- Use file pointers instead of raw I/O, inspired by Kernel code.
- Use OOM_SCORE_ADJ_MIN from linux/oom.h instead of working with
magic values.
- Stricter error checking and descriptive error messages.
The reasoning for using the constant rather than magic values lies
in the fact that this ensures people get the message.
With "-1000", a code reviewer would question if that is really the
lowest possible number or just an arbitrary value.
The kernel ABI probably won't change, but even in the case, we wouldn't
have to modify the code. The OOM killer only is guaranteed to not
kill you if you have OOM_SCORE_ADJ_MIN.
In all honor, the previous usage was formally more correct, but for the
sake of consistency across all the tools having the v-flag, I separated
it from the command-string.
Also, make use of the mandoc macros for the manpage. This makes it
easier to maintain, extend and change in the future.
- Add arg.h and fix usage
Given slock is suid we don't want to have half-measures in place to
parse the arguments in case the code is changed in the future with
somebody not paying enough attention.
Also, fix the usage string output to be more consistent across the
suckless toolbase and make it reflect the manpage entry.
- Comments
Use proper block comments and add/change them where necessary
to help in studying the code.
- Error messages
Consistently prepend them with "slock:" and fix wording and
do a proper cleanup before quitting (XCloseDisplay and free
the locks), making the die() semantics consistent with st's.
- getpwuid() error reporting
Properly present an error message if getpwuid() fails.
- fork() error reporting
Properly present an error message if fork() fails. If we cannot
close the connection within the fork context we abort the
operation and report an error.
- execvp() error handling
If execvp fails, we cannot call die() afterwards as this implies
calling exit(). We must use _exit() to prevent the libc from
doing now "illegal" cleanup-work.
There are 2 arguments why -v and -h are broken:
1) if you are running off git, -v will show the last stable
release, effectively making this option useless.
people running stable versions leave open an attack surface
this way in case there are vulnerabilities found.
99% of the people are also using package managers to keep
their software up to date, instead of running $TOOL -v to
check how old it is.
2) -h is a sad excuse for not just looking at the manual page
(man 1 slock). Given we accept a post_lock_command, we can't
be as liberal and just intercept certain flags.
I changed the manpage to reflect this change.
There really is no need to source a defined variable from a linux
header. The OOM-rank ranges from -1000 to 1000, so we can safely
hardcode -1000, which is a sane thing to do given slock is suid and
we don't want to play around too much here anyway.
On another notice, let's not forget that this still is a shitty
heuristic. The OOM-killer still can kill us (thus I also changed
the wording in the error-message. We do not disable the OOM-killer,
we're just hiding.
