FreeBSD kernel checks headers/trailers pointer against NULL, not
corresponding count. Passing NULL if there are no headers/trailers
helps to avoid unneeded work in kernel, as well as unexpected 0 bytes
GIO in traces.
If process exited abnormally while holding lock on some shared memory zone -
unlock it. It may be not safe thing to do (as crash with lock held may
result in corrupted shared memory structure, and other processes will
subsequently crash while trying to access shared data), therefore complain
loudly if unlock succeeds.
It is currently used from master process on abnormal worker termination to
unlock accept mutex (unlocking of accept mutex was broken in 1.0.2). It is
expected to be used in the future to unlock other mutexes as well.
Shared mutex code was rewritten to make this possible in a safe way, i.e.
with a check if lock was actually held by the exited process. We again use
pid to lock mutex, and use separate atomic variable for a count of processes
waiting in sem_wait().
Previously result of last iteration's writev() was returned. This was
unnoticed as return value was only used if chain contained only one or
two buffers.
syscall(2) uses usual libc convention, it returns -1 on error and
sets errno. Obsolete _syscall(2) returns negative value of error.
Thanks to Hagai Avrahami.
On file retest open_file_cache lost is_directio if file wasn't changed.
This caused unaligned operations under Linux to fail with EINVAL.
It wasn't noticeable with AIO though, as errors wasn't properly logged.
Non-daemon mode is currently used by supervisord, daemontools and so on
or during debugging. The NOACCEPT signal is only used for online upgrade
which is not supported when nginx is run under supervisord, etc.,
so this change should not break existant setups.
NetBSD 5.0+ has SO_ACCEPTFILTER support merged from FreeBSD, and having
accept filter check in FreeBSD-specific ngx_freebsd_config.h prevents it
from being used on NetBSD. Therefore move the check into configure (and
do the same for Linux-specific TCP_DEFER_ACCEPT, just to be in line).
