Give sensible feedback when a repo has no configured servers

This fixes FS#14899. When running an -Sp operation without servers
configured for a repository, we would segfault, so add an assert to the
backend method returning the first server preventing a null pointer
dereference.

In addition, add a new error code to libalpm that indicates we have no
servers configured for a repository. This makes -Sy and -S <package>
operations fail gracefully and helpfully when a repo is set up with no
servers, as the default mirrorlist in Arch is provided this way.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 1d42cd9d..6645335b 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -769,7 +769,9 @@ int _alpm_sync_commit(pmtrans_t *trans, pmdb_t *db_local, alpm_list_t **data)
 			if(_alpm_download_files(files, current->servers, cachedir)) {
 				_alpm_log(PM_LOG_WARNING, _("failed to retrieve some files from %s\n"),
 						current->treename);
-				pm_errno = PM_ERR_RETRIEVE;
+				if(pm_errno == 0) {
+					pm_errno = PM_ERR_RETRIEVE;
+				}
 				goto error;
 			}
 			FREELIST(files);