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authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2013-03-06 22:15:46 -0500
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2013-03-07 00:45:56 -0500
commitaaf080611894aa70af421380af3bca23ad998a8d (patch)
tree8c5baaf6b9b117ee1a4a3c7f65163c8dff37373d
parent1d98d9a62c16c8282d02942d80e025ceec962c9b (diff)
systemd-python: catch only ValueErrors in conversion code
First of all, 'try: ... except: ...' (with no exception specified) is always a no-no, since it catches all BaseExceptions, which includes ^C and other stuff which should almost never be caught. Now the conversion is stricter, and only one conversion is attempted, and only a ValueEror is caught. It seems reasonable to catch ValueErrors, since the entries in the journal are not verified, and any erroneous application might log a field which cannot be converted. The consumer of events must only check if a field is an instance of bytes and can otherwise assume that the conversion was performed correctly. Order of arguments in Reader.__init__ has been changed to match order in _Reader.__init__. Conversions have been updated to work under Python 2 and 3.
-rw-r--r--src/python-systemd/journal.py98
1 files changed, 60 insertions, 38 deletions
diff --git a/src/python-systemd/journal.py b/src/python-systemd/journal.py
index 23e1d65747..80299e6b98 100644
--- a/src/python-systemd/journal.py
+++ b/src/python-systemd/journal.py
@@ -43,13 +43,29 @@ if _sys.version_info >= (3,):
else:
Monotonic = tuple
-_MONOTONIC_CONVERTER = lambda p: Monotonic((_datetime.timedelta(microseconds=p[0]),
- _uuid.UUID(bytes=p[1])))
-_REALTIME_CONVERTER = lambda x: _datetime.datetime.fromtimestamp(x / 1E6)
+def _convert_monotonic(m):
+ return Monotonic((_datetime.timedelta(microseconds=m[0]),
+ _uuid.UUID(bytes=m[1])))
+
+def _convert_source_monotonic(s):
+ return _datetime.timedelta(microseconds=int(s))
+
+def _convert_realtime(t):
+ return _datetime.datetime.fromtimestamp(t / 1E6)
+
+def _convert_timestamp(s):
+ return _datetime.datetime.fromtimestamp(int(s) / 1E6)
+
+if _sys.version_info >= (3,):
+ def _convert_uuid(s):
+ return _uuid.UUID(s.decode())
+else:
+ _convert_uuid = _uuid.UUID
+
DEFAULT_CONVERTERS = {
- 'MESSAGE_ID': _uuid.UUID,
- '_MACHINE_ID': _uuid.UUID,
- '_BOOT_ID': _uuid.UUID,
+ 'MESSAGE_ID': _convert_uuid,
+ '_MACHINE_ID': _convert_uuid,
+ '_BOOT_ID': _convert_uuid,
'PRIORITY': int,
'LEADER': int,
'SESSION_ID': int,
@@ -68,55 +84,60 @@ DEFAULT_CONVERTERS = {
'CODE_LINE': int,
'ERRNO': int,
'EXIT_STATUS': int,
- '_SOURCE_REALTIME_TIMESTAMP': _REALTIME_CONVERTER,
- '__REALTIME_TIMESTAMP': _REALTIME_CONVERTER,
- '_SOURCE_MONOTONIC_TIMESTAMP': _MONOTONIC_CONVERTER,
- '__MONOTONIC_TIMESTAMP': _MONOTONIC_CONVERTER,
+ '_SOURCE_REALTIME_TIMESTAMP': _convert_timestamp,
+ '__REALTIME_TIMESTAMP': _convert_realtime,
+ '_SOURCE_MONOTONIC_TIMESTAMP': _convert_source_monotonic,
+ '__MONOTONIC_TIMESTAMP': _convert_monotonic,
'COREDUMP': bytes,
'COREDUMP_PID': int,
'COREDUMP_UID': int,
'COREDUMP_GID': int,
'COREDUMP_SESSION': int,
'COREDUMP_SIGNAL': int,
- 'COREDUMP_TIMESTAMP': _REALTIME_CONVERTER,
+ 'COREDUMP_TIMESTAMP': _convert_timestamp,
}
-if _sys.version_info >= (3,):
- _convert_unicode = _functools.partial(str, encoding='utf-8')
-else:
- _convert_unicode = _functools.partial(unicode, encoding='utf-8')
-
class Reader(_Reader):
"""Reader allows the access and filtering of systemd journal
entries. Note that in order to access the system journal, a
non-root user must be in the `adm` group.
- Example usage to print out all error or higher level messages
- for systemd-udevd for the boot:
+ Example usage to print out all informational or higher level
+ messages for systemd-udevd for this boot:
- >>> myjournal = journal.Reader()
- >>> myjournal.add_boot_match(journal.CURRENT_BOOT)
- >>> myjournal.add_loglevel_matches(journal.LOG_ERR)
- >>> myjournal.add_match(_SYSTEMD_UNIT="systemd-udevd.service")
- >>> for entry in myjournal:
+ >>> j = journal.Reader()
+ >>> j.this_boot()
+ >>> j.log_level(journal.LOG_INFO)
+ >>> j.add_match(_SYSTEMD_UNIT="systemd-udevd.service")
+ >>> for entry in j:
... print(entry['MESSAGE'])
See systemd.journal-fields(7) for more info on typical fields
found in the journal.
"""
- def __init__(self, converters=None, flags=LOCAL_ONLY, path=None):
+ def __init__(self, flags=LOCAL_ONLY, path=None, converters=None):
"""Create an instance of Reader, which allows filtering and
return of journal entries.
- Argument `converters` is a dictionary which updates the
- DEFAULT_CONVERTERS to convert journal field values.
+
Argument `flags` sets open flags of the journal, which can be one
of, or ORed combination of constants: LOCAL_ONLY (default) opens
journal on local machine only; RUNTIME_ONLY opens only
volatile journal files; and SYSTEM_ONLY opens only
journal files of system services and the kernel.
+
Argument `path` is the directory of journal files. Note that
currently flags are ignored when `path` is present as they are
currently not relevant.
+
+ Argument `converters` is a dictionary which updates the
+ DEFAULT_CONVERTERS to convert journal field values. Field
+ names are used as keys into this dictionary. The values must
+ be single argument functions, which take a `bytes` object and
+ return a converted value. When there's no entry for a field
+ name, then the default UTF-8 decoding will be attempted. If
+ the conversion fails with a ValueError, unconverted bytes
+ object will be returned. (Note that ValueEror is a superclass
+ of UnicodeDecodeError).
"""
super(Reader, self).__init__(flags, path)
if _sys.version_info >= (3,3):
@@ -130,18 +151,19 @@ class Reader(_Reader):
self.converters.update(converters)
def _convert_field(self, key, value):
- """Convert value based on callable from self.converters
- based of field/key"""
+ """Convert value using self.converters[key]
+
+ If `key` is not present in self.converters, a standard unicode
+ decoding will be attempted. If the conversion (either
+ key-specific or the default one) fails with a ValueError, the
+ original bytes object will be returned.
+ """
+ convert = self.converters.get(key, bytes.decode)
try:
- result = self.converters[key](value)
- except:
- # Default conversion in unicode
- try:
- result = _convert_unicode(value)
- except UnicodeDecodeError:
- # Leave in default bytes
- result = value
- return result
+ return convert(value)
+ except ValueError:
+ # Leave in default bytes
+ return value
def _convert_entry(self, entry):
"""Convert entire journal entry utilising _covert_field"""
@@ -217,7 +239,7 @@ class Reader(_Reader):
"""
if 0 <= level <= 7:
for i in range(level+1):
- self.add_match(PRIORITY="%s" % i)
+ self.add_match(PRIORITY="%d" % i)
else:
raise ValueError("Log level must be 0 <= level <= 7")