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fuenfundachtzig
Asked: 2010-10-26 05:07:20 +0800 CST

X11 for apache user

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We are using inkscape to convert SVG images uploaded to our server via a web form. For this inkscape offers a batch mode via the -z option, but this batch mode has a flaw: When inkscape is run by the apache user, it breaks saying

$ inkscape -z -W drawing.svg
X11 connection rejected because of wrong authentication.
The application 'inkscape' lost its connection to the display localhost:11.0;
most likely the X server was shut down or you killed/destroyed
the application.

If you do the same as a normal user you also get errors:

Xlib: connection to "localhost:11.0" refused by server
Xlib: PuTTY X11 proxy: MIT-MAGIC-COOKIE-1 data did not match
(inkscape:24050): Gdk-CRITICAL **: gdk_display_list_devices: assertion `GDK_IS_DISPLAY (display)' failed
301.27942

But at least inkscape gives the correct answer (here the number stating the width of the image).

Does somebody know how to make this also work for the apache user? Does it make sense to authorize apache to use X (if so how)? In any case it doesn't feel like the right solution...

apache-2.2 x11 authorization batch-processing

2 Answers

  1. Best Answer

    This behavior is a recognized bug, let's hope it's gonna be fixed in the next release: https://bugs.launchpad.net/inkscape/+bug/666272

    In the meantime, my google-fu suggests to run vnc-server instead of Xvfb. It can run at the same time as your X server. You can run it as apache user, so apache will have no problems displaying X applications on that buffer.

    This connection is only password authenticated, so it doesn't matter what user is connecting with vncviewer. Note however that the VNC protocol isn't necessarily safe, so be sure to use it locally only and configure your firewall appropriately.

    Start the vnc server as apache user:

    vncserver :2 -geometry 1024x768 - This is to be done only once

    In the script run by apache, only run the application; don't start any vncserver or vncviewer: DISPLAY=:2.0 inkscape -z -W drawing.svg

    Google found the answer here: http://www.linuxquestions.org/questions/programming-9/can-php-script-execute-x11-applications-811779/

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  2. I've encountered a similar issue, the fix is easy, just run Xvfb as a daemon and configure the Apache user (in its environment or in the startup script) with DISPLAY and the appropriate xauth.

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