Be more robust when copying package data

This changes the signature of _alpm_pkg_dup() to return an integer error
code and provide the new package in a passed pointer argument. All
callers are now more robust with checking the return value of this
function to ensure a fatal error did not occur.

We allow load failures to proceed as otherwise we have a chicken and egg
problem- if a 'desc' local database entry is missing, the best way of
restoring said file is `pacman -Sf --dbonly packagename`. This patch
fixes a segfault that was occurring in this case.

Fixes the segfault reported in FS#25667.

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

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 6c30c948..e3e7fa90 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -558,8 +558,12 @@ int _alpm_sync_prepare(alpm_handle_t *handle, alpm_list_t **data)
 		for(j = spkg->removes; j; j = j->next) {
 			alpm_pkg_t *rpkg = j->data;
 			if(!_alpm_pkg_find(trans->remove, rpkg->name)) {
+				alpm_pkg_t *copy;
 				_alpm_log(handle, ALPM_LOG_DEBUG, "adding '%s' to remove list\n", rpkg->name);
-				trans->remove = alpm_list_add(trans->remove, _alpm_pkg_dup(rpkg));
+				if(_alpm_pkg_dup(rpkg, &copy) == -1) {
+					return -1;
+				}
+				trans->remove = alpm_list_add(trans->remove, copy);
 			}
 		}
 	}