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Bug: On Win2k upload can incorreclty fail with zero size file message

In bin/upload you can incorrectly get a file size of zero from the -s or stat methods on the temporary file produced by Apache on a file upload.

Test case

  • On Win2K
  • Try uploading a file - look for message saying attachment is missing or empty

Fix record

Put close $filePath if( $TWiki::OS eq "WINDOWS"); after line with my $createLink ... on it. Some CGI documentation suggets that Window might need to do a file close before exit.

Other things that seem to work:

  • Put sleep 1 before getting the file size - I don't know how complete a fix this is
  • Copy to a temporary file before checking size

Environment

TWiki version: 01 Sep 2001
TWiki plugins: N/A
Server OS: Win2k
Web server: Apache 1.3.14 (Win32)
Perl version: v5.6.0, active state 623
Client OS: Win2k
Web Browser: IE5.5

-- JohnTalintyre - 27 Sep 2001


I've also had problems uploading a zero size file from custom scripts using the Wiki library. This usually happened when I zeroed out a file attached to a page and marked it as "being worked on" by a background process. There was no problem attaching the completed file, but attaching the zero length temporary file failed. My work-around was to lie about the length of the temporary file, setting the value to 1.

-- SimonClift - 18 Dec 2001

Closing a file before exit is good practice for ModPerl, where otherwise you can get file handle leaks that eventually require a web server restart. See ModPerl and http://perl.apache.org/ for more information, latter has a FAQ on porting CGI code to mod_perl that mentions this issue. We should really put in cleanup handlers for use with mod_perl so that files are always closed even if the script is aborted or the user hits the Stop button on the browser.

I've also had problems under Windows with a Perl process that kept a file open, causing CygWin to show the file ownership as null (i.e. blank string in ls -l) and to prevent file being removed.

-- RichardDonkin - 04 Mar 2002


Category: TWikiPatches
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Topic revision: r5 - 2005-02-15 - SamHasler
 
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