From cabbee7d8caeafa3959f4559177ae335567aefb4 Mon Sep 17 00:00:00 2001
From: Dave Barach <dave@barachs.net>
Date: Sat, 18 Nov 2017 08:43:06 -0500
Subject: [PATCH] Call a plugin init function by name

Use this macro to arrange init function ordering between friend
plugins.  Fails in the usual manner if the plugin doesn't exist, or if
the init function symbol is AWOL.

clib_error_t *
thisplug_init (vlib_main_t *vm)
{
  clib_error_t *error = 0;

  if ((error = vlib_plugin_init_function ("otherplug.so", otherplug_init)))
     return error;

  <etc>
  return error;
}
VLIB_INIT_FUNCTION(thisplug_init);

Change-Id: Ideecaf46bc0b1546e85096e54be8ddef87946565
Signed-off-by: Dave Barach <dave@barachs.net>
---
 src/vlib/unix/plugin.h | 26 ++++++++++++++++++++++++++
 src/vppinfra/clib.h    |  3 +++
 2 files changed, 29 insertions(+)

diff --git a/src/vlib/unix/plugin.h b/src/vlib/unix/plugin.h
index d9801ec439a..52da7436e61 100644
--- a/src/vlib/unix/plugin.h
+++ b/src/vlib/unix/plugin.h
@@ -115,6 +115,32 @@ void *vlib_get_plugin_symbol (char *plugin_name, char *symbol_name);
   vlib_plugin_registration_t vlib_plugin_registration \
   __attribute__((__section__(".vlib_plugin_registration")))
 
+/* Call a plugin init function: used for init function dependencies. */
+#define vlib_call_plugin_init_function(vm,p,x)                  \
+({                                                              \
+  clib_error_t *(*_f)(vlib_main_t *);                           \
+  uword *_fptr = 0;                                             \
+  clib_error_t * _error = 0;                                    \
+  _fptr= vlib_get_plugin_symbol                                 \
+    (p, CLIB_STRING_MACRO(_vlib_init_function_##x));            \
+  if (_fptr == 0)                                               \
+    {                                                           \
+      _error = clib_error_return                                \
+        (0, "Plugin %s and/or symbol %s not found.",            \
+         p, CLIB_STRING_MACRO(_vlib_init_function_##x));        \
+    }                                                           \
+  else                                                          \
+    {                                                           \
+      _f = (void *)(_fptr[0]);                                  \
+    }                                                           \
+  if (_fptr && ! hash_get (vm->init_functions_called, _f))      \
+    {                                                           \
+      hash_set1 (vm->init_functions_called, _f);                \
+      _error = _f (vm);                                         \
+    }                                                           \
+  _error;                                                       \
+ })
+
 #endif /* __included_plugin_h__ */
 
 /*
diff --git a/src/vppinfra/clib.h b/src/vppinfra/clib.h
index 33db3b203f9..0d059a0778b 100644
--- a/src/vppinfra/clib.h
+++ b/src/vppinfra/clib.h
@@ -78,6 +78,9 @@
 #define CLIB_PACKED(x)	x __attribute__ ((packed))
 #define CLIB_UNUSED(x)	x __attribute__ ((unused))
 
+/* Make a string from the macro's argument */
+#define CLIB_STRING_MACRO(x) #x
+
 #define __clib_unused __attribute__ ((unused))
 #define __clib_weak __attribute__ ((weak))
 #define __clib_packed __attribute__ ((packed))
-- 
2.16.6