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[Misaki <1444790@xxxxxxxxxxxxxxxxxx>]

After removing custom thumbnailers, copying a jp2 file using ctrl-C
ctrl-V causes nautilus to crash about one time. gnome-thumbnailer tries
to create a thumbnail, but it can take several seconds, and if nautilus
is reopened and navigated to that folder again, it will crash again.
However, after this has been completed, nautilus won't crash. (In fact,
top reveals that it's eog that creates the new thumbnail if you use
ctrl-C ctrl-V in nautilus.)

If the new file name is obtained a different way, like using 'mv' on the
command line, navigating to that folder in nautilus will cause a crash
without attempting to generate a new thumbnail.

So even if you wait several seconds, no thumbnail will exist for the
file and nautilus will crash every time you navigate to that folder
until you delete the file or rename it to a path for which it will have
a valid thumbnail (meaning the file's mtime is correct).

So this might only affect jpeg-2000 files, and not all files for which
there is no valid output. Maybe with other files, the default thumbnail
options (the ones not recorded in /usr/share/thumbnailers) consistently
create at least a failed thumbnail, while this doesn't happen with
jpeg-2000 files. But since nautilus is crashing before eog finishes
creating a thumbnail (if using ctrl-C ctrl-V to copy), nautilus might be
relying on a separate process from what it depends on for, say,
obtaining a 'failed thumbnail' result for incomplete mp4 files, which
don't cause a crash.

One difference is that while gnome-thumbnailer has code for handling
image formats as a fallback method, it isn't for video formats. I'm not
sure if it's nautilus or gnome that's calling eog to create a thumbnail
when ctrl-C ctrl-V is used.

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https://bugs.launchpad.net/bugs/1444790

Title:
  crash if thumbnailer fails to produce output

Status in nautilus package in Ubuntu:
  New

Bug description:
  Step 1: Use a custom thumbnailer which doesn't always produce output.
  I'm personally using this one, since the default size (256x256) often
  produces a png thumbnail which takes more space than the original jpg
  image, and imagemagick's convert seems to have a bug for palette-png
  to grayscale conversion:

  [Thumbnailer Entry]
  TryExec=ffmpeg
  Exec=ffmpeg -i %i -vf "scale='min(iw,128):min(ih,128):force_original_aspect_ratio=decrease',format=rgba|rgb24" -frames 1 -y -f image2 -c:v png %o
  MimeType=image/gif;image/jpeg;image/png;image/jp2;image/x-webp

  Step 2: navigate to a folder that the thumbnailer can't handle. For
  me, that was "balloon.jp2" from http://opf-labs.org/format-corpus
  /jp2k-formats/

  My version of ffmpeg says on the command line that "Progression order
  RPCL is not implemented. [...] Output file is empty, nothing was
  encoded". Not having any file from the thumbnailer, or maybe having an
  empty, 0-byte file (ffmpeg does not produce a 0-byte output file from
  the command line), causes nautilus to freeze and crash.

  This happened multiple times. However, just now I checked and it
  didn't crash, and a thumbnail exists for the jp2 image, /sigh. But
  creating a copy of the jp2 image does lead to crashes. Ok, the reason
  is that eog creates a thumbnail when one doesn't exist and the
  system's default thumbnailers fail. Opening the image gallery in eog
  causes thumbnails to be created for all visible images.

  That is, when running eog from a terminal, opening the image gallery
  caused ffmpeg's output (with the error message) to be displayed in
  that terminal. But the thumbnail is still created, and eog must have
  done it.

  It's also possible nautilus crashes when the fallback gnome-
  thumbnailer fails to create a file, which I think is what happens when
  it tries to open a jpeg-2000 file. A few months ago I noted this bug:

  >Another bug, crashes when trying to generate thumbnail for jpeg-2000
  (jp2). Avoided if thumbnail is already created, maybe in some other
  cases too. Possibly just when thumbnail isn't created quickly enough
  (thumbnailer fails or something).

  ...but apparently I fixed it somehow, not sure.

  So it's totally fine that no thumbnail is created when the existing
  thumbnailer entries aren't sufficient. But nautilus shouldn't crash.
  When running nautilus from the command line, it says there was a
  segmentation fault, core dumped, with a crash file being generated in
  /var/crash (which I'm deleting).

  ProblemType: Bug
  DistroRelease: Ubuntu 14.10
  Package: nautilus 1:3.10.1-0ubuntu15.1
  ProcVersionSignature: Ubuntu 3.16.0-30.40-generic 3.16.7-ckt3
  Uname: Linux 3.16.0-30-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.14.7-0ubuntu8.3
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Wed Apr 15 20:48:20 2015
  GsettingsChanges:
   b'org.gnome.nautilus.list-view' b'default-visible-columns' b"['name', 'size', 'date_modified', 'date_accessed', 'type']"
   b'org.gnome.nautilus.list-view' b'default-column-order' b"['name', 'size', 'date_modified', 'date_accessed', 'type', 'group', 'where', 'mime_type', 'owner', 'permissions']"
  SourcePackage: nautilus
  UpgradeStatus: No upgrade log present (probably fresh install)

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