Title: mmap\'s resize method resizes the file in win32 but not unix
Type: Stage:
Components: Extension Modules Versions: Python 2.4
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: georg.brandl Nosy List: facundobatista, georg.brandl, georg.brandl, josiahcarlson, loewis, myers_carpenter
Priority: normal Keywords:

Created on 2003-04-27 17:44 by myers_carpenter, last changed 2005-08-24 07:19 by georg.brandl. This issue is now closed.

File name Uploaded Description Edit
mmap-resize-diff georg.brandl, 2005-06-03 20:50
Messages (9)
msg15710 - (view) Author: Myers Carpenter (myers_carpenter) Date: 2003-04-27 17:44
In the resize method under win32 you have something
like this:

	/* Move to the desired EOF position */
        SetFilePointer (self->file_handle,
                new_size, NULL, FILE_BEGIN);
        /* Change the size of the file */
        SetEndOfFile (self->file_handle);

Which resizes the file

Under Unix you need to call 

   ftruncate(self->fileno, new_size)

before calling remap() to make it do the same thing.
msg15711 - (view) Author: Martin v. Löwis (loewis) * (Python committer) Date: 2003-05-04 12:36
Logged In: YES 

Would you like to contribute a patch? Please make sure to
include changes to the documentation and test suite.
msg15712 - (view) Author: Facundo Batista (facundobatista) * (Python committer) Date: 2005-01-15 17:55
Logged In: YES 

Please, could you verify if this problem persists in Python 2.3.4
or 2.4?

If yes, in which version? Can you provide a test case?

If the problem is solved, from which version?

Note that if you fail to answer in one month, I'll close this bug
as "Won't fix".

Thank you! 

.    Facundo
msg15713 - (view) Author: Facundo Batista (facundobatista) * (Python committer) Date: 2005-05-30 18:59
Logged In: YES 

Deprecated. Reopen only if still happens in 2.3 or newer. 

.    Facundo
msg15714 - (view) Author: Josiah Carlson (josiahcarlson) * (Python triager) Date: 2005-05-30 23:32
Logged In: YES 

The problem still persists in Python 2.3 and 2.4.  A quick
read of mmapmodule.c shows that ftruncate() is not being
called within the non-windows portion of mmap_resize_method().
msg15715 - (view) Author: Facundo Batista (facundobatista) * (Python committer) Date: 2005-05-30 23:51
Logged In: YES 

Reopened as posted that still is a bug.
msg15716 - (view) Author: Georg Brandl (georg.brandl) * (Python committer) Date: 2005-06-03 20:12
Logged In: YES 

This is not trivial since the filehandle can be closed at
the time the ftruncate() would be necessary.

The Windows specific code duplicates the filehandle upon
mmap creation, perhaps the UNIX code should do this too?
Then, the ftruncate call can be inserted.
msg15717 - (view) Author: Georg Brandl (georg.brandl) * (Python committer) Date: 2005-06-03 20:50
Logged In: YES 

Attaching patch which duplicates the file handle under UNIX
too (btw, the size() method was broken too), mimics Windows
behaviour with resize(), adds a testcase for this and
clarifies the docs.
msg15718 - (view) Author: Georg Brandl (georg.brandl) * (Python committer) Date: 2005-08-24 07:19
Logged In: YES 

Okay, committed as
Modules/mmapmodule.c; 2.50;
Lib/test/; 1.33;
Doc/lib/libmmap.tex; 1.12;
Date User Action Args
2003-04-27 17:44:53myers_carpentercreate