External allocator support.

[ccan] / ccan / talloc / talloc.c

diff --git a/ccan/talloc/talloc.c b/ccan/talloc/talloc.c
index d624b9174dde42b8e892fb5764cb9544bd249671..59a981b48c8631dde962ee5326c1dcfde4d92a00 100644 (file)
--- a/ccan/talloc/talloc.c
+++ b/ccan/talloc/talloc.c
@@ -45,6 +45,7 @@
 #define TALLOC_MAGIC 0xe814ec70
 #define TALLOC_FLAG_FREE 0x01
 #define TALLOC_FLAG_LOOP 0x02
+#define TALLOC_FLAG_EXT_ALLOC 0x04
 #define TALLOC_MAGIC_REFERENCE ((const char *)1)
 
 /* by default we abort when given a bad pointer (such as when talloc_free() is called 
@@ -79,6 +80,10 @@
 static void *null_context;
 static void *autofree_context;
 
+static void *(*tc_external_alloc)(void *parent, size_t size);
+static void (*tc_external_free)(void *ptr, void *parent);
+static void *(*tc_external_realloc)(void *ptr, void *parent, size_t size);
+
 struct talloc_reference_handle {
        struct talloc_reference_handle *next, *prev;
        void *ptr;
@@ -181,6 +186,8 @@ const char *talloc_parent_name(const void *ptr)
 static inline void *__talloc(const void *context, size_t size)
 {
        struct talloc_chunk *tc;
+       struct talloc_chunk *parent = NULL; /* Prevent spurious gcc warning */
+       unsigned flags = TALLOC_MAGIC;
 
        if (unlikely(context == NULL)) {
                context = null_context;
@@ -190,19 +197,28 @@ static inline void *__talloc(const void *context, size_t size)
                return NULL;
        }
 
+       if (likely(context)) {
+               parent = talloc_chunk_from_ptr(context);
+               if (unlikely(parent->flags & TALLOC_FLAG_EXT_ALLOC)) {
+                       tc = tc_external_alloc(TC_PTR_FROM_CHUNK(parent),
+                                              TC_HDR_SIZE+size);
+                       flags |= TALLOC_FLAG_EXT_ALLOC;
+                       goto alloc_done;
+               }
+       }
+
        tc = (struct talloc_chunk *)malloc(TC_HDR_SIZE+size);
+alloc_done:
        if (unlikely(tc == NULL)) return NULL;
 
        tc->size = size;
-       tc->flags = TALLOC_MAGIC;
+       tc->flags = flags;
        tc->destructor = NULL;
        tc->child = NULL;
        tc->name = NULL;
        tc->refs = NULL;
 
        if (likely(context)) {
-               struct talloc_chunk *parent = talloc_chunk_from_ptr(context);
-
                if (parent->child) {
                        parent->child->parent = NULL;
                        tc->next = parent->child;
@@ -319,6 +335,7 @@ void *_talloc_reference(const void *context, const void *ptr)
 static inline int _talloc_free(void *ptr)
 {
        struct talloc_chunk *tc;
+       void *oldparent = NULL;
 
        if (unlikely(ptr == NULL)) {
                return -1;
@@ -362,6 +379,7 @@ static inline int _talloc_free(void *ptr)
        }
 
        if (tc->parent) {
+               oldparent = TC_PTR_FROM_CHUNK(tc->parent);
                _TLIST_REMOVE(tc->parent->child, tc);
                if (tc->parent->child) {
                        tc->parent->child->parent = tc->parent;
@@ -395,7 +413,12 @@ static inline int _talloc_free(void *ptr)
        }
 
        tc->flags |= TALLOC_FLAG_FREE;
-       free(tc);
+
+       if (unlikely(tc->flags & TALLOC_FLAG_EXT_ALLOC))
+               tc_external_free(tc, oldparent);
+       else
+               free(tc);
+
        return 0;
 }
 
@@ -771,18 +794,26 @@ void *_talloc_realloc(const void *context, void *ptr, size_t size, const char *n
                return NULL;
        }
 
-       /* by resetting magic we catch users of the old memory */
-       tc->flags |= TALLOC_FLAG_FREE;
+       if (unlikely(tc->flags & TALLOC_FLAG_EXT_ALLOC)) {
+               /* need to get parent before setting free flag. */
+               void *parent = talloc_parent(ptr);
+               tc->flags |= TALLOC_FLAG_FREE;
+               new_ptr = tc_external_realloc(tc, parent, size + TC_HDR_SIZE);
+       } else {
+               /* by resetting magic we catch users of the old memory */
+               tc->flags |= TALLOC_FLAG_FREE;
 
 #if ALWAYS_REALLOC
-       new_ptr = malloc(size + TC_HDR_SIZE);
-       if (new_ptr) {
-               memcpy(new_ptr, tc, tc->size + TC_HDR_SIZE);
-               free(tc);
-       }
+               new_ptr = malloc(size + TC_HDR_SIZE);
+               if (new_ptr) {
+                       memcpy(new_ptr, tc, tc->size + TC_HDR_SIZE);
+                       free(tc);
+               }
 #else
-       new_ptr = realloc(tc, size + TC_HDR_SIZE);
+               new_ptr = realloc(tc, size + TC_HDR_SIZE);
 #endif
+       }
+
        if (unlikely(!new_ptr)) {       
                tc->flags &= ~TALLOC_FLAG_FREE; 
                return NULL; 
@@ -1401,3 +1432,24 @@ int talloc_is_parent(const void *context, const void *ptr)
        }
        return 0;
 }
+
+void talloc_external_enable(void *(*alloc)(void *parent, size_t size),
+                           void (*free)(void *ptr, void *parent),
+                           void *(*realloc)(void *ptr, void *parent, size_t))
+{
+       tc_external_alloc = alloc;
+       tc_external_free = free;
+       tc_external_realloc = realloc;
+}
+
+void talloc_mark_external(void *context)
+{
+       struct talloc_chunk *tc;
+
+       if (unlikely(context == NULL)) {
+               context = null_context;
+       }
+
+       tc = talloc_chunk_from_ptr(context);
+       tc->flags |= TALLOC_FLAG_EXT_ALLOC;
+}