identify "d:" hangs

[qwerty4030]

Version: ImageMagick 6.9.3-10 Q16 x86_64 2016-05-04 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2016 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC OpenMP
Delegates (built-in): jng jpeg lzma png tiff xml zlib

OS: 4.4.10-22.54.amzn1.x86_64 (amazon linux)

identify hangs on the following commands:

identify "d:" (no output, just hangs forever)
identify "d::" (no output, just hangs forever)
identify "http:"
error : Unknown IO error (hangs after this message)
identify "http::"
error : Unknown IO error (hangs after this message)

[glennrp]

I haven't finished bisecting this bug yet, but I observed that the bug exists at least from 6.9.1-10 through 6.9.4-1 but not in 6.9.4-7 and later nor in 7.0.1-1 and later (testing on Ubuntu 16:04). I don't see anything about it in the ChangeLog.

[mikayla-grace]

ImageMagick previously defaulted to stdin if no filename was specified. With recent versions of ImageMagick, you can replicate the behavior with a dash, e.g. identify -. To prevent reading from stdin, add this policy (see http://www.imagemagick.org/script/security-policy.php):

<policy domain="path" rights="none" pattern="-"/>

With this policy, we get

$ identify -
identify: not authorized `-' @ error/blob.c/OpenBlob/2451.
identify: no decode delegate for this image format `' @ error/constitute.c/ReadImage/508.

[qwerty4030]

Still getting this behavior on an upgraded version:

Version: ImageMagick 6.9.5-10 Q16 x86_64 2016-11-11 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2016 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC OpenMP 
Delegates (built-in): zlib

The following command hangs:

identify "http:"

I noticed that some delegates are missing, working on installing those now. However I do not expect that command to hang.

[dlemstra]

Can you still reproduce this issue @qwerty4030 or can we close it?

[qwerty4030]

@dlemstra If I remember correctly, installing the missing delegates resolved the issue. We are now only passing valid filenames (from the tmp directory) to IM and we have not run into this issue since then.