trace module compares directories as strings (--ignore-dir)

[vrutsky]

BPO	10896
Nosy	@abalkin
Superseder	bpo-10908: Improvements to trace._Ignore
Files	test.py: test Python file test.cmd: shell script to run test test.out: output for shell script trace.diff trace_ignore_case_fix.patch: Fix case for --ignore-dir and file

^{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 = None
created_at = <Date 2011-01-12.14:44:16.332>
labels = ['type-bug', 'library']
title = 'trace module compares directories as strings (--ignore-dir)'
updated_at = <Date 2011-01-19.15:40:45.848>
user = 'https://bugs.python.org/vrutsky'

bugs.python.org fields:

activity = <Date 2011-01-19.15:40:45.848>
actor = 'SilentGhost'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2011-01-12.14:44:16.332>
creator = 'vrutsky'
dependencies = []
files = ['20368', '20369', '20370', '20378', '20452']
hgrepos = []
issue_num = 10896
keywords = ['patch']
message_count = 7.0
messages = ['126101', '126110', '126112', '126272', '126524', '126526', '126535']
nosy_count = 3.0
nosy_names = ['belopolsky', 'SilentGhost', 'vrutsky']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = '10908'
type = 'behavior'
url = 'https://bugs.python.org/issue10896'
versions = ['Python 3.1', 'Python 2.7', 'Python 3.2']

[vrutsky]

This is code from recent trace.py (http://svn.python.org/view/python/branches/release27-maint/Lib/trace.py?view=markup):

trace.py:169:
# Ignore a file when it contains one of the ignorable paths
for d in self._dirs:
# The '+ os.sep' is to ensure that d is a parent directory,
# as compared to cases like:
# d = "/usr/local"
# filename = "/usr/local.py"
# or
# d = "/usr/local.py"
# filename = "/usr/local.py"
if filename.startswith(d + os.sep):
self._ignore[modulename] = 1
return 1

Directories comparison like "filename.startswith(d + os.sep)" works incorrect on case-insensitive filesystems (such as NTFS on Windows).

This leads to confusing results on Windows:
python trace.py --ignore-dir='$prefix' -t test.py
or
python trace.py --ignore-dir C:\Python26\Lib -t test.py
shows all calls from standard library, but this one doesn't:
python trace.py --ignore-dir=c:\python26\lib -t test.py

See attached test files and log for details.

[vrutsky]

Workaround for people on Windows who don't wan't to modify trace.py:
to get clean trace of only your project calls add to ignore list python path with mix of character cases. For me worked out this string:
python -m trace --ignore-dir=c:\python26\lib;C:\python26\lib;C:\Python26\Lib -t main.py

[SilentGhost]

It's due to the os.path.normpath not normalizing case. Here is the patch.

Also affects 3.x

[SilentGhost]

bpo-10908 is dealing with this and other issue re ignored dirs.

[vrutsky]

SilentGhost, thanks for the patch! I can confirm, that adding os.path.normcase fixes issues with different cases of files.

I believe there also may be issue with FAT's long file name mangling, like "C:\PROGRA~1\python26\" instead of "C:\Program Files\python26\". But never experienced such issue with Python.

[vrutsky]

Sorry I was wrong - patch don't fix original issue.

Case should be normalized not only for directories provided through --ignore-dir, but also for directories obtained from __file__. In my tests on Windows Ignore.names(self, filename, modulename) receives `filename''s argument like:
C:\Python26\Lib\site-packages\shapely\init.pyc

Attaching patch fixes this issue for me (for Python 2.7 from http://svn.python.org/projects/python/branches/release27-maint, patch attached by SilentGhost is for 3.X I think).

[SilentGhost]

Vladimir, superseder's patch fixes that too.