[Mediawiki-l] ImageMagic problem solved

[Diederik Oudshoorn]

Hello once again,

After receiving a few pointers to the ImageMagic problem (see: 
MediaWiki-I Digest, Vol 16, Issue 21 (&22) it looks like it that I have 
solved the problem. This is what I did:

Brion and Ashar suggested that the appearance of both / and \ in the 
image path  might cause the problem. It turned out not to be so. After 
digging into the Image.php file (in /includes) I found out that the 
escapeshellarg() command in line  450/451 in the renderThumb() function 
was the culprit. After outputing the $cmd to the debug log I noticed the 
  pathname of the source and destination file of the image was enclosed 
in  single quotes: i.e.

<snip>
C:/convert.exe -quality 85 -background white -geometry 800 
'c:\easyphp\www\mediawiki/images/b/b0/IMG_4028.JPG' 
'c:\easyphp\www\mediawiki/images/thumb/c/c7/800px-IMG_4028.JPG'
</snip>

Cutting and pasting this command in a dos-shell returned the "invalid 
input error" I noticed earlier in the Apache error-log. After manually 
removing the quotes the command executed as it should.

I now have removed the escapeshellarg() command from the syntax leaving 
the following code:

<snip>
$cmd  =  $wgImageMagickConvertCommand .
     " -quality 85 -background white -geometry {$width} ".
     $this->imagePath . " " .
     $thumbPath;
</snip>

instead of:

<snip>
$cmd  =  $wgImageMagickConvertCommand .
     " -quality 85 -background white -geometry {$width} ".
     escapeshellarg($this->imagePath) . " " .
     escapeshellarg($thumbPath);
</snip>

I realize that this is a sort of a hack, because the escapeshellarg() 
was put there on purpose (I think...), so it leaves me with a couple of 
questions:

1) why does escapeshellarg(string arg) add quotes around arg? (the 
PHP.net manual didn't make me wiser), is it a *nix thingy? (alas, I'm 
still using Windows)

2) What is (might be) the penalty for removing escapeshellarg() from the 
code, what is the rational behind it?

3) Is there a more cleaner way to fix this?

thanks for your time

Diederik Oudshoorn