r13397: Propagate the error return from vsnprintf to trap the case where

we aren't linked against a C99 vsnprintf.
(This used to be commit 23782f899aaa5fe488d86d5e67e91be99ff7a146)

1 files changed, 12 insertions, 2 deletions

diff --git a/source4/lib/talloc/talloc.c b/source4/lib/talloc/talloc.c
index ac2fedebdc..6b3328420d 100644
--- a/source4/lib/talloc/talloc.c
+++ b/source4/lib/talloc/talloc.c
@@ -1011,7 +1011,9 @@ char *talloc_vasprintf(const void *t, const char *fmt, va_list ap)
 	
 	VA_COPY(ap2, ap);
 
-	len = vsnprintf(NULL, 0, fmt, ap2);
+	if ((len = vsnprintf(NULL, 0, fmt, ap2)) <= 0) {
+		return NULL;
+	}
 
 	ret = _talloc(t, len+1);
 	if (ret) {
@@ -1060,7 +1062,15 @@ char *talloc_vasprintf_append(char *s, const char *fmt, va_list ap)
 	VA_COPY(ap2, ap);
 
 	s_len = tc->size - 1;
-	len = vsnprintf(NULL, 0, fmt, ap2);
+	if ((len = vsnprintf(NULL, 0, fmt, ap2)) <= 0) {
+		/* Either the vsnprintf failed or the format resulted in
+		 * no characters being formatted. In the former case, we
+		 * ought to return NULL, in the latter we ought to return
+		 * the original string. Most current callers of this 
+		 * function expect it to never return NULL.
+		 */
+		return s;
+	}
 
 	s = talloc_realloc(NULL, s, char, s_len + len+1);
 	if (!s) return NULL;