Mercurial > hg
view i18n/hggettext @ 20742:3681de20b0a7
parsers: fail fast if Python has wrong minor version (issue4110)
This change causes an informative ImportError to be raised when importing
the parsers extension module if the minor version of the currently-running
Python interpreter doesn't match that of the Python used when compiling
the extension module.
This change also exposes a parsers.versionerrortext constant in the
C implementation of the module. Its presence can be used to determine
whether this behavior is present in a version of the module. The value
of the constant is the leading text of the ImportError raised and is set
to "Python minor version mismatch".
Here is an example of what the new error looks like:
Traceback (most recent call last):
File "test.py", line 1, in <module>
import mercurial.parsers
ImportError: Python minor version mismatch: The Mercurial extension
modules were compiled with Python 2.7.6, but Mercurial is currently using
Python with sys.hexversion=33883888: Python 2.5.6
(r256:88840, Nov 18 2012, 05:37:10)
[GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))]
at: /opt/local/Library/Frameworks/Python.framework/Versions/2.5/Resources/
Python.app/Contents/MacOS/Python
The reason for raising an error in this scenario is that Python's C API
is known not to be compatible from minor version to minor version, even
if sys.api_version is the same. See for example this Python bug report
about incompatibilities between 2.5 and 2.6+:
http://bugs.python.org/issue8118
These incompatibilities can cause Mercurial to break in mysterious,
unforeseen ways. For example, when Mercurial compiled with Python 2.7 was
run with 2.5, the following crash occurred when running "hg status":
http://bz.selenic.com/show_bug.cgi?id=4110
After this crash was fixed, running with Python 2.5 no longer crashes, but
the following puzzling behavior still occurs:
$ hg status
...
File ".../mercurial/changelog.py", line 123, in __init__
revlog.revlog.__init__(self, opener, "00changelog.i")
File ".../mercurial/revlog.py", line 251, in __init__
d = self._io.parseindex(i, self._inline)
File ".../mercurial/revlog.py", line 158, in parseindex
index, cache = parsers.parse_index2(data, inline)
TypeError: data is not a string
which can be reproduced more simply with:
import mercurial.parsers as parsers
parsers.parse_index2("", True)
Both the crash and the TypeError occurred because the Python C API's
PyString_Check() returns the wrong value when the C header files from
Python 2.7 are run with Python 2.5. This is an example of an
incompatibility of the sort mentioned in the Python bug report above.
Failing fast with an informative error message results in a better user
experience in cases like the above. The information in the ImportError
also simplifies troubleshooting for those on Mercurial mailing lists, the
bug tracker, etc.
This patch only adds the version check to parsers.c, which is sufficient
to affect command-line commands like "hg status" and "hg summary".
An idea for a future improvement is to move the version-checking C code
to a more central location, and have it run when importing all
Mercurial extension modules and not just parsers.c.
author | Chris Jerdonek <chris.jerdonek@gmail.com> |
---|---|
date | Wed, 04 Dec 2013 20:38:27 -0800 |
parents | 80deae3bc5ea |
children | 2516bba643e7 |
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#!/usr/bin/env python # # hggettext - carefully extract docstrings for Mercurial # # Copyright 2009 Matt Mackall <mpm@selenic.com> and others # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. # The normalize function is taken from pygettext which is distributed # with Python under the Python License, which is GPL compatible. """Extract docstrings from Mercurial commands. Compared to pygettext, this script knows about the cmdtable and table dictionaries used by Mercurial, and will only extract docstrings from functions mentioned therein. Use xgettext like normal to extract strings marked as translatable and join the message cataloges to get the final catalog. """ import os, sys, inspect def escape(s): # The order is important, the backslash must be escaped first # since the other replacements introduce new backslashes # themselves. s = s.replace('\\', '\\\\') s = s.replace('\n', '\\n') s = s.replace('\r', '\\r') s = s.replace('\t', '\\t') s = s.replace('"', '\\"') return s def normalize(s): # This converts the various Python string types into a format that # is appropriate for .po files, namely much closer to C style. lines = s.split('\n') if len(lines) == 1: s = '"' + escape(s) + '"' else: if not lines[-1]: del lines[-1] lines[-1] = lines[-1] + '\n' lines = map(escape, lines) lineterm = '\\n"\n"' s = '""\n"' + lineterm.join(lines) + '"' return s def poentry(path, lineno, s): return ('#: %s:%d\n' % (path, lineno) + 'msgid %s\n' % normalize(s) + 'msgstr ""\n') def offset(src, doc, name, default): """Compute offset or issue a warning on stdout.""" # Backslashes in doc appear doubled in src. end = src.find(doc.replace('\\', '\\\\')) if end == -1: # This can happen if the docstring contains unnecessary escape # sequences such as \" in a triple-quoted string. The problem # is that \" is turned into " and so doc wont appear in src. sys.stderr.write("warning: unknown offset in %s, assuming %d lines\n" % (name, default)) return default else: return src.count('\n', 0, end) def importpath(path): """Import a path like foo/bar/baz.py and return the baz module.""" if path.endswith('.py'): path = path[:-3] if path.endswith('/__init__'): path = path[:-9] path = path.replace('/', '.') mod = __import__(path) for comp in path.split('.')[1:]: mod = getattr(mod, comp) return mod def docstrings(path): """Extract docstrings from path. This respects the Mercurial cmdtable/table convention and will only extract docstrings from functions mentioned in these tables. """ mod = importpath(path) if mod.__doc__: src = open(path).read() lineno = 1 + offset(src, mod.__doc__, path, 7) print poentry(path, lineno, mod.__doc__) functions = list(getattr(mod, 'i18nfunctions', [])) functions = [(f, True) for f in functions] cmdtable = getattr(mod, 'cmdtable', {}) if not cmdtable: # Maybe we are processing mercurial.commands? cmdtable = getattr(mod, 'table', {}) functions.extend((c[0], False) for c in cmdtable.itervalues()) for func, rstrip in functions: if func.__doc__: src = inspect.getsource(func) name = "%s.%s" % (path, func.__name__) lineno = func.func_code.co_firstlineno doc = func.__doc__ if rstrip: doc = doc.rstrip() lineno += offset(src, doc, name, 1) print poentry(path, lineno, doc) def rawtext(path): src = open(path).read() print poentry(path, 1, src) if __name__ == "__main__": # It is very important that we import the Mercurial modules from # the source tree where hggettext is executed. Otherwise we might # accidentally import and extract strings from a Mercurial # installation mentioned in PYTHONPATH. sys.path.insert(0, os.getcwd()) from mercurial import demandimport; demandimport.enable() for path in sys.argv[1:]: if path.endswith('.txt'): rawtext(path) else: docstrings(path)