[Qemu-devel] [PATCH V8 04/20] block: distinguish id and name in bdrv_find_snapshot()

[Wenchao Xia]

  To make it clear about id and name in searching, the API was changed
a bit to distinguish them. Caller can choose to search by id or name now.
Searching will be done with higher priority of id. This function also return
negative value from bdrv_snapshot_list() instead of -ENOENT on error.

Signed-off-by: Wenchao Xia <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
 block/snapshot.c         |   46 ++++++++++++++++++++++++++++++++++++++--------
 include/block/snapshot.h |    2 +-
 savevm.c                 |   10 +++++-----
 3 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index 8de73b4..1449b3d 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -13,8 +13,20 @@
 
 #include "block/snapshot.h"
 
+/*
+ * Try find an internal snapshot with @id or @name, @id have higher priority
+ * in searching.
+ *
+ * @bs: block device to search on, must not be NULL.
+ * @sn_info: snapshot information to be filled in, must not be NULL.
+ * @id: snapshot id to search with, can be NULL.
+ * @name: snapshot name to search with, can be NULL.
+ *
+ * returns 0 and @sn_info is filled with related information if found,
+ * otherwise it returns negative value.
+ */
 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
-                       const char *name)
+                       const char *id, const char *name)
 {
     QEMUSnapshotInfo *sn_tab, *sn;
     int nb_sns, i, ret;
@@ -22,16 +34,34 @@ int bdrv_snapshot_find(BlockDriverState *bs, 
QEMUSnapshotInfo *sn_info,
     ret = -ENOENT;
     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
     if (nb_sns < 0) {
-        return ret;
+        return nb_sns;
     }
-    for (i = 0; i < nb_sns; i++) {
-        sn = &sn_tab[i];
-        if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
-            *sn_info = *sn;
-            ret = 0;
-            break;
+
+    /* search by id */
+    if (id) {
+        for (i = 0; i < nb_sns; i++) {
+            sn = &sn_tab[i];
+            if (!strcmp(sn->id_str, id)) {
+                *sn_info = *sn;
+                ret = 0;
+                goto out;
+            }
         }
     }
+
+    /* search by name */
+    if (name) {
+        for (i = 0; i < nb_sns; i++) {
+            sn = &sn_tab[i];
+            if (!strcmp(sn->name, name)) {
+                *sn_info = *sn;
+                ret = 0;
+                goto out;
+            }
+        }
+    }
+
+ out:
     g_free(sn_tab);
     return ret;
 }
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 369e047..71b8017 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -9,5 +9,5 @@
 #include "block.h"
 
 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
-                       const char *name);
+                       const char *id, const char *name);
 #endif
diff --git a/savevm.c b/savevm.c
index 95f19ca..6557750 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2073,7 +2073,7 @@ static int del_existing_snapshots(Monitor *mon, const 
char *name)
     bs = NULL;
     while ((bs = bdrv_next(bs))) {
         if (bdrv_can_snapshot(bs) &&
-            bdrv_snapshot_find(bs, snapshot, name) >= 0)
+            bdrv_snapshot_find(bs, snapshot, name, name) >= 0)
         {
             ret = bdrv_snapshot_delete(bs, name);
             if (ret < 0) {
@@ -2133,7 +2133,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
     sn->vm_clock_nsec = qemu_get_clock_ns(vm_clock);
 
     if (name) {
-        ret = bdrv_snapshot_find(bs, old_sn, name);
+        ret = bdrv_snapshot_find(bs, old_sn, name, name);
         if (ret >= 0) {
             pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
             pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str);
@@ -2224,7 +2224,7 @@ int load_vmstate(const char *name)
     }
 
     /* Don't even try to load empty VM states */
-    ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
+    ret = bdrv_snapshot_find(bs_vm_state, &sn, name, name);
     if (ret < 0) {
         return ret;
     } else if (sn.vm_state_size == 0) {
@@ -2248,7 +2248,7 @@ int load_vmstate(const char *name)
             return -ENOTSUP;
         }
 
-        ret = bdrv_snapshot_find(bs, &sn, name);
+        ret = bdrv_snapshot_find(bs, &sn, name, name);
         if (ret < 0) {
             error_report("Device '%s' does not have the requested snapshot 
'%s'",
                            bdrv_get_device_name(bs), name);
@@ -2354,7 +2354,7 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
 
         while ((bs1 = bdrv_next(bs1))) {
             if (bdrv_can_snapshot(bs1) && bs1 != bs) {
-                ret = bdrv_snapshot_find(bs1, sn_info, sn->id_str);
+                ret = bdrv_snapshot_find(bs1, sn_info, sn->id_str, NULL);
                 if (ret < 0) {
                     available = 0;
                     break;
-- 
1.7.1