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[tsan] Fix behavior of realloc(nullptr, 0) on Darwin 

On Darwin, there are some apps that rely on realloc(nullptr, 0) returning a valid pointer. TSan currently returns nullptr in this case, let's fix it to avoid breaking binary compatibility.

Differential Revision: https://reviews.llvm.org/D22800

llvm-svn: 277458
This commit is contained in:
Kuba Brecka 2016-08-02 14:22:12 +00:00
parent 7ef9a07f96
commit b5a60ec7fe
2 changed files with 27 additions and 11 deletions
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18
compiler-rt/lib/tsan/rtl/tsan_mman.cc
View File

@ -195,20 +195,16 @@ void OnUserFree(ThreadState *thr, uptr pc, uptr p, bool write) {
}
void *user_realloc(ThreadState *thr, uptr pc, void *p, uptr sz) {
void *p2 = 0;
// FIXME: Handle "shrinking" more efficiently,
// it seems that some software actually does this.
if (sz) {
p2 = user_alloc(thr, pc, sz);
if (p2 == 0)
return 0;
if (p) {
uptr oldsz = user_alloc_usable_size(p);
internal_memcpy(p2, p, min(oldsz, sz));
}
}
if (p)
void *p2 = user_alloc(thr, pc, sz);
if (p2 == 0)
return 0;
if (p) {
uptr oldsz = user_alloc_usable_size(p);
internal_memcpy(p2, p, min(oldsz, sz));
user_free(thr, pc, p);
}
return p2;
}

20
compiler-rt/test/tsan/Darwin/realloc-zero.cc Normal file
View File

@ -0,0 +1,20 @@
// Test that realloc(nullptr, 0) return a non-NULL pointer.
// RUN: %clang_tsan %s -o %t
// RUN: %run %t 2>&1 | FileCheck %s
#include <malloc/malloc.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
int main() {
void *p = realloc(nullptr, 0);
if (!p) {
abort();
}
fprintf(stderr, "Okay.\n");
return 0;
}
// CHECK: Okay.