utils.c: fix xrealloc

(based on suggested patch by Jan-Benedict Glaw):
> While hacking mpd, I noticed that an assert()ion in xrealloc is wrong.
> A null size is perfectly legal, so we shouldn't assert on that.

Since some C libraries return NULL when size == 0, we'll make
sure we get a free()-able pointer since some of those C
libraries also barf on free(NULL).

git-svn-id: https://svn.musicpd.org/mpd/trunk@4740 09075e82-0dd4-0310-85a5-a0d7c8717e4f

1 files changed, 6 insertions, 5 deletions

diff --git a/src/utils.c b/src/utils.c
index 60fa3f135..919553d3e 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -133,13 +133,14 @@ mpd_malloc void *xmalloc(size_t size)
 
 mpd_malloc void *xrealloc(void *ptr, size_t size)
 {
-	void *ret;
+	void *ret = realloc(ptr, size);
 
-	/* hmm... realloc to 0 isn't uncommon..., is it? this check
-	 * may be too extreme... (eric) */
-	assert((mpd_likely(size)));
+	/* some C libraries return NULL when size == 0,
+	 * make sure we get a free()-able pointer (free(NULL)
+	 * doesn't work with all C libraries, either) */
+	if (mpd_unlikely(!ret && !size))
+		ret = realloc(ptr, 1);
 
-	ret = realloc(ptr, size);
 	if (mpd_unlikely(!ret))
 		FATAL("OOM: realloc\n");
 	return ret;