tests: add output filter to python I/O tests helper

Add a 'log' method to iotests.py which prints messages to
stdout, with optional filtering of data. Port over some
standard filters already present in the shell common.filter
code to be usable in python too.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/iotests.py

@@ -30,7 +30,8 @@ import struct
 
 __all__ = ['imgfmt', 'imgproto', 'test_dir' 'qemu_img', 'qemu_io',
            'VM', 'QMPTestCase', 'notrun', 'main', 'verify_image_format',
-           'verify_platform']
+           'verify_platform', 'filter_test_dir', 'filter_win32',
+           'filter_qemu_io', 'filter_chown', 'log']
 
 # This will not work if arguments contain spaces but is necessary if we
 # want to support the override options that ./check supports.
@@ -105,6 +106,28 @@ def create_image(name, size):
         i = i + 512
     file.close()
 
+test_dir_re = re.compile(r"%s" % test_dir)
+def filter_test_dir(msg):
+    return test_dir_re.sub("TEST_DIR", msg)
+
+win32_re = re.compile(r"\r")
+def filter_win32(msg):
+    return win32_re.sub("", msg)
+
+qemu_io_re = re.compile(r"[0-9]* ops; [0-9\/:. sec]* \([0-9\/.inf]* [EPTGMKiBbytes]*\/sec and [0-9\/.inf]* ops\/sec\)")
+def filter_qemu_io(msg):
+    msg = filter_win32(msg)
+    return qemu_io_re.sub("X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)", msg)
+
+chown_re = re.compile(r"chown [0-9]+:[0-9]+")
+def filter_chown(msg):
+    return chown_re.sub("chown UID:GID", msg)
+
+def log(msg, filters=[]):
+    for flt in filters:
+        msg = flt(msg)
+    print msg
+
 # Test if 'match' is a recursive subset of 'event'
 def event_match(event, match=None):
     if match is None: