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);
1750 unsigned char buf[sizeof(size_t)];
1751 /* Try to use /dev/urandom, else fall back on using time */
1752 if ((fd = open("/dev/urandom", O_RDONLY)) >= 0 &&
1753 read(fd, buf, sizeof(buf)) == sizeof(buf)) {
1754 magic = *((size_t *) buf);
1758 #endif /* USE_DEV_RANDOM */
1760 magic = (size_t)(GetTickCount() ^ (size_t)0x55555555U);
1761 #elif defined(LACKS_TIME_H)
1762 magic = (size_t)&magic ^ (size_t)0x55555555U;
1764 magic = (size_t)(time(0) ^ (size_t)0x55555555U);
1766 magic |= (size_t)8U; /* ensure nonzero */
1767 magic &= ~(size_t)7U; /* improve chances of fault for bad values */
1768 /* Until memory modes commonly available, use volatile-write */
1769 (*(volatile size_t *)(&(mparams.magic))) = magic;
1773 RELEASE_MALLOC_GLOBAL_LOCK();
1777 /* support for mallopt */
1778 static int change_mparam(int param_number, int value) {
1780 ensure_initialization();
1781 val = (value == -1)? MAX_SIZE_T : (size_t)value;
1782 switch(param_number) {
1783 case M_TRIM_THRESHOLD:
1784 mparams.trim_threshold = val;
1787 if (val >= mparams.page_size && ((val & (val-1)) == 0)) {
1788 mparams.granularity = val;
1793 case M_MMAP_THRESHOLD:
1794 mparams.mmap_threshold = val;
1802 /* ------------------------- Debugging Support --------------------------- */
1804 /* Check properties of any chunk, whether free, inuse, mmapped etc */
1805 static void do_check_any_chunk(mstate m, mchunkptr p) {
1806 assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
1807 assert(ok_address(m, p));
1810 /* Check properties of top chunk */
1811 static void do_check_top_chunk(mstate m, mchunkptr p) {
1812 msegmentptr sp = segment_holding(m, (char*)p);
1813 size_t sz = p->head & ~INUSE_BITS; /* third-lowest bit can be set! */
1815 assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
1816 assert(ok_address(m, p));
1817 assert(sz == m->topsize);
1819 assert(sz == ((sp->base + sp->size) - (char*)p) - TOP_FOOT_SIZE);
1821 assert(!pinuse(chunk_plus_offset(p, sz)));
1824 /* Check properties of (inuse) mmapped chunks */
1825 static void do_check_mmapped_chunk(mstate m, mchunkptr p) {
1826 size_t sz = chunksize(p);
1827 size_t len = (sz + (p->prev_foot) + MMAP_FOOT_PAD);
1828 assert(is_mmapped(p));
1829 assert(use_mmap(m));
1830 assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
1831 assert(ok_address(m, p));
1832 assert(!is_small(sz));
1833 assert((len & (mparams.page_size-SIZE_T_ONE)) == 0);
1834 assert(chunk_plus_offset(p, sz)->head == FENCEPOST_HEAD);
1835 assert(chunk_plus_offset(p, sz+SIZE_T_SIZE)->head == 0);
1838 /* Check properties of inuse chunks */
1839 static void do_check_inuse_chunk(mstate m, mchunkptr p) {
1840 do_check_any_chunk(m, p);
1841 assert(is_inuse(p));
1842 assert(next_pinuse(p));
1843 /* If not pinuse and not mmapped, previous chunk has OK offset */
1844 assert(is_mmapped(p) || pinuse(p) || next_chunk(prev_chunk(p)) == p);
1846 do_check_mmapped_chunk(m, p);
1849 /* Check properties of free chunks */
1850 static void do_check_free_chunk(mstate m, mchunkptr p) {
1851 size_t sz = chunksize(p);
1852 mchunkptr next = chunk_plus_offset(p, sz);
1853 do_check_any_chunk(m, p);
1854 assert(!is_inuse(p));
1855 assert(!next_pinuse(p));
1856 assert (!is_mmapped(p));
1857 if (p != m->dv && p != m->top) {
1858 if (sz >= MIN_CHUNK_SIZE) {
1859 assert((sz & CHUNK_ALIGN_MASK) == 0);
1860 assert(is_aligned(chunk2mem(p)));
1861 assert(next->prev_foot == sz);
1863 assert (next == m->top || is_inuse(next));
1864 assert(p->fd->bk == p);
1865 assert(p->bk->fd == p);
1867 else /* markers are always of size SIZE_T_SIZE */
1868 assert(sz == SIZE_T_SIZE);
1872 /* Check properties of malloced chunks at the point they are malloced */
1873 static void do_check_malloced_chunk(mstate m, void* mem, size_t s) {
1875 mchunkptr p = mem2chunk(mem);
1876 size_t sz = p->head & ~INUSE_BITS;
1877 do_check_inuse_chunk(m, p);
1878 assert((sz & CHUNK_ALIGN_MASK) == 0);
1879 assert(sz >= MIN_CHUNK_SIZE);
1881 /* unless mmapped, size is less than MIN_CHUNK_SIZE more than request */
1882 assert(is_mmapped(p) || sz < (s + MIN_CHUNK_SIZE));
1886 /* Check a tree and its subtrees. */
1887 static void do_check_tree(mstate m, tchunkptr t) {
1890 bindex_t tindex = t->index;
1891 size_t tsize = chunksize(t);
1893 compute_tree_index(tsize, idx);
1894 assert(tindex == idx);
1895 assert(tsize >= MIN_LARGE_SIZE);
1896 assert(tsize >= minsize_for_tree_index(idx));
1897 assert((idx == NTREEBINS-1) || (tsize < minsize_for_tree_index((idx+1))));
1899 do { /* traverse through chain of same-sized nodes */
1900 do_check_any_chunk(m, ((mchunkptr)u));
1901 assert(u->index == tindex);
1902 assert(chunksize(u) == tsize);
1903 assert(!is_inuse(u));
1904 assert(!next_pinuse(u));
1905 assert(u->fd->bk == u);
1906 assert(u->bk->fd == u);
1907 if (u->parent == 0) {
1908 assert(u->child[0] == 0);
1909 assert(u->child[1] == 0);
1912 assert(head == 0); /* only one node on chain has parent */
1914 assert(u->parent != u);
1915 assert (u->parent->child[0] == u ||
1916 u->parent->child[1] == u ||
1917 *((tbinptr*)(u->parent)) == u);
1918 if (u->child[0] != 0) {
1919 assert(u->child[0]->parent == u);
1920 assert(u->child[0] != u);
1921 do_check_tree(m, u->child[0]);
1923 if (u->child[1] != 0) {
1924 assert(u->child[1]->parent == u);
1925 assert(u->child[1] != u);
1926 do_check_tree(m, u->child[1]);
1928 if (u->child[0] != 0 && u->child[1] != 0) {
1929 assert(chunksize(u->child[0]) < chunksize(u->child[1]));
1937 /* Check all the chunks in a treebin. */
1938 static void do_check_treebin(mstate m, bindex_t i) {
1939 tbinptr* tb = treebin_at(m, i);
1941 int empty = (m->treemap & (1U << i)) == 0;
1945 do_check_tree(m, t);
1948 /* Check all the chunks in a smallbin. */
1949 static void do_check_smallbin(mstate m, bindex_t i) {
1950 sbinptr b = smallbin_at(m, i);
1951 mchunkptr p = b->bk;
1952 unsigned int empty = (m->smallmap & (1U << i)) == 0;
1956 for (; p != b; p = p->bk) {
1957 size_t size = chunksize(p);
1959 /* each chunk claims to be free */
1960 do_check_free_chunk(m, p);
1961 /* chunk belongs in bin */
1962 assert(small_index(size) == i);
1963 assert(p->bk == b || chunksize(p->bk) == chunksize(p));
1964 /* chunk is followed by an inuse chunk */
1966 if (q->head != FENCEPOST_HEAD)
1967 do_check_inuse_chunk(m, q);
1972 /* Find x in a bin. Used in other check functions. */
1973 static int bin_find(mstate m, mchunkptr x) {
1974 size_t size = chunksize(x);
1975 if (is_small(size)) {
1976 bindex_t sidx = small_index(size);
1977 sbinptr b = smallbin_at(m, sidx);
1978 if (smallmap_is_marked(m, sidx)) {
1983 } while ((p = p->fd) != b);
1988 compute_tree_index(size, tidx);
1989 if (treemap_is_marked(m, tidx)) {
1990 tchunkptr t = *treebin_at(m, tidx);
1991 size_t sizebits = size << leftshift_for_tree_index(tidx);
1992 while (t != 0 && chunksize(t) != size) {
1993 t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1];
1999 if (u == (tchunkptr)x)
2001 } while ((u = u->fd) != t);
2008 /* Traverse each chunk and check it; return total */
2009 static size_t traverse_and_check(mstate m) {
2011 if (is_initialized(m)) {
2012 msegmentptr s = &m->seg;
2013 sum += m->topsize + TOP_FOOT_SIZE;
2015 mchunkptr q = align_as_chunk(s->base);
2016 mchunkptr lastq = 0;
2018 while (segment_holds(s, q) &&
2019 q != m->top && q->head != FENCEPOST_HEAD) {
2020 sum += chunksize(q);
2022 assert(!bin_find(m, q));
2023 do_check_inuse_chunk(m, q);
2026 assert(q == m->dv || bin_find(m, q));
2027 assert(lastq == 0 || is_inuse(lastq)); /* Not 2 consecutive free */
2028 do_check_free_chunk(m, q);
2040 /* Check all properties of malloc_state. */
2041 static void do_check_malloc_state(mstate m) {
2045 for (i = 0; i < NSMALLBINS; ++i)
2046 do_check_smallbin(m, i);
2047 for (i = 0; i < NTREEBINS; ++i)
2048 do_check_treebin(m, i);
2050 if (m->dvsize != 0) { /* check dv chunk */
2051 do_check_any_chunk(m, m->dv);
2052 assert(m->dvsize == chunksize(m->dv));
2053 assert(m->dvsize >= MIN_CHUNK_SIZE);
2054 assert(bin_find(m, m->dv) == 0);
2057 if (m->top != 0) { /* check top chunk */
2058 do_check_top_chunk(m, m->top);
2059 /*assert(m->topsize == chunksize(m->top)); redundant */
2060 assert(m->topsize > 0);
2061 assert(bin_find(m, m->top) == 0);
2064 total = traverse_and_check(m);
2065 assert(total <= m->footprint);
2066 assert(m->footprint <= m->max_footprint);
2070 /* ----------------------------- statistics ------------------------------ */
2073 static struct mallinfo internal_mallinfo(mstate m) {
2074 struct mallinfo nm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
2075 ensure_initialization();
2076 if (!PREACTION(m)) {
2077 check_malloc_state(m);
2078 if (is_initialized(m)) {
2079 size_t nfree = SIZE_T_ONE; /* top always free */
2080 size_t mfree = m->topsize + TOP_FOOT_SIZE;
2082 msegmentptr s = &m->seg;
2084 mchunkptr q = align_as_chunk(s->base);
2085 while (segment_holds(s, q) &&
2086 q != m->top && q->head != FENCEPOST_HEAD) {
2087 size_t sz = chunksize(q);
2100 nm.hblkhd = m->footprint - sum;
2101 nm.usmblks = m->max_footprint;
2102 nm.uordblks = m->footprint - mfree;
2103 nm.fordblks = mfree;
2104 nm.keepcost = m->topsize;
2111 #endif /* !NO_MALLINFO */
2113 #if !NO_MALLOC_STATS
2114 static void internal_malloc_stats(mstate m) {
2115 ensure_initialization();
2116 if (!PREACTION(m)) {
2120 check_malloc_state(m);
2121 if (is_initialized(m)) {
2122 msegmentptr s = &m->seg;
2123 maxfp = m->max_footprint;
2125 used = fp - (m->topsize + TOP_FOOT_SIZE);
2128 mchunkptr q = align_as_chunk(s->base);
2129 while (segment_holds(s, q) &&
2130 q != m->top && q->head != FENCEPOST_HEAD) {
2132 used -= chunksize(q);
2138 POSTACTION(m); /* drop lock */
2139 fprintf(stderr, "max system bytes = %10lu\n", (unsigned long)(maxfp));
2140 fprintf(stderr, "system bytes = %10lu\n", (unsigned long)(fp));
2141 fprintf(stderr, "in use bytes = %10lu\n", (unsigned long)(used));
2144 #endif /* NO_MALLOC_STATS */
2146 /* ----------------------- Operations on smallbins ----------------------- */
2149 Various forms of linking and unlinking are defined as macros. Even
2150 the ones for trees, which are very long but have very short typical
2151 paths. This is ugly but reduces reliance on inlining support of
2155 /* Link a free chunk into a smallbin */
2156 #define insert_small_chunk(M, P, S) {\
2157 bindex_t I = small_index(S);\
2158 mchunkptr B = smallbin_at(M, I);\
2160 assert(S >= MIN_CHUNK_SIZE);\
2161 if (!smallmap_is_marked(M, I))\
2162 mark_smallmap(M, I);\
2163 else if (RTCHECK(ok_address(M, B->fd)))\
2166 CORRUPTION_ERROR_ACTION(M);\
2174 /* Unlink a chunk from a smallbin */
2175 #define unlink_small_chunk(M, P, S) {\
2176 mchunkptr F = P->fd;\
2177 mchunkptr B = P->bk;\
2178 bindex_t I = small_index(S);\
2181 assert(chunksize(P) == small_index2size(I));\
2182 if (RTCHECK(F == smallbin_at(M,I) || (ok_address(M, F) && F->bk == P))) { \
2184 clear_smallmap(M, I);\
2186 else if (RTCHECK(B == smallbin_at(M,I) ||\
2187 (ok_address(M, B) && B->fd == P))) {\
2192 CORRUPTION_ERROR_ACTION(M);\
2196 CORRUPTION_ERROR_ACTION(M);\
2200 /* Unlink the first chunk from a smallbin */
2201 #define unlink_first_small_chunk(M, B, P, I) {\
2202 mchunkptr F = P->fd;\
2205 assert(chunksize(P) == small_index2size(I));\
2207 clear_smallmap(M, I);\
2209 else if (RTCHECK(ok_address(M, F) && F->bk == P)) {\
2214 CORRUPTION_ERROR_ACTION(M);\
2218 /* Replace dv node, binning the old one */
2219 /* Used only when dvsize known to be small */
2220 #define replace_dv(M, P, S) {\
2221 size_t DVS = M->dvsize;\
2222 assert(is_small(DVS));\
2224 mchunkptr DV = M->dv;\
2225 insert_small_chunk(M, DV, DVS);\
2231 /* ------------------------- Operations on trees ------------------------- */
2233 /* Insert chunk into tree */
2234 #define insert_large_chunk(M, X, S) {\
2237 compute_tree_index(S, I);\
2238 H = treebin_at(M, I);\
2240 X->child[0] = X->child[1] = 0;\
2241 if (!treemap_is_marked(M, I)) {\
2242 mark_treemap(M, I);\
2244 X->parent = (tchunkptr)H;\
2249 size_t K = S << leftshift_for_tree_index(I);\
2251 if (chunksize(T) != S) {\
2252 tchunkptr* C = &(T->child[(K >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]);\
2256 else if (RTCHECK(ok_address(M, C))) {\
2263 CORRUPTION_ERROR_ACTION(M);\
2268 tchunkptr F = T->fd;\
2269 if (RTCHECK(ok_address(M, T) && ok_address(M, F))) {\
2277 CORRUPTION_ERROR_ACTION(M);\
2288 1. If x is a chained node, unlink it from its same-sized fd/bk links
2289 and choose its bk node as its replacement.
2290 2. If x was the last node of its size, but not a leaf node, it must
2291 be replaced with a leaf node (not merely one with an open left or
2292 right), to make sure that lefts and rights of descendents
2293 correspond properly to bit masks. We use the rightmost descendent
2294 of x. We could use any other leaf, but this is easy to locate and
2295 tends to counteract removal of leftmosts elsewhere, and so keeps
2296 paths shorter than minimally guaranteed. This doesn't loop much
2297 because on average a node in a tree is near the bottom.
2298 3. If x is the base of a chain (i.e., has parent links) relink
2299 x's parent and children to x's replacement (or null if none).
2302 #define unlink_large_chunk(M, X) {\
2303 tchunkptr XP = X->parent;\
2306 tchunkptr F = X->fd;\
2308 if (RTCHECK(ok_address(M, F) && F->bk == X && R->fd == X)) {\
2313 CORRUPTION_ERROR_ACTION(M);\
2318 if (((R = *(RP = &(X->child[1]))) != 0) ||\
2319 ((R = *(RP = &(X->child[0]))) != 0)) {\
2321 while ((*(CP = &(R->child[1])) != 0) ||\
2322 (*(CP = &(R->child[0])) != 0)) {\
2325 if (RTCHECK(ok_address(M, RP)))\
2328 CORRUPTION_ERROR_ACTION(M);\
2333 tbinptr* H = treebin_at(M, X->index);\
2335 if ((*H = R) == 0) \
2336 clear_treemap(M, X->index);\
2338 else if (RTCHECK(ok_address(M, XP))) {\
2339 if (XP->child[0] == X) \
2345 CORRUPTION_ERROR_ACTION(M);\
2347 if (RTCHECK(ok_address(M, R))) {\
2350 if ((C0 = X->child[0]) != 0) {\
2351 if (RTCHECK(ok_address(M, C0))) {\
2356 CORRUPTION_ERROR_ACTION(M);\
2358 if ((C1 = X->child[1]) != 0) {\
2359 if (RTCHECK(ok_address(M, C1))) {\
2364 CORRUPTION_ERROR_ACTION(M);\
2368 CORRUPTION_ERROR_ACTION(M);\
2373 /* Relays to large vs small bin operations */
2375 #define insert_chunk(M, P, S)\
2376 if (is_small(S)) insert_small_chunk(M, P, S)\
2377 else { tchunkptr TP = (tchunkptr)(P); insert_large_chunk(M, TP, S); }
2379 #define unlink_chunk(M, P, S)\
2380 if (is_small(S)) unlink_small_chunk(M, P, S)\
2381 else { tchunkptr TP = (tchunkptr)(P); unlink_large_chunk(M, TP); }
2384 /* Relays to internal calls to malloc/free from realloc, memalign etc */
2387 #define internal_malloc(m, b) mspace_malloc(m, b)
2388 #define internal_free(m, mem) mspace_free(m,mem);
2389 #else /* ONLY_MSPACES */
2391 #define internal_malloc(m, b)\
2392 ((m == gm)? dlmalloc(b) : mspace_malloc(m, b))
2393 #define internal_free(m, mem)\
2394 if (m == gm) dlfree(mem); else mspace_free(m,mem);
2396 #define internal_malloc(m, b) dlmalloc(b)
2397 #define internal_free(m, mem) dlfree(mem)
2398 #endif /* MSPACES */
2399 #endif /* ONLY_MSPACES */
2401 /* ----------------------- Direct-mmapping chunks ----------------------- */
2404 Directly mmapped chunks are set up with an offset to the start of
2405 the mmapped region stored in the prev_foot field of the chunk. This
2406 allows reconstruction of the required argument to MUNMAP when freed,
2407 and also allows adjustment of the returned chunk to meet alignment
2408 requirements (especially in memalign).
2411 /* Malloc using mmap */
2412 static void* mmap_alloc(mstate m, size_t nb) {
2413 size_t mmsize = mmap_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
2414 if (m->footprint_limit != 0) {
2415 size_t fp = m->footprint + mmsize;
2416 if (fp <= m->footprint || fp > m->footprint_limit)
2419 if (mmsize > nb) { /* Check for wrap around 0 */
2420 char* mm = (char*)(CALL_DIRECT_MMAP(mmsize));
2422 size_t offset = align_offset(chunk2mem(mm));
2423 size_t psize = mmsize - offset - MMAP_FOOT_PAD;
2424 mchunkptr p = (mchunkptr)(mm + offset);
2425 p->prev_foot = offset;
2427 mark_inuse_foot(m, p, psize);
2428 chunk_plus_offset(p, psize)->head = FENCEPOST_HEAD;
2429 chunk_plus_offset(p, psize+SIZE_T_SIZE)->head = 0;
2431 if (m->least_addr == 0 || mm < m->least_addr)
2433 if ((m->footprint += mmsize) > m->max_footprint)
2434 m->max_footprint = m->footprint;
2435 assert(is_aligned(chunk2mem(p)));
2436 check_mmapped_chunk(m, p);
2437 return chunk2mem(p);
2443 /* Realloc using mmap */
2444 static mchunkptr mmap_resize(mstate m, mchunkptr oldp, size_t nb, int flags) {
2445 size_t oldsize = chunksize(oldp);
2446 (void)flags; /* placate people compiling -Wunused */
2447 if (is_small(nb)) /* Can't shrink mmap regions below small size */
2449 /* Keep old chunk if big enough but not too big */
2450 if (oldsize >= nb + SIZE_T_SIZE &&
2451 (oldsize - nb) <= (mparams.granularity << 1))
2454 size_t offset = oldp->prev_foot;
2455 size_t oldmmsize = oldsize + offset + MMAP_FOOT_PAD;
2456 size_t newmmsize = mmap_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
2457 char* cp = (char*)CALL_MREMAP((char*)oldp - offset,
2458 oldmmsize, newmmsize, flags);
2460 mchunkptr newp = (mchunkptr)(cp + offset);
2461 size_t psize = newmmsize - offset - MMAP_FOOT_PAD;
2463 mark_inuse_foot(m, newp, psize);
2464 chunk_plus_offset(newp, psize)->head = FENCEPOST_HEAD;
2465 chunk_plus_offset(newp, psize+SIZE_T_SIZE)->head = 0;
2467 if (cp < m->least_addr)
2469 if ((m->footprint += newmmsize - oldmmsize) > m->max_footprint)
2470 m->max_footprint = m->footprint;
2471 check_mmapped_chunk(m, newp);
2479 /* -------------------------- mspace management -------------------------- */
2481 /* Initialize top chunk and its size */
2482 static void init_top(mstate m, mchunkptr p, size_t psize) {
2483 /* Ensure alignment */
2484 size_t offset = align_offset(chunk2mem(p));
2485 p = (mchunkptr)((char*)p + offset);
2490 p->head = psize | PINUSE_BIT;
2491 /* set size of fake trailing chunk holding overhead space only once */
2492 chunk_plus_offset(p, psize)->head = TOP_FOOT_SIZE;
2493 m->trim_check = mparams.trim_threshold; /* reset on each update */
2496 /* Initialize bins for a new mstate that is otherwise zeroed out */
2497 static void init_bins(mstate m) {
2498 /* Establish circular links for smallbins */
2500 for (i = 0; i < NSMALLBINS; ++i) {
2501 sbinptr bin = smallbin_at(m,i);
2502 bin->fd = bin->bk = bin;
2506 #if PROCEED_ON_ERROR
2508 /* default corruption action */
2509 static void reset_on_error(mstate m) {
2511 ++malloc_corruption_error_count;
2512 /* Reinitialize fields to forget about all memory */
2513 m->smallmap = m->treemap = 0;
2514 m->dvsize = m->topsize = 0;
2519 for (i = 0; i < NTREEBINS; ++i)
2520 *treebin_at(m, i) = 0;
2523 #endif /* PROCEED_ON_ERROR */
2525 /* Allocate chunk and prepend remainder with chunk in successor base. */
2526 static void* prepend_alloc(mstate m, char* newbase, char* oldbase,
2528 mchunkptr p = align_as_chunk(newbase);
2529 mchunkptr oldfirst = align_as_chunk(oldbase);
2530 size_t psize = (char*)oldfirst - (char*)p;
2531 mchunkptr q = chunk_plus_offset(p, nb);
2532 size_t qsize = psize - nb;
2533 set_size_and_pinuse_of_inuse_chunk(m, p, nb);
2535 assert((char*)oldfirst > (char*)q);
2536 assert(pinuse(oldfirst));
2537 assert(qsize >= MIN_CHUNK_SIZE);
2539 /* consolidate remainder with first chunk of old base */
2540 if (oldfirst == m->top) {
2541 size_t tsize = m->topsize += qsize;
2543 q->head = tsize | PINUSE_BIT;
2544 check_top_chunk(m, q);
2546 else if (oldfirst == m->dv) {
2547 size_t dsize = m->dvsize += qsize;
2549 set_size_and_pinuse_of_free_chunk(q, dsize);
2552 if (!is_inuse(oldfirst)) {
2553 size_t nsize = chunksize(oldfirst);
2554 unlink_chunk(m, oldfirst, nsize);
2555 oldfirst = chunk_plus_offset(oldfirst, nsize);
2558 set_free_with_pinuse(q, qsize, oldfirst);
2559 insert_chunk(m, q, qsize);
2560 check_free_chunk(m, q);
2563 check_malloced_chunk(m, chunk2mem(p), nb);
2564 return chunk2mem(p);
2567 /* Add a segment to hold a new noncontiguous region */
2568 static void add_segment(mstate m, char* tbase, size_t tsize, flag_t mmapped) {
2569 /* Determine locations and sizes of segment, fenceposts, old top */
2570 char* old_top = (char*)m->top;
2571 msegmentptr oldsp = segment_holding(m, old_top);
2572 char* old_end = oldsp->base + oldsp->size;
2573 size_t ssize = pad_request(sizeof(struct malloc_segment));
2574 char* rawsp = old_end - (ssize + FOUR_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
2575 size_t offset = align_offset(chunk2mem(rawsp));
2576 char* asp = rawsp + offset;
2577 char* csp = (asp < (old_top + MIN_CHUNK_SIZE))? old_top : asp;
2578 mchunkptr sp = (mchunkptr)csp;
2579 msegmentptr ss = (msegmentptr)(chunk2mem(sp));
2580 mchunkptr tnext = chunk_plus_offset(sp, ssize);
2581 mchunkptr p = tnext;
2584 /* reset top to new space */
2585 init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
2587 /* Set up segment record */
2588 assert(is_aligned(ss));
2589 set_size_and_pinuse_of_inuse_chunk(m, sp, ssize);
2590 *ss = m->seg; /* Push current record */
2591 m->seg.base = tbase;
2592 m->seg.size = tsize;
2593 m->seg.sflags = mmapped;
2596 /* Insert trailing fenceposts */
2598 mchunkptr nextp = chunk_plus_offset(p, SIZE_T_SIZE);
2599 p->head = FENCEPOST_HEAD;
2601 if ((char*)(&(nextp->head)) < old_end)
2606 assert(nfences >= 2);
2608 /* Insert the rest of old top into a bin as an ordinary free chunk */
2609 if (csp != old_top) {
2610 mchunkptr q = (mchunkptr)old_top;
2611 size_t psize = csp - old_top;
2612 mchunkptr tn = chunk_plus_offset(q, psize);
2613 set_free_with_pinuse(q, psize, tn);
2614 insert_chunk(m, q, psize);
2617 check_top_chunk(m, m->top);
2620 /* -------------------------- System allocation -------------------------- */
2622 /* Get memory from system using MORECORE or MMAP */
2623 static void* sys_alloc(mstate m, size_t nb) {
2624 char* tbase = CMFAIL;
2626 flag_t mmap_flag = 0;
2627 size_t asize; /* allocation size */
2629 ensure_initialization();
2631 if (use_noexpand(m))
2634 /* Directly map large chunks, but only if already initialized */
2635 if (use_mmap(m) && nb >= mparams.mmap_threshold && m->topsize != 0) {
2636 void* mem = mmap_alloc(m, nb);
2641 asize = granularity_align(nb + SYS_ALLOC_PADDING);
2643 return 0; /* wraparound */
2644 if (m->footprint_limit != 0) {
2645 size_t fp = m->footprint + asize;
2646 if (fp <= m->footprint || fp > m->footprint_limit)
2651 Try getting memory in any of three ways (in most-preferred to
2652 least-preferred order):
2653 1. A call to MORECORE that can normally contiguously extend memory.
2654 (disabled if not MORECORE_CONTIGUOUS or not HAVE_MORECORE or
2655 or main space is mmapped or a previous contiguous call failed)
2656 2. A call to MMAP new space (disabled if not HAVE_MMAP).
2657 Note that under the default settings, if MORECORE is unable to
2658 fulfill a request, and HAVE_MMAP is true, then mmap is
2659 used as a noncontiguous system allocator. This is a useful backup
2660 strategy for systems with holes in address spaces -- in this case
2661 sbrk cannot contiguously expand the heap, but mmap may be able to
2663 3. A call to MORECORE that cannot usually contiguously extend memory.
2664 (disabled if not HAVE_MORECORE)
2666 In all cases, we need to request enough bytes from system to ensure
2667 we can malloc nb bytes upon success, so pad with enough space for
2668 top_foot, plus alignment-pad to make sure we don't lose bytes if
2669 not on boundary, and round this up to a granularity unit.
2672 if (MORECORE_CONTIGUOUS && !use_noncontiguous(m)) {
2674 size_t ssize = asize; /* sbrk call size */
2675 msegmentptr ss = (m->top == 0)? 0 : segment_holding(m, (char*)m->top);
2676 ACQUIRE_MALLOC_GLOBAL_LOCK();
2678 if (ss == 0) { /* First time through or recovery */
2679 char* base = (char*)CALL_MORECORE(0);
2680 if (base != CMFAIL) {
2682 /* Adjust to end on a page boundary */
2683 if (!is_page_aligned(base))
2684 ssize += (page_align((size_t)base) - (size_t)base);
2685 fp = m->footprint + ssize; /* recheck limits */
2686 if (ssize > nb && ssize < HALF_MAX_SIZE_T &&
2687 (m->footprint_limit == 0 ||
2688 (fp > m->footprint && fp <= m->footprint_limit)) &&
2689 (br = (char*)(CALL_MORECORE(ssize))) == base) {
2696 /* Subtract out existing available top space from MORECORE request. */
2697 ssize = granularity_align(nb - m->topsize + SYS_ALLOC_PADDING);
2698 /* Use mem here only if it did continuously extend old space */
2699 if (ssize < HALF_MAX_SIZE_T &&
2700 (br = (char*)(CALL_MORECORE(ssize))) == ss->base+ss->size) {
2706 if (tbase == CMFAIL) { /* Cope with partial failure */
2707 if (br != CMFAIL) { /* Try to use/extend the space we did get */
2708 if (ssize < HALF_MAX_SIZE_T &&
2709 ssize < nb + SYS_ALLOC_PADDING) {
2710 size_t esize = granularity_align(nb + SYS_ALLOC_PADDING - ssize);
2711 if (esize < HALF_MAX_SIZE_T) {
2712 char* end = (char*)CALL_MORECORE(esize);
2715 else { /* Can't use; try to release */
2716 (void) CALL_MORECORE(-ssize);
2722 if (br != CMFAIL) { /* Use the space we did get */
2727 disable_contiguous(m); /* Don't try contiguous path in the future */
2730 RELEASE_MALLOC_GLOBAL_LOCK();
2733 if (HAVE_MMAP && tbase == CMFAIL) { /* Try MMAP */
2734 char* mp = (char*)(CALL_MMAP(asize));
2738 mmap_flag = USE_MMAP_BIT;
2742 if (HAVE_MORECORE && tbase == CMFAIL) { /* Try noncontiguous MORECORE */
2743 if (asize < HALF_MAX_SIZE_T) {
2746 ACQUIRE_MALLOC_GLOBAL_LOCK();
2747 br = (char*)(CALL_MORECORE(asize));
2748 end = (char*)(CALL_MORECORE(0));
2749 RELEASE_MALLOC_GLOBAL_LOCK();
2750 if (br != CMFAIL && end != CMFAIL && br < end) {
2751 size_t ssize = end - br;
2752 if (ssize > nb + TOP_FOOT_SIZE) {
2760 if (tbase != CMFAIL) {
2762 if ((m->footprint += tsize) > m->max_footprint)
2763 m->max_footprint = m->footprint;
2765 if (!is_initialized(m)) { /* first-time initialization */
2766 if (m->least_addr == 0 || tbase < m->least_addr)
2767 m->least_addr = tbase;
2768 m->seg.base = tbase;
2769 m->seg.size = tsize;
2770 m->seg.sflags = mmap_flag;
2771 m->magic = mparams.magic;
2772 m->release_checks = MAX_RELEASE_CHECK_RATE;
2776 init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
2780 /* Offset top by embedded malloc_state */
2781 mchunkptr mn = next_chunk(mem2chunk(m));
2782 init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) -TOP_FOOT_SIZE);
2787 /* Try to merge with an existing segment */
2788 msegmentptr sp = &m->seg;
2789 /* Only consider most recent segment if traversal suppressed */
2790 while (sp != 0 && tbase != sp->base + sp->size)
2791 sp = (NO_SEGMENT_TRAVERSAL) ? 0 : sp->next;
2793 !is_extern_segment(sp) &&
2794 (sp->sflags & USE_MMAP_BIT) == mmap_flag &&
2795 segment_holds(sp, m->top)) { /* append */
2797 init_top(m, m->top, m->topsize + tsize);
2800 if (tbase < m->least_addr)
2801 m->least_addr = tbase;
2803 while (sp != 0 && sp->base != tbase + tsize)
2804 sp = (NO_SEGMENT_TRAVERSAL) ? 0 : sp->next;
2806 !is_extern_segment(sp) &&
2807 (sp->sflags & USE_MMAP_BIT) == mmap_flag) {
2808 char* oldbase = sp->base;
2811 return prepend_alloc(m, tbase, oldbase, nb);
2814 add_segment(m, tbase, tsize, mmap_flag);
2818 if (nb < m->topsize) { /* Allocate from new or extended top space */
2819 size_t rsize = m->topsize -= nb;
2820 mchunkptr p = m->top;
2821 mchunkptr r = m->top = chunk_plus_offset(p, nb);
2822 r->head = rsize | PINUSE_BIT;
2823 set_size_and_pinuse_of_inuse_chunk(m, p, nb);
2824 check_top_chunk(m, m->top);
2825 check_malloced_chunk(m, chunk2mem(p), nb);
2826 return chunk2mem(p);
2830 MALLOC_FAILURE_ACTION;
2834 /* ----------------------- system deallocation -------------------------- */
2836 /* Unmap and unlink any mmapped segments that don't contain used chunks */
2837 static size_t release_unused_segments(mstate m) {
2838 size_t released = 0;
2840 msegmentptr pred = &m->seg;
2841 msegmentptr sp = pred->next;
2843 char* base = sp->base;
2844 size_t size = sp->size;
2845 msegmentptr next = sp->next;
2847 if (is_mmapped_segment(sp) && !is_extern_segment(sp)) {
2848 mchunkptr p = align_as_chunk(base);
2849 size_t psize = chunksize(p);
2850 /* Can unmap if first chunk holds entire segment and not pinned */
2851 if (!is_inuse(p) && (char*)p + psize >= base + size - TOP_FOOT_SIZE) {
2852 tchunkptr tp = (tchunkptr)p;
2853 assert(segment_holds(sp, (char*)sp));
2859 unlink_large_chunk(m, tp);
2861 if (CALL_MUNMAP(base, size) == 0) {
2863 m->footprint -= size;
2864 /* unlink obsoleted record */
2868 else { /* back out if cannot unmap */
2869 insert_large_chunk(m, tp, psize);
2873 if (NO_SEGMENT_TRAVERSAL) /* scan only first segment */
2878 /* Reset check counter */
2879 m->release_checks = (((size_t) nsegs > (size_t) MAX_RELEASE_CHECK_RATE)?
2880 (size_t) nsegs : (size_t) MAX_RELEASE_CHECK_RATE);
2884 static int sys_trim(mstate m, size_t pad) {
2885 size_t released = 0;
2886 ensure_initialization();
2887 if (pad < MAX_REQUEST && is_initialized(m)) {
2888 pad += TOP_FOOT_SIZE; /* ensure enough room for segment overhead */
2890 if (m->topsize > pad) {
2891 /* Shrink top space in granularity-size units, keeping at least one */
2892 size_t unit = mparams.granularity;
2893 size_t extra = ((m->topsize - pad + (unit - SIZE_T_ONE)) / unit -
2895 msegmentptr sp = segment_holding(m, (char*)m->top);
2897 if (!is_extern_segment(sp)) {
2898 if (is_mmapped_segment(sp)) {
2900 sp->size >= extra &&
2901 !has_segment_link(m, sp)) { /* can't shrink if pinned */
2902 size_t newsize = sp->size - extra;
2903 (void)newsize; /* placate people compiling -Wunused-variable */
2904 /* Prefer mremap, fall back to munmap */
2905 if ((CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL) ||
2906 (CALL_MUNMAP(sp->base + newsize, extra) == 0)) {
2911 else if (HAVE_MORECORE) {
2912 if (extra >= HALF_MAX_SIZE_T) /* Avoid wrapping negative */
2913 extra = (HALF_MAX_SIZE_T) + SIZE_T_ONE - unit;
2914 ACQUIRE_MALLOC_GLOBAL_LOCK();
2916 /* Make sure end of memory is where we last set it. */
2917 char* old_br = (char*)(CALL_MORECORE(0));
2918 if (old_br == sp->base + sp->size) {
2919 char* rel_br = (char*)(CALL_MORECORE(-extra));
2920 char* new_br = (char*)(CALL_MORECORE(0));
2921 if (rel_br != CMFAIL && new_br < old_br)
2922 released = old_br - new_br;
2925 RELEASE_MALLOC_GLOBAL_LOCK();
2929 if (released != 0) {
2930 sp->size -= released;
2931 m->footprint -= released;
2932 init_top(m, m->top, m->topsize - released);
2933 check_top_chunk(m, m->top);
2937 /* Unmap any unused mmapped segments */
2939 released += release_unused_segments(m);
2941 /* On failure, disable autotrim to avoid repeated failed future calls */
2942 if (released == 0 && m->topsize > m->trim_check)
2943 m->trim_check = MAX_SIZE_T;
2946 return (released != 0)? 1 : 0;
2949 /* Consolidate and bin a chunk. Differs from exported versions
2950 of free mainly in that the chunk need not be marked as inuse.
2952 static void dispose_chunk(mstate m, mchunkptr p, size_t psize) {
2953 mchunkptr next = chunk_plus_offset(p, psize);
2956 size_t prevsize = p->prev_foot;
2957 if (is_mmapped(p)) {
2958 psize += prevsize + MMAP_FOOT_PAD;
2959 if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
2960 m->footprint -= psize;
2963 prev = chunk_minus_offset(p, prevsize);
2966 if (RTCHECK(ok_address(m, prev))) { /* consolidate backward */
2968 unlink_chunk(m, p, prevsize);
2970 else if ((next->head & INUSE_BITS) == INUSE_BITS) {
2972 set_free_with_pinuse(p, psize, next);
2977 CORRUPTION_ERROR_ACTION(m);
2981 if (RTCHECK(ok_address(m, next))) {
2982 if (!cinuse(next)) { /* consolidate forward */
2983 if (next == m->top) {
2984 size_t tsize = m->topsize += psize;
2986 p->head = tsize | PINUSE_BIT;
2993 else if (next == m->dv) {
2994 size_t dsize = m->dvsize += psize;
2996 set_size_and_pinuse_of_free_chunk(p, dsize);
3000 size_t nsize = chunksize(next);
3002 unlink_chunk(m, next, nsize);
3003 set_size_and_pinuse_of_free_chunk(p, psize);
3011 set_free_with_pinuse(p, psize, next);
3013 insert_chunk(m, p, psize);
3016 CORRUPTION_ERROR_ACTION(m);
3020 /* ---------------------------- malloc --------------------------- */
3022 /* allocate a large request from the best fitting chunk in a treebin */
3023 static void* tmalloc_large(mstate m, size_t nb) {
3025 size_t rsize = -nb; /* Unsigned negation */
3028 compute_tree_index(nb, idx);
3029 if ((t = *treebin_at(m, idx)) != 0) {
3030 /* Traverse tree for this bin looking for node with size == nb */
3031 size_t sizebits = nb << leftshift_for_tree_index(idx);
3032 tchunkptr rst = 0; /* The deepest untaken right subtree */
3035 size_t trem = chunksize(t) - nb;
3038 if ((rsize = trem) == 0)
3042 t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1];
3043 if (rt != 0 && rt != t)
3046 t = rst; /* set t to least subtree holding sizes > nb */
3052 if (t == 0 && v == 0) { /* set t to root of next non-empty treebin */
3053 binmap_t leftbits = left_bits(idx2bit(idx)) & m->treemap;
3054 if (leftbits != 0) {
3056 binmap_t leastbit = least_bit(leftbits);
3057 compute_bit2idx(leastbit, i);
3058 t = *treebin_at(m, i);
3062 while (t != 0) { /* find smallest of tree or subtree */
3063 size_t trem = chunksize(t) - nb;
3068 t = leftmost_child(t);
3071 /* If dv is a better fit, return 0 so malloc will use it */
3072 if (v != 0 && rsize < (size_t)(m->dvsize - nb)) {
3073 if (RTCHECK(ok_address(m, v))) { /* split */
3074 mchunkptr r = chunk_plus_offset(v, nb);
3075 assert(chunksize(v) == rsize + nb);
3076 if (RTCHECK(ok_next(v, r))) {
3077 unlink_large_chunk(m, v);
3078 if (rsize < MIN_CHUNK_SIZE)
3079 set_inuse_and_pinuse(m, v, (rsize + nb));
3081 set_size_and_pinuse_of_inuse_chunk(m, v, nb);
3082 set_size_and_pinuse_of_free_chunk(r, rsize);
3083 insert_chunk(m, r, rsize);
3085 return chunk2mem(v);
3088 CORRUPTION_ERROR_ACTION(m);
3093 /* allocate a small request from the best fitting chunk in a treebin */
3094 static void* tmalloc_small(mstate m, size_t nb) {
3098 binmap_t leastbit = least_bit(m->treemap);
3099 compute_bit2idx(leastbit, i);
3100 v = t = *treebin_at(m, i);
3101 rsize = chunksize(t) - nb;
3103 while ((t = leftmost_child(t)) != 0) {
3104 size_t trem = chunksize(t) - nb;
3111 if (RTCHECK(ok_address(m, v))) {
3112 mchunkptr r = chunk_plus_offset(v, nb);
3113 assert(chunksize(v) == rsize + nb);
3114 if (RTCHECK(ok_next(v, r))) {
3115 unlink_large_chunk(m, v);
3116 if (rsize < MIN_CHUNK_SIZE)
3117 set_inuse_and_pinuse(m, v, (rsize + nb));
3119 set_size_and_pinuse_of_inuse_chunk(m, v, nb);
3120 set_size_and_pinuse_of_free_chunk(r, rsize);
3121 replace_dv(m, r, rsize);
3123 return chunk2mem(v);
3127 CORRUPTION_ERROR_ACTION(m);
3133 void* dlmalloc(size_t bytes) {
3136 If a small request (< 256 bytes minus per-chunk overhead):
3137 1. If one exists, use a remainderless chunk in associated smallbin.
3138 (Remainderless means that there are too few excess bytes to
3139 represent as a chunk.)
3140 2. If it is big enough, use the dv chunk, which is normally the
3141 chunk adjacent to the one used for the most recent small request.
3142 3. If one exists, split the smallest available chunk in a bin,
3143 saving remainder in dv.
3144 4. If it is big enough, use the top chunk.
3145 5. If available, get memory from system and use it
3146 Otherwise, for a large request:
3147 1. Find the smallest available binned chunk that fits, and use it
3148 if it is better fitting than dv chunk, splitting if necessary.
3149 2. If better fitting than any binned chunk, use the dv chunk.
3150 3. If it is big enough, use the top chunk.
3151 4. If request size >= mmap threshold, try to directly mmap this chunk.
3152 5. If available, get memory from system and use it
3154 The ugly goto's here ensure that postaction occurs along all paths.
3158 ensure_initialization(); /* initialize in sys_alloc if not using locks */
3161 if (!PREACTION(gm)) {
3164 if (bytes <= MAX_SMALL_REQUEST) {
3167 nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes);
3168 idx = small_index(nb);
3169 smallbits = gm->smallmap >> idx;
3171 if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */
3173 idx += ~smallbits & 1; /* Uses next bin if idx empty */
3174 b = smallbin_at(gm, idx);
3176 assert(chunksize(p) == small_index2size(idx));
3177 unlink_first_small_chunk(gm, b, p, idx);
3178 set_inuse_and_pinuse(gm, p, small_index2size(idx));
3180 check_malloced_chunk(gm, mem, nb);
3184 else if (nb > gm->dvsize) {
3185 if (smallbits != 0) { /* Use chunk in next nonempty smallbin */
3189 binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx));
3190 binmap_t leastbit = least_bit(leftbits);
3191 compute_bit2idx(leastbit, i);
3192 b = smallbin_at(gm, i);
3194 assert(chunksize(p) == small_index2size(i));
3195 unlink_first_small_chunk(gm, b, p, i);
3196 rsize = small_index2size(i) - nb;
3197 /* Fit here cannot be remainderless if 4byte sizes */
3198 if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
3199 set_inuse_and_pinuse(gm, p, small_index2size(i));
3201 set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
3202 r = chunk_plus_offset(p, nb);
3203 set_size_and_pinuse_of_free_chunk(r, rsize);
3204 replace_dv(gm, r, rsize);
3207 check_malloced_chunk(gm, mem, nb);
3211 else if (gm->treemap != 0 && (mem = tmalloc_small(gm, nb)) != 0) {
3212 check_malloced_chunk(gm, mem, nb);
3217 else if (bytes >= MAX_REQUEST)
3218 nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */
3220 nb = pad_request(bytes);
3221 if (gm->treemap != 0 && (mem = tmalloc_large(gm, nb)) != 0) {
3222 check_malloced_chunk(gm, mem, nb);
3227 if (nb <= gm->dvsize) {
3228 size_t rsize = gm->dvsize - nb;
3229 mchunkptr p = gm->dv;
3230 if (rsize >= MIN_CHUNK_SIZE) { /* split dv */
3231 mchunkptr r = gm->dv = chunk_plus_offset(p, nb);
3233 set_size_and_pinuse_of_free_chunk(r, rsize);
3234 set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
3236 else { /* exhaust dv */
3237 size_t dvs = gm->dvsize;
3240 set_inuse_and_pinuse(gm, p, dvs);
3243 check_malloced_chunk(gm, mem, nb);
3247 else if (nb < gm->topsize) { /* Split top */
3248 size_t rsize = gm->topsize -= nb;
3249 mchunkptr p = gm->top;
3250 mchunkptr r = gm->top = chunk_plus_offset(p, nb);
3251 r->head = rsize | PINUSE_BIT;
3252 set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
3254 check_top_chunk(gm, gm->top);
3255 check_malloced_chunk(gm, mem, nb);
3259 mem = sys_alloc(gm, nb);
3269 /* ---------------------------- free --------------------------- */
3271 void dlfree(void* mem) {
3273 Consolidate freed chunks with preceeding or succeeding bordering
3274 free chunks, if they exist, and then place in a bin. Intermixed
3275 with special cases for top, dv, mmapped chunks, and usage errors.
3279 mchunkptr p = mem2chunk(mem);
3281 mstate fm = get_mstate_for(p);
3282 if (!ok_magic(fm)) {
3283 USAGE_ERROR_ACTION(fm, p);
3288 #endif /* FOOTERS */
3289 if (!PREACTION(fm)) {
3290 check_inuse_chunk(fm, p);
3291 if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
3292 size_t psize = chunksize(p);
3293 mchunkptr next = chunk_plus_offset(p, psize);
3295 size_t prevsize = p->prev_foot;
3296 if (is_mmapped(p)) {
3297 psize += prevsize + MMAP_FOOT_PAD;
3298 if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
3299 fm->footprint -= psize;
3303 mchunkptr prev = chunk_minus_offset(p, prevsize);
3306 if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */
3308 unlink_chunk(fm, p, prevsize);
3310 else if ((next->head & INUSE_BITS) == INUSE_BITS) {
3312 set_free_with_pinuse(p, psize, next);
3321 if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) {
3322 if (!cinuse(next)) { /* consolidate forward */
3323 if (next == fm->top) {
3324 size_t tsize = fm->topsize += psize;
3326 p->head = tsize | PINUSE_BIT;
3331 if (should_trim(fm, tsize))
3335 else if (next == fm->dv) {
3336 size_t dsize = fm->dvsize += psize;
3338 set_size_and_pinuse_of_free_chunk(p, dsize);
3342 size_t nsize = chunksize(next);
3344 unlink_chunk(fm, next, nsize);
3345 set_size_and_pinuse_of_free_chunk(p, psize);
3353 set_free_with_pinuse(p, psize, next);
3355 if (is_small(psize)) {
3356 insert_small_chunk(fm, p, psize);
3357 check_free_chunk(fm, p);
3360 tchunkptr tp = (tchunkptr)p;
3361 insert_large_chunk(fm, tp, psize);
3362 check_free_chunk(fm, p);
3363 if (--fm->release_checks == 0)
3364 release_unused_segments(fm);
3370 USAGE_ERROR_ACTION(fm, p);
3377 #endif /* FOOTERS */
3380 void* dlcalloc(size_t n_elements, size_t elem_size) {
3383 if (n_elements != 0) {
3384 req = n_elements * elem_size;
3385 if (((n_elements | elem_size) & ~(size_t)0xffff) &&
3386 (req / n_elements != elem_size))
3387 req = MAX_SIZE_T; /* force downstream failure on overflow */
3389 mem = dlmalloc(req);
3390 if (mem != 0 && calloc_must_clear(mem2chunk(mem)))
3391 memset(mem, 0, req);
3395 #endif /* !ONLY_MSPACES */
3397 /* ------------ Internal support for realloc, memalign, etc -------------- */
3399 /* Try to realloc; only in-place unless can_move true */
3400 static mchunkptr try_realloc_chunk(mstate m, mchunkptr p, size_t nb,
3403 size_t oldsize = chunksize(p);
3404 mchunkptr next = chunk_plus_offset(p, oldsize);
3405 if (RTCHECK(ok_address(m, p) && ok_inuse(p) &&
3406 ok_next(p, next) && ok_pinuse(next))) {
3407 if (is_mmapped(p)) {
3408 newp = mmap_resize(m, p, nb, can_move);
3410 else if (oldsize >= nb) { /* already big enough */
3411 size_t rsize = oldsize - nb;
3412 if (rsize >= MIN_CHUNK_SIZE) { /* split off remainder */
3413 mchunkptr r = chunk_plus_offset(p, nb);
3414 set_inuse(m, p, nb);
3415 set_inuse(m, r, rsize);
3416 dispose_chunk(m, r, rsize);
3420 else if (next == m->top) { /* extend into top */
3421 if (oldsize + m->topsize > nb) {
3422 size_t newsize = oldsize + m->topsize;
3423 size_t newtopsize = newsize - nb;
3424 mchunkptr newtop = chunk_plus_offset(p, nb);
3425 set_inuse(m, p, nb);
3426 newtop->head = newtopsize |PINUSE_BIT;
3428 m->topsize = newtopsize;
3432 else if (next == m->dv) { /* extend into dv */
3433 size_t dvs = m->dvsize;
3434 if (oldsize + dvs >= nb) {
3435 size_t dsize = oldsize + dvs - nb;
3436 if (dsize >= MIN_CHUNK_SIZE) {
3437 mchunkptr r = chunk_plus_offset(p, nb);
3438 mchunkptr n = chunk_plus_offset(r, dsize);
3439 set_inuse(m, p, nb);
3440 set_size_and_pinuse_of_free_chunk(r, dsize);
3445 else { /* exhaust dv */
3446 size_t newsize = oldsize + dvs;
3447 set_inuse(m, p, newsize);
3454 else if (!cinuse(next)) { /* extend into next free chunk */
3455 size_t nextsize = chunksize(next);
3456 if (oldsize + nextsize >= nb) {
3457 size_t rsize = oldsize + nextsize - nb;
3458 unlink_chunk(m, next, nextsize);
3459 if (rsize < MIN_CHUNK_SIZE) {
3460 size_t newsize = oldsize + nextsize;
3461 set_inuse(m, p, newsize);
3464 mchunkptr r = chunk_plus_offset(p, nb);
3465 set_inuse(m, p, nb);
3466 set_inuse(m, r, rsize);
3467 dispose_chunk(m, r, rsize);
3474 USAGE_ERROR_ACTION(m, chunk2mem(p));
3479 static void* internal_memalign(mstate m, size_t alignment, size_t bytes) {
3481 if (alignment < MIN_CHUNK_SIZE) /* must be at least a minimum chunk size */
3482 alignment = MIN_CHUNK_SIZE;
3483 if ((alignment & (alignment-SIZE_T_ONE)) != 0) {/* Ensure a power of 2 */
3484 size_t a = MALLOC_ALIGNMENT << 1;
3485 while (a < alignment) a <<= 1;
3488 if (bytes >= MAX_REQUEST - alignment) {
3489 if (m != 0) { /* Test isn't needed but avoids compiler warning */
3490 MALLOC_FAILURE_ACTION;
3494 size_t nb = request2size(bytes);
3495 size_t req = nb + alignment + MIN_CHUNK_SIZE - CHUNK_OVERHEAD;
3496 mem = internal_malloc(m, req);
3498 mchunkptr p = mem2chunk(mem);
3501 if ((((size_t)(mem)) & (alignment - 1)) != 0) { /* misaligned */
3503 Find an aligned spot inside chunk. Since we need to give
3504 back leading space in a chunk of at least MIN_CHUNK_SIZE, if
3505 the first calculation places us at a spot with less than
3506 MIN_CHUNK_SIZE leader, we can move to the next aligned spot.
3507 We've allocated enough total room so that this is always
3510 char* br = (char*)mem2chunk((size_t)(((size_t)((char*)mem + alignment -
3513 char* pos = ((size_t)(br - (char*)(p)) >= MIN_CHUNK_SIZE)?
3515 mchunkptr newp = (mchunkptr)pos;
3516 size_t leadsize = pos - (char*)(p);
3517 size_t newsize = chunksize(p) - leadsize;
3519 if (is_mmapped(p)) { /* For mmapped chunks, just adjust offset */
3520 newp->prev_foot = p->prev_foot + leadsize;
3521 newp->head = newsize;
3523 else { /* Otherwise, give back leader, use the rest */
3524 set_inuse(m, newp, newsize);
3525 set_inuse(m, p, leadsize);
3526 dispose_chunk(m, p, leadsize);
3531 /* Give back spare room at the end */
3532 if (!is_mmapped(p)) {
3533 size_t size = chunksize(p);
3534 if (size > nb + MIN_CHUNK_SIZE) {
3535 size_t remainder_size = size - nb;
3536 mchunkptr remainder = chunk_plus_offset(p, nb);
3537 set_inuse(m, p, nb);
3538 set_inuse(m, remainder, remainder_size);
3539 dispose_chunk(m, remainder, remainder_size);
3544 assert (chunksize(p) >= nb);
3545 assert(((size_t)mem & (alignment - 1)) == 0);
3546 check_inuse_chunk(m, p);
3554 Common support for independent_X routines, handling
3555 all of the combinations that can result.
3557 bit 0 set if all elements are same size (using sizes[0])
3558 bit 1 set if elements should be zeroed
3560 static void** ialloc(mstate m,
3566 size_t element_size; /* chunksize of each element, if all same */
3567 size_t contents_size; /* total size of elements */
3568 size_t array_size; /* request size of pointer array */
3569 void* mem; /* malloced aggregate space */
3570 mchunkptr p; /* corresponding chunk */
3571 size_t remainder_size; /* remaining bytes while splitting */
3572 void** marray; /* either "chunks" or malloced ptr array */
3573 mchunkptr array_chunk; /* chunk for malloced ptr array */
3574 flag_t was_enabled; /* to disable mmap */
3578 ensure_initialization();
3579 /* compute array length, if needed */
3581 if (n_elements == 0)
3582 return chunks; /* nothing to do */
3587 /* if empty req, must still return chunk representing empty array */
3588 if (n_elements == 0)
3589 return (void**)internal_malloc(m, 0);
3591 array_size = request2size(n_elements * (sizeof(void*)));
3594 /* compute total element size */
3595 if (opts & 0x1) { /* all-same-size */
3596 element_size = request2size(*sizes);
3597 contents_size = n_elements * element_size;
3599 else { /* add up all the sizes */
3602 for (i = 0; i != n_elements; ++i)
3603 contents_size += request2size(sizes[i]);
3606 size = contents_size + array_size;
3609 Allocate the aggregate chunk. First disable direct-mmapping so
3610 malloc won't use it, since we would not be able to later
3611 free/realloc space internal to a segregated mmap region.
3613 was_enabled = use_mmap(m);
3615 mem = internal_malloc(m, size - CHUNK_OVERHEAD);
3621 if (PREACTION(m)) return 0;
3623 remainder_size = chunksize(p);
3625 assert(!is_mmapped(p));
3627 if (opts & 0x2) { /* optionally clear the elements */
3628 memset((size_t*)mem, 0, remainder_size - SIZE_T_SIZE - array_size);
3631 /* If not provided, allocate the pointer array as final part of chunk */
3633 size_t array_chunk_size;
3634 array_chunk = chunk_plus_offset(p, contents_size);
3635 array_chunk_size = remainder_size - contents_size;
3636 marray = (void**) (chunk2mem(array_chunk));
3637 set_size_and_pinuse_of_inuse_chunk(m, array_chunk, array_chunk_size);
3638 remainder_size = contents_size;
3641 /* split out elements */
3642 for (i = 0; ; ++i) {
3643 marray[i] = chunk2mem(p);
3644 if (i != n_elements-1) {
3645 if (element_size != 0)
3646 size = element_size;
3648 size = request2size(sizes[i]);
3649 remainder_size -= size;
3650 set_size_and_pinuse_of_inuse_chunk(m, p, size);
3651 p = chunk_plus_offset(p, size);
3653 else { /* the final element absorbs any overallocation slop */
3654 set_size_and_pinuse_of_inuse_chunk(m, p, remainder_size);
3660 if (marray != chunks) {
3661 /* final element must have exactly exhausted chunk */
3662 if (element_size != 0) {
3663 assert(remainder_size == element_size);
3666 assert(remainder_size == request2size(sizes[i]));
3668 check_inuse_chunk(m, mem2chunk(marray));
3670 for (i = 0; i != n_elements; ++i)
3671 check_inuse_chunk(m, mem2chunk(marray[i]));
3679 /* Try to free all pointers in the given array.
3680 Note: this could be made faster, by delaying consolidation,
3681 at the price of disabling some user integrity checks, We
3682 still optimize some consolidations by combining adjacent
3683 chunks before freeing, which will occur often if allocated
3684 with ialloc or the array is sorted.
3686 static size_t internal_bulk_free(mstate m, void* array[], size_t nelem) {
3688 if (!PREACTION(m)) {
3690 void** fence = &(array[nelem]);
3691 for (a = array; a != fence; ++a) {
3694 mchunkptr p = mem2chunk(mem);
3695 size_t psize = chunksize(p);
3697 if (get_mstate_for(p) != m) {
3702 check_inuse_chunk(m, p);
3704 if (RTCHECK(ok_address(m, p) && ok_inuse(p))) {
3705 void ** b = a + 1; /* try to merge with next chunk */
3706 mchunkptr next = next_chunk(p);
3707 if (b != fence && *b == chunk2mem(next)) {
3708 size_t newsize = chunksize(next) + psize;
3709 set_inuse(m, p, newsize);
3713 dispose_chunk(m, p, psize);
3716 CORRUPTION_ERROR_ACTION(m);
3721 if (should_trim(m, m->topsize))
3729 #if MALLOC_INSPECT_ALL
3730 static void internal_inspect_all(mstate m,
3731 void(*handler)(void *start,
3734 void* callback_arg),
3736 if (is_initialized(m)) {
3737 mchunkptr top = m->top;
3739 for (s = &m->seg; s != 0; s = s->next) {
3740 mchunkptr q = align_as_chunk(s->base);
3741 while (segment_holds(s, q) && q->head != FENCEPOST_HEAD) {
3742 mchunkptr next = next_chunk(q);
3743 size_t sz = chunksize(q);
3747 used = sz - CHUNK_OVERHEAD; /* must not be mmapped */
3748 start = chunk2mem(q);
3752 if (is_small(sz)) { /* offset by possible bookkeeping */
3753 start = (void*)((char*)q + sizeof(struct malloc_chunk));
3756 start = (void*)((char*)q + sizeof(struct malloc_tree_chunk));
3759 if (start < (void*)next) /* skip if all space is bookkeeping */
3760 handler(start, next, used, arg);
3768 #endif /* MALLOC_INSPECT_ALL */
3770 /* ------------------ Exported realloc, memalign, etc -------------------- */
3774 void* dlrealloc(void* oldmem, size_t bytes) {
3777 mem = dlmalloc(bytes);
3779 else if (bytes >= MAX_REQUEST) {
3780 MALLOC_FAILURE_ACTION;
3782 #ifdef REALLOC_ZERO_BYTES_FREES
3783 else if (bytes == 0) {
3786 #endif /* REALLOC_ZERO_BYTES_FREES */
3788 size_t nb = request2size(bytes);
3789 mchunkptr oldp = mem2chunk(oldmem);
3793 mstate m = get_mstate_for(oldp);
3795 USAGE_ERROR_ACTION(m, oldmem);
3798 #endif /* FOOTERS */
3799 if (!PREACTION(m)) {
3800 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 1);
3803 check_inuse_chunk(m, newp);
3804 mem = chunk2mem(newp);
3807 mem = internal_malloc(m, bytes);
3809 size_t oc = chunksize(oldp) - overhead_for(oldp);
3810 memcpy(mem, oldmem, (oc < bytes)? oc : bytes);
3811 internal_free(m, oldmem);
3819 void* dlrealloc_in_place(void* oldmem, size_t bytes) {
3822 if (bytes >= MAX_REQUEST) {
3823 MALLOC_FAILURE_ACTION;
3826 size_t nb = request2size(bytes);
3827 mchunkptr oldp = mem2chunk(oldmem);
3831 mstate m = get_mstate_for(oldp);
3833 USAGE_ERROR_ACTION(m, oldmem);
3836 #endif /* FOOTERS */
3837 if (!PREACTION(m)) {
3838 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 0);
3841 check_inuse_chunk(m, newp);
3850 void* dlmemalign(size_t alignment, size_t bytes) {
3851 if (alignment <= MALLOC_ALIGNMENT) {
3852 return dlmalloc(bytes);
3854 return internal_memalign(gm, alignment, bytes);
3857 int dlposix_memalign(void** pp, size_t alignment, size_t bytes) {
3859 if (alignment == MALLOC_ALIGNMENT)
3860 mem = dlmalloc(bytes);
3862 size_t d = alignment / sizeof(void*);
3863 size_t r = alignment % sizeof(void*);
3864 if (r != 0 || d == 0 || (d & (d-SIZE_T_ONE)) != 0)
3866 else if (bytes <= MAX_REQUEST - alignment) {
3867 if (alignment < MIN_CHUNK_SIZE)
3868 alignment = MIN_CHUNK_SIZE;
3869 mem = internal_memalign(gm, alignment, bytes);
3880 void* dlvalloc(size_t bytes) {
3882 ensure_initialization();
3883 pagesz = mparams.page_size;
3884 return dlmemalign(pagesz, bytes);
3887 void* dlpvalloc(size_t bytes) {
3889 ensure_initialization();
3890 pagesz = mparams.page_size;
3891 return dlmemalign(pagesz, (bytes + pagesz - SIZE_T_ONE) & ~(pagesz - SIZE_T_ONE));
3894 void** dlindependent_calloc(size_t n_elements, size_t elem_size,
3896 size_t sz = elem_size; /* serves as 1-element array */
3897 return ialloc(gm, n_elements, &sz, 3, chunks);
3900 void** dlindependent_comalloc(size_t n_elements, size_t sizes[],
3902 return ialloc(gm, n_elements, sizes, 0, chunks);
3905 size_t dlbulk_free(void* array[], size_t nelem) {
3906 return internal_bulk_free(gm, array, nelem);
3909 #if MALLOC_INSPECT_ALL
3910 void dlmalloc_inspect_all(void(*handler)(void *start,
3913 void* callback_arg),
3915 ensure_initialization();
3916 if (!PREACTION(gm)) {
3917 internal_inspect_all(gm, handler, arg);
3921 #endif /* MALLOC_INSPECT_ALL */
3923 int dlmalloc_trim(size_t pad) {
3925 ensure_initialization();
3926 if (!PREACTION(gm)) {
3927 result = sys_trim(gm, pad);
3933 size_t dlmalloc_footprint(void) {
3934 return gm->footprint;
3937 size_t dlmalloc_max_footprint(void) {
3938 return gm->max_footprint;
3941 size_t dlmalloc_footprint_limit(void) {
3942 size_t maf = gm->footprint_limit;
3943 return maf == 0 ? MAX_SIZE_T : maf;
3946 size_t dlmalloc_set_footprint_limit(size_t bytes) {
3947 size_t result; /* invert sense of 0 */
3949 result = granularity_align(1); /* Use minimal size */
3950 if (bytes == MAX_SIZE_T)
3951 result = 0; /* disable */
3953 result = granularity_align(bytes);
3954 return gm->footprint_limit = result;
3958 struct mallinfo dlmallinfo(void) {
3959 return internal_mallinfo(gm);
3961 #endif /* NO_MALLINFO */
3963 #if !NO_MALLOC_STATS
3964 void dlmalloc_stats() {
3965 internal_malloc_stats(gm);
3967 #endif /* NO_MALLOC_STATS */
3969 int dlmallopt(int param_number, int value) {
3970 return change_mparam(param_number, value);
3973 size_t dlmalloc_usable_size(void* mem) {
3975 mchunkptr p = mem2chunk(mem);
3977 return chunksize(p) - overhead_for(p);
3982 #endif /* !ONLY_MSPACES */
3984 /* ----------------------------- user mspaces ---------------------------- */
3988 static mstate init_user_mstate(char* tbase, size_t tsize) {
3989 size_t msize = pad_request(sizeof(struct malloc_state));
3991 mchunkptr msp = align_as_chunk(tbase);
3992 mstate m = (mstate)(chunk2mem(msp));
3993 memset(m, 0, msize);
3994 (void)INITIAL_LOCK(&m->mutex);
3995 msp->head = (msize|INUSE_BITS);
3996 m->seg.base = m->least_addr = tbase;
3997 m->seg.size = m->footprint = m->max_footprint = tsize;
3998 m->magic = mparams.magic;
3999 m->release_checks = MAX_RELEASE_CHECK_RATE;
4000 m->mflags = mparams.default_mflags;
4003 disable_contiguous(m);
4005 mn = next_chunk(mem2chunk(m));
4006 init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) - TOP_FOOT_SIZE);
4007 check_top_chunk(m, m->top);
4011 mspace create_mspace(size_t capacity, int locked) {
4014 ensure_initialization();
4015 msize = pad_request(sizeof(struct malloc_state));
4016 if (capacity < (size_t) -(msize + TOP_FOOT_SIZE + mparams.page_size)) {
4017 size_t rs = ((capacity == 0)? mparams.granularity :
4018 (capacity + TOP_FOOT_SIZE + msize));
4019 size_t tsize = granularity_align(rs);
4020 char* tbase = (char*)(CALL_MMAP(tsize));
4021 if (tbase != CMFAIL) {
4022 m = init_user_mstate(tbase, tsize);
4023 m->seg.sflags = USE_MMAP_BIT;
4024 set_lock(m, locked);
4030 mspace create_mspace_with_base(void* base, size_t capacity, int locked) {
4033 ensure_initialization();
4034 msize = pad_request(sizeof(struct malloc_state));
4035 if (capacity > msize + TOP_FOOT_SIZE &&
4036 capacity < (size_t) -(msize + TOP_FOOT_SIZE + mparams.page_size)) {
4037 m = init_user_mstate((char*)base, capacity);
4038 m->seg.sflags = EXTERN_BIT;
4039 set_lock(m, locked);
4044 int mspace_track_large_chunks(mspace msp, int enable) {
4046 mstate ms = (mstate)msp;
4047 if (!PREACTION(ms)) {
4048 if (!use_mmap(ms)) {
4061 size_t destroy_mspace(mspace msp) {
4063 mstate ms = (mstate)msp;
4065 msegmentptr sp = &ms->seg;
4066 (void)DESTROY_LOCK(&ms->mutex); /* destroy before unmapped */
4068 char* base = sp->base;
4069 size_t size = sp->size;
4070 flag_t flag = sp->sflags;
4071 (void)base; /* placate people compiling -Wunused-variable */
4073 if ((flag & USE_MMAP_BIT) && !(flag & EXTERN_BIT) &&
4074 CALL_MUNMAP(base, size) == 0)
4079 USAGE_ERROR_ACTION(ms,ms);
4084 void mspace_get_address_and_size (mspace msp, unsigned long long *addrp,
4085 unsigned long long *sizep)
4091 this_seg = &ms->seg;
4093 *addrp = (unsigned long long) this_seg->base;
4094 *sizep = this_seg->size;
4097 int mspace_is_heap_object (mspace msp, void *p)
4105 this_seg = &ms->seg;
4110 base = this_seg->base;
4111 if (pp >= base && pp < (base + this_seg->size))
4113 this_seg = this_seg->next;
4118 void *mspace_least_addr (mspace msp)
4120 mstate ms = (mstate) msp;
4121 return (void *) ms->least_addr;
4124 void mspace_disable_expand (mspace msp)
4126 mstate ms = (mstate)msp;
4128 disable_expand (ms);
4131 int mspace_enable_disable_trace (mspace msp, int enable)
4133 mstate ms = (mstate)msp;
4134 int was_enabled = 0;
4144 return (was_enabled);
4147 void* mspace_get_aligned (mspace msp,
4148 unsigned long long n_user_data_bytes,
4149 unsigned long long align,
4150 unsigned long long align_offset) {
4152 unsigned long long searchp;
4153 unsigned *wwp; /* "where's Waldo" pointer */
4154 mstate ms = (mstate)msp;
4157 * Allocate space for the "Where's Waldo?" pointer
4158 * the base of the dlmalloc object
4160 n_user_data_bytes += sizeof(unsigned);
4163 * Alignment requests less than the size of an mmx vector are ignored
4166 rv = mspace_malloc (msp, n_user_data_bytes);
4170 if (use_trace(ms)) {
4171 mchunkptr p = mem2chunk(rv);
4172 size_t psize = chunksize(p);
4174 mheap_get_trace ((u64)rv + sizeof (unsigned), psize);
4177 wwp = (unsigned *)rv;
4179 rv += sizeof (unsigned);
4185 * Alignment requests greater than 4K must be at offset zero,
4186 * and must be freed using mspace_free_no_offset - or never freed -
4187 * since the "Where's Waldo?" pointer would waste too much space.
4189 * Waldo is the address of the chunk of memory returned by mspace_malloc,
4190 * which we need later to call mspace_free...
4192 if (align > 4<<10 || align_offset == ~0ULL) {
4193 n_user_data_bytes -= sizeof(unsigned);
4194 assert(align_offset == 0);
4195 rv = internal_memalign(ms, (size_t)align, n_user_data_bytes);
4197 /* Trace the allocation */
4198 if (rv && use_trace(ms)) {
4199 mchunkptr p = mem2chunk(rv);
4200 size_t psize = chunksize(p);
4201 mheap_get_trace ((u64)rv, psize);
4206 align = clib_max (align, MALLOC_ALIGNMENT);
4207 align = max_pow2 (align);
4209 /* Correct align offset to be smaller than alignment. */
4210 align_offset &= (align - 1);
4212 n_user_data_bytes += align;
4213 rv = mspace_malloc (msp, n_user_data_bytes);
4218 /* Honor the alignment request */
4219 searchp = (unsigned long long)(rv + sizeof (unsigned));
4221 #if 0 /* this is the idea... */
4222 while ((searchp + align_offset) % align)
4227 unsigned long long where_now, delta;
4229 where_now = (searchp + align_offset) % align;
4230 delta = align - where_now;
4235 wwp = (unsigned *)(searchp - sizeof(unsigned));
4236 *wwp = (searchp - (((unsigned long long) rv) + sizeof (*wwp)));
4237 assert (*wwp < align);
4239 if (use_trace(ms)) {
4240 mchunkptr p = mem2chunk(rv);
4241 size_t psize = chunksize(p);
4242 mheap_get_trace ((u64)rv, psize);
4244 return (void *) searchp;
4247 void mspace_put (mspace msp, void *p_arg)
4249 char *object_header;
4251 mstate ms = (mstate)msp;
4253 /* Find the object header delta */
4254 wwp = (unsigned *)p_arg;
4257 /* Recover the dlmalloc object pointer */
4258 object_header = (char *)wwp;
4259 object_header -= *wwp;
4261 /* Tracing (if enabled) */
4264 mchunkptr p = mem2chunk(object_header);
4265 size_t psize = chunksize(p);
4267 mheap_put_trace ((u64)p_arg, psize);
4270 /* And free it... */
4271 mspace_free (msp, object_header);
4274 void mspace_put_no_offset (mspace msp, void *p_arg)
4276 mstate ms = (mstate)msp;
4280 mchunkptr p = mem2chunk(p_arg);
4281 size_t psize = chunksize(p);
4283 mheap_put_trace ((u64)p_arg, psize);
4285 mspace_free (msp, p_arg);
4288 size_t mspace_usable_size_with_delta (const void *p)
4291 char *object_header;
4294 /* Find the object header delta */
4295 wwp = (unsigned *)p;
4298 /* Recover the dlmalloc object pointer */
4299 object_header = (char *)wwp;
4300 object_header -= *wwp;
4302 usable_size = mspace_usable_size (object_header);
4303 /* account for the offset and the size of the offset... */
4304 usable_size -= (*wwp + sizeof (*wwp));
4309 mspace versions of routines are near-clones of the global
4310 versions. This is not so nice but better than the alternatives.
4313 void* mspace_malloc(mspace msp, size_t bytes) {
4314 mstate ms = (mstate)msp;
4315 if (!ok_magic(ms)) {
4316 USAGE_ERROR_ACTION(ms,ms);
4319 if (!PREACTION(ms)) {
4322 if (bytes <= MAX_SMALL_REQUEST) {
4325 nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes);
4326 idx = small_index(nb);
4327 smallbits = ms->smallmap >> idx;
4329 if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */
4331 idx += ~smallbits & 1; /* Uses next bin if idx empty */
4332 b = smallbin_at(ms, idx);
4334 assert(chunksize(p) == small_index2size(idx));
4335 unlink_first_small_chunk(ms, b, p, idx);
4336 set_inuse_and_pinuse(ms, p, small_index2size(idx));
4338 check_malloced_chunk(ms, mem, nb);
4342 else if (nb > ms->dvsize) {
4343 if (smallbits != 0) { /* Use chunk in next nonempty smallbin */
4347 binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx));
4348 binmap_t leastbit = least_bit(leftbits);
4349 compute_bit2idx(leastbit, i);
4350 b = smallbin_at(ms, i);
4352 assert(chunksize(p) == small_index2size(i));
4353 unlink_first_small_chunk(ms, b, p, i);
4354 rsize = small_index2size(i) - nb;
4355 /* Fit here cannot be remainderless if 4byte sizes */
4356 if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
4357 set_inuse_and_pinuse(ms, p, small_index2size(i));
4359 set_size_and_pinuse_of_inuse_chunk(ms, p, nb);
4360 r = chunk_plus_offset(p, nb);
4361 set_size_and_pinuse_of_free_chunk(r, rsize);
4362 replace_dv(ms, r, rsize);
4365 check_malloced_chunk(ms, mem, nb);
4369 else if (ms->treemap != 0 && (mem = tmalloc_small(ms, nb)) != 0) {
4370 check_malloced_chunk(ms, mem, nb);
4375 else if (bytes >= MAX_REQUEST)
4376 nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */
4378 nb = pad_request(bytes);
4379 if (ms->treemap != 0 && (mem = tmalloc_large(ms, nb)) != 0) {
4380 check_malloced_chunk(ms, mem, nb);
4385 if (nb <= ms->dvsize) {
4386 size_t rsize = ms->dvsize - nb;
4387 mchunkptr p = ms->dv;
4388 if (rsize >= MIN_CHUNK_SIZE) { /* split dv */
4389 mchunkptr r = ms->dv = chunk_plus_offset(p, nb);
4391 set_size_and_pinuse_of_free_chunk(r, rsize);
4392 set_size_and_pinuse_of_inuse_chunk(ms, p, nb);
4394 else { /* exhaust dv */
4395 size_t dvs = ms->dvsize;
4398 set_inuse_and_pinuse(ms, p, dvs);
4401 check_malloced_chunk(ms, mem, nb);
4405 else if (nb < ms->topsize) { /* Split top */
4406 size_t rsize = ms->topsize -= nb;
4407 mchunkptr p = ms->top;
4408 mchunkptr r = ms->top = chunk_plus_offset(p, nb);
4409 r->head = rsize | PINUSE_BIT;
4410 set_size_and_pinuse_of_inuse_chunk(ms, p, nb);
4412 check_top_chunk(ms, ms->top);
4413 check_malloced_chunk(ms, mem, nb);
4417 mem = sys_alloc(ms, nb);
4427 void mspace_free(mspace msp, void* mem) {
4429 mchunkptr p = mem2chunk(mem);
4431 mstate fm = get_mstate_for(p);
4432 (void)msp; /* placate people compiling -Wunused */
4434 mstate fm = (mstate)msp;
4435 #endif /* FOOTERS */
4436 if (!ok_magic(fm)) {
4437 USAGE_ERROR_ACTION(fm, p);
4440 if (!PREACTION(fm)) {
4441 check_inuse_chunk(fm, p);
4442 if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
4443 size_t psize = chunksize(p);
4444 mchunkptr next = chunk_plus_offset(p, psize);
4446 size_t prevsize = p->prev_foot;
4447 if (is_mmapped(p)) {
4448 psize += prevsize + MMAP_FOOT_PAD;
4449 if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
4450 fm->footprint -= psize;
4454 mchunkptr prev = chunk_minus_offset(p, prevsize);
4457 if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */
4459 unlink_chunk(fm, p, prevsize);
4461 else if ((next->head & INUSE_BITS) == INUSE_BITS) {
4463 set_free_with_pinuse(p, psize, next);
4472 if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) {
4473 if (!cinuse(next)) { /* consolidate forward */
4474 if (next == fm->top) {
4475 size_t tsize = fm->topsize += psize;
4477 p->head = tsize | PINUSE_BIT;
4482 if (should_trim(fm, tsize))
4486 else if (next == fm->dv) {
4487 size_t dsize = fm->dvsize += psize;
4489 set_size_and_pinuse_of_free_chunk(p, dsize);
4493 size_t nsize = chunksize(next);
4495 unlink_chunk(fm, next, nsize);
4496 set_size_and_pinuse_of_free_chunk(p, psize);
4504 set_free_with_pinuse(p, psize, next);
4506 if (is_small(psize)) {
4507 insert_small_chunk(fm, p, psize);
4508 check_free_chunk(fm, p);
4511 tchunkptr tp = (tchunkptr)p;
4512 insert_large_chunk(fm, tp, psize);
4513 check_free_chunk(fm, p);
4514 if (--fm->release_checks == 0)
4515 release_unused_segments(fm);
4521 USAGE_ERROR_ACTION(fm, p);
4528 void* mspace_calloc(mspace msp, size_t n_elements, size_t elem_size) {
4531 mstate ms = (mstate)msp;
4532 if (!ok_magic(ms)) {
4533 USAGE_ERROR_ACTION(ms,ms);
4536 if (n_elements != 0) {
4537 req = n_elements * elem_size;
4538 if (((n_elements | elem_size) & ~(size_t)0xffff) &&
4539 (req / n_elements != elem_size))
4540 req = MAX_SIZE_T; /* force downstream failure on overflow */
4542 mem = internal_malloc(ms, req);
4543 if (mem != 0 && calloc_must_clear(mem2chunk(mem)))
4544 memset(mem, 0, req);
4548 void* mspace_realloc(mspace msp, void* oldmem, size_t bytes) {
4551 mem = mspace_malloc(msp, bytes);
4553 else if (bytes >= MAX_REQUEST) {
4554 MALLOC_FAILURE_ACTION;
4556 #ifdef REALLOC_ZERO_BYTES_FREES
4557 else if (bytes == 0) {
4558 mspace_free(msp, oldmem);
4560 #endif /* REALLOC_ZERO_BYTES_FREES */
4562 size_t nb = request2size(bytes);
4563 mchunkptr oldp = mem2chunk(oldmem);
4565 mstate m = (mstate)msp;
4567 mstate m = get_mstate_for(oldp);
4569 USAGE_ERROR_ACTION(m, oldmem);
4572 #endif /* FOOTERS */
4573 if (!PREACTION(m)) {
4574 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 1);
4577 check_inuse_chunk(m, newp);
4578 mem = chunk2mem(newp);
4581 mem = mspace_malloc(m, bytes);
4583 size_t oc = chunksize(oldp) - overhead_for(oldp);
4584 memcpy(mem, oldmem, (oc < bytes)? oc : bytes);
4585 mspace_free(m, oldmem);
4593 void* mspace_realloc_in_place(mspace msp, void* oldmem, size_t bytes) {
4596 if (bytes >= MAX_REQUEST) {
4597 MALLOC_FAILURE_ACTION;
4600 size_t nb = request2size(bytes);
4601 mchunkptr oldp = mem2chunk(oldmem);
4603 mstate m = (mstate)msp;
4605 mstate m = get_mstate_for(oldp);
4606 (void)msp; /* placate people compiling -Wunused */
4608 USAGE_ERROR_ACTION(m, oldmem);
4611 #endif /* FOOTERS */
4612 if (!PREACTION(m)) {
4613 mchunkptr newp = try_realloc_chunk(m, oldp, nb, 0);
4616 check_inuse_chunk(m, newp);
4625 void* mspace_memalign(mspace msp, size_t alignment, size_t bytes) {
4626 mstate ms = (mstate)msp;
4627 if (!ok_magic(ms)) {
4628 USAGE_ERROR_ACTION(ms,ms);
4631 if (alignment <= MALLOC_ALIGNMENT)
4632 return mspace_malloc(msp, bytes);
4633 return internal_memalign(ms, alignment, bytes);
4636 void** mspace_independent_calloc(mspace msp, size_t n_elements,
4637 size_t elem_size, void* chunks[]) {
4638 size_t sz = elem_size; /* serves as 1-element array */
4639 mstate ms = (mstate)msp;
4640 if (!ok_magic(ms)) {
4641 USAGE_ERROR_ACTION(ms,ms);
4644 return ialloc(ms, n_elements, &sz, 3, chunks);
4647 void** mspace_independent_comalloc(mspace msp, size_t n_elements,
4648 size_t sizes[], void* chunks[]) {
4649 mstate ms = (mstate)msp;
4650 if (!ok_magic(ms)) {
4651 USAGE_ERROR_ACTION(ms,ms);
4654 return ialloc(ms, n_elements, sizes, 0, chunks);
4657 size_t mspace_bulk_free(mspace msp, void* array[], size_t nelem) {
4658 return internal_bulk_free((mstate)msp, array, nelem);
4661 #if MALLOC_INSPECT_ALL
4662 void mspace_inspect_all(mspace msp,
4663 void(*handler)(void *start,
4666 void* callback_arg),
4668 mstate ms = (mstate)msp;
4670 if (!PREACTION(ms)) {
4671 internal_inspect_all(ms, handler, arg);
4676 USAGE_ERROR_ACTION(ms,ms);
4679 #endif /* MALLOC_INSPECT_ALL */
4681 int mspace_trim(mspace msp, size_t pad) {
4683 mstate ms = (mstate)msp;
4685 if (!PREACTION(ms)) {
4686 result = sys_trim(ms, pad);
4691 USAGE_ERROR_ACTION(ms,ms);
4696 #if !NO_MALLOC_STATS
4697 void mspace_malloc_stats(mspace msp) {
4698 mstate ms = (mstate)msp;
4700 internal_malloc_stats(ms);
4703 USAGE_ERROR_ACTION(ms,ms);
4706 #endif /* NO_MALLOC_STATS */
4708 size_t mspace_footprint(mspace msp) {
4710 mstate ms = (mstate)msp;
4712 result = ms->footprint;
4715 USAGE_ERROR_ACTION(ms,ms);
4720 size_t mspace_max_footprint(mspace msp) {
4722 mstate ms = (mstate)msp;
4724 result = ms->max_footprint;
4727 USAGE_ERROR_ACTION(ms,ms);
4732 size_t mspace_footprint_limit(mspace msp) {
4734 mstate ms = (mstate)msp;
4736 size_t maf = ms->footprint_limit;
4737 result = (maf == 0) ? MAX_SIZE_T : maf;
4740 USAGE_ERROR_ACTION(ms,ms);
4745 size_t mspace_set_footprint_limit(mspace msp, size_t bytes) {
4747 mstate ms = (mstate)msp;
4750 result = granularity_align(1); /* Use minimal size */
4751 if (bytes == MAX_SIZE_T)
4752 result = 0; /* disable */
4754 result = granularity_align(bytes);
4755 ms->footprint_limit = result;
4758 USAGE_ERROR_ACTION(ms,ms);
4764 struct mallinfo mspace_mallinfo(mspace msp) {
4765 mstate ms = (mstate)msp;
4766 if (!ok_magic(ms)) {
4767 USAGE_ERROR_ACTION(ms,ms);
4769 return internal_mallinfo(ms);
4771 #endif /* NO_MALLINFO */
4773 size_t mspace_usable_size(const void* mem) {
4775 mchunkptr p = mem2chunk(mem);
4777 return chunksize(p) - overhead_for(p);
4782 int mspace_mallopt(int param_number, int value) {
4783 return change_mparam(param_number, value);
4786 #endif /* MSPACES */
4789 /* -------------------- Alternative MORECORE functions ------------------- */
4792 Guidelines for creating a custom version of MORECORE:
4794 * For best performance, MORECORE should allocate in multiples of pagesize.
4795 * MORECORE may allocate more memory than requested. (Or even less,
4796 but this will usually result in a malloc failure.)
4797 * MORECORE must not allocate memory when given argument zero, but
4798 instead return one past the end address of memory from previous
4800 * For best performance, consecutive calls to MORECORE with positive
4801 arguments should return increasing addresses, indicating that
4802 space has been contiguously extended.
4803 * Even though consecutive calls to MORECORE need not return contiguous
4804 addresses, it must be OK for malloc'ed chunks to span multiple
4805 regions in those cases where they do happen to be contiguous.
4806 * MORECORE need not handle negative arguments -- it may instead
4807 just return MFAIL when given negative arguments.
4808 Negative arguments are always multiples of pagesize. MORECORE
4809 must not misinterpret negative args as large positive unsigned
4810 args. You can suppress all such calls from even occurring by defining
4811 MORECORE_CANNOT_TRIM,
4813 As an example alternative MORECORE, here is a custom allocator
4814 kindly contributed for pre-OSX macOS. It uses virtually but not
4815 necessarily physically contiguous non-paged memory (locked in,
4816 present and won't get swapped out). You can use it by uncommenting
4817 this section, adding some #includes, and setting up the appropriate
4820 #define MORECORE osMoreCore
4822 There is also a shutdown routine that should somehow be called for
4823 cleanup upon program exit.
4825 #define MAX_POOL_ENTRIES 100
4826 #define MINIMUM_MORECORE_SIZE (64 * 1024U)
4827 static int next_os_pool;
4828 void *our_os_pools[MAX_POOL_ENTRIES];
4830 void *osMoreCore(int size)
4833 static void *sbrk_top = 0;
4837 if (size < MINIMUM_MORECORE_SIZE)
4838 size = MINIMUM_MORECORE_SIZE;
4839 if (CurrentExecutionLevel() == kTaskLevel)
4840 ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
4843 return (void *) MFAIL;
4845 // save ptrs so they can be freed during cleanup
4846 our_os_pools[next_os_pool] = ptr;
4848 ptr = (void *) ((((size_t) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
4849 sbrk_top = (char *) ptr + size;
4854 // we don't currently support shrink behavior
4855 return (void *) MFAIL;
4863 // cleanup any allocated memory pools
4864 // called as last thing before shutting down driver
4866 void osCleanupMem(void)
4870 for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
4873 PoolDeallocate(*ptr);
4881 /* -----------------------------------------------------------------------
4883 v2.8.6 Wed Aug 29 06:57:58 2012 Doug Lea
4884 * fix bad comparison in dlposix_memalign
4885 * don't reuse adjusted asize in sys_alloc
4886 * add LOCK_AT_FORK -- thanks to Kirill Artamonov for the suggestion
4887 * reduce compiler warnings -- thanks to all who reported/suggested these
4889 v2.8.5 Sun May 22 10:26:02 2011 Doug Lea (dl at gee)
4890 * Always perform unlink checks unless INSECURE
4891 * Add posix_memalign.
4892 * Improve realloc to expand in more cases; expose realloc_in_place.
4893 Thanks to Peter Buhr for the suggestion.
4894 * Add footprint_limit, inspect_all, bulk_free. Thanks
4895 to Barry Hayes and others for the suggestions.
4896 * Internal refactorings to avoid calls while holding locks
4897 * Use non-reentrant locks by default. Thanks to Roland McGrath
4899 * Small fixes to mspace_destroy, reset_on_error.
4900 * Various configuration extensions/changes. Thanks
4901 to all who contributed these.
4903 V2.8.4a Thu Apr 28 14:39:43 2011 (dl at gee.cs.oswego.edu)
4904 * Update Creative Commons URL
4906 V2.8.4 Wed May 27 09:56:23 2009 Doug Lea (dl at gee)
4907 * Use zeros instead of prev foot for is_mmapped
4908 * Add mspace_track_large_chunks; thanks to Jean Brouwers
4909 * Fix set_inuse in internal_realloc; thanks to Jean Brouwers
4910 * Fix insufficient sys_alloc padding when using 16byte alignment
4911 * Fix bad error check in mspace_footprint
4912 * Adaptations for ptmalloc; thanks to Wolfram Gloger.
4913 * Reentrant spin locks; thanks to Earl Chew and others
4914 * Win32 improvements; thanks to Niall Douglas and Earl Chew
4915 * Add NO_SEGMENT_TRAVERSAL and MAX_RELEASE_CHECK_RATE options
4916 * Extension hook in malloc_state
4917 * Various small adjustments to reduce warnings on some compilers
4918 * Various configuration extensions/changes for more platforms. Thanks
4919 to all who contributed these.
4921 V2.8.3 Thu Sep 22 11:16:32 2005 Doug Lea (dl at gee)
4922 * Add max_footprint functions
4923 * Ensure all appropriate literals are size_t
4924 * Fix conditional compilation problem for some #define settings
4925 * Avoid concatenating segments with the one provided
4926 in create_mspace_with_base
4927 * Rename some variables to avoid compiler shadowing warnings
4928 * Use explicit lock initialization.
4929 * Better handling of sbrk interference.
4930 * Simplify and fix segment insertion, trimming and mspace_destroy
4931 * Reinstate REALLOC_ZERO_BYTES_FREES option from 2.7.x
4932 * Thanks especially to Dennis Flanagan for help on these.
4934 V2.8.2 Sun Jun 12 16:01:10 2005 Doug Lea (dl at gee)
4935 * Fix memalign brace error.
4937 V2.8.1 Wed Jun 8 16:11:46 2005 Doug Lea (dl at gee)
4938 * Fix improper #endif nesting in C++
4939 * Add explicit casts needed for C++
4941 V2.8.0 Mon May 30 14:09:02 2005 Doug Lea (dl at gee)
4942 * Use trees for large bins
4944 * Use segments to unify sbrk-based and mmap-based system allocation,
4945 removing need for emulation on most platforms without sbrk.
4946 * Default safety checks
4947 * Optional footer checks. Thanks to William Robertson for the idea.
4948 * Internal code refactoring
4949 * Incorporate suggestions and platform-specific changes.
4950 Thanks to Dennis Flanagan, Colin Plumb, Niall Douglas,
4951 Aaron Bachmann, Emery Berger, and others.
4952 * Speed up non-fastbin processing enough to remove fastbins.
4953 * Remove useless cfree() to avoid conflicts with other apps.
4954 * Remove internal memcpy, memset. Compilers handle builtins better.
4955 * Remove some options that no one ever used and rename others.
4957 V2.7.2 Sat Aug 17 09:07:30 2002 Doug Lea (dl at gee)
4958 * Fix malloc_state bitmap array misdeclaration
4960 V2.7.1 Thu Jul 25 10:58:03 2002 Doug Lea (dl at gee)
4961 * Allow tuning of FIRST_SORTED_BIN_SIZE
4962 * Use PTR_UINT as type for all ptr->int casts. Thanks to John Belmonte.
4963 * Better detection and support for non-contiguousness of MORECORE.
4964 Thanks to Andreas Mueller, Conal Walsh, and Wolfram Gloger
4965 * Bypass most of malloc if no frees. Thanks To Emery Berger.
4966 * Fix freeing of old top non-contiguous chunk im sysmalloc.
4967 * Raised default trim and map thresholds to 256K.
4968 * Fix mmap-related #defines. Thanks to Lubos Lunak.
4969 * Fix copy macros; added LACKS_FCNTL_H. Thanks to Neal Walfield.
4970 * Branch-free bin calculation
4971 * Default trim and mmap thresholds now 256K.
4973 V2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
4974 * Introduce independent_comalloc and independent_calloc.
4975 Thanks to Michael Pachos for motivation and help.
4976 * Make optional .h file available
4977 * Allow > 2GB requests on 32bit systems.
4978 * new WIN32 sbrk, mmap, munmap, lock code from <Walter@GeNeSys-e.de>.
4979 Thanks also to Andreas Mueller <a.mueller at paradatec.de>,
4981 * Allow override of MALLOC_ALIGNMENT (Thanks to Ruud Waij for
4983 * memalign: check alignment arg
4984 * realloc: don't try to shift chunks backwards, since this
4985 leads to more fragmentation in some programs and doesn't
4986 seem to help in any others.
4987 * Collect all cases in malloc requiring system memory into sysmalloc
4988 * Use mmap as backup to sbrk
4989 * Place all internal state in malloc_state
4990 * Introduce fastbins (although similar to 2.5.1)
4991 * Many minor tunings and cosmetic improvements
4992 * Introduce USE_PUBLIC_MALLOC_WRAPPERS, USE_MALLOC_LOCK
4993 * Introduce MALLOC_FAILURE_ACTION, MORECORE_CONTIGUOUS
4994 Thanks to Tony E. Bennett <tbennett@nvidia.com> and others.
4995 * Include errno.h to support default failure action.
4997 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee)
4998 * return null for negative arguments
4999 * Added Several WIN32 cleanups from Martin C. Fong <mcfong at yahoo.com>
5000 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
5001 (e.g. WIN32 platforms)
5002 * Cleanup header file inclusion for WIN32 platforms
5003 * Cleanup code to avoid Microsoft Visual C++ compiler complaints
5004 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
5005 memory allocation routines
5006 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
5007 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
5008 usage of 'assert' in non-WIN32 code
5009 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
5011 * Always call 'fREe()' rather than 'free()'
5013 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)
5014 * Fixed ordering problem with boundary-stamping
5016 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
5017 * Added pvalloc, as recommended by H.J. Liu
5018 * Added 64bit pointer support mainly from Wolfram Gloger
5019 * Added anonymously donated WIN32 sbrk emulation
5020 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
5021 * malloc_extend_top: fix mask error that caused wastage after
5023 * Add linux mremap support code from HJ Liu
5025 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
5026 * Integrated most documentation with the code.
5027 * Add support for mmap, with help from
5028 Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
5029 * Use last_remainder in more cases.
5030 * Pack bins using idea from colin@nyx10.cs.du.edu
5031 * Use ordered bins instead of best-fit threshhold
5032 * Eliminate block-local decls to simplify tracing and debugging.
5033 * Support another case of realloc via move into top
5034 * Fix error occuring when initial sbrk_base not word-aligned.
5035 * Rely on page size for units instead of SBRK_UNIT to
5036 avoid surprises about sbrk alignment conventions.
5037 * Add mallinfo, mallopt. Thanks to Raymond Nijssen
5038 (raymond@es.ele.tue.nl) for the suggestion.
5039 * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
5040 * More precautions for cases where other routines call sbrk,
5041 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
5042 * Added macros etc., allowing use in linux libc from
5043 H.J. Lu (hjl@gnu.ai.mit.edu)
5044 * Inverted this history list
5046 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
5047 * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
5048 * Removed all preallocation code since under current scheme
5049 the work required to undo bad preallocations exceeds
5050 the work saved in good cases for most test programs.
5051 * No longer use return list or unconsolidated bins since
5052 no scheme using them consistently outperforms those that don't
5053 given above changes.
5054 * Use best fit for very large chunks to prevent some worst-cases.
5055 * Added some support for debugging
5057 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
5058 * Removed footers when chunks are in use. Thanks to
5059 Paul Wilson (wilson@cs.texas.edu) for the suggestion.
5061 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
5062 * Added malloc_trim, with help from Wolfram Gloger
5063 (wmglo@Dent.MED.Uni-Muenchen.DE).
5065 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
5067 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
5068 * realloc: try to expand in both directions
5069 * malloc: swap order of clean-bin strategy;
5070 * realloc: only conditionally expand backwards
5071 * Try not to scavenge used bins
5072 * Use bin counts as a guide to preallocation
5073 * Occasionally bin return list chunks in first scan
5074 * Add a few optimizations from colin@nyx10.cs.du.edu
5076 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
5077 * faster bin computation & slightly different binning
5078 * merged all consolidations to one part of malloc proper
5079 (eliminating old malloc_find_space & malloc_clean_bin)
5080 * Scan 2 returns chunks (not just 1)
5081 * Propagate failure in realloc if malloc returns 0
5082 * Add stuff to allow compilation on non-ANSI compilers
5083 from kpv@research.att.com
5085 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
5086 * removed potential for odd address access in prev_chunk
5087 * removed dependency on getpagesize.h
5088 * misc cosmetics and a bit more internal documentation
5089 * anticosmetics: mangled names in macros to evade debugger strangeness
5090 * tested on sparc, hp-700, dec-mips, rs6000
5091 with gcc & native cc (hp, dec only) allowing
5092 Detlefs & Zorn comparison study (in SIGPLAN Notices.)
5094 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
5095 * Based loosely on libg++-1.2X malloc. (It retains some of the overall
5096 structure of old version, but most details differ.)