GNU bug report logs - #15003
24.3; Function run-python fails on MS-Windows 7

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: lewcreary <at> cs.com
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3; Function run-python fails on MS-Windows 7
Date: Thu, 1 Aug 2013 17:13:11 -0400 (EDT)

[Message part 1 (text/plain, inline)]

 This bug report will be sent to the Bug-GNU-Emacs mailing list and the GNU bug tracker at debbugs.gnu.org. ?Please check that the From: line contains a valid email address. ?After a delay of up to one day, you should receive an acknowledgment at that address.


Please describe exactly what actions triggered the bug, and the precise symptoms of the bug.
----------------------------------


Emacs-version: "GNU Emacs 24.3.1 (i386-mingw-nt6.1.7601)
?of 2013-03-17 on MARVIN" ?(a pre-compiled version for MS-Windows)


Operating System: Microsoft Windows 7 Professional (Copyright 2009)


Function-definition (from python.el):
?(defun run-python (cmd &optional dedicated show) ?... ...)


Typical invocation with Emacs running under MS-Windows 7:
?(run-python "c:/Program Files (x86)/Python/Python31/python.exe -i" nil t)


[Note- I have successfully debugged and patched the bug to be described here; the facts reported below were ascertained during the debugging process.]


This bug occurs whenever the function run-python is invoked, whether by a M-x run-python command, or by C-c C-p or <menu-bar> <Python> <Start interpreter> while editing a file in python-mode, provided that the first argument given to run-python has a pathname containing at least one space (see example invocation shown above -- this is typical when running under MS-Windows 7). When run-python is invoked under these circumstances, it fails with the error message "Spawning child process: invalid argument".


The root cause of this failure is that the space-containing command pathname in the first argument to function run-python is mangled during processing in the function python-shell-make-comint, which is called by run-python. ?This mangling occurs while processing the following line of code in python-shell-make-comint:


? ? ? ? (let* ((cmdlist (split-string-and-unquote cmd))


Since the mangling is actually done in the function split-string-and-unquote, the solution is to avoid applying split-string-and-unquote to the (possibly) space-containing command pathname. ?The successful patch I have constructed does this conservatively by changing the single line of code just displayed to be


? ? ? ? (let* ((cmdlist (list-cmd-components cmd))


where list-cmd-components is a newly written function that first extracts the (possibly) space-containing command path from the command-string while preserving it unchanged, and then calls function split-string-and-unquote on the remainder of the command-string (if any) to separate the command arguments (if any).


I've attached to this e-mail a patch file, Emacs-Bugfix.el, containing the revised definition of function python-shell-make-comint and the new definition of function list-cmd-components. ?When loaded after python.el, this patch file fixes the bug.


? -- ?Lew Creary

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Message #8 received at 15003 <at> debbugs.gnu.org (full text, mbox):

From: lewcreary <at> cs.com
To: 15003 <at> debbugs.gnu.org
Subject: P.S.  My bugfix is not platform-general
Date: Thu, 15 Aug 2013 23:57:59 -0400 (EDT)

I should have mentioned that my bugfix will work only on computing 
platforms on which the python executable pathname ends in ".exe" (MS 
Windows, at least).  The GNU maintainers will have to generalize it to 
work on other platforms.

 --  Lew Creary

Message #11 received at 15003 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: lewcreary <at> cs.com
Cc: 15003 <at> debbugs.gnu.org
Subject: Re: bug#15003: 24.3; Function run-python fails on MS-Windows 7
Date: Fri, 16 Aug 2013 00:12:23 -0400

> (run-python "c:/Program Files (x86)/Python/Python31/python.exe -i" nil t)

This is ambiguous: maybe the program you want to run is in the file
"c:/Program".  Or is it "c:/Program Files"?  Oh wait, maybe you meant
the executable "c:/Program Files (x86)/Python/Python31/python.exe -i"?

> ? ? ? ? (let* ((cmdlist (split-string-and-unquote cmd))

split-string-and-unquote was specifically used so that the user can
resolve those ambiguities by quoting the elements that contain
embedded spaces.  E.g. try

 (run-python "\"c:/Program Files (x86)/Python/Python31/python.exe\" -i" nil t)


-- Stefan

Message #16 received at 15003-done <at> debbugs.gnu.org (full text, mbox):

From: fgallina <at> gnu.org
To: 15003-done <at> debbugs.gnu.org
Subject: 24.3; Function run-python fails on MS-Windows 7
Date: Mon, 02 Sep 2013 11:26:10 -0300

Closing this one as it is clearly a configuration thing.

Regards,
Fabián.

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