Review Request 125613: Race condition and error notification loss in ListJob

[Alberto Jiménez Ruiz]

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https://git.reviewboard.kde.org/r/125613/
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(Updated Oct. 12, 2015, 7:11 p.m.)


Review request for kdelibs.


Bugs: 333436
    http://bugs.kde.org/show_bug.cgi?id=333436


Repository: kdelibs


Description
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Race condition and error notification loss in ListJob


Diffs
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  kio/kio/job.cpp 91712e3 
  kio/kio/jobclasses.h d771cfe 

Diff: https://git.reviewboard.kde.org/r/125613/diff/


Testing
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Tests done on Kubuntu 15.10:

With this folder structure in ~:
src
######c (Folder)
##############b (Folder chmod'ed to 700 and owned by root)
#######################d (10MB file made of /dev/urandom data)
##############a (10MB file made of /dev/urandom data)

Then, (as a normal user execute: "kioclient ~/src ~/dst")

Expected result: Notification that some files were not able to be copied (Cannot access "b" folder)
Result with latest kdelibs: Silent copying where b folder is owned by user but nothing inside.
---When all kdebugdialog flags are set, a backtrace is also seen.
      
subError notifications for listjob subjobs are lost, Copyjob uses this signal to skip data.

Also, this fix prevents a race condition. 

ListJob has another ListJob as a subjob.

Chaild fails for whatever reason and calls error, which calls slotError, which calls slotsFinished and emitResult.
The result of the child gets collected by parent. slotResult of parent gets called, removes subjob and emitsresult because there are no subjobs left.
---That's fine as long as the slave associated with the parent emits finished before the child fails. If it doesn't, parent calls emitsResult twice.


Result after patch: kioclient shows a MessageBox telling the copy operation could not be completed.


Thanks,

Alberto Jiménez Ruiz

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