Review Request: Quit LibArchiveInterface::list() and the associated ListJob before deleting LibArchiveInterface in Archive's destructor

[Nathan Mills]

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http://git.reviewboard.kde.org/r/105404/
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(Updated Oct. 26, 2012, 5:53 p.m.)


Review request for KDE Utils and Raphael Kubo da Costa.


Changes
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If LibArchiveInterface::doKill() is called before list() sets m_listing, the check for whether list() is running in Archive's destructor will succeed, causing LibArchiveInterface to be deleted. Protect against this by returning from list() immediately if this ever happens.


Description
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This patch fixes the crash when initially opening an archive with Ark using libarchive. The patch prevents a Job from using a deleted LibArchiveInterface by making sure that the Job quits before the LibArchiveInterface is deleted.
When an Archive instance is being destroyed, the destructor first asks its ReadOnlyArchiveInterface instance to quit. The instance, which is really a LibArchiveInterface, then waits for its list() method to quit. Then the Archive instance's destructor waits for the most recently started Job to quit. Archive's destructor only waits for the Job to quit if the Archive's ReadOnlyArchiveInterface supports doKill().
This patch could easily be extended to other Jobs as follows: For DeleteJob, the interface's doKill() method needs to quit the deleteFiles() call cleanly. For ExtractJob, the interface's doKill() method needs to quit copyFiles() cleanly. For AddJob, the interface's doKill() method needs to quit the addFiles() method cleanly. These three jobs should probably ask the user whether to continue with the operation, halt the operation, or delete the added/copied files.


This addresses bug 193908.
    http://bugs.kde.org/show_bug.cgi?id=193908


Diffs (updated)
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  kerfuffle/archive.h 515788f 
  kerfuffle/archive.cpp c2c5b18 
  kerfuffle/jobs.h d704dfc 
  kerfuffle/jobs.cpp aedc62c 
  plugins/libarchive/libarchivehandler.h 9ec7541 
  plugins/libarchive/libarchivehandler.cpp cd473ee 

Diff: http://git.reviewboard.kde.org/r/105404/diff/


Testing
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I started the patched version of Ark with a large tar archive and a small tar archive pressing Ctrl+Q each time. Then I reverted the patch, compiled Ark, and compared how long the unpatched version took to quit to make sure the patch didn't cause excessively long waits.


Thanks,

Nathan Mills

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