Login fails with no error message when NFS home directory is over quota

[Peter Benie]

If a user is over quota, or if the home directory disk is full, they get logged out straight after logging in, when the home directory is on NFS. No information is presented to the user that would let them know the problem.

This is because of an error in the way that lightdm writes to the ~/.Xauthority file in src/x-authority.c.

It does check that each write() succeeds, but in the NFS case, the data isn't actually written by the client until fsync() is called; the status of that system call isn't checked so the quota problem is undetected.

Calling fsync() is not necessary; the effect of committing the data to disk is implied by close(), which is done on the next line anyway.

Ubuntu 14.04.5 LTS
lightdm 1.10.6-0ubuntu1

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "lightdm-check-close-status.patch" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

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