Allow xrealloc to act as a free() when size=0, per SuS2.

 -Erik

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index f3b294be2ad0592eb2f0d1059590dc712b567c02..eb93bf139d617a3950870cf98737a0e3b0ebb87a 100644 (file)
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -44,7 +44,17 @@ extern void *xmalloc(size_t size)
 
 extern void *xrealloc(void *old, size_t size)
 {
-       void *ptr = realloc(old, size);
+       void *ptr;
+
+       /* SuS2 says "If size is 0 and ptr is not a null pointer, the
+        * object pointed to is freed."  Do that here, in case realloc
+        * returns a NULL, since we don't want to choke in that case. */
+       if (size==0 && old) {
+               free(old);
+               return NULL;
+       }
+
+       ptr = realloc(old, size);
        if (!ptr)
                error_msg_and_die(memory_exhausted);
        return ptr;