block/qcow2: qcow2_get_specific_info(): drop error propagation

Don't use error propagation in qcow2_get_specific_info(). For this
refactor qcow2_get_bitmap_info_list, its current interface is rather
weird.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210202124956.63146-9-vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
[eblake: separate local 'tail' variable from 'info_list' parameter]
Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 5eef82fa55..3c9dcaf0a2 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1089,30 +1089,32 @@ static Qcow2BitmapInfoFlagsList *get_bitmap_info_flags(uint32_t flags)
 /*
  * qcow2_get_bitmap_info_list()
  * Returns a list of QCOW2 bitmap details.
- * In case of no bitmaps, the function returns NULL and
- * the @errp parameter is not set.
- * When bitmap information can not be obtained, the function returns
- * NULL and the @errp parameter is set.
+ * On success return true with info_list set (note, that if there are no
+ * bitmaps, info_list is set to NULL).
+ * On failure return false with errp set.
  */
-Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
-                                                Error **errp)
+bool qcow2_get_bitmap_info_list(BlockDriverState *bs,
+                                Qcow2BitmapInfoList **info_list, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     Qcow2BitmapList *bm_list;
     Qcow2Bitmap *bm;
-    Qcow2BitmapInfoList *list = NULL;
-    Qcow2BitmapInfoList **tail = &list;
+    Qcow2BitmapInfoList **tail;
 
     if (s->nb_bitmaps == 0) {
-        return NULL;
+        *info_list = NULL;
+        return true;
     }
 
     bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
                                s->bitmap_directory_size, errp);
-    if (bm_list == NULL) {
-        return NULL;
+    if (!bm_list) {
+        return false;
     }
 
+    *info_list = NULL;
+    tail = info_list;
+
     QSIMPLEQ_FOREACH(bm, bm_list, entry) {
         Qcow2BitmapInfo *info = g_new0(Qcow2BitmapInfo, 1);
         info->granularity = 1U << bm->granularity_bits;
@@ -1123,7 +1125,7 @@ Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
 
     bitmap_list_free(bm_list);
 
-    return list;
+    return true;
 }
 
 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)