path: root/src/malloc/lite_malloc.c
diff options
authorRich Felker <>2018-04-17 18:36:19 -0400
committerRich Felker <>2018-04-18 14:22:49 -0400
commitc9f415d7ea2dace5bf77f6518b6afc36bb7a5732 (patch)
tree53e90cc28b51fd50185527bfbd71411e1ef05843 /src/malloc/lite_malloc.c
parentc1014a812c90bab3c9c989863e4ebb129e987de6 (diff)
allow interposition/replacement of allocator (malloc)
replacement is subject to conditions on the replacement functions. they may only call functions which are async-signal-safe, as specified either by POSIX or as an implementation-defined extension. if any allocator functions are replaced, at least malloc, realloc, and free must be provided. if calloc is not provided, it will behave as malloc+memset. any of the memalign-family functions not provided will fail with ENOMEM. in order to implement the above properties, calloc and __memalign check that they are using their own malloc or free, respectively. choice to check malloc or free is based on considerations of supporting __simple_malloc. in order to make this work, calloc is split into separate versions for __simple_malloc and full malloc; commit ba819787ee93ceae94efd274f7849e317c1bff58 already did most of the split anyway, and completing it saves an extra call frame. previously, use of -Bsymbolic-functions made dynamic interposition impossible. now, we are using an explicit dynamic-list, so add allocator functions to the list. most are not referenced anyway, but all are added for completeness.
Diffstat (limited to 'src/malloc/lite_malloc.c')
1 files changed, 11 insertions, 1 deletions
diff --git a/src/malloc/lite_malloc.c b/src/malloc/lite_malloc.c
index 701f60b4..29cccb10 100644
--- a/src/malloc/lite_malloc.c
+++ b/src/malloc/lite_malloc.c
@@ -47,4 +47,14 @@ static void *__simple_malloc(size_t n)
weak_alias(__simple_malloc, malloc);
-weak_alias(__simple_malloc, __malloc0);
+static void *__simple_calloc(size_t m, size_t n)
+ if (n && m > (size_t)-1/n || malloc != __simple_malloc) {
+ errno = ENOMEM;
+ return 0;
+ }
+ return __simple_malloc(n * m);
+weak_alias(__simple_calloc, calloc);