc_global_mutex_status;
569 /* Use spin loop to initialize global lock */
570 static void init_malloc_global_mutex() {
572 long stat = malloc_global_mutex_status;
575 /* transition to < 0 while initializing, then to > 0) */
577 interlockedcompareexchange(&malloc_global_mutex_status, (LONG)-1, (LONG)0) == 0) {
578 InitializeCriticalSection(&malloc_global_mutex);
579 interlockedexchange(&malloc_global_mutex_status, (LONG)1);
586 #else /* pthreads-based locks */
587 #define MLOCK_T pthread_mutex_t
588 #define ACQUIRE_LOCK(lk) pthread_mutex_lock(lk)
589 #define RELEASE_LOCK(lk) pthread_mutex_unlock(lk)
590 #define TRY_LOCK(lk) (!pthread_mutex_trylock(lk))
591 #define INITIAL_LOCK(lk) pthread_init_lock(lk)
592 #define DESTROY_LOCK(lk) pthread_mutex_destroy(lk)
594 #if defined(USE_RECURSIVE_LOCKS) && USE_RECURSIVE_LOCKS != 0 && defined(linux) && !defined(PTHREAD_MUTEX_RECURSIVE)
595 /* Cope with old-style linux recursive lock initialization by adding */
596 /* skipped internal declaration from pthread.h */
597 extern int pthread_mutexattr_setkind_np __P ((pthread_mutexattr_t *__attr,
599 #define PTHREAD_MUTEX_RECURSIVE PTHREAD_MUTEX_RECURSIVE_NP
600 #define pthread_mutexattr_settype(x,y) pthread_mutexattr_setkind_np(x,y)
601 #endif /* USE_RECURSIVE_LOCKS ... */
603 static MLOCK_T malloc_global_mutex = PTHREAD_MUTEX_INITIALIZER;
605 static int pthread_init_lock (MLOCK_T *lk) {
606 pthread_mutexattr_t attr;
607 if (pthread_mutexattr_init(&attr)) return 1;
608 #if defined(USE_RECURSIVE_LOCKS) && USE_RECURSIVE_LOCKS != 0
609 if (pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE)) return 1;
611 if (pthread_mutex_init(lk, &attr)) return 1;
612 if (pthread_mutexattr_destroy(&attr)) return 1;
616 #endif /* ... lock types ... */
618 /* Common code for all lock types */
619 #define USE_LOCK_BIT (2U)
621 #ifndef ACQUIRE_MALLOC_GLOBAL_LOCK
622 #define ACQUIRE_MALLOC_GLOBAL_LOCK() ACQUIRE_LOCK(&malloc_global_mutex);
625 #ifndef RELEASE_MALLOC_GLOBAL_LOCK
626 #define RELEASE_MALLOC_GLOBAL_LOCK() RELEASE_LOCK(&malloc_global_mutex);
629 #endif /* USE_LOCKS */
631 /* ----------------------- Chunk representations ------------------------ */
634 (The following includes lightly edited explanations by Colin Plumb.)
636 The malloc_chunk declaration below is misleading (but accurate and
637 necessary). It declares a "view" into memory allowing access to
638 necessary fields at known offsets from a given base.
640 Chunks of memory are maintained using a `boundary tag' method as
641 originally described by Knuth. (See the paper by Paul Wilson
642 ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a survey of such
643 techniques.) Sizes of free chunks are stored both in the front of
644 each chunk and at the end. This makes consolidating fragmented
645 chunks into bigger chunks fast. The head fields also hold bits
646 representing whether chunks are free or in use.
648 Here are some pictures to make it clearer. They are "exploded" to
649 show that the state of a chunk can be thought of as extending from
650 the high 31 bits of the head field of its header through the
651 prev_foot and PINUSE_BIT bit of the following chunk header.
653 A chunk that's in use looks like:
655 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
656 | Size of previous chunk (if P = 0) |
657 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
658 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
659 | Size of this chunk 1| +-+
660 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
666 +- size - sizeof(size_t) available payload bytes -+
670 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
671 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|
672 | Size of next chunk (may or may not be in use) | +-+
673 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
675 And if it's free, it looks like this:
678 | User payload (must be in use, or we would have merged!) |
679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
680 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
681 | Size of this chunk 0| +-+
682 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
684 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
686 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
688 +- size - sizeof(struct chunk) unused bytes -+
690 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
691 | Size of this chunk |
692 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
693 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|
694 | Size of next chunk (must be in use, or we would have merged)| +-+
695 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
699 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
702 Note that since we always merge adjacent free chunks, the chunks
703 adjacent to a free chunk must be in use.
705 Given a pointer to a chunk (which can be derived trivially from the
706 payload pointer) we can, in O(1) time, find out whether the adjacent
707 chunks are free, and if so, unlink them from the lists that they
708 are on and merge them with the current chunk.
710 Chunks always begin on even word boundaries, so the mem portion
711 (which is returned to the user) is also on an even word boundary, and
712 thus at least double-word aligned.
714 The P (PINUSE_BIT) bit, stored in the unused low-order bit of the
715 chunk size (which is always a multiple of two words), is an in-use
716 bit for the *previous* chunk. If that bit is *clear*, then the
717 word before the current chunk size contains the previous chunk
718 size, and can be used to find the front of the previous chunk.
719 The very first chunk allocated always has this bit set, preventing
720 access to non-existent (or non-owned) memory. If pinuse is set for
721 any given chunk, then you CANNOT determine the size of the
722 previous chunk, and might even get a memory addressing fault when
725 The C (CINUSE_BIT) bit, stored in the unused second-lowest bit of
726 the chunk size redundantly records whether the current chunk is
727 inuse (unless the chunk is mmapped). This redundancy enables usage
728 checks within free and realloc, and reduces indirection when freeing
729 and consolidating chunks.
731 Each freshly allocated chunk must have both cinuse and pinuse set.
732 That is, each allocated chunk borders either a previously allocated
733 and still in-use chunk, or the base of its memory arena. This is
734 ensured by making all allocations from the `lowest' part of any
735 found chunk. Further, no free chunk physically borders another one,
736 so each free chunk is known to be preceded and followed by either
737 inuse chunks or the ends of memory.
739 Note that the `foot' of the current chunk is actually represented
740 as the prev_foot of the NEXT chunk. This makes it easier to
741 deal with alignments etc but can be very confusing when trying
742 to extend or adapt this code.
744 The exceptions to all this are
746 1. The special chunk `top' is the top-most available chunk (i.e.,
747 the one bordering the end of available memory). It is treated
748 specially. Top is never included in any bin, is used only if
749 no other chunk is available, and is released back to the
750 system if it is very large (see M_TRIM_THRESHOLD). In effect,
751 the top chunk is treated as larger (and thus less well
752 fitting) than any other available chunk. The top chunk
753 doesn't update its trailing size field since there is no next
754 contiguous chunk that would have to index off it. However,
755 space is still allocated for it (TOP_FOOT_SIZE) to enable
756 separation or merging when space is extended.
758 3. Chunks allocated via mmap, have both cinuse and pinuse bits
759 cleared in their head fields. Because they are allocated
760 one-by-one, each must carry its own prev_foot field, which is
761 also used to hold the offset this chunk has within its mmapped
762 region, which is needed to preserve alignment. Each mmapped
763 chunk is trailed by the first two fields of a fake next-chunk
764 for sake of usage checks.
768 struct malloc_chunk {
769 size_t prev_foot; /* Size of previous chunk (if free). */
770 size_t head; /* Size and inuse bits. */
771 struct malloc_chunk* fd; /* double links -- used only if free. */
772 struct malloc_chunk* bk;
775 typedef struct malloc_chunk mchunk;
776 typedef struct malloc_chunk* mchunkptr;
777 typedef struct malloc_chunk* sbinptr; /* The type of bins of chunks */
778 typedef unsigned int bindex_t; /* Described below */
779 typedef unsigned int binmap_t; /* Described below */
780 typedef unsigned int flag_t; /* The type of various bit flag sets */
782 /* ------------------- Chunks sizes and alignments ----------------------- */
784 #define MCHUNK_SIZE (sizeof(mchunk))
787 #define CHUNK_OVERHEAD (TWO_SIZE_T_SIZES)
789 #define CHUNK_OVERHEAD (SIZE_T_SIZE)
792 /* MMapped chunks need a second word of overhead ... */
793 #define MMAP_CHUNK_OVERHEAD (TWO_SIZE_T_SIZES)
794 /* ... and additional padding for fake next-chunk at foot */
795 #define MMAP_FOOT_PAD (FOUR_SIZE_T_SIZES)
797 /* The smallest size we can malloc is an aligned minimal chunk */
798 #define MIN_CHUNK_SIZE\
799 ((MCHUNK_SIZE + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK)
801 /* conversion from malloc headers to user pointers, and back */
802 #define chunk2mem(p) ((void*)((char*)(p) + TWO_SIZE_T_SIZES))
803 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - TWO_SIZE_T_SIZES))
804 /* chunk associated with aligned address A */
805 #define align_as_chunk(A) (mchunkptr)((A) + align_offset(chunk2mem(A)))
807 /* Bounds on request (not chunk) sizes. */
808 #define MAX_REQUEST ((-MIN_CHUNK_SIZE) << 2)
809 #define MIN_REQUEST (MIN_CHUNK_SIZE - CHUNK_OVERHEAD - SIZE_T_ONE)
811 /* pad request bytes into a usable size */
812 #define pad_request(req) \
813 (((req) + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK)
815 /* pad request, checking for minimum (but not maximum) */
816 #define request2size(req) \
817 (((req) < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(req))
820 /* ------------------ Operations on head and foot fields ----------------- */
823 The head field of a chunk is or'ed with PINUSE_BIT when previous
824 adjacent chunk in use, and or'ed with CINUSE_BIT if this chunk is in
825 use, unless mmapped, in which case both bits are cleared.
827 FLAG4_BIT is not used by this malloc, but might be useful in extensions.
830 #define PINUSE_BIT (SIZE_T_ONE)
831 #define CINUSE_BIT (SIZE_T_TWO)
832 #define FLAG4_BIT (SIZE_T_FOUR)
833 #define INUSE_BITS (PINUSE_BIT|CINUSE_BIT)
834 #define FLAG_BITS (PINUSE_BIT|CINUSE_BIT|FLAG4_BIT)
836 /* Head value for fenceposts */
837 #define FENCEPOST_HEAD (INUSE_BITS|SIZE_T_SIZE)
839 /* extraction of fields from head words */
840 #define cinuse(p) ((p)->head & CINUSE_BIT)
841 #define pinuse(p) ((p)->head & PINUSE_BIT)
842 #define flag4inuse(p) ((p)->head & FLAG4_BIT)
843 #define is_inuse(p) (((p)->head & INUSE_BITS) != PINUSE_BIT)
844 #define is_mmapped(p) (((p)->head & INUSE_BITS) == 0)
846 #define chunksize(p) ((p)->head & ~(FLAG_BITS))
848 #define clear_pinuse(p) ((p)->head &= ~PINUSE_BIT)
849 #define set_flag4(p) ((p)->head |= FLAG4_BIT)
850 #define clear_flag4(p) ((p)->head &= ~FLAG4_BIT)
852 /* Treat space at ptr +/- offset as a chunk */
853 #define chunk_plus_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
854 #define chunk_minus_offset(p, s) ((mchunkptr)(((char*)(p)) - (s)))
856 /* Ptr to next or previous physical malloc_chunk. */
857 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->head & ~FLAG_BITS)))
858 #define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_foot) ))
860 /* extract next chunk's pinuse bit */
861 #define next_pinuse(p) ((next_chunk(p)->head) & PINUSE_BIT)
863 /* Get/set size at footer */
864 #define get_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_foot)
865 #define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_foot = (s))
867 /* Set size, pinuse bit, and foot */
868 #define set_size_and_pinuse_of_free_chunk(p, s)\
869 ((p)->head = (s|PINUSE_BIT), set_foot(p, s))
871 /* Set size, pinuse bit, foot, and clear next pinuse */
872 #define set_free_with_pinuse(p, s, n)\
873 (clear_pinuse(n), set_size_and_pinuse_of_free_chunk(p, s))
875 /* Get the internal overhead associated with chunk p */
876 #define overhead_for(p)\
877 (is_mmapped(p)? MMAP_CHUNK_OVERHEAD : CHUNK_OVERHEAD)
879 /* Return true if malloced space is not necessarily cleared */
881 #define calloc_must_clear(p) (!is_mmapped(p))
882 #else /* MMAP_CLEARS */
883 #define calloc_must_clear(p) (1)
884 #endif /* MMAP_CLEARS */
886 /* ---------------------- Overlaid data structures ----------------------- */
889 When chunks are not in use, they are treated as nodes of either
892 "Small" chunks are stored in circular doubly-linked lists, and look
895 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
896 | Size of previous chunk |
897 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
898 `head:' | Size of chunk, in bytes |P|
899 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
900 | Forward pointer to next chunk in list |
901 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
902 | Back pointer to previous chunk in list |
903 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
904 | Unused space (may be 0 bytes long) .
907 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
908 `foot:' | Size of chunk, in bytes |
909 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
911 Larger chunks are kept in a form of bitwise digital trees (aka
912 tries) keyed on chunksizes. Because malloc_tree_chunks are only for
913 free chunks greater than 256 bytes, their size doesn't impose any
914 constraints on user chunk sizes. Each node looks like:
916 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
917 | Size of previous chunk |
918 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
919 `head:' | Size of chunk, in bytes |P|
920 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
921 | Forward pointer to next chunk of same size |
922 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
923 | Back pointer to previous chunk of same size |
924 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
925 | Pointer to left child (child[0]) |
926 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
927 | Pointer to right child (child[1]) |
928 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
929 | Pointer to parent |
930 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
931 | bin index of this chunk |
932 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
935 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
936 `foot:' | Size of chunk, in bytes |
937 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
939 Each tree holding treenodes is a tree of unique chunk sizes. Chunks
940 of the same size are arranged in a circularly-linked list, with only
941 the oldest chunk (the next to be used, in our FIFO ordering)
942 actually in the tree. (Tree members are distinguished by a non-null
943 parent pointer.) If a chunk with the same size an an existing node
944 is inserted, it is linked off the existing node using pointers that
945 work in the same way as fd/bk pointers of small chunks.
947 Each tree contains a power of 2 sized range of chunk sizes (the
948 smallest is 0x100 <= x < 0x180), which is is divided in half at each
949 tree level, with the chunks in the smaller half of the range (0x100
950 <= x < 0x140 for the top nose) in the left subtree and the larger
951 half (0x140 <= x < 0x180) in the right subtree. This is, of course,
952 done by inspecting individual bits.
954 Using these rules, each node's left subtree contains all smaller
955 sizes than its right subtree. However, the node at the root of each
956 subtree has no particular ordering relationship to either. (The
957 dividing line between the subtree sizes is based on trie relation.)
958 If we remove the last chunk of a given size from the interior of the
959 tree, we need to replace it with a leaf node. The tree ordering
960 rules permit a node to be replaced by any leaf below it.
962 The smallest chunk in a tree (a common operation in a best-fit
963 allocator) can be found by walking a path to the leftmost leaf in
964 the tree. Unlike a usual binary tree, where we follow left child
965 pointers until we reach a null, here we follow the right child
966 pointer any time the left one is null, until we reach a leaf with
967 both child pointers null. The smallest chunk in the tree will be
968 somewhere along that path.
970 The worst case number of steps to add, find, or remove a node is
971 bounded by the number of bits differentiating chunks within
972 bins. Under current bin calculations, this ranges from 6 up to 21
973 (for 32 bit sizes) or up to 53 (for 64 bit sizes). The typical case
974 is of course much better.
977 struct malloc_tree_chunk {
978 /* The first four fields must be compatible with malloc_chunk */
981 struct malloc_tree_chunk* fd;
982 struct malloc_tree_chunk* bk;
984 struct malloc_tree_chunk* child[2];
985 struct malloc_tree_chunk* parent;
989 typedef struct malloc_tree_chunk tchunk;
990 typedef struct malloc_tree_chunk* tchunkptr;
991 typedef struct malloc_tree_chunk* tbinptr; /* The type of bins of trees */
993 /* A little helper macro for trees */
994 #define leftmost_child(t) ((t)->child[0] != 0? (t)->child[0] : (t)->child[1])
996 /* ----------------------------- Segments -------------------------------- */
999 Each malloc space may include non-contiguous segments, held in a
1000 list headed by an embedded malloc_segment record representing the
1001 top-most space. Segments also include flags holding properties of
1002 the space. Large chunks that are directly allocated by mmap are not
1003 included in this list. They are instead independently created and
1004 destroyed without otherwise keeping track of them.
1006 Segment management mainly comes into play for spaces allocated by
1007 MMAP. Any call to MMAP might or might not return memory that is
1008 adjacent to an existing segment. MORECORE normally contiguously
1009 extends the current space, so this space is almost always adjacent,
1010 which is simpler and faster to deal with. (This is why MORECORE is
1011 used preferentially to MMAP when both are available -- see
1012 sys_alloc.) When allocating using MMAP, we don't use any of the
1013 hinting mechanisms (inconsistently) supported in various
1014 implementations of unix mmap, or distinguish reserving from
1015 committing memory. Instead, we just ask for space, and exploit
1016 contiguity when we get it. It is probably possible to do
1017 better than this on some systems, but no general scheme seems
1018 to be significantly better.
1020 Management entails a simpler variant of the consolidation scheme
1021 used for chunks to reduce fragmentation -- new adjacent memory is
1022 normally prepended or appended to an existing segment. However,
1023 there are limitations compared to chunk consolidation that mostly
1024 reflect the fact that segment processing is relatively infrequent
1025 (occurring only when getting memory from system) and that we
1026 don't expect to have huge numbers of segments:
1028 * Segments are not indexed, so traversal requires linear scans. (It
1029 would be possible to index these, but is not worth the extra
1030 overhead and complexity for most programs on most platforms.)
1031 * New segments are only appended to old ones when holding top-most
1032 memory; if they cannot be prepended to others, they are held in
1035 Except for the top-most segment of an mstate, each segment record
1036 is kept at the tail of its segment. Segments are added by pushing
1037 segment records onto the list headed by &mstate.seg for the
1040 Segment flags control allocation/merge/deallocation policies:
1041 * If EXTERN_BIT set, then we did not allocate this segment,
1042 and so should not try to deallocate or merge with others.
1043 (This currently holds only for the initial segment passed
1044 into create_mspace_with_base.)
1045 * If USE_MMAP_BIT set, the segment may be merged with
1046 other surrounding mmapped segments and trimmed/de-allocated
1048 * If neither bit is set, then the segment was obtained using
1049 MORECORE so can be merged with surrounding MORECORE'd segments
1050 and deallocated/trimmed using MORECORE with negative arguments.
1053 struct malloc_segment {
1054 char* base; /* base address */
1055 size_t size; /* allocated size */
1056 struct malloc_segment* next; /* ptr to next segment */
1057 flag_t sflags; /* mmap and extern flag */
1060 #define is_mmapped_segment(S) ((S)->sflags & USE_MMAP_BIT)
1061 #define is_extern_segment(S) ((S)->sflags & EXTERN_BIT)
1063 typedef struct malloc_segment msegment;
1064 typedef struct malloc_segment* msegmentptr;
1066 /* ---------------------------- malloc_state ----------------------------- */
1069 A malloc_state holds all of the bookkeeping for a space.
1070 The main fields are:
1073 The topmost chunk of the currently active segment. Its size is
1074 cached in topsize. The actual size of topmost space is
1075 topsize+TOP_FOOT_SIZE, which includes space reserved for adding
1076 fenceposts and segment records if necessary when getting more
1077 space from the system. The size at which to autotrim top is
1078 cached from mparams in trim_check, except that it is disabled if
1081 Designated victim (dv)
1082 This is the preferred chunk for servicing small requests that
1083 don't have exact fits. It is normally the chunk split off most
1084 recently to service another small request. Its size is cached in
1085 dvsize. The link fields of this chunk are not maintained since it
1086 is not kept in a bin.
1089 An array of bin headers for free chunks. These bins hold chunks
1090 with sizes less than MIN_LARGE_SIZE bytes. Each bin contains
1091 chunks of all the same size, spaced 8 bytes apart. To simplify
1092 use in double-linked lists, each bin header acts as a malloc_chunk
1093 pointing to the real first node, if it exists (else pointing to
1094 itself). This avoids special-casing for headers. But to avoid
1095 waste, we allocate only the fd/bk pointers of bins, and then use
1096 repositioning tricks to treat these as the fields of a chunk.
1099 Treebins are pointers to the roots of trees holding a range of
1100 sizes. There are 2 equally spaced treebins for each power of two
1101 from TREE_SHIFT to TREE_SHIFT+16. The last bin holds anything
1105 There is one bit map for small bins ("smallmap") and one for
1106 treebins ("treemap). Each bin sets its bit when non-empty, and
1107 clears the bit when empty. Bit operations are then used to avoid
1108 bin-by-bin searching -- nearly all "search" is done without ever
1109 looking at bins that won't be selected. The bit maps
1110 conservatively use 32 bits per map word, even if on 64bit system.
1111 For a good description of some of the bit-based techniques used
1112 here, see Henry S. Warren Jr's book "Hacker's Delight" (and
1113 supplement at http://hackersdelight.org/). Many of these are
1114 intended to reduce the branchiness of paths through malloc etc, as
1115 well as to reduce the number of memory locations read or written.
1118 A list of segments headed by an embedded malloc_segment record
1119 representing the initial space.
1121 Address check support
1122 The least_addr field is the least address ever obtained from
1123 MORECORE or MMAP. Attempted frees and reallocs of any address less
1124 than this are trapped (unless INSECURE is defined).
1127 A cross-check field that should always hold same value as mparams.magic.
1129 Max allowed footprint
1130 The maximum allowed bytes to allocate from system (zero means no limit)
1133 Bits recording whether to use MMAP, locks, or contiguous MORECORE
1136 Each space keeps track of current and maximum system memory
1137 obtained via MORECORE or MMAP.
1140 Fields holding the amount of unused topmost memory that should trigger
1141 trimming, and a counter to force periodic scanning to release unused
1142 non-topmost segments.
1145 If USE_LOCKS is defined, the "mutex" lock is acquired and released
1146 around every public call using this mspace.
1149 A void* pointer and a size_t field that can be used to help implement
1150 extensions to this malloc.
1153 /* Bin types, widths and sizes */
1154 #define NSMALLBINS (32U)
1155 #define NTREEBINS (32U)
1156 #define SMALLBIN_SHIFT (3U)
1157 #define SMALLBIN_WIDTH (SIZE_T_ONE << SMALLBIN_SHIFT)
1158 #define TREEBIN_SHIFT (8U)
1159 #define MIN_LARGE_SIZE (SIZE_T_ONE << TREEBIN_SHIFT)
1160 #define MAX_SMALL_SIZE (MIN_LARGE_SIZE - SIZE_T_ONE)
1161 #define MAX_SMALL_REQUEST (MAX_SMALL_SIZE - CHUNK_ALIGN_MASK - CHUNK_OVERHEAD)
1163 struct malloc_state {
1172 size_t release_checks;
1174 mchunkptr smallbins[(NSMALLBINS+1)*2];
1175 tbinptr treebins[NTREEBINS];
1177 size_t max_footprint;
1178 size_t footprint_limit; /* zero means no limit */
1181 MLOCK_T mutex; /* locate lock among fields that rarely change */
1182 #endif /* USE_LOCKS */
1184 void* extp; /* Unused but available for extensions */
1188 typedef struct malloc_state* mstate;
1190 /* ------------- Global malloc_state and malloc_params ------------------- */
1193 malloc_params holds global properties, including those that can be
1194 dynamically set using mallopt. There is a single instance, mparams,
1195 initialized in init_mparams. Note that the non-zeroness of "magic"
1196 also serves as an initialization flag.
1199 struct malloc_params {
1203 size_t mmap_threshold;
1204 size_t trim_threshold;
1205 flag_t default_mflags;
1208 static struct malloc_params mparams;
1210 /* Ensure mparams initialized */
1211 #define ensure_initialization() (void)(mparams.magic != 0 || init_mparams())
1215 /* The global malloc_state used for all non-"mspace" calls */
1216 static struct malloc_state _gm_;
1218 #define is_global(M) ((M) == &_gm_)
1220 #endif /* !ONLY_MSPACES */
1222 #define is_initialized(M) ((M)->top != 0)
1224 /* -------------------------- system alloc setup ------------------------- */
1226 /* Operations on mflags */
1228 #define use_lock(M) ((M)->mflags & USE_LOCK_BIT)
1229 #define enable_lock(M) ((M)->mflags |= USE_LOCK_BIT)
1231 #define disable_lock(M) ((M)->mflags &= ~USE_LOCK_BIT)
1233 #define disable_lock(M)
1236 #define use_mmap(M) ((M)->mflags & USE_MMAP_BIT)
1237 #define enable_mmap(M) ((M)->mflags |= USE_MMAP_BIT)
1239 #define disable_mmap(M) ((M)->mflags &= ~USE_MMAP_BIT)
1241 #define disable_mmap(M)
1244 #define use_noncontiguous(M) ((M)->mflags & USE_NONCONTIGUOUS_BIT)
1245 #define disable_contiguous(M) ((M)->mflags |= USE_NONCONTIGUOUS_BIT)
1246 #define use_noexpand(M) ((M)->mflags & USE_NOEXPAND_BIT)
1247 #define disable_expand(M) ((M)->mflags |= USE_NOEXPAND_BIT)
1248 #define use_trace(M) ((M)->mflags & USE_TRACE_BIT)
1249 #define enable_trace(M) ((M)->mflags |= USE_TRACE_BIT)
1250 #define disable_trace(M) ((M)->mflags |= USE_TRACE_BIT)
1252 #define set_lock(M,L)\
1253 ((M)->mflags = (L)?\
1254 ((M)->mflags | USE_LOCK_BIT) :\
1255 ((M)->mflags & ~USE_LOCK_BIT))
1257 /* page-align a size */
1258 #define page_align(S)\
1259 (((S) + (mparams.page_size - SIZE_T_ONE)) & ~(mparams.page_size - SIZE_T_ONE))
1261 /* granularity-align a size */
1262 #define granularity_align(S)\
1263 (((S) + (mparams.granularity - SIZE_T_ONE))\
1264 & ~(mparams.granularity - SIZE_T_ONE))
1267 /* For mmap, use granularity alignment on windows, else page-align */
1269 #define mmap_align(S) granularity_align(S)
1271 #define mmap_align(S) page_align(S)
1274 /* For sys_alloc, enough padding to ensure can malloc request on success */
1275 #define SYS_ALLOC_PADDING (TOP_FOOT_SIZE + MALLOC_ALIGNMENT)
1277 #define is_page_aligned(S)\
1278 (((size_t)(S) & (mparams.page_size - SIZE_T_ONE)) == 0)
1279 #define is_granularity_aligned(S)\
1280 (((size_t)(S) & (mparams.granularity - SIZE_T_ONE)) == 0)
1282 /* True if segment S holds address A */
1283 #define segment_holds(S, A)\
1284 ((char*)(A) >= S->base && (char*)(A) < S->base + S->size)
1286 /* Return segment holding given address */
1287 static msegmentptr segment_holding(mstate m, char* addr) {
1288 msegmentptr sp = &m->seg;
1290 if (addr >= sp->base && addr < sp->base + sp->size)
1292 if ((sp = sp->next) == 0)
1297 /* Return true if segment contains a segment link */
1298 static int has_segment_link(mstate m, msegmentptr ss) {
1299 msegmentptr sp = &m->seg;
1301 if ((char*)sp >= ss->base && (char*)sp < ss->base + ss->size)
1303 if ((sp = sp->next) == 0)
1308 #ifndef MORECORE_CANNOT_TRIM
1309 #define should_trim(M,s) ((s) > (M)->trim_check)
1310 #else /* MORECORE_CANNOT_TRIM */
1311 #define should_trim(M,s) (0)
1312 #endif /* MORECORE_CANNOT_TRIM */
1315 TOP_FOOT_SIZE is padding at the end of a segment, including space
1316 that may be needed to place segment records and fenceposts when new
1317 noncontiguous segments are added.
1319 #define TOP_FOOT_SIZE\
1320 (align_offset(chunk2mem(0))+pad_request(sizeof(struct malloc_segment))+MIN_CHUNK_SIZE)
1323 /* ------------------------------- Hooks -------------------------------- */
1326 PREACTION should be defined to return 0 on success, and nonzero on
1327 failure. If you are not using locking, you can redefine these to do
1332 #define PREACTION(M) ((use_lock(M))? ACQUIRE_LOCK(&(M)->mutex) : 0)
1333 #define POSTACTION(M) { if (use_lock(M)) RELEASE_LOCK(&(M)->mutex); }
1334 #else /* USE_LOCKS */
1337 #define PREACTION(M) (0)
1338 #endif /* PREACTION */
1341 #define POSTACTION(M)
1342 #endif /* POSTACTION */
1344 #endif /* USE_LOCKS */
1347 CORRUPTION_ERROR_ACTION is triggered upon detected bad addresses.
1348 USAGE_ERROR_ACTION is triggered on detected bad frees and
1349 reallocs. The argument p is an address that might have triggered the
1350 fault. It is ignored by the two predefined actions, but might be
1351 useful in custom actions that try to help diagnose errors.
1354 #if PROCEED_ON_ERROR
1356 /* A count of the number of corruption errors causing resets */
1357 int malloc_corruption_error_count;
1359 /* default corruption action */
1360 static void reset_on_error(mstate m);
1362 #define CORRUPTION_ERROR_ACTION(m) reset_on_error(m)
1363 #define USAGE_ERROR_ACTION(m, p)
1365 #else /* PROCEED_ON_ERROR */
1367 #ifndef CORRUPTION_ERROR_ACTION
1368 #define CORRUPTION_ERROR_ACTION(m) DLM_ABORT
1369 #endif /* CORRUPTION_ERROR_ACTION */
1371 #ifndef USAGE_ERROR_ACTION
1372 #define USAGE_ERROR_ACTION(m,p) DLM_ABORT
1373 #endif /* USAGE_ERROR_ACTION */
1375 #endif /* PROCEED_ON_ERROR */
1378 /* -------------------------- Debugging setup ---------------------------- */
1382 #define check_free_chunk(M,P)
1383 #define check_inuse_chunk(M,P)
1384 #define check_malloced_chunk(M,P,N)
1385 #define check_mmapped_chunk(M,P)
1386 #define check_malloc_state(M)
1387 #define check_top_chunk(M,P)
1390 #define check_free_chunk(M,P) do_check_free_chunk(M,P)
1391 #define check_inuse_chunk(M,P) do_check_inuse_chunk(M,P)
1392 #define check_top_chunk(M,P) do_check_top_chunk(M,P)
1393 #define check_malloced_chunk(M,P,N) do_check_malloced_chunk(M,P,N)
1394 #define check_mmapped_chunk(M,P) do_check_mmapped_chunk(M,P)
1395 #define check_malloc_state(M) do_check_malloc_state(M)
1397 static void do_check_any_chunk(mstate m, mchunkptr p);
1398 static void do_check_top_chunk(mstate m, mchunkptr p);
1399 static void do_check_mmapped_chunk(mstate m, mchunkptr p);
1400 static void do_check_inuse_chunk(mstate m, mchunkptr p);
1401 static void do_check_free_chunk(mstate m, mchunkptr p);
1402 static void do_check_malloced_chunk(mstate m, void* mem, size_t s);
1403 static void do_check_tree(mstate m, tchunkptr t);
1404 static void do_check_treebin(mstate m, bindex_t i);
1405 static void do_check_smallbin(mstate m, bindex_t i);
1406 static void do_check_malloc_state(mstate m);
1407 static int bin_find(mstate m, mchunkptr x);
1408 static size_t traverse_and_check(mstate m);
1411 /* ---------------------------- Indexing Bins ---------------------------- */
1413 #define is_small(s) (((s) >> SMALLBIN_SHIFT) < NSMALLBINS)
1414 #define small_index(s) (bindex_t)((s) >> SMALLBIN_SHIFT)
1415 #define small_index2size(i) ((i) << SMALLBIN_SHIFT)
1416 #define MIN_SMALL_INDEX (small_index(MIN_CHUNK_SIZE))
1418 /* addressing by index. See above about smallbin repositioning */
1419 #define smallbin_at(M, i) ((sbinptr)((char*)&((M)->smallbins[(i)<<1])))
1420 #define treebin_at(M,i) (&((M)->treebins[i]))
1422 /* assign tree index for size S to variable I. Use x86 asm if possible */
1423 #if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
1424 #define compute_tree_index(S, I)\
1426 unsigned int X = S >> TREEBIN_SHIFT;\
1429 else if (X > 0xFFFF)\
1432 unsigned int K = (unsigned) sizeof(X)*__CHAR_BIT__ - 1 - (unsigned) __builtin_clz(X); \
1433 I = (bindex_t)((K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1)));\
1437 #elif defined (__INTEL_COMPILER)
1438 #define compute_tree_index(S, I)\
1440 size_t X = S >> TREEBIN_SHIFT;\
1443 else if (X > 0xFFFF)\
1446 unsigned int K = _bit_scan_reverse (X); \
1447 I = (bindex_t)((K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1)));\
1451 #elif defined(_MSC_VER) && _MSC_VER>=1300
1452 #define compute_tree_index(S, I)\
1454 size_t X = S >> TREEBIN_SHIFT;\
1457 else if (X > 0xFFFF)\
1461 _BitScanReverse((DWORD *) &K, (DWORD) X);\
1462 I = (bindex_t)((K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1)));\
1467 #define compute_tree_index(S, I)\
1469 size_t X = S >> TREEBIN_SHIFT;\
1472 else if (X > 0xFFFF)\
1475 unsigned int Y = (unsigned int)X;\
1476 unsigned int N = ((Y - 0x100) >> 16) & 8;\
1477 unsigned int K = (((Y <<= N) - 0x1000) >> 16) & 4;\
1479 N += K = (((Y <<= K) - 0x4000) >> 16) & 2;\
1480 K = 14 - N + ((Y <<= K) >> 15);\
1481 I = (K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1));\
1486 /* Bit representing maximum resolved size in a treebin at i */
1487 #define bit_for_tree_index(i) \
1488 (i == NTREEBINS-1)? (SIZE_T_BITSIZE-1) : (((i) >> 1) + TREEBIN_SHIFT - 2)
1490 /* Shift placing maximum resolved bit in a treebin at i as sign bit */
1491 #define leftshift_for_tree_index(i) \
1492 ((i == NTREEBINS-1)? 0 : \
1493 ((SIZE_T_BITSIZE-SIZE_T_ONE) - (((i) >> 1) + TREEBIN_SHIFT - 2)))
1495 /* The size of the smallest chunk held in bin with index i */
1496 #define minsize_for_tree_index(i) \
1497 ((SIZE_T_ONE << (((i) >> 1) + TREEBIN_SHIFT)) | \
1498 (((size_t)((i) & SIZE_T_ONE)) << (((i) >> 1) + TREEBIN_SHIFT - 1)))
1501 /* ------------------------ Operations on bin maps ----------------------- */
1503 /* bit corresponding to given index */
1504 #define idx2bit(i) ((binmap_t)(1) << (i))
1506 /* Mark/Clear bits with given index */
1507 #define mark_smallmap(M,i) ((M)->smallmap |= idx2bit(i))
1508 #define clear_smallmap(M,i) ((M)->smallmap &= ~idx2bit(i))
1509 #define smallmap_is_marked(M,i) ((M)->smallmap & idx2bit(i))
1511 #define mark_treemap(M,i) ((M)->treemap |= idx2bit(i))
1512 #define clear_treemap(M,i) ((M)->treemap &= ~idx2bit(i))
1513 #define treemap_is_marked(M,i) ((M)->treemap & idx2bit(i))
1515 /* isolate the least set bit of a bitmap */
1516 #define least_bit(x) ((x) & -(x))
1518 /* mask with all bits to left of least bit of x on */
1519 #define left_bits(x) ((x<<1) | -(x<<1))
1521 /* mask with all bits to left of or equal to least bit of x on */
1522 #define same_or_left_bits(x) ((x) | -(x))
1524 /* index corresponding to given bit. Use x86 asm if possible */
1526 #if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
1527 #define compute_bit2idx(X, I)\
1530 J = __builtin_ctz(X); \
1534 #elif defined (__INTEL_COMPILER)
1535 #define compute_bit2idx(X, I)\
1538 J = _bit_scan_forward (X); \
1542 #elif defined(_MSC_VER) && _MSC_VER>=1300
1543 #define compute_bit2idx(X, I)\
1546 _BitScanForward((DWORD *) &J, X);\
1550 #elif USE_BUILTIN_FFS
1551 #define compute_bit2idx(X, I) I = ffs(X)-1
1554 #define compute_bit2idx(X, I)\
1556 unsigned int Y = X - 1;\
1557 unsigned int K = Y >> (16-4) & 16;\
1558 unsigned int N = K; Y >>= K;\
1559 N += K = Y >> (8-3) & 8; Y >>= K;\
1560 N += K = Y >> (4-2) & 4; Y >>= K;\
1561 N += K = Y >> (2-1) & 2; Y >>= K;\
1562 N += K = Y >> (1-0) & 1; Y >>= K;\
1563 I = (bindex_t)(N + Y);\
1568 /* ----------------------- Runtime Check Support ------------------------- */
1571 For security, the main invariant is that malloc/free/etc never
1572 writes to a static address other than malloc_state, unless static
1573 malloc_state itself has been corrupted, which cannot occur via
1574 malloc (because of these checks). In essence this means that we
1575 believe all pointers, sizes, maps etc held in malloc_state, but
1576 check all of those linked or offsetted from other embedded data
1577 structures. These checks are interspersed with main code in a way
1578 that tends to minimize their run-time cost.
1580 When FOOTERS is defined, in addition to range checking, we also
1581 verify footer fields of inuse chunks, which can be used guarantee
1582 that the mstate controlling malloc/free is intact. This is a
1583 streamlined version of the approach described by William Robertson
1584 et al in "Run-time Detection of Heap-based Overflows" LISA'03
1585 http://www.usenix.org/events/lisa03/tech/robertson.html The footer
1586 of an inuse chunk holds the xor of its mstate and a random seed,
1587 that is checked upon calls to free() and realloc(). This is
1588 (probabalistically) unguessable from outside the program, but can be
1589 computed by any code successfully malloc'ing any chunk, so does not
1590 itself provide protection against code that has already broken
1591 security through some other means. Unlike Robertson et al, we
1592 always dynamically check addresses of all offset chunks (previous,
1593 next, etc). This turns out to be cheaper than relying on hashes.
1597 /* Check if address a is at least as high as any from MORECORE or MMAP */
1598 #define ok_address(M, a) ((char*)(a) >= (M)->least_addr)
1599 /* Check if address of next chunk n is higher than base chunk p */
1600 #define ok_next(p, n) ((char*)(p) < (char*)(n))
1601 /* Check if p has inuse status */
1602 #define ok_inuse(p) is_inuse(p)
1603 /* Check if p has its pinuse bit on */
1604 #define ok_pinuse(p) pinuse(p)
1606 #else /* !INSECURE */
1607 #define ok_address(M, a) (1)
1608 #define ok_next(b, n) (1)
1609 #define ok_inuse(p) (1)
1610 #define ok_pinuse(p) (1)
1611 #endif /* !INSECURE */
1613 #if (FOOTERS && !INSECURE)
1614 /* Check if (alleged) mstate m has expected magic field */
1615 #define ok_magic(M) ((M)->magic == mparams.magic)
1616 #else /* (FOOTERS && !INSECURE) */
1617 #define ok_magic(M) (1)
1618 #endif /* (FOOTERS && !INSECURE) */
1620 /* In gcc, use __builtin_expect to minimize impact of checks */
1622 #if defined(__GNUC__) && __GNUC__ >= 3
1623 #define RTCHECK(e) __builtin_expect(e, 1)
1625 #define RTCHECK(e) (e)
1627 #else /* !INSECURE */
1628 #define RTCHECK(e) (1)
1629 #endif /* !INSECURE */
1631 /* macros to set up inuse chunks with or without footers */
1635 #define mark_inuse_foot(M,p,s)
1637 /* Macros for setting head/foot of non-mmapped chunks */
1639 /* Set cinuse bit and pinuse bit of next chunk */
1640 #define set_inuse(M,p,s)\
1641 ((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\
1642 ((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT)
1644 /* Set cinuse and pinuse of this chunk and pinuse of next chunk */
1645 #define set_inuse_and_pinuse(M,p,s)\
1646 ((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
1647 ((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT)
1649 /* Set size, cinuse and pinuse bit of this chunk */
1650 #define set_size_and_pinuse_of_inuse_chunk(M, p, s)\
1651 ((p)->head = (s|PINUSE_BIT|CINUSE_BIT))
1655 /* Set foot of inuse chunk to be xor of mstate and seed */
1656 #define mark_inuse_foot(M,p,s)\
1657 (((mchunkptr)((char*)(p) + (s)))->prev_foot = ((size_t)(M) ^ mparams.magic))
1659 #define get_mstate_for(p)\
1660 ((mstate)(((mchunkptr)((char*)(p) +\
1661 (chunksize(p))))->prev_foot ^ mparams.magic))
1663 #define set_inuse(M,p,s)\
1664 ((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\
1665 (((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT), \
1666 mark_inuse_foot(M,p,s))
1668 #define set_inuse_and_pinuse(M,p,s)\
1669 ((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
1670 (((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT),\
1671 mark_inuse_foot(M,p,s))
1673 #define set_size_and_pinuse_of_inuse_chunk(M, p, s)\
1674 ((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
1675 mark_inuse_foot(M, p, s))
1677 #endif /* !FOOTERS */
1679 /* ---------------------------- setting mparams -------------------------- */
1682 static void pre_fork(void) { ACQUIRE_LOCK(&(gm)->mutex); }
1683 static void post_fork_parent(void) { RELEASE_LOCK(&(gm)->mutex); }
1684 static void post_fork_child(void) { INITIAL_LOCK(&(gm)->mutex); }
1685 #endif /* LOCK_AT_FORK */
1687 /* Initialize mparams */
1688 static int init_mparams(void) {
1689 #ifdef NEED_GLOBAL_LOCK_INIT
1690 if (malloc_global_mutex_status <= 0)
1691 init_malloc_global_mutex();
1694 ACQUIRE_MALLOC_GLOBAL_LOCK();
1695 if (mparams.magic == 0) {
1701 psize = malloc_getpagesize;
1702 gsize = ((DEFAULT_GRANULARITY != 0)? DEFAULT_GRANULARITY : psize);
1705 SYSTEM_INFO system_info;
1706 GetSystemInfo(&system_info);
1707 psize = system_info.dwPageSize;
1708 gsize = ((DEFAULT_GRANULARITY != 0)?
1709 DEFAULT_GRANULARITY : system_info.dwAllocationGranularity);
1713 /* Sanity-check configuration:
1714 size_t must be unsigned and as wide as pointer type.
1715 ints must be at least 4 bytes.
1716 alignment must be at least 8.
1717 Alignment, min chunk size, and page size must all be powers of 2.
1719 if ((sizeof(size_t) != sizeof(char*)) ||
1720 (MAX_SIZE_T < MIN_CHUNK_SIZE) ||
1721 (sizeof(int) < 4) ||
1722 (MALLOC_ALIGNMENT < (size_t)8U) ||
1723 ((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-SIZE_T_ONE)) != 0) ||
1724 ((MCHUNK_SIZE & (MCHUNK_SIZE-SIZE_T_ONE)) != 0) ||
1725 ((gsize & (gsize-SIZE_T_ONE)) != 0) ||
1726 ((psize & (psize-SIZE_T_ONE)) != 0))
1728 mparams.granularity = gsize;
1729 mparams.page_size = psize;
1730 mparams.mmap_threshold = DEFAULT_MMAP_THRESHOLD;
1731 mparams.trim_threshold = DEFAULT_TRIM_THRESHOLD;
1732 #if MORECORE_CONTIGUOUS
1733 mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT;
1734 #else /* MORECORE_CONTIGUOUS */
1735 mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT|USE_NONCONTIGUOUS_BIT;
1736 #endif /* MORECORE_CONTIGUOUS */
1739 /* Set up lock for main malloc area */
1740 gm->mflags = mparams.default_mflags;
1741 (void)INITIAL_LOCK(&gm->mutex);
1744 pthread_atfork(&pre_fork, &post_fork_parent, &post_fork_child);
1748 #ifndef DLM_MAGIC_CONSTANT
1751 unsigned char buf[sizeof(size_t)];
1752 /* Try to use /dev/urandom, else fall back on using time */
1753 if ((fd = open("/dev/urandom", O_RDONLY)) >= 0 &&
1754 read(fd, buf, sizeof(buf)) == sizeof(buf)) {
1755 magic = *((size_t *) buf);
1759 #endif /* USE_DEV_RANDOM */
1761 magic = (size_t)(GetTickCount() ^ (size_t)0x55555555U);
1762 #elif defined(LACKS_TIME_H)
1763 magic = (size_t)&magic ^ (size_t)0x55555555U;
1765 magic = (size_t)(time(0) ^ (size_t)0x55555555U);
1767 magic |= (size_t)8U; /* ensure nonzero */
1768 magic &= ~(size_t)7U; /* improve chances of fault for bad values */
1770 magic = DLM_MAGIC_CONSTANT;
1772 /* Until memory modes commonly available, use volatile-write */
1773 (*(volatile size_t *)(&(mparams.magic))) = magic;
1777 RELEASE_MALLOC_GLOBAL_LOCK();
1781 /* support for mallopt */
1782 static int change_mparam(int param_number, int value) {
1784 ensure_initialization();
1785 val = (value == -1)? MAX_SIZE_T : (size_t)value;
1786 switch(param_number) {
1787 case M_TRIM_THRESHOLD:
1788 mparams.trim_threshold = val;
1791 if (val >= mparams.page_size && ((val & (val-1)) == 0)) {
1792 mparams.granularity = val;
1797 case M_MMAP_THRESHOLD:
1798 mparams.mmap_threshold = val;
1806 /* ------------------------- Debugging Support --------------------------- */
1808 /* Check properties of any chunk, whether free, inuse, mmapped etc */
1809 static void do_check_any_chunk(mstate m, mchunkptr p) {
1810 assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
1811 assert(ok_address(m, p));
1814 /* Check properties of top chunk */
1815 static void do_check_top_chunk(mstate m, mchunkptr p) {
1816 msegmentptr sp = segment_holding(m, (char*)p);
1817 size_t sz = p->head & ~INUSE_BITS; /* third-lowest bit can be set! */
1819 assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
1820 assert(ok_address(m, p));
1821 assert(sz == m->topsize);
1823 assert(sz == ((sp->base + sp->size) - (char*)p) - TOP_FOOT_SIZE);
1825 assert(!pinuse(chunk_plus_offset(p, sz)));
1828 /* Check properties of (inuse) mmapped chunks */
1829 static void do_check_mmapped_chunk(mstate m, mchunkptr p) {
1830 size_t sz = chunksize(p);
1831 size_t len = (sz + (p->prev_foot) + MMAP_FOOT_PAD);
1832 assert(is_mmapped(p));
1833 assert(use_mmap(m));
1834 assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
1835 assert(ok_address(m, p));
1836 assert(!is_small(sz));
1837 assert((len & (mparams.page_size-SIZE_T_ONE)) == 0);
1838 assert(chunk_plus_offset(p, sz)->head == FENCEPOST_HEAD);
1839 assert(chunk_plus_offset(p, sz+SIZE_T_SIZE)->head == 0);
1842 /* Check properties of inuse chunks */
1843 static void do_check_inuse_chunk(mstate m, mchunkptr p) {
1844 do_check_any_chunk(m, p);
1845 assert(is_inuse(p));
1846 assert(next_pinuse(p));
1847 /* If not pinuse and not mmapped, previous chunk has OK offset */
1848 assert(is_mmapped(p) || pinuse(p) || next_chunk(prev_chunk(p)) == p);
1850 do_check_mmapped_chunk(m, p);
1853 /* Check properties of free chunks */
1854 static void do_check_free_chunk(mstate m, mchunkptr p) {
1855 size_t sz = chunksize(p);
1856 mchunkptr next = chunk_plus_offset(p, sz);
1857 do_check_any_chunk(m, p);
1858 assert(!is_inuse(p));
1859 assert(!next_pinuse(p));
1860 assert (!is_mmapped(p));
1861 if (p != m->dv && p != m->top) {
1862 if (sz >= MIN_CHUNK_SIZE) {
1863 assert((sz & CHUNK_ALIGN_MASK) == 0);
1864 assert(is_aligned(chunk2mem(p)));
1865 assert(next->prev_foot == sz);
1867 assert (next == m->top || is_inuse(next));
1868 assert(p->fd->bk == p);
1869 assert(p->bk->fd == p);
1871 else /* markers are always of size SIZE_T_SIZE */
1872 assert(sz == SIZE_T_SIZE);
1876 /* Check properties of malloced chunks at the point they are malloced */
1877 static void do_check_malloced_chunk(mstate m, void* mem, size_t s) {
1879 mchunkptr p = mem2chunk(mem);
1880 size_t sz = p->head & ~INUSE_BITS;
1881 do_check_inuse_chunk(m, p);
1882 assert((sz & CHUNK_ALIGN_MASK) == 0);
1883 assert(sz >= MIN_CHUNK_SIZE);
1885 /* unless mmapped, size is less than MIN_CHUNK_SIZE more than request */
1886 assert(is_mmapped(p) || sz < (s + MIN_CHUNK_SIZE));
1890 /* Check a tree and its subtrees. */
1891 static void do_check_tree(mstate m, tchunkptr t) {
1894 bindex_t tindex = t->index;
1895 size_t tsize = chunksize(t);
1897 compute_tree_index(tsize, idx);
1898 assert(tindex == idx);
1899 assert(tsize >= MIN_LARGE_SIZE);
1900 assert(tsize >= minsize_for_tree_index(idx));
1901 assert((idx == NTREEBINS-1) || (tsize < minsize_for_tree_index((idx+1))));
1903 do { /* traverse through chain of same-sized nodes */
1904 do_check_any_chunk(m, ((mchunkptr)u));
1905 assert(u->index == tindex);
1906 assert(chunksize(u) == tsize);
1907 assert(!is_inuse(u));
1908 assert(!next_pinuse(u));
1909 assert(u->fd->bk == u);
1910 assert(u->bk->fd == u);
1911 if (u->parent == 0) {
1912 assert(u->child[0] == 0);
1913 assert(u->child[1] == 0);
1916 assert(head == 0); /* only one node on chain has parent */
1918 assert(u->parent != u);
1919 assert (u->parent->child[0] == u ||
1920 u->parent->child[1] == u ||
1921 *((tbinptr*)(u->parent)) == u);
1922 if (u->child[0] != 0) {
1923 assert(u->child[0]->parent == u);
1924 assert(u->child[0] != u);
1925 do_check_tree(m, u->child[0]);
1927 if (u->child[1] != 0) {
1928 assert(u->child[1]->parent == u);
1929 assert(u->child[1] != u);
1930 do_check_tree(m, u->child[1]);
1932 if (u->child[0] != 0 && u->child[1] != 0) {
1933 assert(chunksize(u->child[0]) < chunksize(u->child[1]));
1941 /* Check all the chunks in a treebin. */
1942 static void do_check_treebin(mstate m, bindex_t i) {
1943 tbinptr* tb = treebin_at(m, i);
1945 int empty = (m->treemap & (1U << i)) == 0;
1949 do_check_tree(m, t);
1952 /* Check all the chunks in a smallbin. */
1953 static void do_check_smallbin(mstate m, bindex_t i) {
1954 sbinptr b = smallbin_at(m, i);
1955 mchunkptr p = b->bk;
1956 unsigned int empty = (m->smallmap & (1U << i)) == 0;
1960 for (; p != b; p = p->bk) {
1961 size_t size = chunksize(p);
1963 /* each chunk claims to be free */
1964 do_check_free_chunk(m, p);
1965 /* chunk belongs in bin */
1966 assert(small_index(size) == i);
1967 assert(p->bk == b || chunksize(p->bk) == chunksize(p));
1968 /* chunk is followed by an inuse chunk */
1970 if (q->head != FENCEPOST_HEAD)
1971 do_check_inuse_chunk(m, q);
1976 /* Find x in a bin. Used in other check functions. */
1977 static int bin_find(mstate m, mchunkptr x) {
1978 size_t size = chunksize(x);
1979 if (is_small(size)) {
1980 bindex_t sidx = small_index(size);
1981 sbinptr b = smallbin_at(m, sidx);
1982 if (smallmap_is_marked(m, sidx)) {
1987 } while ((p = p->fd) != b);
1992 compute_tree_index(size, tidx);
1993 if (treemap_is_marked(m, tidx)) {
1994 tchunkptr t = *treebin_at(m, tidx);
1995 size_t sizebits = size << leftshift_for_tree_index(tidx);
1996 while (t != 0 && chunksize(t) != size) {
1997 t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1];
2003 if (u == (tchunkptr)x)
2005 } while ((u = u->fd) != t);
2012 /* Traverse each chunk and check it; return total */
2013 static size_t traverse_and_check(mstate m) {
2015 if (is_initialized(m)) {
2016 msegmentptr s = &m->seg;
2017 sum += m->topsize + TOP_FOOT_SIZE;
2019 mchunkptr q = align_as_chunk(s->base);
2020 mchunkptr lastq = 0;
2022 while (segment_holds(s, q) &&
2023 q != m->top && q->head != FENCEPOST_HEAD) {
2024 sum += chunksize(q);
2026 assert(!bin_find(m, q));
2027 do_check_inuse_chunk(m, q);
2030 assert(q == m->dv || bin_find(m, q));
2031 assert(lastq == 0 || is_inuse(lastq)); /* Not 2 consecutive free */
2032 do_check_free_chunk(m, q);
2044 /* Check all properties of malloc_state. */
2045 static void do_check_malloc_state(mstate m) {
2049 for (i = 0; i < NSMALLBINS; ++i)
2050 do_check_smallbin(m, i);
2051 for (i = 0; i < NTREEBINS; ++i)
2052 do_check_treebin(m, i);
2054 if (m->dvsize != 0) { /* check dv chunk */
2055 do_check_any_chunk(m, m->dv);
2056 assert(m->dvsize == chunksize(m->dv));
2057 assert(m->dvsize >= MIN_CHUNK_SIZE);
2058 assert(bin_find(m, m->dv) == 0);
2061 if (m->top != 0) { /* check top chunk */
2062 do_check_top_chunk(m, m->top);
2063 /*assert(m->topsize == chunksize(m->top)); redundant */
2064 assert(m->topsize > 0);
2065 assert(bin_find(m, m->top) == 0);
2068 total = traverse_and_check(m);
2069 assert(total <= m->footprint);
2070 assert(m->footprint <= m->max_footprint);
2074 /* ----------------------------- statistics ------------------------------ */
2077 static struct mallinfo internal_mallinfo(mstate m) {
2078 struct mallinfo nm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
2079 ensure_initialization();
2080 if (!PREACTION(m)) {
2081 check_malloc_state(m);
2082 if (is_initialized(m)) {
2083 size_t nfree = SIZE_T_ONE; /* top always free */
2084 size_t mfree = m->topsize + TOP_FOOT_SIZE;
2086 msegmentptr s = &m->seg;
2088 mchunkptr q = align_as_chunk(s->base);
2089 while (segment_holds(s, q) &&
2090 q != m->top && q->head != FENCEPOST_HEAD) {
2091 size_t sz = chunksize(q);
2104 nm.hblkhd = m->footprint - sum;
2105 nm.usmblks = m->max_footprint;
2106 nm.uordblks = m->footprint - mfree;
2107 nm.fordblks = mfree;
2108 nm.keepcost = m->topsize;
2115 #endif /* !NO_MALLINFO */
2117 #if !NO_MALLOC_STATS
2118 static void internal_malloc_stats(mstate m) {
2119 ensure_initialization();
2120 if (!PREACTION(m)) {
2124 check_malloc_state(m);
2125 if (is_initialized(m)) {
2126 msegmentptr s = &m->seg;
2127 maxfp = m->max_footprint;
2129 used = fp - (m->topsize + TOP_FOOT_SIZE);
2132 mchunkptr q = align_as_chunk(s->base);
2133 while (segment_holds(s, q) &&
2134 q != m->top && q->head != FENCEPOST_HEAD) {
2136 used -= chunksize(q);
2142 POSTACTION(m); /* drop lock */
2143 fprintf(stderr, "max system bytes = %10lu\n", (unsigned long)(maxfp));
2144 fprintf(stderr, "system bytes = %10lu\n", (unsigned long)(fp));
2145 fprintf(stderr, "in use bytes = %10lu\n", (unsigned long)(used));
2148 #endif /* NO_MALLOC_STATS */
2150 /* ----------------------- Operations on smallbins ----------------------- */
2153 Various forms of linking and unlinking are defined as macros. Even
2154 the ones for trees, which are very long but have very short typical
2155 paths. This is ugly but reduces reliance on inlining support of
2159 /* Link a free chunk into a smallbin */
2160 #define insert_small_chunk(M, P, S) {\
2161 bindex_t I = small_index(S);\
2162 mchunkptr B = smallbin_at(M, I);\
2164 assert(S >= MIN_CHUNK_SIZE);\
2165 if (!smallmap_is_marked(M, I))\
2166 mark_smallmap(M, I);\
2167 else if (RTCHECK(ok_address(M, B->fd)))\
2170 CORRUPTION_ERROR_ACTION(M);\
2178 /* Unlink a chunk from a smallbin */
2179 #define unlink_small_chunk(M, P, S) {\
2180 mchunkptr F = P->fd;\
2181 mchunkptr B = P->bk;\
2182 bindex_t I = small_index(S);\
2185 assert(chunksize(P) == small_index2size(I));\
2186 if (RTCHECK(F == smallbin_at(M,I) || (ok_address(M, F) && F->bk == P))) { \
2188 clear_smallmap(M, I);\
2190 else if (RTCHECK(B == smallbin_at(M,I) ||\
2191 (ok_address(M, B) && B->fd == P))) {\
2196 CORRUPTION_ERROR_ACTION(M);\
2200 CORRUPTION_ERROR_ACTION(M);\
2204 /* Unlink the first chunk from a smallbin */
2205 #define unlink_first_small_chunk(M, B, P, I) {\
2206 mchunkptr F = P->fd;\
2209 assert(chunksize(P) == small_index2size(I));\
2211 clear_smallmap(M, I);\
2213 else if (RTCHECK(ok_address(M, F) && F->bk == P)) {\
2218 CORRUPTION_ERROR_ACTION(M);\
2222 /* Replace dv node, binning the old one */
2223 /* Used only when dvsize known to be small */
2224 #define replace_dv(M, P, S) {\
2225 size_t DVS = M->dvsize;\
2226 assert(is_small(DVS));\
2228 mchunkptr DV = M->dv;\
2229 insert_small_chunk(M, DV, DVS);\
2235 /* ------------------------- Operations on trees ------------------------- */
2237 /* Insert chunk into tree */
2238 #define insert_large_chunk(M, X, S) {\
2241 compute_tree_index(S, I);\
2242 H = treebin_at(M, I);\
2244 X->child[0] = X->child[1] = 0;\
2245 if (!treemap_is_marked(M, I)) {\
2246 mark_treemap(M, I);\
2248 X->parent = (tchunkptr)H;\
2253 size_t K = S << leftshift_for_tree_index(I);\
2255 if (chunksize(T) != S) {\
2256 tchunkptr* C = &(T->child[(K >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]);\
2260 else if (RTCHECK(ok_address(M, C))) {\
2267 CORRUPTION_ERROR_ACTION(M);\
2272 tchunkptr F = T->fd;\
2273 if (RTCHECK(ok_address(M, T) && ok_address(M, F))) {\
2281 CORRUPTION_ERROR_ACTION(M);\
2292 1. If x is a chained node, unlink it from its same-sized fd/bk links
2293 and choose its bk node as its replacement.
2294 2. If x was the last node of its size, but not a leaf node, it must
2295 be replaced with a leaf node (not merely one with an open left or
2296 right), to make sure that lefts and rights of descendents
2297 correspond properly to bit masks. We use the rightmost descendent
2298 of x. We could use any other leaf, but this is easy to locate and
2299 tends to counteract removal of leftmosts elsewhere, and so keeps
2300 paths shorter than minimally guaranteed. This doesn't loop much
2301 because on average a node in a tree is near the bottom.
2302 3. If x is the base of a chain (i.e., has parent links) relink
2303 x's parent and children to x's replacement (or null if none).
2306 #define unlink_large_chunk(M, X) {\
2307 tchunkptr XP = X->parent;\
2310 tchunkptr F = X->fd;\
2312 if (RTCHECK(ok_address(M, F) && F->bk == X && R->fd == X)) {\
2317 CORRUPTION_ERROR_ACTION(M);\
2322 if (((R = *(RP = &(X->child[1]))) != 0) ||\
2323 ((R = *(RP = &(X->child[0]))) != 0)) {\
2325 while ((*(CP = &(R->child[1])) != 0) ||\
2326 (*(CP = &(R->child[0])) != 0)) {\
2329 if (RTCHECK(ok_address(M, RP)))\
2332 CORRUPTION_ERROR_ACTION(M);\
2337 tbinptr* H = treebin_at(M, X->index);\
2339 if ((*H = R) == 0) \
2340 clear_treemap(M, X->index);\
2342 else if (RTCHECK(ok_address(M, XP))) {\
2343 if (XP->child[0] == X) \
2349 CORRUPTION_ERROR_ACTION(M);\
2351 if (RTCHECK(ok_address(M, R))) {\
2354 if ((C0 = X->child[0]) != 0) {\
2355 if (RTCHECK(ok_address(M, C0))) {\
2360 CORRUPTION_ERROR_ACTION(M);\
2362 if ((C1 = X->child[1]) != 0) {\
2363 if (RTCHECK(ok_address(M, C1))) {\
2368 CORRUPTION_ERROR_ACTION(M);\
2372 CORRUPTION_ERROR_ACTION(M);\
2377 /* Relays to large vs small bin operations */
2379 #define insert_chunk(M, P, S)\
2380 if (is_small(S)) insert_small_chunk(M, P, S)\
2381 else { tchunkptr TP = (tchunkptr)(P); insert_large_chunk(M, TP, S); }
2383 #define unlink_chunk(M, P, S)\
2384 if (is_small(S)) unlink_small_chunk(M, P, S)\
2385 else { tchunkptr TP = (tchunkptr)(P); unlink_large_chunk(M, TP); }
2388 /* Relays to internal calls to malloc/free from realloc, memalign etc */
2391 #define internal_malloc(m, b) mspace_malloc(m, b)
2392 #define internal_free(m, mem) mspace_free(m,mem);
2393 #else /* ONLY_MSPACES */
2395 #define internal_malloc(m, b)\
2396 ((m == gm)? dlmalloc(b) : mspace_malloc(m, b))
2397 #define internal_free(m, mem)\
2398 if (m == gm) dlfree(mem); else mspace_free(m,mem);
2400 #define internal_malloc(m, b) dlmalloc(b)
2401 #define internal_free(m, mem) dlfree(mem)
2402 #endif /* MSPACES */
2403 #endif /* ONLY_MSPACES */
2405 /* ----------------------- Direct-mmapping chunks ----------------------- */
2408 Directly mmapped chunks are set up with an offset to the start of
2409 the mmapped region stored in the prev_foot field of the chunk. This
2410 allows reconstruction of the required argument to MUNMAP when freed,
2411 and also allows adjustment of the returned chunk to meet alignment
2412 requirements (especially in memalign).
2415 /* Malloc using mmap */
2416 static void* mmap_alloc(mstate m, size_t nb) {
2417 size_t mmsize = mmap_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
2418 if (m->footprint_limit != 0) {
2419 size_t fp = m->footprint + mmsize;
2420 if (fp <= m->footprint || fp > m->footprint_limit)
2423 if (mmsize > nb) { /* Check for wrap around 0 */
2424 char* mm = (char*)(CALL_DIRECT_MMAP(mmsize));
2426 size_t offset = align_offset(chunk2mem(mm));
2427 size_t psize = mmsize - offset - MMAP_FOOT_PAD;
2428 mchunkptr p = (mchunkptr)(mm + offset);
2429 p->prev_foot = offset;
2431 mark_inuse_foot(m, p, psize);
2432 chunk_plus_offset(p, psize)->head = FENCEPOST_HEAD;
2433 chunk_plus_offset(p, psize+SIZE_T_SIZE)->head = 0;
2435 if (m->least_addr == 0 || mm < m->least_addr)
2437 if ((m->footprint += mmsize) > m->max_footprint)
2438 m->max_footprint = m->footprint;
2439 assert(is_aligned(chunk2mem(p)));
2440 check_mmapped_chunk(m, p);
2441 return chunk2mem(p);
2447 /* Realloc using mmap */
2448 static mchunkptr mmap_resize(mstate m, mchunkptr oldp, size_t nb, int flags) {
2449 size_t oldsize = chunksize(oldp);
2450 (void)flags; /* placate people compiling -Wunused */
2451 if (is_small(nb)) /* Can't shrink mmap regions below small size */
2453 /* Keep old chunk if big enough but not too big */
2454 if (oldsize >= nb + SIZE_T_SIZE &&
2455 (oldsize - nb) <= (mparams.granularity << 1))
2458 size_t offset = oldp->prev_foot;
2459 size_t oldmmsize = oldsize + offset + MMAP_FOOT_PAD;
2460 size_t newmmsize = mmap_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
2461 char* cp = (char*)CALL_MREMAP((char*)oldp - offset,
2462 oldmmsize, newmmsize, flags);
2464 mchunkptr newp = (mchunkptr)(cp + offset);
2465 size_t psize = newmmsize - offset - MMAP_FOOT_PAD;
2467 mark_inuse_foot(m, newp, psize);
2468 chunk_plus_offset(newp, psize)->head = FENCEPOST_HEAD;
2469 chunk_plus_offset(newp, psize+SIZE_T_SIZE)->head = 0;
2471 if (cp < m->least_addr)
2473 if ((m->footprint += newmmsize - oldmmsize) > m->max_footprint)
2474 m->max_footprint = m->footprint;
2475 check_mmapped_chunk(m, newp);
2483 /* -------------------------- mspace management -------------------------- */
2485 /* Initialize top chunk and its size */
2486 static void init_top(mstate m, mchunkptr p, size_t psize) {
2487 /* Ensure alignment */
2488 size_t offset = align_offset(chunk2mem(p));
2489 p = (mchunkptr)((char*)p + offset);
2494 p->head = psize | PINUSE_BIT;
2495 /* set size of fake trailing chunk holding overhead space only once */
2496 chunk_plus_offset(p, psize)->head = TOP_FOOT_SIZE;
2497 m->trim_check = mparams.trim_threshold; /* reset on each update */
2500 /* Initialize bins for a new mstate that is otherwise zeroed out */
2501 static void init_bins(mstate m) {
2502 /* Establish circular links for smallbins */
2504 for (i = 0; i < NSMALLBINS; ++i) {
2505 sbinptr bin = smallbin_at(m,i);
2506 bin->fd = bin->bk = bin;
2510 #if PROCEED_ON_ERROR
2512 /* default corruption action */
2513 static void reset_on_error(mstate m) {
2515 ++malloc_corruption_error_count;
2516 /* Reinitialize fields to forget about all memory */
2517 m->smallmap = m->treemap = 0;
2518 m->dvsize = m->topsize = 0;
2523 for (i = 0; i < NTREEBINS; ++i)
2524 *treebin_at(m, i) = 0;
2527 #endif /* PROCEED_ON_ERROR */
2529 /* Allocate chunk and prepend remainder with chunk in successor base. */
2530 static void* prepend_alloc(mstate m, char* newbase, char* oldbase,
2532 mchunkptr p = align_as_chunk(newbase);
2533 mchunkptr oldfirst = align_as_chunk(oldbase);
2534 size_t psize = (char*)oldfirst - (char*)p;
2535 mchunkptr q = chunk_plus_offset(p, nb);
2536 size_t qsize = psize - nb;
2537 set_size_and_pinuse_of_inuse_chunk(m, p, nb);
2539 assert((char*)oldfirst > (char*)q);
2540 assert(pinuse(oldfirst));
2541 assert(qsize >= MIN_CHUNK_SIZE);
2543 /* consolidate remainder with first chunk of old base */
2544 if (oldfirst == m->top) {
2545 size_t tsize = m->topsize += qsize;
2547 q->head = tsize | PINUSE_BIT;
2548 check_top_chunk(m, q);
2550 else if (oldfirst == m->dv) {
2551 size_t dsize = m->dvsize += qsize;
2553 set_size_and_pinuse_of_free_chunk(q, dsize);
2556 if (!is_inuse(oldfirst)) {
2557 size_t nsize = chunksize(oldfirst);
2558 unlink_chunk(m, oldfirst, nsize);
2559 oldfirst = chunk_plus_offset(oldfirst, nsize);
2562 set_free_with_pinuse(q, qsize, oldfirst);
2563 insert_chunk(m, q, qsize);
2564 check_free_chunk(m, q);
2567 check_malloced_chunk(m, chunk2mem(p), nb);
2568 return chunk2mem(p);
2571 /* Add a segment to hold a new noncontiguous region */
2572 static void add_segment(mstate m, char* tbase, size_t tsize, flag_t mmapped) {
2573 /* Determine locations and sizes of segment, fenceposts, old top */
2574 char* old_top = (char*)m->top;
2575 msegmentptr oldsp = segment_holding(m, old_top);
2576 char* old_end = oldsp->base + oldsp->size;
2577 size_t ssize = pad_request(sizeof(struct malloc_segment));
2578 char* rawsp = old_end - (ssize + FOUR_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
2579 size_t offset = align_offset(chunk2mem(rawsp));
2580 char* asp = rawsp + offset;
2581 char* csp = (asp < (old_top + MIN_CHUNK_SIZE))? old_top : asp;
2582 mchunkptr sp = (mchunkptr)csp;
2583 msegmentptr ss = (msegmentptr)(chunk2mem(sp));
2584 mchunkptr tnext = chunk_plus_offset(sp, ssize);
2585 mchunkptr p = tnext;
2588 /* reset top to new space */
2589 init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
2591 /* Set up segment record */
2592 assert(is_aligned(ss));
2593 set_size_and_pinuse_of_inuse_chunk(m, sp, ssize);
2594 *ss = m->seg; /* Push current record */
2595 m->seg.base = tbase;
2596 m->seg.size = tsize;
2597 m->seg.sflags = mmapped;
2600 /* Insert trailing fenceposts */
2602 mchunkptr nextp = chunk_plus_offset(p, SIZE_T_SIZE);
2603 p->head = FENCEPOST_HEAD;
2605 if ((char*)(&(nextp->head)) < old_end)
2610 assert(nfences >= 2);
2612 /* Insert the rest of old top into a bin as an ordinary free chunk */
2613 if (csp != old_top) {
2614 mchunkptr q = (mchunkptr)old_top;
2615 size_t psize = csp - old_top;
2616 mchunkptr tn = chunk_plus_offset(q, psize);
2617 set_free_with_pinuse(q, psize, tn);
2618 insert_chunk(m, q, psize);
2621 check_top_chunk(m, m->top);
2624 /* -------------------------- System allocation -------------------------- */
2626 /* Get memory from system using MORECORE or MMAP */
2627 static void* sys_alloc(mstate m, size_t nb) {
2628 char* tbase = CMFAIL;
2630 flag_t mmap_flag = 0;
2631 size_t asize; /* allocation size */
2633 ensure_initialization();
2635 if (use_noexpand(m))
2638 /* Directly map large chunks, but only if already initialized */
2639 if (use_mmap(m) && nb >= mparams.mmap_threshold && m->topsize != 0) {
2640 void* mem = mmap_alloc(m, nb);
2645 asize = granularity_align(nb + SYS_ALLOC_PADDING);
2647 return 0; /* wraparound */
2648 if (m->footprint_limit != 0) {
2649 size_t fp = m->footprint + asize;
2650 if (fp <= m->footprint || fp > m->footprint_limit)
2655 Try getting memory in any of three ways (in most-preferred to
2656 least-preferred order):
2657 1. A call to MORECORE that can normally contiguously extend memory.
2658 (disabled if not MORECORE_CONTIGUOUS or not HAVE_MORECORE or
2659 or main space is mmapped or a previous contiguous call failed)
2660 2. A call to MMAP new space (disabled if not HAVE_MMAP).
2661 Note that under the default settings, if MORECORE is unable to
2662 fulfill a request, and HAVE_MMAP is true, then mmap is
2663 used as a noncontiguous system allocator. This is a useful backup
2664 strategy for systems with holes in address spaces -- in this case
2665 sbrk cannot contiguously expand the heap, but mmap may be able to
2667 3. A call to MORECORE that cannot usually contiguously extend memory.
2668 (disabled if not HAVE_MORECORE)
2670 In all cases, we need to request enough bytes from system to ensure
2671 we can malloc nb bytes upon success, so pad with enough space for
2672 top_foot, plus alignment-pad to make sure we don't lose bytes if
2673 not on boundary, and round this up to a granularity unit.
2676 if (MORECORE_CONTIGUOUS && !use_noncontiguous(m)) {
2678 size_t ssize = asize; /* sbrk call size */
2679 msegmentptr ss = (m->top == 0)? 0 : segment_holding(m, (char*)m->top);
2680 ACQUIRE_MALLOC_GLOBAL_LOCK();
2682 if (ss == 0) { /* First time through or recovery */
2683 char* base = (char*)CALL_MORECORE(0);
2684 if (base != CMFAIL) {
2686 /* Adjust to end on a page boundary */
2687 if (!is_page_aligned(base))
2688 ssize += (page_align((size_t)base) - (size_t)base);
2689 fp = m->footprint + ssize; /* recheck limits */
2690 if (ssize > nb && ssize < HALF_MAX_SIZE_T &&
2691 (m->footprint_limit == 0 ||
2692 (fp > m->footprint && fp <= m->footprint_limit)) &&
2693 (br = (char*)(CALL_MORECORE(ssize))) == base) {
2700 /* Subtract out existing available top space from MORECORE request. */
2701 ssize = granularity_align(nb - m->topsize + SYS_ALLOC_PADDING);
2702 /* Use mem here only if it did continuously extend old space */
2703 if (ssize < HALF_MAX_SIZE_T &&
2704 (br = (char*)(CALL_MORECORE(ssize))) == ss->base+ss->size) {
2710 if (tbase == CMFAIL) { /* Cope with partial failure */
2711 if (br != CMFAIL) { /* Try to use/extend the space we did get */
2712 if (ssize < HALF_MAX_SIZE_T &&
2713 ssize < nb + SYS_ALLOC_PADDING) {
2714 size_t esize = granularity_align(nb + SYS_ALLOC_PADDING - ssize);
2715 if (esize < HALF_MAX_SIZE_T) {
2716 char* end = (char*)CALL_MORECORE(esize);
2719 else { /* Can't use; try to release */
2720 (void) CALL_MORECORE(-ssize);
2726 if (br != CMFAIL) { /* Use the space we did get */
2731 disable_contiguous(m); /* Don't try contiguous path in the future */
2734 RELEASE_MALLOC_GLOBAL_LOCK();
2737 if (HAVE_MMAP && tbase == CMFAIL) { /* Try MMAP */
2738 char* mp = (char*)(CALL_MMAP(asize));
2742 mmap_flag = USE_MMAP_BIT;
2746 if (HAVE_MORECORE && tbase == CMFAIL) { /* Try noncontiguous MORECORE */
2747 if (asize < HALF_MAX_SIZE_T) {
2750 ACQUIRE_MALLOC_GLOBAL_LOCK();
2751 br = (char*)(CALL_MORECORE(asize));
2752 end = (char*)(CALL_MORECORE(0));
2753 RELEASE_MALLOC_GLOBAL_LOCK();
2754 if (br != CMFAIL && end != CMFAIL && br < end) {
2755 size_t ssize = end - br;
2756 if (ssize > nb + TOP_FOOT_SIZE) {
2764 if (tbase != CMFAIL) {
2766 if ((m->footprint += tsize) > m->max_footprint)
2767 m->max_footprint = m->footprint;
2769 if (!is_initialized(m)) { /* first-time initialization */
2770 if (m->least_addr == 0 || tbase < m->least_addr)
2771 m->least_addr = tbase;
2772 m->seg.base = tbase;
2773 m->seg.size = tsize;
2774 m->seg.sflags = mmap_flag;
2775 m->magic = mparams.magic;
2776 m->release_checks = MAX_RELEASE_CHECK_RATE;
2780 init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
2784 /* Offset top by embedded malloc_state */
2785 mchunkptr mn = next_chunk(mem2chunk(m));
2786 init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) -TOP_FOOT_SIZE);
2791 /* Try to merge with an existing segment */
2792 msegmentptr sp = &m->seg;
2793 /* Only consider most recent segment if traversal suppressed */
2794 while (sp != 0 && tbase != sp->base + sp->size)
2795 sp = (NO_SEGMENT_TRAVERSAL) ? 0 : sp->next;
2797 !is_extern_segment(sp) &&
2798 (sp->sflags & USE_MMAP_BIT) == mmap_flag &&
2799 segment_holds(sp, m->top)) { /* append */
2801 init_top(m, m->top, m->topsize + tsize);
2804 if (tbase < m->least_addr)
2805 m->least_addr = tbase;
2807 while (sp != 0 && sp->base != tbase + tsize)
2808 sp = (NO_SEGMENT_TRAVERSAL) ? 0 : sp->next;
2810 !is_extern_segment(sp) &&
2811 (sp->sflags & USE_MMAP_BIT) == mmap_flag) {
2812 char* oldbase = sp->base;
2815 return prepend_alloc(m, tbase, oldbase, nb);
2818 add_segment(m, tbase, tsize, mmap_flag);
2822 if (nb < m->topsize) { /* Allocate from new or extended top space */
2823 size_t rsize = m->topsize -= nb;
2824 mchunkptr p = m->top;
2825 mchunkptr r = m->top = chunk_plus_offset(p, nb);
2826 r->head = rsize | PINUSE_BIT;
2827 set_size_and_pinuse_of_inuse_chunk(m, p, nb);
2828 check_top_chunk(m, m->top);
2829 check_malloced_chunk(m, chunk2mem(p), nb);
2830 return chunk2mem(p);
2834 MALLOC_FAILURE_ACTION;
2838 /* ----------------------- system deallocation -------------------------- */
2840 /* Unmap and unlink any mmapped segments that don't contain used chunks */
2841 static size_t release_unused_segments(mstate m) {
2842 size_t released = 0;
2844 msegmentptr pred = &m->seg;
2845 msegmentptr sp = pred->next;
2847 char* base = sp->base;
2848 size_t size = sp->size;
2849 msegmentptr next = sp->next;
2851 if (is_mmapped_segment(sp) && !is_extern_segment(sp)) {
2852 mchunkptr p = align_as_chunk(base);
2853 size_t psize = chunksize(p);
2854 /* Can unmap if first chunk holds entire segment and not pinned */
2855 if (!is_inuse(p) && (char*)p + psize >= base + size - TOP_FOOT_SIZE) {
2856 tchunkptr tp = (tchunkptr)p;
2857 assert(segment_holds(sp, (char*)sp));
2863 unlink_large_chunk(m, tp);
2865 if (CALL_MUNMAP(base, size) == 0) {
2867 m->footprint -= size;
2868 /* unlink obsoleted record */
2872 else { /* back out if cannot unmap */
2873 insert_large_chunk(m, tp, psize);
2877 if (NO_SEGMENT_TRAVERSAL) /* scan only first segment */
2882 /* Reset check counter */
2883 m->release_checks = (((size_t) nsegs > (size_t) MAX_RELEASE_CHECK_RATE)?
2884 (size_t) nsegs : (size_t) MAX_RELEASE_CHECK_RATE);
2888 static int sys_trim(mstate m, size_t pad) {
2889 size_t released = 0;
2890 ensure_initialization();
2891 if (pad < MAX_REQUEST && is_initialized(m)) {
2892 pad += TOP_FOOT_SIZE; /* ensure enough room for segment overhead */
2894 if (m->topsize > pad) {
2895 /* Shrink top space in granularity-size units, keeping at least one */
2896 size_t unit = mparams.granularity;
2897 size_t extra = ((m->topsize - pad + (unit - SIZE_T_ONE)) / unit -
2899 msegmentptr sp = segment_holding(m, (char*)m->top);
2901 if (!is_extern_segment(sp)) {
2902 if (is_mmapped_segment(sp)) {
2904 sp->size >= extra &&
2905 !has_segment_link(m, sp)) { /* can't shrink if pinned */
2906 size_t newsize = sp->size - extra;
2907 (void)newsize; /* placate people compiling -Wunused-variable */
2908 /* Prefer mremap, fall back to munmap */
2909 if ((CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL) ||
2910 (CALL_MUNMAP(sp->base + newsize, extra) == 0)) {
2915 else if (HAVE_MORECORE) {
2916 if (extra >= HALF_MAX_SIZE_T) /* Avoid wrapping negative */
2917 extra = (HALF_MAX_SIZE_T) + SIZE_T_ONE - unit;
2918 ACQUIRE_MALLOC_GLOBAL_LOCK();
2920 /* Make sure end of memory is where we last set it. */
2921 char* old_br = (char*)(CALL_MORECORE(0));
2922 if (old_br == sp->base + sp->size) {
2923 char* rel_br = (char*)(CALL_MORECORE(-extra));
2924 char* new_br = (char*)(CALL_MORECORE(0));
2925 if (rel_br != CMFAIL && new_br < old_br)
2926 released = old_br - new_br;
2929 RELEASE_MALLOC_GLOBAL_LOCK();
2933 if (released != 0) {
2934 sp->size -= released;
2935 m->footprint -= released;
2936 init_top(m, m->top, m->topsize - released);
2937 check_top_chunk(m, m->top);
2941 /* Unmap any unused mmapped segments */
2943 released += release_unused_segments(m);
2945 /* On failure, disable autotrim to avoid repeated failed future calls */
2946 if (released == 0 && m->topsize > m->trim_check)
2947 m->trim_check = MAX_SIZE_T;
2950 return (released != 0)? 1 : 0;
2953 /* Consolidate and bin a chunk. Differs from exported versions
2954 of free mainly in that the chunk need not be marked as inuse.
2956 static void dispose_chunk(mstate m, mchunkptr p, size_t psize) {
2957 mchunkptr next = chunk_plus_offset(p, psize);
2960 size_t prevsize = p->prev_foot;
2961 if (is_mmapped(p)) {
2962 psize += prevsize + MMAP_FOOT_PAD;
2963 if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
2964 m->footprint -= psize;
2967 prev = chunk_minus_offset(p, prevsize);
2970 if (RTCHECK(ok_address(m, prev))) { /* consolidate backward */
2972 unlink_chunk(m, p, prevsize);
2974 else if ((next->head & INUSE_BITS) == INUSE_BITS) {
2976 set_free_with_pinuse(p, psize, next);
2981 CORRUPTION_ERROR_ACTION(m);
2985 if (RTCHECK(ok_address(m, next))) {
2986 if (!cinuse(next)) { /* consolidate forward */
2987 if (next == m->top) {
2988 size_t tsize = m->topsize += psize;
2990 p->head = tsize | PINUSE_BIT;
2997 else if (next == m->dv) {
2998 size_t dsize = m->dvsize += psize;
3000 set_size_and_pinuse_of_free_chunk(p, dsize);
3004 size_t nsize = chunksize(next);
3006 unlink_chunk(m, next, nsize);
3007 set_size_and_pinuse_of_free_chunk(p, psize);
3015 set_free_with_pinuse(p, psize, next);
3017 insert_chunk(m, p, psize);
3020 CORRUPTION_ERROR_ACTION(m);
3024 /* ---------------------------- malloc --------------------------- */
3026 /* allocate a large request from the best fitting chunk in a treebin */
3027 static void* tmalloc_large(mstate m, size_t nb) {
3029 size_t rsize = -nb; /* Unsigned negation */
3032 compute_tree_index(nb, idx);
3033 if ((t = *treebin_at(m, idx)) != 0) {
3034 /* Traverse tree for this bin looking for node with size == nb */
3035 size_t sizebits = nb << leftshift_for_tree_index(idx);
3036 tchunkptr rst = 0; /* The deepest untaken right subtree */
3039 size_t trem = chunksize(t) - nb;
3042 if ((rsize = trem) == 0)
3046 t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1];
3047 if (rt != 0 && rt != t)
3050 t = rst; /* set t to least subtree holding sizes > nb */
3056 if (t == 0 && v == 0) { /* set t to root of next non-empty treebin */
3057 binmap_t leftbits = left_bits(idx2bit(idx)) & m->treemap;
3058 if (leftbits != 0) {
3060 binmap_t leastbit = least_bit(leftbits);
3061 compute_bit2idx(leastbit, i);
3062 t = *treebin_at(m, i);
3066 while (t != 0) { /* find smallest of tree or subtree */
3067 size_t trem = chunksize(t) - nb;
3072 t = leftmost_child(t);
3075 /* If dv is a better fit, return 0 so malloc will use it */
3076 if (v != 0 && rsize < (size_t)(m->dvsize - nb)) {
3077 if (RTCHECK(ok_address(m, v))) { /* split */
3078 mchunkptr r = chunk_plus_offset(v, nb);
3079 assert(chunksize(v) == rsize + nb);
3080 if (RTCHECK(ok_next(v, r))) {
3081 unlink_large_chunk(m, v);
3082 if (rsize < MIN_CHUNK_SIZE)
3083 set_inuse_and_pinuse(m, v, (rsize + nb));
3085 set_size_and_pinuse_of_inuse_chunk(m, v, nb);
3086 set_size_and_pinuse_of_free_chunk(r, rsize);
3087 insert_chunk(m, r, rsize);
3089 return chunk2mem(v);
3092 CORRUPTION_ERROR_ACTION(m);
3097 /* allocate a small request from the best fitting chunk in a treebin */
3098 static void* tmalloc_small(mstate m, size_t nb) {
3102 binmap_t leastbit = least_bit(m->treemap);
3103 compute_bit2idx(leastbit, i);
3104 v = t = *treebin_at(m, i);
3105 rsize = chunksize(t) - nb;
3107 while ((t = leftmost_child(t)) != 0) {
3108 size_t trem = chunksize(t) - nb;
3115 if (RTCHECK(ok_address(m, v))) {
3116 mchunkptr r = chunk_plus_offset(v, nb);
3117 assert(chunksize(v) == rsize + nb);
3118 if (RTCHECK(ok_next(v, r))) {
3119 unlink_large_chunk(m, v);
3120 if (rsize < MIN_CHUNK_SIZE)
3121 set_inuse_and_pinuse(m, v, (rsize + nb));
3123 set_size_and_pinuse_of_inuse_chunk(m, v, nb);
3124 set_size_and_pinuse_of_free_chunk(r, rsize);
3125 replace_dv(m, r, rsize);
3127 return chunk2mem(v);
3131 CORRUPTION_ERROR_ACTION(m);
3137 void* dlmalloc(size_t bytes) {
3140 If a small request (< 256 bytes minus per-chunk overhead):
3141 1. If one exists, use a remainderless chunk in associated smallbin.
3142 (Remainderless means that there are too few excess bytes to
3143 represent as a chunk.)
3144 2. If it is big enough, use the dv chunk, which is normally the
3145 chunk adjacent to the one used for the most recent small request.
3146 3. If one exists, split the smallest available chunk in a bin,
3147 saving remainder in dv.
3148 4. If it is big enough, use the top chunk.
3149 5. If available, get memory from system and use it
3150 Otherwise, for a large request:
3151 1. Find the smallest available binned chunk that fits, and use it
3152 if it is better fitting than dv chunk, splitting if necessary.
3153 2. If better fitting than any binned chunk, use the dv chunk.
3154 3. If it is big enough, use the top chunk.
3155 4. If request size >= mmap threshold, try to directly mmap this chunk.
3156 5. If available, get memory from system and use it
3158 The ugly goto's here ensure that postaction occurs along all paths.
3162 ensure_initialization(); /* initialize in sys_alloc if not using locks */
3165 if (!PREACTION(gm)) {
3168 if (bytes <= MAX_SMALL_REQUEST) {
3171 nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes);
3172 idx = small_index(nb);
3173 smallbits = gm->smallmap >> idx;
3175 if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */
3177 idx += ~smallbits & 1; /* Uses next bin if idx empty */
3178 b = smallbin_at(gm, idx);
3180 assert(chunksize(p) == small_index2size(idx));
3181 unlink_first_small_chunk(gm, b, p, idx);
3182 set_inuse_and_pinuse(gm, p, small_index2size(idx));
3184 check_malloced_chunk(gm, mem, nb);
3188 else if (nb > gm->dvsize) {
3189 if (smallbits != 0) { /* Use chunk in next nonempty smallbin */
3193 binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx));
3194 binmap_t leastbit = least_bit(leftbits);
3195 compute_bit2idx(leastbit, i);
3196 b = smallbin_at(gm, i);
3198 assert(chunksize(p) == small_index2size(i));
3199 unlink_first_small_chunk(gm, b, p, i);
3200 rsize = small_index2size(i) - nb;
3201 /* Fit here cannot be remainderless if 4byte sizes */
3202 if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
3203 set_inuse_and_pinuse(gm, p, small_index2size(i));
3205 set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
3206 r = chunk_plus_offset(p, nb);
3207 set_size_and_pinuse_of_free_chunk(r, rsize);
3208 replace_dv(gm, r, rsize);
3211 check_malloced_chunk(gm, mem, nb);
3215 else if (gm->treemap != 0 && (mem = tmalloc_small(gm, nb)) != 0) {
3216 check_malloced_chunk(gm, mem, nb);
3221 else if (bytes >= MAX_REQUEST)
3222 nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */
3224 nb = pad_request(bytes);
3225 if (gm->treemap != 0 && (mem = tmalloc_large(gm, nb)) != 0) {
3226 check_malloced_chunk(gm, mem, nb);
3231 if (nb <= gm->dvsize) {
3232 size_t rsize = gm->dvsize - nb;
3233 mchunkptr p = gm->dv;
3234 if (rsize >= MIN_CHUNK_SIZE) { /* split dv */
3235 mchunkptr r = gm->dv = chunk_plus_offset(p, nb);
3237 set_size_and_pinuse_of_free_chunk(r, rsize);
3238 set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
3240 else { /* exhaust dv */
3241 size_t dvs = gm->dvsize;
3244 set_inuse_and_pinuse(gm, p, dvs);
3247 check_malloced_chunk(gm, mem, nb);
3251 else if (nb < gm->topsize) { /* Split top */
3252 size_t rsize = gm->topsize -= nb;
3253 mchunkptr p = gm->top;
3254 mchunkptr r = gm->top = chunk_plus_offset(p, nb);
3255 r->head = rsize | PINUSE_BIT;
3256 set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
3258 check_top_chunk(gm, gm->top);
3259 check_malloced_chunk(gm, mem, nb);
3263 mem = sys_alloc(gm, nb);
3273 /* ---------------------------- free --------------------------- */
3275 void dlfree(void* mem) {
3277 Consolidate freed chunks with preceeding or succeeding bordering
3278 free chunks, if they exist, and then place in a bin. Intermixed
3279 with special cases for top, dv, mmapped chunks, and usage errors.
3283 mchunkptr p = mem2chunk(mem);
3285 mstate fm = get_mstate_for(p);
3286 if (!ok_magic(fm)) {
3287 USAGE_ERROR_ACTION(fm, p);
3292 #endif /* FOOTERS */
3293 if (!PREACTION(fm)) {
3294 check_inuse_chunk(fm, p);
3295 if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
3296 size_t psize = chunksize(p);
3297 mchunkptr next = chunk_plus_offset(p, psize);
3299 size_t prevsize = p->prev_foot;
3300 if (is_mmapped(p)) {
3301 psize += prevsize + MMAP_FOOT_PAD;
3302 if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
3303 fm->footprint -= psize;
3307 mchunkptr prev = chunk_minus_offset(p, prevsize);
3310 if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */
3312 unlink_chunk(fm, p, prevsize);
3314 else if ((next->head & INUSE_BITS) == INUSE_BITS) {
3316 set_free_with_pinuse(p, psize, next);
3325 if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) {
3326 if (!cinuse(next)) { /* consolidate forward */
3327 if (next == fm->top) {
3328 size_t tsize = fm->topsize += psize;
3330 p->head = tsize | PINUSE_BIT;
3335 if (should_trim(fm, tsize))
3339 else if (next == fm->dv) {
3340 size_t dsize = fm->dvsize += psize;
3342 set_size_and_pinuse_of_free_chunk(p, dsize);
3346 size_t nsize = chunksize(next);
3348 unlink_chunk(fm, next, nsize);
3349 set_size_and_pinuse_of_free_chunk(p, psize);
3357 set_free_with_pinuse(p, psize, next);
3359 if (is_small(psize)) {
3360 insert_small_chunk(fm, p, psize);
3361 check_free_chunk(fm, p);
3364 tchunkptr tp = (tchunkptr)p;
3365 insert_large_chunk(fm, tp, psize);
3366 check_free_chunk(fm, p);
3367 if (--fm->release_checks == 0)
3368 release_unused_segments(fm);
3374 USAGE_ERROR_ACTION(fm, p);
3381 #endif /* FOOTERS */
3384 void* dlcalloc(size_t n_elements, size_t elem_size) {
3387 if (n_elements != 0) {
3388 req = n_elements * elem_size;
3389 if (((n_elements | elem_size) & ~(size_t)0xffff) &&
3390 (req / n_elements != elem_size))
3391 req = MAX_SIZE_T; /* force downstream failure on overflow */
3393 mem = dlmalloc(req);
3394 if (mem != 0 && calloc_must_clear(mem2chunk(mem)))
3395 memset(mem, 0, req);
3399 #endif /* !ONLY_MSPACES */
3401 /* ------------ Internal support for realloc, memalign, etc -------------- */
3403 /* Try to realloc; only in-place unless can_move true */
3404 static mchunkptr try_realloc_chunk(mstate m, mchunkptr p, size_t nb,
3407 size_t oldsize = chunksize(p);
3408 mchunkptr next = chunk_plus_offset(p, oldsize);
3409 if (RTCHECK(ok_address(m, p) && ok_inuse(p) &&
3410 ok_next(p, next) && ok_pinuse(next))) {
3411 if (is_mmapped(p)) {
3412 newp = mmap_resize(m, p, nb, can_move);
3414 else if (oldsize >= nb) { /* already big enough */
3415 size_t rsize = oldsize - nb;
3416 if (rsize >= MIN_CHUNK_SIZE) { /* split off remainder */
3417 mchunkptr r = chunk_plus_offset(p, nb);
3418 set_inuse(m, p, nb);
3419 set_inuse(m, r, rsize);
3420 dispose_chunk(m, r, rsize);
3424 else if (next == m->top) { /* extend into top */
3425 if (oldsize + m->topsize > nb) {
3426 size_t newsize = oldsize + m->topsize;
3427 size_t newtopsize = newsize - nb;
3428 mchunkptr newtop = chunk_plus_offset(p, nb);
3429 set_inuse(m, p, nb);
3430 newtop->head = newtopsize |PINUSE_BIT;
3432 m->topsize = newtopsize;
3436 else if (next == m->dv) { /* extend into dv */
3437 size_t dvs = m->dvsize;
3438 if (oldsize + dvs >= nb) {
3439 size_t dsize = oldsize + dvs - nb;
3440 if (dsize >= MIN_CHUNK_SIZE) {
3441 mchunkptr r = chunk_plus_offset(p, nb);
3442 mchunkptr n = chunk_plus_offset(r, dsize);
3443 set_inuse(m, p, nb);
3444 set_size_and_pinuse_of_free_chunk(r, dsize);
3449 else { /* exhaust dv */
3450 size_t newsize = oldsize + dvs;
3451 set_inuse(m, p, newsize);
3458 else if (!cinuse(next)) { /* extend into next free chunk */
3459 size_t nextsize = chunksize(next);
3460 if (oldsize + nextsize >= nb) {
3461 size_t rsize = oldsize + nextsize - nb;
3462 unlink_chunk(m, next, nextsize);
3463 if (rsize < MIN_CHUNK_SIZE) {
3464 size_t newsize = oldsize + nextsize;
3465 set_inuse(m, p, newsize);
3468 mchunkptr r = chunk_plus_offset(p, nb);
3469 set_inuse(m, p, nb);
3470 set_inuse(m, r, rsize);
3471 dispose_chunk(m, r, rsize);
3478 USAGE_ERROR_ACTION(m, chunk2mem(p));
3483 static void* internal_memalign(mstate m, size_t alignment, size_t bytes) {
3485 if (alignment < MIN_CHUNK_SIZE) /* must be at least a minimum chunk size */
3486 alignment = MIN_CHUNK_SIZE;
3487 if ((alignment & (alignment-SIZE_T_ONE)) != 0) {/* Ensure a power of 2 */
3488 size_t a = MALLOC_ALIGNMENT << 1;
3489 while (a < alignment) a <<= 1;
3492 if (bytes >= MAX_REQUEST - alignment) {
3493 if (m != 0) { /* Test isn't needed but avoids compiler warning */
3494 MALLOC_FAILURE_ACTION;
3498 size_t nb = request2size(bytes);
3499 size_t req = nb + alignment + MIN_CHUNK_SIZE - CHUNK_OVERHEAD;
3500 mem = internal_malloc(m, req);
3502 mchunkptr p = mem2chunk(mem);
3505 if ((((size_t)(mem)) & (alignment - 1)) != 0) { /* misaligned */
3507 Find an aligned spot inside chunk. Since we need to give
3508 back leading space in a chunk of at least MIN_CHUNK_SIZE, if
3509 the first calculation places us at a spot with less than
3510 MIN_CHUNK_SIZE leader, we can move to the next aligned spot.
3511 We've allocated enough total room so that this is always
3514 char* br = (char*)mem2chunk((size_t)(((size_t)((char*)mem + alignment -
3517 char* pos = ((size_t)(br - (char*)(p)) >= MIN_CHUNK_SIZE)?
3519 mchunkptr newp = (mchunkptr)pos;
3520 size_t leadsize = pos - (char*)(p);
3521 size_t newsize = chunksize(p) - leadsize;
3523 if (is_mmapped(p)) { /* For mmapped chunks, just adjust offset */
3524 newp->prev_foot = p->prev_foot + leadsize;
3525 newp->head = newsize;
3527 else { /* Otherwise, give back leader, use the rest */
3528 set_inuse(m, newp, newsize);
3529 set_inuse(m, p, leadsize);
3530 dispose_chunk(m, p, leadsize);
3535 /* Give back spare room at the end */
3536 if (!is_mmapped(p)) {
3537 size_t size = chunksize(p);
3538 if (size > nb + MIN_CHUNK_SIZE) {
3539 size_t remainder_size = size - nb;
3540 mchunkptr remainder = chunk_plus_offset(p, nb);
3541 set_inuse(m, p, nb);
3542 set_inuse(m, remainder, remainder_size);
3543 dispose_chunk(m, remainder, remainder_size);
3548 assert (chunksize(p) >= nb);
3549 assert(((size_t)mem & (alignment - 1)) == 0);
3550 check_inuse_chunk(m, p);
3558 Common support for independent_X routines, handling
3559 all of the combinations that can result.
3561 bit 0 set if all elements are same size (using sizes[0])
3562 bit 1 set if elements should be zeroed
3564 static void** ialloc(mstate m,
3570 size_t element_size; /* chunksize of each element, if all same */
3571 size_t contents_size; /* total size of elements */
3572 size_t array_size; /* request size of pointer array */
3573 void* mem; /* malloced aggregate space */
3574 mchunkptr p; /* corresponding chunk */
3575 size_t remainder_size; /* remaining bytes while splitting */
3576 void** marray; /* either "chunks" or malloced ptr array */
3577 mchunkptr array_chunk; /* chunk for malloced ptr array */
3578 flag_t was_enabled; /* to disable mmap */
3582 ensure_initialization();
3583 /* compute array length, if needed */
3585 if (n_elements == 0)
3586 return chunks; /* nothing to do */
3591 /* if empty req, must still return chunk representing empty array */
3592 if (n_elements == 0)
3593 return (void**)internal_malloc(m, 0);
3595 array_size = request2size(n_elements * (sizeof(void*)));
3598 /* compute total element size */
3599 if (opts & 0x1) { /* all-same-size */
3600 element_size = request2size(*sizes);
3601 contents_size = n_elements * element_size;
3603 else { /* add up all the sizes */
3606 for (i = 0; i != n_elements; ++i)
3607 contents_size += request2size(sizes[i]);
3610 size = contents_size + array_size;
3613 Allocate the aggregate chunk. First disable direct-mmapping so
3614 malloc won't use it, since we would not be able to later
3615 free/realloc space internal to a segregated mmap region.
3617 was_enabled = use_mmap(m);
3619 mem = internal_malloc(m, size - CHUNK_OVERHEAD);
3625 if (PREACTION(m)) return 0;
3627 remainder_size = chunksize(p);
3629 assert(!is_mmapped(p));
3631 if (opts & 0x2) { /* optionally clear the elements */
3632 memset((size_t*)mem, 0, remainder_size - SIZE_T_SIZE - array_size);
3635 /* If not provided, allocate the pointer array as final part of chunk */
3637 size_t array_chunk_size;
3638 array_chunk = chunk_plus_offset(p, contents_size);
3639 array_chunk_size = remainder_size - contents_size;
3640 marray = (void**) (chunk2mem(array_chunk));
3641 set_size_and_pinuse_of_inuse_chunk(m, array_chunk, array_chunk_size);
3642 remainder_size = contents_size;
3645 /* split out elements */
3646 for (i = 0; ; ++i) {
3647 marray[i] = chunk2mem(p);
3648 if (i != n_elements-1) {
3649 if (element_size != 0)
3650 size = element_size;
3652 size = request2size(sizes[i]);
3653 remainder_size -= size;
3654 set_size_and_pinuse_of_inuse_chunk(m, p, size);
3655 p = chunk_plus_offset(p, size);
3657 else { /* the final element absorbs any overallocation slop */
3658 set_size_and_pinuse_of_inuse_chunk(m, p, remainder_size);
3664 if (marray != chunks) {
3665 /* final element must have exactly exhausted chunk */
3666 if (element_size != 0) {
3667 assert(remainder_size == element_size);
3670 assert(remainder_size == request2size(sizes[i]));
3672 check_inuse_chunk(m, mem2chunk(marray));
3674 for (i = 0; i != n_elements; ++i)
3675 check_inuse_chunk(m, mem2chunk(marray[i]));
3683 /* Try to free all pointers in the given array.
3684 Note: this could be made faster, by delaying consolidation,
3685 at the price of disabling some user integrity checks, We
3686 still optimize some consolidations by combining adjacent
3687 chunks before freeing, which will occur often if allocated
3688 with ialloc or the array is sorted.
3690 static size_t internal_bulk_free(mstate m, void* array[], size_t nelem) {
3692 if (!PREACTION(m)) {
3694 void** fence = &(array[nelem]);
3695 for (a = array; a != fence; ++a) {
3698 mchunkptr p = mem2chunk(mem);
3699 size_t psize = chunksize(p);
3701 if (get_mstate_for(p) != m) {
3706 check_inuse_chunk(m, p);
3708 if (RTCHECK(ok_address(m, p) && ok_inuse(p))) {
3709 void ** b = a + 1; /* try to merge with next chunk */
3710 mchunkptr next = next_chunk(p);
3711 if (b != fence && *b == chunk2mem(next)) {
3712 size_t newsize = chunksize(next) + psize;
3713 set_inuse(m, p, newsize);
3717 dispose_chunk(m, p, psize);
3720 CORRUPTION_ERROR_ACTION(m);
3725 if (should_trim(m, m->topsize))
3733 #if MALLOC_INSPECT_ALL
3734 static void internal_inspect_all(mstate m,
3735 void(*handler)(void *start,
3738 void* callback_arg),
3740 if (is_initialized(m)) {
3741 mchunkptr top = m->top;
3743 for (s = &m->seg; s != 0; s = s->next) {
3744 mchunkptr q = align_as_chunk(s->base);
3745 while (segment_holds(s, q) && q->head != FENCEPOST_HEAD) {
3746 mchunkptr next = next_chunk(q);
3747 size_t sz = chunksize(q);
3751 used = sz - CHUNK_OVERHEAD; /* must not be mmapped */
3752 start = chunk2mem(q);
3756 if (is_small(sz)) { /* offset by possible bookkeeping */
3757 start = (void*)((char*)q + sizeof(struct malloc_chunk));
3760 start = (void*)((char*)q + sizeof(struct malloc_tree_chunk));
3763 if (start < (void*)next) /* skip if all space is bookkeeping */
3764 handler(start, next, used, arg);
3772 #endif /* MALLOC_INSPECT_ALL */
3774 /* ------------------ Exported realloc, memalign, etc -------------------- */
3778 void* dlrealloc(void* oldmem, size_t bytes) {
3781 mem = dlmalloc(bytes);
3783 else if (bytes >= MAX_REQUEST) {
3784 MALLOC_FAILURE_ACTION;
3786 #ifdef REALLOC_ZERO_BYTES_FREES
3787 else if (bytes == 0) {
3790 #endif /* REALLOC_ZERO_BYTES_FREES */
3792 size_t nb = request2size(bytes);
3793 mchunkptr oldp = mem2chunk(oldmem);
3797 mstate m = get_mstate_for(oldp);
3799 USAGE_ERROR_ACTION(m, oldmem);
3802 #endif /* FOOTERS */
3803 if (!PREACTION(m)) {
3804 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 1);
3807 check_inuse_chunk(m, newp);
3808 mem = chunk2mem(newp);
3811 mem = internal_malloc(m, bytes);
3813 size_t oc = chunksize(oldp) - overhead_for(oldp);
3814 memcpy(mem, oldmem, (oc < bytes)? oc : bytes);
3815 internal_free(m, oldmem);
3823 void* dlrealloc_in_place(void* oldmem, size_t bytes) {
3826 if (bytes >= MAX_REQUEST) {
3827 MALLOC_FAILURE_ACTION;
3830 size_t nb = request2size(bytes);
3831 mchunkptr oldp = mem2chunk(oldmem);
3835 mstate m = get_mstate_for(oldp);
3837 USAGE_ERROR_ACTION(m, oldmem);
3840 #endif /* FOOTERS */
3841 if (!PREACTION(m)) {
3842 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 0);
3845 check_inuse_chunk(m, newp);
3854 void* dlmemalign(size_t alignment, size_t bytes) {
3855 if (alignment <= MALLOC_ALIGNMENT) {
3856 return dlmalloc(bytes);
3858 return internal_memalign(gm, alignment, bytes);
3861 int dlposix_memalign(void** pp, size_t alignment, size_t bytes) {
3863 if (alignment == MALLOC_ALIGNMENT)
3864 mem = dlmalloc(bytes);
3866 size_t d = alignment / sizeof(void*);
3867 size_t r = alignment % sizeof(void*);
3868 if (r != 0 || d == 0 || (d & (d-SIZE_T_ONE)) != 0)
3870 else if (bytes <= MAX_REQUEST - alignment) {
3871 if (alignment < MIN_CHUNK_SIZE)
3872 alignment = MIN_CHUNK_SIZE;
3873 mem = internal_memalign(gm, alignment, bytes);
3884 void* dlvalloc(size_t bytes) {
3886 ensure_initialization();
3887 pagesz = mparams.page_size;
3888 return dlmemalign(pagesz, bytes);
3891 void* dlpvalloc(size_t bytes) {
3893 ensure_initialization();
3894 pagesz = mparams.page_size;
3895 return dlmemalign(pagesz, (bytes + pagesz - SIZE_T_ONE) & ~(pagesz - SIZE_T_ONE));
3898 void** dlindependent_calloc(size_t n_elements, size_t elem_size,
3900 size_t sz = elem_size; /* serves as 1-element array */
3901 return ialloc(gm, n_elements, &sz, 3, chunks);
3904 void** dlindependent_comalloc(size_t n_elements, size_t sizes[],
3906 return ialloc(gm, n_elements, sizes, 0, chunks);
3909 size_t dlbulk_free(void* array[], size_t nelem) {
3910 return internal_bulk_free(gm, array, nelem);
3913 #if MALLOC_INSPECT_ALL
3914 void dlmalloc_inspect_all(void(*handler)(void *start,
3917 void* callback_arg),
3919 ensure_initialization();
3920 if (!PREACTION(gm)) {
3921 internal_inspect_all(gm, handler, arg);
3925 #endif /* MALLOC_INSPECT_ALL */
3927 int dlmalloc_trim(size_t pad) {
3929 ensure_initialization();
3930 if (!PREACTION(gm)) {
3931 result = sys_trim(gm, pad);
3937 size_t dlmalloc_footprint(void) {
3938 return gm->footprint;
3941 size_t dlmalloc_max_footprint(void) {
3942 return gm->max_footprint;
3945 size_t dlmalloc_footprint_limit(void) {
3946 size_t maf = gm->footprint_limit;
3947 return maf == 0 ? MAX_SIZE_T : maf;
3950 size_t dlmalloc_set_footprint_limit(size_t bytes) {
3951 size_t result; /* invert sense of 0 */
3953 result = granularity_align(1); /* Use minimal size */
3954 if (bytes == MAX_SIZE_T)
3955 result = 0; /* disable */
3957 result = granularity_align(bytes);
3958 return gm->footprint_limit = result;
3962 struct mallinfo dlmallinfo(void) {
3963 return internal_mallinfo(gm);
3965 #endif /* NO_MALLINFO */
3967 #if !NO_MALLOC_STATS
3968 void dlmalloc_stats() {
3969 internal_malloc_stats(gm);
3971 #endif /* NO_MALLOC_STATS */
3973 int dlmallopt(int param_number, int value) {
3974 return change_mparam(param_number, value);
3977 size_t dlmalloc_usable_size(void* mem) {
3979 mchunkptr p = mem2chunk(mem);
3981 return chunksize(p) - overhead_for(p);
3986 #endif /* !ONLY_MSPACES */
3988 /* ----------------------------- user mspaces ---------------------------- */
3992 static mstate init_user_mstate(char* tbase, size_t tsize) {
3993 size_t msize = pad_request(sizeof(struct malloc_state));
3995 mchunkptr msp = align_as_chunk(tbase);
3996 mstate m = (mstate)(chunk2mem(msp));
3997 memset(m, 0, msize);
3998 (void)INITIAL_LOCK(&m->mutex);
3999 msp->head = (msize|INUSE_BITS);
4000 m->seg.base = m->least_addr = tbase;
4001 m->seg.size = m->footprint = m->max_footprint = tsize;
4002 m->magic = mparams.magic;
4003 m->release_checks = MAX_RELEASE_CHECK_RATE;
4004 m->mflags = mparams.default_mflags;
4007 disable_contiguous(m);
4009 mn = next_chunk(mem2chunk(m));
4010 init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) - TOP_FOOT_SIZE);
4011 check_top_chunk(m, m->top);
4015 mspace create_mspace(size_t capacity, int locked) {
4018 ensure_initialization();
4019 msize = pad_request(sizeof(struct malloc_state));
4020 if (capacity < (size_t) -(msize + TOP_FOOT_SIZE + mparams.page_size)) {
4021 size_t rs = ((capacity == 0)? mparams.granularity :
4022 (capacity + TOP_FOOT_SIZE + msize));
4023 size_t tsize = granularity_align(rs);
4024 char* tbase = (char*)(CALL_MMAP(tsize));
4025 if (tbase != CMFAIL) {
4026 m = init_user_mstate(tbase, tsize);
4027 m->seg.sflags = USE_MMAP_BIT;
4028 set_lock(m, locked);
4034 mspace create_mspace_with_base(void* base, size_t capacity, int locked) {
4037 ensure_initialization();
4038 msize = pad_request(sizeof(struct malloc_state));
4039 if (capacity > msize + TOP_FOOT_SIZE &&
4040 capacity < (size_t) -(msize + TOP_FOOT_SIZE + mparams.page_size)) {
4041 m = init_user_mstate((char*)base, capacity);
4042 m->seg.sflags = EXTERN_BIT;
4043 set_lock(m, locked);
4048 int mspace_track_large_chunks(mspace msp, int enable) {
4050 mstate ms = (mstate)msp;
4051 if (!PREACTION(ms)) {
4052 if (!use_mmap(ms)) {
4065 size_t destroy_mspace(mspace msp) {
4067 mstate ms = (mstate)msp;
4069 msegmentptr sp = &ms->seg;
4070 (void)DESTROY_LOCK(&ms->mutex); /* destroy before unmapped */
4072 char* base = sp->base;
4073 size_t size = sp->size;
4074 flag_t flag = sp->sflags;
4075 (void)base; /* placate people compiling -Wunused-variable */
4077 if ((flag & USE_MMAP_BIT) && !(flag & EXTERN_BIT) &&
4078 CALL_MUNMAP(base, size) == 0)
4083 USAGE_ERROR_ACTION(ms,ms);
4088 void mspace_get_address_and_size (mspace msp, unsigned long long *addrp,
4089 unsigned long long *sizep)
4095 this_seg = &ms->seg;
4097 *addrp = (unsigned long long) this_seg->base;
4098 *sizep = this_seg->size;
4101 int mspace_is_heap_object (mspace msp, void *p)
4109 this_seg = &ms->seg;
4114 base = this_seg->base;
4115 if (pp >= base && pp < (base + this_seg->size))
4117 this_seg = this_seg->next;
4122 void *mspace_least_addr (mspace msp)
4124 mstate ms = (mstate) msp;
4125 return (void *) ms->least_addr;
4128 void mspace_disable_expand (mspace msp)
4130 mstate ms = (mstate)msp;
4132 disable_expand (ms);
4135 int mspace_enable_disable_trace (mspace msp, int enable)
4137 mstate ms = (mstate)msp;
4138 int was_enabled = 0;
4148 return (was_enabled);
4151 void* mspace_get_aligned (mspace msp,
4152 unsigned long long n_user_data_bytes,
4153 unsigned long long align,
4154 unsigned long long align_offset) {
4156 unsigned long long searchp;
4157 unsigned *wwp; /* "where's Waldo" pointer */
4158 mstate ms = (mstate)msp;
4161 * Allocate space for the "Where's Waldo?" pointer
4162 * the base of the dlmalloc object
4164 n_user_data_bytes += sizeof(unsigned);
4167 * Alignment requests less than the size of an mmx vector are ignored
4170 rv = mspace_malloc (msp, n_user_data_bytes);
4174 if (use_trace(ms)) {
4175 mchunkptr p = mem2chunk(rv);
4176 size_t psize = chunksize(p);
4178 mheap_get_trace ((u64)rv + sizeof (unsigned), psize);
4181 wwp = (unsigned *)rv;
4183 rv += sizeof (unsigned);
4189 * Alignment requests greater than 4K must be at offset zero,
4190 * and must be freed using mspace_free_no_offset - or never freed -
4191 * since the "Where's Waldo?" pointer would waste too much space.
4193 * Waldo is the address of the chunk of memory returned by mspace_malloc,
4194 * which we need later to call mspace_free...
4196 if (align > 4<<10 || align_offset == ~0ULL) {
4197 n_user_data_bytes -= sizeof(unsigned);
4198 assert(align_offset == 0);
4199 rv = internal_memalign(ms, (size_t)align, n_user_data_bytes);
4201 /* Trace the allocation */
4202 if (rv && use_trace(ms)) {
4203 mchunkptr p = mem2chunk(rv);
4204 size_t psize = chunksize(p);
4205 mheap_get_trace ((u64)rv, psize);
4210 align = clib_max (align, MALLOC_ALIGNMENT);
4211 align = max_pow2 (align);
4213 /* Correct align offset to be smaller than alignment. */
4214 align_offset &= (align - 1);
4216 n_user_data_bytes += align;
4217 rv = mspace_malloc (msp, n_user_data_bytes);
4222 /* Honor the alignment request */
4223 searchp = (unsigned long long)(rv + sizeof (unsigned));
4225 #if 0 /* this is the idea... */
4226 while ((searchp + align_offset) % align)
4231 unsigned long long where_now, delta;
4233 where_now = (searchp + align_offset) % align;
4234 delta = align - where_now;
4239 wwp = (unsigned *)(searchp - sizeof(unsigned));
4240 *wwp = (searchp - (((unsigned long long) rv) + sizeof (*wwp)));
4241 assert (*wwp < align);
4243 if (use_trace(ms)) {
4244 mchunkptr p = mem2chunk(rv);
4245 size_t psize = chunksize(p);
4246 mheap_get_trace ((u64)rv, psize);
4248 return (void *) searchp;
4251 void mspace_put (mspace msp, void *p_arg)
4253 char *object_header;
4255 mstate ms = (mstate)msp;
4257 /* Find the object header delta */
4258 wwp = (unsigned *)p_arg;
4261 /* Recover the dlmalloc object pointer */
4262 object_header = (char *)wwp;
4263 object_header -= *wwp;
4265 /* Tracing (if enabled) */
4268 mchunkptr p = mem2chunk(object_header);
4269 size_t psize = chunksize(p);
4271 mheap_put_trace ((u64)p_arg, psize);
4274 /* And free it... */
4275 mspace_free (msp, object_header);
4278 void mspace_put_no_offset (mspace msp, void *p_arg)
4280 mstate ms = (mstate)msp;
4284 mchunkptr p = mem2chunk(p_arg);
4285 size_t psize = chunksize(p);
4287 mheap_put_trace ((u64)p_arg, psize);
4289 mspace_free (msp, p_arg);
4292 size_t mspace_usable_size_with_delta (const void *p)
4295 char *object_header;
4298 /* Find the object header delta */
4299 wwp = (unsigned *)p;
4302 /* Recover the dlmalloc object pointer */
4303 object_header = (char *)wwp;
4304 object_header -= *wwp;
4306 usable_size = mspace_usable_size (object_header);
4307 /* account for the offset and the size of the offset... */
4308 usable_size -= (*wwp + sizeof (*wwp));
4313 mspace versions of routines are near-clones of the global
4314 versions. This is not so nice but better than the alternatives.
4317 void* mspace_malloc(mspace msp, size_t bytes) {
4318 mstate ms = (mstate)msp;
4319 if (!ok_magic(ms)) {
4320 USAGE_ERROR_ACTION(ms,ms);
4323 if (!PREACTION(ms)) {
4326 if (bytes <= MAX_SMALL_REQUEST) {
4329 nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes);
4330 idx = small_index(nb);
4331 smallbits = ms->smallmap >> idx;
4333 if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */
4335 idx += ~smallbits & 1; /* Uses next bin if idx empty */
4336 b = smallbin_at(ms, idx);
4338 assert(chunksize(p) == small_index2size(idx));
4339 unlink_first_small_chunk(ms, b, p, idx);
4340 set_inuse_and_pinuse(ms, p, small_index2size(idx));
4342 check_malloced_chunk(ms, mem, nb);
4346 else if (nb > ms->dvsize) {
4347 if (smallbits != 0) { /* Use chunk in next nonempty smallbin */
4351 binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx));
4352 binmap_t leastbit = least_bit(leftbits);
4353 compute_bit2idx(leastbit, i);
4354 b = smallbin_at(ms, i);
4356 assert(chunksize(p) == small_index2size(i));
4357 unlink_first_small_chunk(ms, b, p, i);
4358 rsize = small_index2size(i) - nb;
4359 /* Fit here cannot be remainderless if 4byte sizes */
4360 if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
4361 set_inuse_and_pinuse(ms, p, small_index2size(i));
4363 set_size_and_pinuse_of_inuse_chunk(ms, p, nb);
4364 r = chunk_plus_offset(p, nb);
4365 set_size_and_pinuse_of_free_chunk(r, rsize);
4366 replace_dv(ms, r, rsize);
4369 check_malloced_chunk(ms, mem, nb);
4373 else if (ms->treemap != 0 && (mem = tmalloc_small(ms, nb)) != 0) {
4374 check_malloced_chunk(ms, mem, nb);
4379 else if (bytes >= MAX_REQUEST)
4380 nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */
4382 nb = pad_request(bytes);
4383 if (ms->treemap != 0 && (mem = tmalloc_large(ms, nb)) != 0) {
4384 check_malloced_chunk(ms, mem, nb);
4389 if (nb <= ms->dvsize) {
4390 size_t rsize = ms->dvsize - nb;
4391 mchunkptr p = ms->dv;
4392 if (rsize >= MIN_CHUNK_SIZE) { /* split dv */
4393 mchunkptr r = ms->dv = chunk_plus_offset(p, nb);
4395 set_size_and_pinuse_of_free_chunk(r, rsize);
4396 set_size_and_pinuse_of_inuse_chunk(ms, p, nb);
4398 else { /* exhaust dv */
4399 size_t dvs = ms->dvsize;
4402 set_inuse_and_pinuse(ms, p, dvs);
4405 check_malloced_chunk(ms, mem, nb);
4409 else if (nb < ms->topsize) { /* Split top */
4410 size_t rsize = ms->topsize -= nb;
4411 mchunkptr p = ms->top;
4412 mchunkptr r = ms->top = chunk_plus_offset(p, nb);
4413 r->head = rsize | PINUSE_BIT;
4414 set_size_and_pinuse_of_inuse_chunk(ms, p, nb);
4416 check_top_chunk(ms, ms->top);
4417 check_malloced_chunk(ms, mem, nb);
4421 mem = sys_alloc(ms, nb);
4431 void mspace_free(mspace msp, void* mem) {
4433 mchunkptr p = mem2chunk(mem);
4435 mstate fm = get_mstate_for(p);
4436 (void)msp; /* placate people compiling -Wunused */
4438 mstate fm = (mstate)msp;
4439 #endif /* FOOTERS */
4440 if (!ok_magic(fm)) {
4441 USAGE_ERROR_ACTION(fm, p);
4444 if (!PREACTION(fm)) {
4445 check_inuse_chunk(fm, p);
4446 if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
4447 size_t psize = chunksize(p);
4448 mchunkptr next = chunk_plus_offset(p, psize);
4450 size_t prevsize = p->prev_foot;
4451 if (is_mmapped(p)) {
4452 psize += prevsize + MMAP_FOOT_PAD;
4453 if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
4454 fm->footprint -= psize;
4458 mchunkptr prev = chunk_minus_offset(p, prevsize);
4461 if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */
4463 unlink_chunk(fm, p, prevsize);
4465 else if ((next->head & INUSE_BITS) == INUSE_BITS) {
4467 set_free_with_pinuse(p, psize, next);
4476 if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) {
4477 if (!cinuse(next)) { /* consolidate forward */
4478 if (next == fm->top) {
4479 size_t tsize = fm->topsize += psize;
4481 p->head = tsize | PINUSE_BIT;
4486 if (should_trim(fm, tsize))
4490 else if (next == fm->dv) {
4491 size_t dsize = fm->dvsize += psize;
4493 set_size_and_pinuse_of_free_chunk(p, dsize);
4497 size_t nsize = chunksize(next);
4499 unlink_chunk(fm, next, nsize);
4500 set_size_and_pinuse_of_free_chunk(p, psize);
4508 set_free_with_pinuse(p, psize, next);
4510 if (is_small(psize)) {
4511 insert_small_chunk(fm, p, psize);
4512 check_free_chunk(fm, p);
4515 tchunkptr tp = (tchunkptr)p;
4516 insert_large_chunk(fm, tp, psize);
4517 check_free_chunk(fm, p);
4518 if (--fm->release_checks == 0)
4519 release_unused_segments(fm);
4525 USAGE_ERROR_ACTION(fm, p);
4532 void* mspace_calloc(mspace msp, size_t n_elements, size_t elem_size) {
4535 mstate ms = (mstate)msp;
4536 if (!ok_magic(ms)) {
4537 USAGE_ERROR_ACTION(ms,ms);
4540 if (n_elements != 0) {
4541 req = n_elements * elem_size;
4542 if (((n_elements | elem_size) & ~(size_t)0xffff) &&
4543 (req / n_elements != elem_size))
4544 req = MAX_SIZE_T; /* force downstream failure on overflow */
4546 mem = internal_malloc(ms, req);
4547 if (mem != 0 && calloc_must_clear(mem2chunk(mem)))
4548 memset(mem, 0, req);
4552 void* mspace_realloc(mspace msp, void* oldmem, size_t bytes) {
4555 mem = mspace_malloc(msp, bytes);
4557 else if (bytes >= MAX_REQUEST) {
4558 MALLOC_FAILURE_ACTION;
4560 #ifdef REALLOC_ZERO_BYTES_FREES
4561 else if (bytes == 0) {
4562 mspace_free(msp, oldmem);
4564 #endif /* REALLOC_ZERO_BYTES_FREES */
4566 size_t nb = request2size(bytes);
4567 mchunkptr oldp = mem2chunk(oldmem);
4569 mstate m = (mstate)msp;
4571 mstate m = get_mstate_for(oldp);
4573 USAGE_ERROR_ACTION(m, oldmem);
4576 #endif /* FOOTERS */
4577 if (!PREACTION(m)) {
4578 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 1);
4581 check_inuse_chunk(m, newp);
4582 mem = chunk2mem(newp);
4585 mem = mspace_malloc(m, bytes);
4587 size_t oc = chunksize(oldp) - overhead_for(oldp);
4588 memcpy(mem, oldmem, (oc < bytes)? oc : bytes);
4589 mspace_free(m, oldmem);
4597 void* mspace_realloc_in_place(mspace msp, void* oldmem, size_t bytes) {
4600 if (bytes >= MAX_REQUEST) {
4601 MALLOC_FAILURE_ACTION;
4604 size_t nb = request2size(bytes);
4605 mchunkptr oldp = mem2chunk(oldmem);
4607 mstate m = (mstate)msp;
4609 mstate m = get_mstate_for(oldp);
4610 (void)msp; /* placate people compiling -Wunused */
4612 USAGE_ERROR_ACTION(m, oldmem);
4615 #endif /* FOOTERS */
4616 if (!PREACTION(m)) {
4617 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 0);
4620 check_inuse_chunk(m, newp);
4629 void* mspace_memalign(mspace msp, size_t alignment, size_t bytes) {
4630 mstate ms = (mstate)msp;
4631 if (!ok_magic(ms)) {
4632 USAGE_ERROR_ACTION(ms,ms);
4635 if (alignment <= MALLOC_ALIGNMENT)
4636 return mspace_malloc(msp, bytes);
4637 return internal_memalign(ms, alignment, bytes);
4640 void** mspace_independent_calloc(mspace msp, size_t n_elements,
4641 size_t elem_size, void* chunks[]) {
4642 size_t sz = elem_size; /* serves as 1-element array */
4643 mstate ms = (mstate)msp;
4644 if (!ok_magic(ms)) {
4645 USAGE_ERROR_ACTION(ms,ms);
4648 return ialloc(ms, n_elements, &sz, 3, chunks);
4651 void** mspace_independent_comalloc(mspace msp, size_t n_elements,
4652 size_t sizes[], void* chunks[]) {
4653 mstate ms = (mstate)msp;
4654 if (!ok_magic(ms)) {
4655 USAGE_ERROR_ACTION(ms,ms);
4658 return ialloc(ms, n_elements, sizes, 0, chunks);
4661 size_t mspace_bulk_free(mspace msp, void* array[], size_t nelem) {
4662 return internal_bulk_free((mstate)msp, array, nelem);
4665 #if MALLOC_INSPECT_ALL
4666 void mspace_inspect_all(mspace msp,
4667 void(*handler)(void *start,
4670 void* callback_arg),
4672 mstate ms = (mstate)msp;
4674 if (!PREACTION(ms)) {
4675 internal_inspect_all(ms, handler, arg);
4680 USAGE_ERROR_ACTION(ms,ms);
4683 #endif /* MALLOC_INSPECT_ALL */
4685 int mspace_trim(mspace msp, size_t pad) {
4687 mstate ms = (mstate)msp;
4689 if (!PREACTION(ms)) {
4690 result = sys_trim(ms, pad);
4695 USAGE_ERROR_ACTION(ms,ms);
4700 #if !NO_MALLOC_STATS
4701 void mspace_malloc_stats(mspace msp) {
4702 mstate ms = (mstate)msp;
4704 internal_malloc_stats(ms);
4707 USAGE_ERROR_ACTION(ms,ms);
4710 #endif /* NO_MALLOC_STATS */
4712 size_t mspace_footprint(mspace msp) {
4714 mstate ms = (mstate)msp;
4716 result = ms->footprint;
4719 USAGE_ERROR_ACTION(ms,ms);
4724 size_t mspace_max_footprint(mspace msp) {
4726 mstate ms = (mstate)msp;
4728 result = ms->max_footprint;
4731 USAGE_ERROR_ACTION(ms,ms);
4736 size_t mspace_footprint_limit(mspace msp) {
4738 mstate ms = (mstate)msp;
4740 size_t maf = ms->footprint_limit;
4741 result = (maf == 0) ? MAX_SIZE_T : maf;
4744 USAGE_ERROR_ACTION(ms,ms);
4749 size_t mspace_set_footprint_limit(mspace msp, size_t bytes) {
4751 mstate ms = (mstate)msp;
4754 result = granularity_align(1); /* Use minimal size */
4755 if (bytes == MAX_SIZE_T)
4756 result = 0; /* disable */
4758 result = granularity_align(bytes);
4759 ms->footprint_limit = result;
4762 USAGE_ERROR_ACTION(ms,ms);
4768 struct mallinfo mspace_mallinfo(mspace msp) {
4769 mstate ms = (mstate)msp;
4770 if (!ok_magic(ms)) {
4771 USAGE_ERROR_ACTION(ms,ms);
4773 return internal_mallinfo(ms);
4775 #endif /* NO_MALLINFO */
4777 size_t mspace_usable_size(const void* mem) {
4779 mchunkptr p = mem2chunk(mem);
4781 return chunksize(p) - overhead_for(p);
4786 int mspace_mallopt(int param_number, int value) {
4787 return change_mparam(param_number, value);
4790 #endif /* MSPACES */
4793 /* -------------------- Alternative MORECORE functions ------------------- */
4796 Guidelines for creating a custom version of MORECORE:
4798 * For best performance, MORECORE should allocate in multiples of pagesize.
4799 * MORECORE may allocate more memory than requested. (Or even less,
4800 but this will usually result in a malloc failure.)
4801 * MORECORE must not allocate memory when given argument zero, but
4802 instead return one past the end address of memory from previous
4804 * For best performance, consecutive calls to MORECORE with positive
4805 arguments should return increasing addresses, indicating that
4806 space has been contiguously extended.
4807 * Even though consecutive calls to MORECORE need not return contiguous
4808 addresses, it must be OK for malloc'ed chunks to span multiple
4809 regions in those cases where they do happen to be contiguous.
4810 * MORECORE need not handle negative arguments -- it may instead
4811 just return MFAIL when given negative arguments.
4812 Negative arguments are always multiples of pagesize. MORECORE
4813 must not misinterpret negative args as large positive unsigned
4814 args. You can suppress all such calls from even occurring by defining
4815 MORECORE_CANNOT_TRIM,
4817 As an example alternative MORECORE, here is a custom allocator
4818 kindly contributed for pre-OSX macOS. It uses virtually but not
4819 necessarily physically contiguous non-paged memory (locked in,
4820 present and won't get swapped out). You can use it by uncommenting
4821 this section, adding some #includes, and setting up the appropriate
4824 #define MORECORE osMoreCore
4826 There is also a shutdown routine that should somehow be called for
4827 cleanup upon program exit.
4829 #define MAX_POOL_ENTRIES 100
4830 #define MINIMUM_MORECORE_SIZE (64 * 1024U)
4831 static int next_os_pool;
4832 void *our_os_pools[MAX_POOL_ENTRIES];
4834 void *osMoreCore(int size)
4837 static void *sbrk_top = 0;
4841 if (size < MINIMUM_MORECORE_SIZE)
4842 size = MINIMUM_MORECORE_SIZE;
4843 if (CurrentExecutionLevel() == kTaskLevel)
4844 ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
4847 return (void *) MFAIL;
4849 // save ptrs so they can be freed during cleanup
4850 our_os_pools[next_os_pool] = ptr;
4852 ptr = (void *) ((((size_t) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
4853 sbrk_top = (char *) ptr + size;
4858 // we don't currently support shrink behavior
4859 return (void *) MFAIL;
4867 // cleanup any allocated memory pools
4868 // called as last thing before shutting down driver
4870 void osCleanupMem(void)
4874 for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
4877 PoolDeallocate(*ptr);
4885 /* -----------------------------------------------------------------------
4887 v2.8.6 Wed Aug 29 06:57:58 2012 Doug Lea
4888 * fix bad comparison in dlposix_memalign
4889 * don't reuse adjusted asize in sys_alloc
4890 * add LOCK_AT_FORK -- thanks to Kirill Artamonov for the suggestion
4891 * reduce compiler warnings -- thanks to all who reported/suggested these
4893 v2.8.5 Sun May 22 10:26:02 2011 Doug Lea (dl at gee)
4894 * Always perform unlink checks unless INSECURE
4895 * Add posix_memalign.
4896 * Improve realloc to expand in more cases; expose realloc_in_place.
4897 Thanks to Peter Buhr for the suggestion.
4898 * Add footprint_limit, inspect_all, bulk_free. Thanks
4899 to Barry Hayes and others for the suggestions.
4900 * Internal refactorings to avoid calls while holding locks
4901 * Use non-reentrant locks by default. Thanks to Roland McGrath
4903 * Small fixes to mspace_destroy, reset_on_error.
4904 * Various configuration extensions/changes. Thanks
4905 to all who contributed these.
4907 V2.8.4a Thu Apr 28 14:39:43 2011 (dl at gee.cs.oswego.edu)
4908 * Update Creative Commons URL
4910 V2.8.4 Wed May 27 09:56:23 2009 Doug Lea (dl at gee)
4911 * Use zeros instead of prev foot for is_mmapped
4912 * Add mspace_track_large_chunks; thanks to Jean Brouwers
4913 * Fix set_inuse in internal_realloc; thanks to Jean Brouwers
4914 * Fix insufficient sys_alloc padding when using 16byte alignment
4915 * Fix bad error check in mspace_footprint
4916 * Adaptations for ptmalloc; thanks to Wolfram Gloger.
4917 * Reentrant spin locks; thanks to Earl Chew and others
4918 * Win32 improvements; thanks to Niall Douglas and Earl Chew
4919 * Add NO_SEGMENT_TRAVERSAL and MAX_RELEASE_CHECK_RATE options
4920 * Extension hook in malloc_state
4921 * Various small adjustments to reduce warnings on some compilers
4922 * Various configuration extensions/changes for more platforms. Thanks
4923 to all who contributed these.
4925 V2.8.3 Thu Sep 22 11:16:32 2005 Doug Lea (dl at gee)
4926 * Add max_footprint functions
4927 * Ensure all appropriate literals are size_t
4928 * Fix conditional compilation problem for some #define settings
4929 * Avoid concatenating segments with the one provided
4930 in create_mspace_with_base
4931 * Rename some variables to avoid compiler shadowing warnings
4932 * Use explicit lock initialization.
4933 * Better handling of sbrk interference.
4934 * Simplify and fix segment insertion, trimming and mspace_destroy
4935 * Reinstate REALLOC_ZERO_BYTES_FREES option from 2.7.x
4936 * Thanks especially to Dennis Flanagan for help on these.
4938 V2.8.2 Sun Jun 12 16:01:10 2005 Doug Lea (dl at gee)
4939 * Fix memalign brace error.
4941 V2.8.1 Wed Jun 8 16:11:46 2005 Doug Lea (dl at gee)
4942 * Fix improper #endif nesting in C++
4943 * Add explicit casts needed for C++
4945 V2.8.0 Mon May 30 14:09:02 2005 Doug Lea (dl at gee)
4946 * Use trees for large bins
4948 * Use segments to unify sbrk-based and mmap-based system allocation,
4949 removing need for emulation on most platforms without sbrk.
4950 * Default safety checks
4951 * Optional footer checks. Thanks to William Robertson for the idea.
4952 * Internal code refactoring
4953 * Incorporate suggestions and platform-specific changes.
4954 Thanks to Dennis Flanagan, Colin Plumb, Niall Douglas,
4955 Aaron Bachmann, Emery Berger, and others.
4956 * Speed up non-fastbin processing enough to remove fastbins.
4957 * Remove useless cfree() to avoid conflicts with other apps.
4958 * Remove internal memcpy, memset. Compilers handle builtins better.
4959 * Remove some options that no one ever used and rename others.
4961 V2.7.2 Sat Aug 17 09:07:30 2002 Doug Lea (dl at gee)
4962 * Fix malloc_state bitmap array misdeclaration
4964 V2.7.1 Thu Jul 25 10:58:03 2002 Doug Lea (dl at gee)
4965 * Allow tuning of FIRST_SORTED_BIN_SIZE
4966 * Use PTR_UINT as type for all ptr->int casts. Thanks to John Belmonte.
4967 * Better detection and support for non-contiguousness of MORECORE.
4968 Thanks to Andreas Mueller, Conal Walsh, and Wolfram Gloger
4969 * Bypass most of malloc if no frees. Thanks To Emery Berger.
4970 * Fix freeing of old top non-contiguous chunk im sysmalloc.
4971 * Raised default trim and map thresholds to 256K.
4972 * Fix mmap-related #defines. Thanks to Lubos Lunak.
4973 * Fix copy macros; added LACKS_FCNTL_H. Thanks to Neal Walfield.
4974 * Branch-free bin calculation
4975 * Default trim and mmap thresholds now 256K.
4977 V2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
4978 * Introduce independent_comalloc and independent_calloc.
4979 Thanks to Michael Pachos for motivation and help.
4980 * Make optional .h file available
4981 * Allow > 2GB requests on 32bit systems.
4982 * new WIN32 sbrk, mmap, munmap, lock code from <Walter@GeNeSys-e.de>.
4983 Thanks also to Andreas Mueller <a.mueller at paradatec.de>,
4985 * Allow override of MALLOC_ALIGNMENT (Thanks to Ruud Waij for
4987 * memalign: check alignment arg
4988 * realloc: don't try to shift chunks backwards, since this
4989 leads to more fragmentation in some programs and doesn't
4990 seem to help in any others.
4991 * Collect all cases in malloc requiring system memory into sysmalloc
4992 * Use mmap as backup to sbrk
4993 * Place all internal state in malloc_state
4994 * Introduce fastbins (although similar to 2.5.1)
4995 * Many minor tunings and cosmetic improvements
4996 * Introduce USE_PUBLIC_MALLOC_WRAPPERS, USE_MALLOC_LOCK
4997 * Introduce MALLOC_FAILURE_ACTION, MORECORE_CONTIGUOUS
4998 Thanks to Tony E. Bennett <tbennett@nvidia.com> and others.
4999 * Include errno.h to support default failure action.
5001 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee)
5002 * return null for negative arguments
5003 * Added Several WIN32 cleanups from Martin C. Fong <mcfong at yahoo.com>
5004 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
5005 (e.g. WIN32 platforms)
5006 * Cleanup header file inclusion for WIN32 platforms
5007 * Cleanup code to avoid Microsoft Visual C++ compiler complaints
5008 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
5009 memory allocation routines
5010 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
5011 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
5012 usage of 'assert' in non-WIN32 code
5013 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
5015 * Always call 'fREe()' rather than 'free()'
5017 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)
5018 * Fixed ordering problem with boundary-stamping
5020 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
5021 * Added pvalloc, as recommended by H.J. Liu
5022 * Added 64bit pointer support mainly from Wolfram Gloger
5023 * Added anonymously donated WIN32 sbrk emulation
5024 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
5025 * malloc_extend_top: fix mask error that caused wastage after
5027 * Add linux mremap support code from HJ Liu
5029 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
5030 * Integrated most documentation with the code.
5031 * Add support for mmap, with help from
5032 Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
5033 * Use last_remainder in more cases.
5034 * Pack bins using idea from colin@nyx10.cs.du.edu
5035 * Use ordered bins instead of best-fit threshhold
5036 * Eliminate block-local decls to simplify tracing and debugging.
5037 * Support another case of realloc via move into top
5038 * Fix error occuring when initial sbrk_base not word-aligned.
5039 * Rely on page size for units instead of SBRK_UNIT to
5040 avoid surprises about sbrk alignment conventions.
5041 * Add mallinfo, mallopt. Thanks to Raymond Nijssen
5042 (raymond@es.ele.tue.nl) for the suggestion.
5043 * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
5044 * More precautions for cases where other routines call sbrk,
5045 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
5046 * Added macros etc., allowing use in linux libc from
5047 H.J. Lu (hjl@gnu.ai.mit.edu)
5048 * Inverted this history list
5050 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
5051 * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
5052 * Removed all preallocation code since under current scheme
5053 the work required to undo bad preallocations exceeds
5054 the work saved in good cases for most test programs.
5055 * No longer use return list or unconsolidated bins since
5056 no scheme using them consistently outperforms those that don't
5057 given above changes.
5058 * Use best fit for very large chunks to prevent some worst-cases.
5059 * Added some support for debugging
5061 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
5062 * Removed footers when chunks are in use. Thanks to
5063 Paul Wilson (wilson@cs.texas.edu) for the suggestion.
5065 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
5066 * Added malloc_trim, with help from Wolfram Gloger
5067 (wmglo@Dent.MED.Uni-Muenchen.DE).
5069 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
5071 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
5072 * realloc: try to expand in both directions
5073 * malloc: swap order of clean-bin strategy;
5074 * realloc: only conditionally expand backwards
5075 * Try not to scavenge used bins
5076 * Use bin counts as a guide to preallocation
5077 * Occasionally bin return list chunks in first scan
5078 * Add a few optimizations from colin@nyx10.cs.du.edu
5080 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
5081 * faster bin computation & slightly different binning
5082 * merged all consolidations to one part of malloc proper
5083 (eliminating old malloc_find_space & malloc_clean_bin)
5084 * Scan 2 returns chunks (not just 1)
5085 * Propagate failure in realloc if malloc returns 0
5086 * Add stuff to allow compilation on non-ANSI compilers
5087 from kpv@research.att.com
5089 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
5090 * removed potential for odd address access in prev_chunk
5091 * removed dependency on getpagesize.h
5092 * misc cosmetics and a bit more internal documentation
5093 * anticosmetics: mangled names in macros to evade debugger strangeness
5094 * tested on sparc, hp-700, dec-mips, rs6000
5095 with gcc & native cc (hp, dec only) allowing
5096 Detlefs & Zorn comparison study (in SIGPLAN Notices.)
5098 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
5099 * Based loosely on libg++-1.2X malloc. (It retains some of the overall
5100 structure of old version, but most details differ.)