Verify the disk file exists before running qemu-img on it.

Should resolve bug 955788, although it is a little hard to tell
because the bug is so old.

Change-Id: Ic0c47f4b6181f56a98cf58d4ebe2cc926d06d524

4 files changed, 38 insertions, 0 deletions

diff --git a/nova/tests/test_image_utils.py b/nova/tests/test_image_utils.py
index 9c040f2e1..a9768f821 100644
--- a/nova/tests/test_image_utils.py
+++ b/nova/tests/test_image_utils.py
@@ -14,6 +14,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import os
+
 from nova import test
 from nova import utils
 
@@ -41,7 +43,9 @@ disk size: 96K
                 'format': f,
                 'path': path,
             })
+            self.mox.StubOutWithMock(os.path, 'exists')
             self.mox.StubOutWithMock(utils, 'execute')
+            os.path.exists(path).AndReturn(True)
             utils.execute('env', 'LC_ALL=C', 'LANG=C',
                           'qemu-img', 'info', path).AndReturn((output, ''))
             self.mox.ReplayAll()
@@ -60,7 +64,9 @@ disk size: 96K
         output = template_output % ({
             'path': path,
         })
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((output, ''))
         self.mox.ReplayAll()
@@ -84,7 +90,9 @@ disk size: 96K
                 'vsize_b': i,
                 'path': path,
             })
+            self.mox.StubOutWithMock(os.path, 'exists')
             self.mox.StubOutWithMock(utils, 'execute')
+            os.path.exists(path).AndReturn(True)
             utils.execute('env', 'LC_ALL=C', 'LANG=C',
                           'qemu-img', 'info', path).AndReturn((output, ''))
             self.mox.ReplayAll()
@@ -96,7 +104,9 @@ disk size: 96K
                 'vsize_b': i,
                 'path': path,
             })
+            self.mox.StubOutWithMock(os.path, 'exists')
             self.mox.StubOutWithMock(utils, 'execute')
+            os.path.exists(path).AndReturn(True)
             utils.execute('env', 'LC_ALL=C', 'LANG=C',
                           'qemu-img', 'info', path).AndReturn((output, ''))
             self.mox.ReplayAll()
@@ -113,7 +123,9 @@ cluster_size: 65536
 disk size: 96K
 blah BLAH: bb
 """
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((example_output, ''))
         self.mox.ReplayAll()
@@ -133,7 +145,9 @@ cluster_size: 65536
 disk size: 963434
 backing file: /var/lib/nova/a328c7998805951a_2
 """
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((example_output, ''))
         self.mox.ReplayAll()
@@ -158,7 +172,9 @@ ID        TAG                 VM SIZE                DATE       VM CLOCK
 1     d9a9784a500742a7bb95627bb3aace38      0 2012-08-20 10:52:46 00:00:00.000
 backing file: /var/lib/nova/a328c7998805951a_2 (actual path: /b/3a988059e51a_2)
 """
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((example_output, ''))
         self.mox.ReplayAll()
@@ -184,7 +200,9 @@ ID        TAG                 VM SIZE                DATE       VM CLOCK
 4        d9a9784a500742a7bb95627bb3aace38    0 2012-08-20 10:52:46 00:00:00.000
 junk stuff: bbb
 """
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((example_output, ''))
         self.mox.ReplayAll()
@@ -206,7 +224,9 @@ ID        TAG                 VM SIZE                DATE       VM CLOCK
 3        d9a9784a500742a7bb95627bb3aace38    0 2012-08-20 10:52:46 00:00:00.000
 4        d9a9784a500742a7bb95627bb3aace38    0 2012-08-20 10:52:46 00:00:00.000
 """
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((example_output, ''))
         self.mox.ReplayAll()
diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 6e941cb45..e4466fdf3 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -2366,6 +2366,9 @@ class LibvirtConnTestCase(test.TestCase):
                "cluster_size: 2097152\n"
                "backing file: /test/dummy (actual path: /backing/file)\n")
 
+        self.mox.StubOutWithMock(os.path, "exists")
+        os.path.exists('/test/disk.local').AndReturn(True)
+
         self.mox.StubOutWithMock(utils, "execute")
         utils.execute('env', 'LC_ALL=C', 'LANG=C', 'qemu-img', 'info',
                       '/test/disk.local').AndReturn((ret, ''))
@@ -3866,8 +3869,10 @@ class LibvirtUtilsTestCase(test.TestCase):
         libvirt_utils.create_image('qcow2', '/some/stuff', '1234567891234')
 
     def test_create_cow_image(self):
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
         rval = ('', '')
+        os.path.exists('/some/path').AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', '/some/path').AndReturn(rval)
         utils.execute('qemu-img', 'create', '-f', 'qcow2',
@@ -3891,7 +3896,9 @@ class LibvirtUtilsTestCase(test.TestCase):
                 self.assertEquals(result, expected_result)
 
     def test_get_disk_size(self):
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists('/some/path').AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C', 'qemu-img', 'info',
                       '/some/path').AndReturn(('''image: 00000001
 file format: raw
@@ -4050,7 +4057,11 @@ disk size: 4.4M''', ''))
                         "backing file: /foo/bar/baz\n"
                         "...: ...\n"), ''
 
+        def return_true(*args, **kwargs):
+            return True
+
         self.stubs.Set(utils, 'execute', fake_execute)
+        self.stubs.Set(os.path, 'exists', return_true)
 
         out = libvirt_utils.get_disk_backing_file('')
         self.assertEqual(out, 'baz')
diff --git a/nova/tests/test_libvirt_utils.py b/nova/tests/test_libvirt_utils.py
index 89410390b..60f0682a8 100644
--- a/nova/tests/test_libvirt_utils.py
+++ b/nova/tests/test_libvirt_utils.py
@@ -15,6 +15,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import os
+
 from nova import test
 from nova import utils
 from nova.virt.libvirt import utils as libvirt_utils
@@ -30,7 +32,9 @@ cluster_size: 65536
 disk size: 96K
 blah BLAH: bb
 """
+        self.mox.StubOutWithMock(os.path, 'exists')
         self.mox.StubOutWithMock(utils, 'execute')
+        os.path.exists(path).AndReturn(True)
         utils.execute('env', 'LC_ALL=C', 'LANG=C',
                       'qemu-img', 'info', path).AndReturn((example_output, ''))
         self.mox.ReplayAll()
diff --git a/nova/virt/images.py b/nova/virt/images.py
index 514c8755f..244b33ab7 100644
--- a/nova/virt/images.py
+++ b/nova/virt/images.py
@@ -176,6 +176,9 @@ class QemuImgInfo(object):
 
 def qemu_img_info(path):
     """Return a object containing the parsed output from qemu-img info."""
+    if not os.path.exists(path):
+        return QemuImgInfo()
+
     out, err = utils.execute('env', 'LC_ALL=C', 'LANG=C',
                              'qemu-img', 'info', path)
     return QemuImgInfo(out)