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@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/* start from scratch, but only download if our local is out of date.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