Handle null pkgcache for local/sync db_populate()

In sync_db_populate() and local_db_populate(), a NULL db->pkgcache is not
caught, allowing the functions to continue instead of exiting.

A later alpm_list_msort() call which uses alpm_list_nth() will thus traverse
invalid pointers in a non-existent db->pkgcache->list.

pm_errno is set to PM_ERR_MEMORY as _alpm_pkghash_create() will only return
NULL when we run out of memory / exceed max hash table size. The local/sync
db_populate() functions are also exited.

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/libalpm/be_local.c b/lib/libalpm/be_local.c
index c5b24982..58582705 100644
--- a/lib/libalpm/be_local.c
+++ b/lib/libalpm/be_local.c
@@ -393,6 +393,10 @@ static int local_db_populate(pmdb_t *db)
 
 	/* initialize hash at 50% full */
 	db->pkgcache = _alpm_pkghash_create(est_count * 2);
+	if(db->pkgcache == NULL){
+		closedir(dbdir);
+		RET_ERR(PM_ERR_MEMORY, -1);
+	}
 
 	while((ent = readdir(dbdir)) != NULL) {
 		const char *name = ent->d_name;