Merge pull request #3 from bjohnsto/fix_corrupt_vdo

dmtest: Write random data instead of zeroes to geometry block

Author: bjohnsto

src/dmtest/assertions.py

@@ -1,3 +1,5 @@
+import re
+
 def assert_raises(callback):
     failed = False
     try:
@@ -28,3 +30,9 @@ def assert_string_in(actual, expected, message=None):
         error_message = f"{message}: " if message else ""
         error_message += f"expected '{expected}', but got {actual}"
         raise AssertionError(error_message)
+
+def assert_matches(actual, pattern, message=None):
+    if not re.search(pattern, actual):
+        error_message = f"{message}: " if message else ""
+        error_message += f"expected match for '{pattern}', but got {actual}"
+        raise AssertionError(error_message)

src/dmtest/utils.py

@@ -149,6 +149,10 @@ def wipe_device(dev, sectors=None):
     _dd_device("/dev/zero", _to_path(dev), "oflag=direct", sectors, sync=True)
 
 
+def trash_device(dev, sectors=None):
+    _dd_device("/dev/urandom", _to_path(dev), "oflag=direct", sectors, sync=True)
+
+
 def dev_size(dev):
     (_, stdout, _) = process.run(f"blockdev --getsz {_to_path(dev)}")
     return int(stdout)

src/dmtest/vdo/load_failure_tests.py

@@ -1,6 +1,6 @@
-from dmtest.assertions import assert_string_in
+from dmtest.assertions import assert_matches, assert_string_in
 from dmtest.vdo.utils import standard_vdo, standard_stack
-from dmtest.utils import get_dmesg_log, wipe_device
+from dmtest.utils import get_dmesg_log, trash_device
 import logging as log
 import time
 
@@ -52,8 +52,8 @@ def t_corrupt_geometry(fix):
     with standard_vdo(fix) as vdo:
         pass
     start_time = time.time()
-    # Trash just one (4kB) block
-    wipe_device(fix.cfg["data_dev"], 8)
+    # Overwrite just one (4kB) block with random data
+    trash_device(fix.cfg["data_dev"], 8)
     stack = standard_stack(fix, format = False)
     started = False
     try:
@@ -62,7 +62,7 @@ def t_corrupt_geometry(fix):
     except:
         message = get_dmesg_log(start_time)
         log.info(message)
-        assert_string_in(message, "Could not load geometry block")
+        assert_matches(message, r"Could not (load|parse) geometry block")
     if started:
         raise AssertionError("VDO device shouldn't have started")