preserve errno across free

[musl] / src / malloc / mallocng / free.c

diff --git a/src/malloc/mallocng/free.c b/src/malloc/mallocng/free.c
index 40745f9..418a085 100644 (file)
--- a/src/malloc/mallocng/free.c
+++ b/src/malloc/mallocng/free.c
@@ -119,7 +119,11 @@ void free(void *p)
        if (((uintptr_t)(start-1) ^ (uintptr_t)end) >= 2*PGSZ && g->last_idx) {
                unsigned char *base = start + (-(uintptr_t)start & (PGSZ-1));
                size_t len = (end-base) & -PGSZ;
-               if (len) madvise(base, len, MADV_FREE);
+               if (len) {
+                       int e = errno;
+                       madvise(base, len, MADV_FREE);
+                       errno = e;
+               }
        }
 
        // atomic free without locking if this is neither first or last slot
@@ -139,5 +143,9 @@ void free(void *p)
        wrlock();
        struct mapinfo mi = nontrivial_free(g, idx);
        unlock();
-       if (mi.len) munmap(mi.base, mi.len);
+       if (mi.len) {
+               int e = errno;
+               munmap(mi.base, mi.len);
+               errno = e;
+       }
 }