[pacman-dev] [PATCH] libalpm: prevent download error pages ending up in package files

[Allan McRae]

Some servers respond with error pages (e.g. 404.html) when a package is
not present. These were getting written to packages before moving onto
the next server. Reset the download progress on 400+ error conditions
to avoid this.

Signed-off-by: Allan McRae <allan at archlinux.org>
---

This is a replacement for Morgan's patch:
libalpm: fix 404 pages ending up inside package downloads

This approach is less heavy handed, allowing previously partially
downloaded packages to be continued.

I'm still not sure if there is total download amount tracking issue,
but error downloads should be small...

 lib/libalpm/dload.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/libalpm/dload.c b/lib/libalpm/dload.c
index 2d8b4d6d..3eea998b 100644
--- a/lib/libalpm/dload.c
+++ b/lib/libalpm/dload.c
@@ -510,6 +510,16 @@ static int curl_check_finished_download(CURLM *curlm, CURLMsg *msg,
 							payload->remote_name, hostname, payload->error_buffer);
 					server_soft_error(handle, payload->fileurl);
 				}
+
+				fflush(payload->localf);
+				if(fstat(fileno(payload->localf), &st) == 0 && st.st_size != payload->initial_size) {
+					/* an html error page was written to the file, reset it */
+					if(ftruncate(fileno(payload->localf), payload->initial_size)) {
+						RET_ERR(handle, ALPM_ERR_SYSTEM, -1);
+					}
+					fseek(payload->localf, payload->initial_size, SEEK_SET);
+				}
+
 				if(curl_retry_next_server(curlm, curl, payload) == 0) {
 					(*active_downloads_num)++;
 					return 2;
-- 
2.31.1