\OC_Helper::tmpFile can break Imagemagick

[oparoz]

Steps to reproduce

OC generates temp filenames without any extension (i.e. .mp3). It concatenates everything instead.
This test case proves that this will break Imagemagick.

1. Install Imagemagick in your test env
2. Upload a OTF font
3. Rename the font 23926b6bec09d849d770a606d8403b96otf
4. Use identify to let Imagemagick determine what's in the file

Tested with OTF fonts, but could happen with more file types down the line.

Expected behaviour

Imagemagick should be able to identify the file as an OTF font

Actual behaviour

Instead

# identify /tmp/23926b6bec09d849d770a606d8403b96otf
identify: no decode delegate for this image format `' @ error/constitute.c/ReadImage/501.

If you rename the file so that extension is kept after the dot.

# identify /tmp/23926b6bec09d849d770a606d8403b96.otf
/tmp/23926b6bec09d849d770a606d8403b96.otf OTF 800x480 800x480+0+0 16-bit sRGB 96.6KB 0.039u 0:00.039

Server configuration

Operating system: FreeBSD

Web server: Apache

PHP version: 5.5 with Imagemagick 6.8 or 6.9

ownCloud version: 7.0.3

Updated from an older ownCloud or fresh install: Updated

The content of config/config.php:

  'enabledPreviewProviders' =>
    array(
      'OC\Preview\Image',
      'OC\Preview\MP3',
      'OC\Preview\TXT',
      'OC\Preview\MarkDown',
      'OC\Preview\Movies',
      'OC\Preview\MSOffice2003',
      'OC\Preview\MSOffice2007',
      'OC\Preview\MSOfficeDoc',
      'OC\Preview\OpenDocument',
      'OC\Preview\PDF',
      'OC\Preview\StarOffice',
      'OC\Preview\SVG',
      'OC\Preview\TIFF',
      'OC\Preview\Illustrator',
      'OC\Preview\Postscript',
      'OC\Preview\Photoshop',
      'OC\Preview\SFNT',
    ),

Are you using encryption: no

[oparoz]

In master, the function has moved to TempManager, but it has the same problem.

If this is considered to be only an issue with Imagemagick, I could take care of the problem locally by adding the dot to $tmpfile, if extensions are normalised (3 chars), but this problem could affect other parts of the app.

[oparoz]

Updated the test case to make it easy to test

[karlitschek]

@georgehrke What is your opinion?

[oparoz]

I think this will only affect ImageMagick as it tries to use the file extension in order to magically convert files it can't identify after a first parse.
If that's the case, then the responsibility could be put on the shoulders of the classes which extend Provider and if most use Imagick, then an extra method could be added to introduce a dot.

[georgehrke]

iirc you can hand over a suffix for \OC_Helper::tmpFile(), I'll check and prepare a pull request

[georgehrke]

@oparoz Can you still reproduce it on latest master? This should have been fixed with your commit, as we are now using toTmpFile() which uses \OC_Helper::tmpFile with extensions.

[oparoz]

I need to rebase my patch to support font previews to be able to test. It's going to take a few days...

[oparoz]

Still a problem.
The tmp file is named oc_tmp_d20d57d7da3bcb6236f3cd4faacacd32otf
We need a dot in front the extension: oc_tmp_d20d57d7da3bcb6236f3cd4faacacd32.otf

[oparoz]

The behaviour can be tested from within OC using this PR #13648
You won't get a preview for OTF fonts unless you fix \OC_Helper::tmpFile()

[oparoz]

This is also killing any Raw picture conversion as these formats can embed other formats as well for quick previewing

[oparoz]

Fix is in #13654

[MorrisJobke]

Fixed via #13654