I looked at some of the programs that use pidfile(3) in base, and they
pretty much all get it wrong. Consider these two scenarios:
1) common case
process A process B
main()
pidfile_open() -> success
perform_initialization()
daemon()
pidfile_write() -> success
perform_work() main()
pidfile_open() -> EEXIST
exit()
2) very unlikely but still possible case
process A process B
main()
pidfile_open() -> success main()
perform_initialization() pidfile_open() -> EAGAIN
daemon() perform_initialization()
pidfile_write() -> success daemon()
perform_work() perform_work()
The problem is that most of them (at least the ones I checked) ignore a
pidfile_open() failure unless errno == EEXIST.
How do we fix this? My suggestion is to loop until pidfile_open()
succeeds or errno != EAGAIN. Does anyone have any objections to that
approach?
DES
--
Dag-Erling Smørgrav - d...@des.no
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
