When no -l/-a/-c/-d specified, assume -l (list).

Use the same values for SNAPSHOT_LIST/etc constants as the
option chars (lacd), this makes it possible to simplify
option handling a lot, combining cases for 4 options into
one.

Also remove bdrv_oflags handling (only list can use RO mode).

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 docs/tools/qemu-img.rst |  2 +-
 qemu-img.c              | 52 ++++++++++++++---------------------------
 2 files changed, 19 insertions(+), 35 deletions(-)

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 9b628c4da5..df184d15b9 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -256,7 +256,7 @@ Parameters to snapshot subcommand:
 
 .. option:: -l
 
-  Lists all snapshots in the given image
+  Lists all snapshots in the given image (default action)
 
 Command description:
 
diff --git a/qemu-img.c b/qemu-img.c
index 8adc324496..967f6343de 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3585,10 +3585,11 @@ out:
     return ret < 0;
 }
 
-#define SNAPSHOT_LIST   1
-#define SNAPSHOT_CREATE 2
-#define SNAPSHOT_APPLY  3
-#define SNAPSHOT_DELETE 4
+/* the same as options */
+#define SNAPSHOT_LIST   'l'
+#define SNAPSHOT_CREATE 'c'
+#define SNAPSHOT_APPLY  'a'
+#define SNAPSHOT_DELETE 'd'
 
 static int img_snapshot(const img_cmd_t *ccmd, int argc, char **argv)
 {
@@ -3596,7 +3597,7 @@ static int img_snapshot(const img_cmd_t *ccmd, int argc, char **argv)
     BlockDriverState *bs;
     QEMUSnapshotInfo sn;
     char *filename, *fmt = NULL, *snapshot_name = NULL;
-    int c, ret = 0, bdrv_oflags;
+    int c, ret = 0;
     int action = 0;
     bool quiet = false;
     Error *err = NULL;
@@ -3604,7 +3605,6 @@ static int img_snapshot(const img_cmd_t *ccmd, int argc, char **argv)
     bool force_share = false;
     int64_t rt;
 
-    bdrv_oflags = BDRV_O_RDWR;
     /* Parse commandline parameters */
     for(;;) {
         static const struct option long_options[] = {
@@ -3632,36 +3632,15 @@ static int img_snapshot(const img_cmd_t *ccmd, int argc, char **argv)
         case 'f':
             fmt = optarg;
             break;
-        case 'l':
-            if (action) {
-                error_exit(argv[0], "Cannot mix '-l', '-a', '-c', '-d'");
-                return 0;
-            }
-            action = SNAPSHOT_LIST;
-            bdrv_oflags &= ~BDRV_O_RDWR; /* no need for RW */
-            break;
-        case 'a':
+        case SNAPSHOT_LIST:
+        case SNAPSHOT_APPLY:
+        case SNAPSHOT_CREATE:
+        case SNAPSHOT_DELETE:
             if (action) {
                 error_exit(argv[0], "Cannot mix '-l', '-a', '-c', '-d'");
                 return 0;
             }
-            action = SNAPSHOT_APPLY;
-            snapshot_name = optarg;
-            break;
-        case 'c':
-            if (action) {
-                error_exit(argv[0], "Cannot mix '-l', '-a', '-c', '-d'");
-                return 0;
-            }
-            action = SNAPSHOT_CREATE;
-            snapshot_name = optarg;
-            break;
-        case 'd':
-            if (action) {
-                error_exit(argv[0], "Cannot mix '-l', '-a', '-c', '-d'");
-                return 0;
-            }
-            action = SNAPSHOT_DELETE;
+            action = c;
             snapshot_name = optarg;
             break;
         case 'q':
@@ -3684,9 +3663,14 @@ static int img_snapshot(const img_cmd_t *ccmd, int argc, char **argv)
     }
     filename = argv[optind++];
 
+    if (!action) {
+        action = SNAPSHOT_LIST;
+    }
+
     /* Open the image */
-    blk = img_open(image_opts, filename, fmt, bdrv_oflags, false, quiet,
-                   force_share);
+    blk = img_open(image_opts, filename, fmt,
+                   action == SNAPSHOT_LIST ? 0 : BDRV_O_RDWR,
+                   false, quiet, force_share);
     if (!blk) {
         return 1;
     }
-- 
2.39.5