[PATCH 2/3] Fix Wunused-return warnings

[Steve Grubb]

On Friday, February 08, 2013 07:12:34 PM Tyler Hicks wrote:
> When building with -D_FORTIFY_SOURCE=2 and -W-unused-return, there are a
> number of warnings caused by return values of functions marked with the
> warn_unused_result attribute being ignored. The audit codebase makes an
> attempt to suppress these warnings by casting the return value to void, but
> that does not work when D_FORITY_SOURCE is in use.
> 
> Here's an explanation of how this patch fixes the warnings and how the
> potential error conditions are handled:
> 
> Errors writing to the auditd pid file should be logged since errors opening
> the pid file are logged. These write() errors aren't treated as fatal.
> 
> Problems adjusting auditd's out of memory score should be logged, if simply
> to catch a change to the kernel interface. These errors aren't treated as
> fatal.
> 
> Auditd refuses to start when nice() fails during initialization, so it
> should take disk_error_action whenever nice() fails during a reconfigure.

During a reconfigure, I would not consider this fatal. Its better to stay 
running than exit. I'll adjust the patch.

-Steve

> Failure to chdir("/") while daemonizing should be logged and treated as
> fatal since errors while redirecting stdin, stdout, and stderr are logged
> and considered fatal.
>
> All nice() return values are handled sufficiently by relying on errno.
> However, they still throw warnings when D_FORTIFY_SOURCE is used. This patch
> quiets those warnings by capturing the return value and using it and errno
> to determine if nice() failed.
> 
> Failure to adjust audit log file owner (fchown) and permissions (fchmod) are
> logged and considered fatal when opening the log file for the first time.
> They are not treated as fatal when the operations fail on during log
> rotation since we made sure that they file owner and permissions were
> correct when originally opening the log file.