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authorRich Felker <dalias@aerifal.cx>2020-06-16 00:53:57 -0400
committerRich Felker <dalias@aerifal.cx>2020-06-16 00:58:22 -0400
commitfca7428c096066482d8c3f52450810288e27515c (patch)
tree985334c5d64519bbaa87a7502654718cd5bb577e /src
parentcb5babdc8d624a3e3e7bea0b4e28a677a2f2fc46 (diff)
downloadmusl-fca7428c096066482d8c3f52450810288e27515c.tar.gz
only use memcpy realloc to shrink if an exact-sized free chunk exists
otherwise, shrink in-place. as explained in the description of commit 3e16313f8fe2ed143ae0267fd79d63014c24779f, the split here is valid without holding split_merge_lock because all chunks involved are in the in-use state.
Diffstat (limited to 'src')
-rw-r--r--src/malloc/oldmalloc/malloc.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/src/malloc/oldmalloc/malloc.c b/src/malloc/oldmalloc/malloc.c
index 52af1975..c0997ad8 100644
--- a/src/malloc/oldmalloc/malloc.c
+++ b/src/malloc/oldmalloc/malloc.c
@@ -385,6 +385,18 @@ void *realloc(void *p, size_t n)
/* Crash on corrupted footer (likely from buffer overflow) */
if (next->psize != self->csize) a_crash();
+ if (n < n0) {
+ int i = bin_index_up(n);
+ int j = bin_index(n0);
+ if (i<j && (mal.binmap & (1ULL << i)))
+ goto copy_realloc;
+ struct chunk *split = (void *)((char *)self + n);
+ self->csize = split->psize = n | C_INUSE;
+ split->csize = next->psize = n0-n | C_INUSE;
+ __bin_chunk(split);
+ return CHUNK_TO_MEM(self);
+ }
+
lock(mal.split_merge_lock);
size_t nsize = next->csize & C_INUSE ? 0 : CHUNK_SIZE(next);