block: Improve some block-commit, block-stream error messages

block-commit defaults @base-node to the deepest backing image.  When
there is none, it fails with "Base 'NULL' not found".  Improve to
"There is no backing image".

block-commit and block-stream reject a @base argument that doesn't
resolve with "Base 'BASE' not found".  Commit 6b33f3ae8b "qemu-img:
Improve commit invalid base message" improved this message in
qemu-img.  Improve it here, too: "Can't find '%s' in the backing
chain".

QERR_BASE_NOT_FOUND is now unused.  Drop.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201113082626.2725812-4-armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

3 files changed, 15 insertions, 14 deletions

diff --git a/blockdev.c b/blockdev.c
index fe6fb5dc1d..d05a8740f4 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2531,7 +2531,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
     if (has_base) {
         base_bs = bdrv_find_backing_image(bs, base);
         if (base_bs == NULL) {
-            error_setg(errp, QERR_BASE_NOT_FOUND, base);
+            error_setg(errp, "Can't find '%s' in the backing chain", base);
             goto out;
         }
         assert(bdrv_get_aio_context(base_bs) == aio_context);
@@ -2703,13 +2703,16 @@ void qmp_block_commit(bool has_job_id, const char *job_id, const char *device,
         }
     } else if (has_base && base) {
         base_bs = bdrv_find_backing_image(top_bs, base);
+        if (base_bs == NULL) {
+            error_setg(errp, "Can't find '%s' in the backing chain", base);
+            goto out;
+        }
     } else {
         base_bs = bdrv_find_base(top_bs);
-    }
-
-    if (base_bs == NULL) {
-        error_setg(errp, QERR_BASE_NOT_FOUND, base ? base : "NULL");
-        goto out;
+        if (base_bs == NULL) {
+            error_setg(errp, "There is no backimg image");
+            goto out;
+        }
     }
 
     assert(bdrv_get_aio_context(base_bs) == aio_context);
diff --git a/include/qapi/qmp/qerror.h b/include/qapi/qmp/qerror.h
index c272e3fc29..5d7e69cc1f 100644
--- a/include/qapi/qmp/qerror.h
+++ b/include/qapi/qmp/qerror.h
@@ -16,8 +16,6 @@
  * These macros will go away, please don't use in new code, and do not
  * add new ones!
  */
-#define QERR_BASE_NOT_FOUND \
-    "Base '%s' not found"
 
 #define QERR_BUS_NO_HOTPLUG \
     "Bus '%s' does not support hotplugging"
diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
index caf286571a..dc6069edc0 100755
--- a/tests/qemu-iotests/040
+++ b/tests/qemu-iotests/040
@@ -156,7 +156,7 @@ class TestSingleDrive(ImageCommitTestCase):
         self.assert_no_active_block_jobs()
         result = self.vm.qmp('block-commit', device='drive0', top='%s' % backing_img, base='%s' % backing_img)
         self.assert_qmp(result, 'error/class', 'GenericError')
-        self.assert_qmp(result, 'error/desc', 'Base \'%s\' not found' % backing_img)
+        self.assert_qmp(result, 'error/desc', "Can't find '%s' in the backing chain" % backing_img)
 
     def test_top_invalid(self):
         self.assert_no_active_block_jobs()
@@ -168,7 +168,7 @@ class TestSingleDrive(ImageCommitTestCase):
         self.assert_no_active_block_jobs()
         result = self.vm.qmp('block-commit', device='drive0', top='%s' % mid_img, base='badfile')
         self.assert_qmp(result, 'error/class', 'GenericError')
-        self.assert_qmp(result, 'error/desc', 'Base \'badfile\' not found')
+        self.assert_qmp(result, 'error/desc', "Can't find 'badfile' in the backing chain")
 
     def test_top_node_invalid(self):
         self.assert_no_active_block_jobs()
@@ -208,7 +208,7 @@ class TestSingleDrive(ImageCommitTestCase):
         self.assert_no_active_block_jobs()
         result = self.vm.qmp('block-commit', device='drive0', top='%s' % backing_img, base='%s' % mid_img)
         self.assert_qmp(result, 'error/class', 'GenericError')
-        self.assert_qmp(result, 'error/desc', 'Base \'%s\' not found' % mid_img)
+        self.assert_qmp(result, 'error/desc', "Can't find '%s' in the backing chain" % mid_img)
 
     def test_top_and_base_node_reversed(self):
         self.assert_no_active_block_jobs()
@@ -349,7 +349,7 @@ class TestRelativePaths(ImageCommitTestCase):
         self.assert_no_active_block_jobs()
         result = self.vm.qmp('block-commit', device='drive0', top='%s' % self.mid_img, base='%s' % self.mid_img)
         self.assert_qmp(result, 'error/class', 'GenericError')
-        self.assert_qmp(result, 'error/desc', 'Base \'%s\' not found' % self.mid_img)
+        self.assert_qmp(result, 'error/desc', "Can't find '%s' in the backing chain" % self.mid_img)
 
     def test_top_invalid(self):
         self.assert_no_active_block_jobs()
@@ -361,7 +361,7 @@ class TestRelativePaths(ImageCommitTestCase):
         self.assert_no_active_block_jobs()
         result = self.vm.qmp('block-commit', device='drive0', top='%s' % self.mid_img, base='badfile')
         self.assert_qmp(result, 'error/class', 'GenericError')
-        self.assert_qmp(result, 'error/desc', 'Base \'badfile\' not found')
+        self.assert_qmp(result, 'error/desc', "Can't find 'badfile' in the backing chain")
 
     def test_top_is_active(self):
         self.run_commit_test(self.test_img, self.backing_img)
@@ -372,7 +372,7 @@ class TestRelativePaths(ImageCommitTestCase):
         self.assert_no_active_block_jobs()
         result = self.vm.qmp('block-commit', device='drive0', top='%s' % self.backing_img, base='%s' % self.mid_img)
         self.assert_qmp(result, 'error/class', 'GenericError')
-        self.assert_qmp(result, 'error/desc', 'Base \'%s\' not found' % self.mid_img)
+        self.assert_qmp(result, 'error/desc', "Can't find '%s' in the backing chain" % self.mid_img)
 
 
 class TestSetSpeed(ImageCommitTestCase):