[pacman-dev] [PATCH 1/2] Avoid stat() on NULL path in curl_download_internal()

[Lukas Fleischer]

stat()'s behaviour is undefined if the first argument is NULL and might
be prone to segfault. Add an additional check to skip the stat()
invocation if no destfile is used.

Signed-off-by: Lukas Fleischer <archlinux at cryptocrack.de>
---
 lib/libalpm/dload.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index 5a63e48..731d807 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -260,7 +260,7 @@ static int curl_download_internal(struct dload_payload *payload,
 		curl_easy_setopt(handle->curl, CURLOPT_USERAGENT, useragent);
 	}
 
-	if(!payload->allow_resume && !payload->force && stat(destfile, &st) == 0) {
+	if(!payload->allow_resume && !payload->force && destfile && stat(destfile, &st) == 0) {
 		/* start from scratch, but only download if our local is out of date. */
 		curl_easy_setopt(handle->curl, CURLOPT_TIMECONDITION, CURL_TIMECOND_IFMODSINCE);
 		curl_easy_setopt(handle->curl, CURLOPT_TIMEVALUE, (long)st.st_mtime);
-- 
1.7.6