minix/lib/libc/sys/sigqueue.2
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

157 lines
4.3 KiB
Groff

.\" $NetBSD: sigqueue.2,v 1.2 2011/01/10 06:26:30 wiz Exp $
.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
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.\" $FreeBSD: src/lib/libc/sys/sigqueue.2,v 1.8 2006/09/17 21:27:34 ru Exp $
.\"
.Dd January 9, 2011
.Dt SIGQUEUE 2
.Os
.Sh NAME
.Nm sigqueue
.Nd queue a signal to a process (REALTIME)
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In signal.h
.Ft int
.Fn sigqueue "pid_t pid" "int signo" "const union sigval value"
.Ft int
.Fn sigqueueinfo "pid_t pid" "const siginfo_t *info"
.Sh DESCRIPTION
The
.Fn sigqueue
system call causes the signal specified by
.Fa signo
to be sent with the value specified by
.Fa value
to the process specified by
.Fa pid .
If
.Fa signo
is zero (the null signal), error checking is performed but
no signal is actually sent.
The null signal can be used to check the
validity of PID.
.Pp
The conditions required for a process to have permission to queue a
signal to another process are the same as for the
.Xr kill 2
system call.
The
.Fn sigqueue
system call queues a signal to a single process specified by the
.Fa pid
argument.
.Pp
The
.Fn sigqueue
system call is implemented using
.Fn sigqueueinfo
and passing the appropriate information in the
.Fa info
argument.
.Pp
The
.Fn sigqueue
system call returns immediately.
If the resources were
available to queue the signal, the signal will be queued and sent to
the receiving process.
.Pp
If the value of
.Fa pid
causes
.Fa signo
to be generated for the sending process, and if
.Fa signo
is not blocked for the calling thread and if no other thread has
.Fa signo
unblocked or is waiting in a
.Fn sigwait
system call for
.Fa signo ,
either
.Fa signo
or at least the pending, unblocked signal will be delivered to the
calling thread before
.Fn sigqueue
returns.
Should any multiple pending signals in the range
.Dv SIGRTMIN
to
.Dv SIGRTMAX
be selected for delivery, it is the lowest numbered
one.
The selection order between realtime and non-realtime signals, or
between multiple pending non-realtime signals, is unspecified.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The
.Fn sigqueue
system call
will fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
No resources are available to queue the signal.
The process has already queued
.Brq Dv SIGQUEUE_MAX
signals that are still pending at the receiver(s),
or a system-wide resource limit has been exceeded.
.It Bq Er EEPERM
The process does not have the appropriate privilege to send the signal
to the receiving process.
.It Bq Er EINVAL
The value of the
.Fa signo
argument is an invalid or unsupported signal number.
.It Bq Er ESRCH
The process
.Fa pid
does not exist.
.El
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr siginfo 2 ,
.Xr sigpending 2 ,
.Xr sigsuspend 2 ,
.Xr sigtimedwait 2 ,
.Xr sigwait 2 ,
.Xr sigwaitinfo 2 ,
.Xr pause 3 ,
.Xr pthread_sigmask 3
.Sh STANDARDS
The
.Fn sigqueue
system call conforms to
.St -p1003.1-2004 .
.Sh HISTORY
Support for
.Tn POSIX
realtime signal queue first appeared in
.Nx 6.0 .