[pacman-dev] [PATCH 1/1] alpm: use flock() for db lock

[Christian Hesse]

Andrew Gregory <andrew.gregory.8 at gmail.com> on Tue, 2017/06/06 17:56:
> On 06/06/17 at 11:26pm, Christian Hesse wrote:
> > From: Christian Hesse <mail at eworm.de>
> > 
> > We used to check for file existens, but that suffers from stale lock
> > files caused by unexpected events like crash, shutdown, etc.
> > 
> > Instead use flock() to lock the file. It does not matter whether or
> > not the file exists but whether an exclusive lock can be obtained.
> > 
> > Also remove the hint about removing the file from pacman.
> > 
> > Signed-off-by: Christian Hesse <mail at eworm.de>
> > ---
> >  lib/libalpm/handle.c | 17 +++++++++++++++--
> >  src/pacman/util.c    |  5 -----
> >  2 files changed, 15 insertions(+), 7 deletions(-)  
> 
> Refusing to run when a lock file is leftover from a previous
> invocation is intentional.  It serves as an indicator that the user
> needs to verify the integrity of their system.  Also, see
> https://lists.archlinux.org/pipermail/pacman-dev/2013-August/017733.html
> for previous discussion regarding flock().

Thanks for the heads-up. I did not know this thread. Looks like I should
invest more time searching for this kind of information before reinventing
the wheel.

Perhaps anybody should add a comment to lib/libalpm/handle.c why we are *not*
adding flock(). ;)

BTW, it is interesting what systems actually do run pacman...
-- 
main(a){char*c=/*    Schoene Gruesse                         */"B?IJj;MEH"
"CX:;",b;for(a/*    Best regards             my address:    */=0;b=c[a++];)
putchar(b-1/(/*    Chris            cc -ox -xc - && ./x    */b/42*2-3)*42);}
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