From c9f415d7ea2dace5bf77f6518b6afc36bb7a5732 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Tue, 17 Apr 2018 18:36:19 -0400 Subject: 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. --- src/malloc/memalign.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'src/malloc/memalign.c') diff --git a/src/malloc/memalign.c b/src/malloc/memalign.c index 006bd21c..35b67599 100644 --- a/src/malloc/memalign.c +++ b/src/malloc/memalign.c @@ -3,9 +3,7 @@ #include #include "libc.h" -/* This function should work with most dlmalloc-like chunk bookkeeping - * systems, but it's only guaranteed to work with the native implementation - * used in this library. */ +void __internal_free(void *); void *__memalign(size_t align, size_t len) { @@ -17,7 +15,7 @@ void *__memalign(size_t align, size_t len) return NULL; } - if (len > SIZE_MAX - align) { + if (len > SIZE_MAX - align || free != __internal_free) { errno = ENOMEM; return NULL; } -- cgit v1.2.1