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>

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)

block/qcow2.c

@@ -5066,12 +5066,10 @@ static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs,
     BDRVQcow2State *s = bs->opaque;
     ImageInfoSpecific *spec_info;
     QCryptoBlockInfo *encrypt_info = NULL;
-    Error *local_err = NULL;
 
     if (s->crypto != NULL) {
-        encrypt_info = qcrypto_block_get_info(s->crypto, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        encrypt_info = qcrypto_block_get_info(s->crypto, errp);
+        if (!encrypt_info) {
             return NULL;
         }
     }
@@ -5088,9 +5086,7 @@ static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs,
         };
     } else if (s->qcow_version == 3) {
         Qcow2BitmapInfoList *bitmaps;
-        bitmaps = qcow2_get_bitmap_info_list(bs, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        if (!qcow2_get_bitmap_info_list(bs, &bitmaps, errp)) {
             qapi_free_ImageInfoSpecific(spec_info);
             qapi_free_QCryptoBlockInfo(encrypt_info);
             return NULL;

block/qcow2.h

@@ -979,8 +979,8 @@ int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
                                   void **refcount_table,
                                   int64_t *refcount_table_size);
 bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp);
-Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
-                                                Error **errp);
+bool qcow2_get_bitmap_info_list(BlockDriverState *bs,
+                                Qcow2BitmapInfoList **info_list, Error **errp);
 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
 int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp);
 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,