qemu-img check: Distinguish different kinds of errors

People think that their images are corrupted when in fact there are just some
leaked clusters. Differentiating several error cases should make the messages
more comprehensible.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 48 insertions, 15 deletions

diff --git a/qemu-img.c b/qemu-img.c
index 700af21841..e300f911cb 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -425,11 +425,20 @@ out:
     return 0;
 }
 
+/*
+ * Checks an image for consistency. Exit codes:
+ *
+ * 0 - Check completed, image is good
+ * 1 - Check not completed because of internal errors
+ * 2 - Check completed, image is corrupted
+ * 3 - Check completed, image has leaked clusters, but is good otherwise
+ */
 static int img_check(int argc, char **argv)
 {
     int c, ret;
     const char *filename, *fmt;
     BlockDriverState *bs;
+    BdrvCheckResult result;
 
     fmt = NULL;
     for(;;) {
@@ -453,28 +462,52 @@ static int img_check(int argc, char **argv)
     if (!bs) {
         return 1;
     }
-    ret = bdrv_check(bs);
-    switch(ret) {
-    case 0:
-        printf("No errors were found on the image.\n");
-        break;
-    case -ENOTSUP:
+    ret = bdrv_check(bs, &result);
+
+    if (ret == -ENOTSUP) {
         error("This image format does not support checks");
-        break;
-    default:
-        if (ret < 0) {
-            error("An error occurred during the check");
-        } else {
-            printf("%d errors were found on the image.\n", ret);
+        bdrv_delete(bs);
+        return 1;
+    }
+
+    if (!(result.corruptions || result.leaks || result.check_errors)) {
+        printf("No errors were found on the image.\n");
+    } else {
+        if (result.corruptions) {
+            printf("\n%d errors were found on the image.\n"
+                "Data may be corrupted, or further writes to the image "
+                "may corrupt it.\n",
+                result.corruptions);
+        }
+
+        if (result.leaks) {
+            printf("\n%d leaked clusters were found on the image.\n"
+                "This means waste of disk space, but no harm to data.\n",
+                result.leaks);
+        }
+
+        if (result.check_errors) {
+            printf("\n%d internal errors have occurred during the check.\n",
+                result.check_errors);
         }
-        break;
     }
 
     bdrv_delete(bs);
-    if (ret) {
+
+    if (ret < 0 || result.check_errors) {
+        printf("\nAn error has occurred during the check: %s\n"
+            "The check is not complete and may have missed error.\n",
+            strerror(-ret));
         return 1;
     }
-    return 0;
+
+    if (result.corruptions) {
+        return 2;
+    } else if (result.leaks) {
+        return 3;
+    } else {
+        return 0;
+    }
 }
 
 static int img_commit(int argc, char **argv)