Mercurial > hg
annotate contrib/hgweb.fcgi @ 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 | 85cba926cb59 |
children | 99e231afc29c |
rev | line source |
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4391
722417b3d7fa
Add hgwebdir.fcgi to contrib
Michael Gebetsroither <michael.geb@gmx.at>
parents:
diff
changeset
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1 #!/usr/bin/env python |
722417b3d7fa
Add hgwebdir.fcgi to contrib
Michael Gebetsroither <michael.geb@gmx.at>
parents:
diff
changeset
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2 # |
11002
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
changeset
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3 # An example FastCGI script for use with flup, edit as necessary |
4391
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Add hgwebdir.fcgi to contrib
Michael Gebetsroither <michael.geb@gmx.at>
parents:
diff
changeset
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4 |
11002
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hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
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5 # Path to repo or hgweb config to serve (see 'hg help hgweb') |
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
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6 config = "/path/to/repo/or/config" |
5244
79279b5583c6
cgi: sys.path.insert should be before importing mercurial
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
5197
diff
changeset
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7 |
15475
85cba926cb59
hgweb: add hint about finding library path with debuginstall
Matt Mackall <mpm@selenic.com>
parents:
11002
diff
changeset
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8 # Uncomment and adjust if Mercurial is not installed system-wide |
85cba926cb59
hgweb: add hint about finding library path with debuginstall
Matt Mackall <mpm@selenic.com>
parents:
11002
diff
changeset
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9 # (consult "installed modules" path from 'hg debuginstall'): |
11002
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hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
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10 #import sys; sys.path.insert(0, "/path/to/python/lib") |
5197
55860a45bbf2
Enable demandimport only in scripts, not in importable modules (issue605)
Thomas Arendsen Hein <thomas@intevation.de>
parents:
4391
diff
changeset
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11 |
6085
e1f11b8a1e9e
hgweb: disable cgitb by default in hgwebdir.fcgi too
Maxim Dounin <mdounin@mdounin.ru>
parents:
5995
diff
changeset
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12 # Uncomment to send python tracebacks to the browser if an error occurs: |
11002
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
changeset
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13 #import cgitb; cgitb.enable() |
4391
722417b3d7fa
Add hgwebdir.fcgi to contrib
Michael Gebetsroither <michael.geb@gmx.at>
parents:
diff
changeset
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14 |
11002
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
changeset
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15 from mercurial import demandimport; demandimport.enable() |
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
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16 from mercurial.hgweb import hgweb |
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
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17 from flup.server.fcgi import WSGIServer |
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
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18 application = hgweb(config) |
b1739ebb9f3f
hgweb: synchronize fcgi and wsgi scripts
Matt Mackall <mpm@selenic.com>
parents:
7799
diff
changeset
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19 WSGIServer(application).run() |