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authorRich Felker <dalias@aerifal.cx>2021-01-30 17:28:08 -0500
committerRich Felker <dalias@aerifal.cx>2021-01-30 17:28:08 -0500
commit9b77aaca86b53c367f23505c24dd3c02e240efad (patch)
tree7922f847a292971a7dbe61f68acd503d9a58a371 /src/malloc/oldmalloc/malloc.c
parent98b9df994c85dcb6a8a5a9099495dd44c7cf2bce (diff)
downloadmusl-9b77aaca86b53c367f23505c24dd3c02e240efad.tar.gz
oldmalloc: preserve errno across free
as an outcome of Austin Group issue #385, future versions of the standard will require free not to alter the value of errno. save and restore it individually around the calls to madvise and munmap so that the cost is not imposed on calls to free that do not result in any syscall.
Diffstat (limited to 'src/malloc/oldmalloc/malloc.c')
-rw-r--r--src/malloc/oldmalloc/malloc.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/malloc/oldmalloc/malloc.c b/src/malloc/oldmalloc/malloc.c
index a5cbdb68..25d00d44 100644
--- a/src/malloc/oldmalloc/malloc.c
+++ b/src/malloc/oldmalloc/malloc.c
@@ -481,12 +481,14 @@ void __bin_chunk(struct chunk *self)
if (size > RECLAIM && (size^(size-osize)) > size-osize) {
uintptr_t a = (uintptr_t)self + SIZE_ALIGN+PAGE_SIZE-1 & -PAGE_SIZE;
uintptr_t b = (uintptr_t)next - SIZE_ALIGN & -PAGE_SIZE;
+ int e = errno;
#if 1
__madvise((void *)a, b-a, MADV_DONTNEED);
#else
__mmap((void *)a, b-a, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0);
#endif
+ errno = e;
}
unlock_bin(i);
@@ -499,7 +501,9 @@ static void unmap_chunk(struct chunk *self)
size_t len = CHUNK_SIZE(self) + extra;
/* Crash on double free */
if (extra & 1) a_crash();
+ int e = errno;
__munmap(base, len);
+ errno = e;
}
void free(void *p)