bug#22920: [PATCH] libparted/disk.c(ped_disk_get_partition): Fix assert error

[lu4nx]

From: Xi Lu <l...@shellcodes.org>

if forget create a partition, and execute:

`name 1 grub`

ped_disk_get_partition() will trigger an exception:

  Assertion (disk != NULL)
---
 libparted/disk.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libparted/disk.c b/libparted/disk.c
index fe82f44..9f36d10 100644
--- a/libparted/disk.c
+++ b/libparted/disk.c
@@ -1594,7 +1594,10 @@ ped_disk_get_partition (const PedDisk* disk, int num)
 {
        PedPartition*   walk;
 
-       PED_ASSERT (disk != NULL);
+        if (disk == NULL) {
+          fprintf(stderr, "you must specify partition.");
+          return NULL;
+        }
 
        for (walk = disk->part_list; walk;
             walk = ped_disk_next_partition (disk, walk)) {
-- 
2.5.0