logging using the SysLog handler fails if locale is set

[misa]

BPO	1524081
Nosy	@vsajip, @gnprice
Files	logging-broken.py: Simple test script to show the problem. Call it after setting LANG=tr_TR.UTF-8

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-08-17.23:38:43.754>
created_at = <Date 2006-07-17.19:33:18.000>
labels = ['library']
title = 'logging using the SysLog handler fails if locale is set'
updated_at = <Date 2020-08-17.23:38:43.754>
user = 'https://bugs.python.org/misa'

bugs.python.org fields:

activity = <Date 2020-08-17.23:38:43.754>
actor = 'Greg Price'
assignee = 'none'
closed = True
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2006-07-17.19:33:18.000>
creator = 'misa'
dependencies = []
files = ['2071']
hgrepos = []
issue_num = 1524081
keywords = []
message_count = 3.0
messages = ['29194', '29195', '375577']
nosy_count = 3.0
nosy_names = ['vinay.sajip', 'misa', 'Greg Price']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1524081'
versions = ['Python 2.5']

[misa]

This affectes b2 and python 2.4 too.
Initially reported here:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=198971

Looking at logging/handlers.py:

Line 635:
self.encodePriority(self.facility,
string.lower(record.levelname)), msg)

Line 611 in encodePriority:
priority = self.priority_names[priority]

priority_names is declared on line 527:
priority_names = {
"alert": LOG_ALERT,
"crit": LOG_CRIT,
...
"info": LOG_INFO,
...

Now, if one initializes the locale (i.e.
locale.setlocale(locale.LC_ALL, "")

and then tries to use the logging module, it will fail
with an exception looking kinda like:

File "/usr/lib64/python2.4/logging/handlers.py", line
627, in encodePriority
priority = self.priority_names[priority]
KeyError: 'Info'

if they choose LANG=tr_TR.UTF-8

This happens because in that particular locale,
"INFO".lower() != "info"

[vsajip]

Logged In: YES
user_id=308438

Fixed by using a dict to map logging level names to syslog
priority level names. This also facilitates usage when
custom logging levels are present.

Fix is checked into Subversion.

[gnprice]

For the record because this issue is mentioned in a comment in logging/handlers.py and people are sometimes confused by it today:

This happens because in that particular locale,
"INFO".lower() != "info"

Since Python 3, this no longer happens: str.lower() and friends do not depend on the current locale.

Specifically, the lower() and similar methods on Unicode strings (now "str", previously "unicode") were always independent of the current locale. The corresponding methods on byte strings (now "bytes", previously "str") did have this locale-dependent behavior, but that was replaced in commit 6ccd3f2, in 2007.

See also bpo-37848, for a 2019 discussion of potentially adding an optional parameter to use an *explicit* locale.