diff options
Diffstat (limited to 'lib/libc/gen/sem_timedwait.3')
| -rw-r--r-- | lib/libc/gen/sem_timedwait.3 | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/lib/libc/gen/sem_timedwait.3 b/lib/libc/gen/sem_timedwait.3 new file mode 100644 index 000000000000..9481c90802d7 --- /dev/null +++ b/lib/libc/gen/sem_timedwait.3 @@ -0,0 +1,122 @@ +.\" Copyright (c) 2008, David Xu <davidxu@freebsd.org> +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" Portions of this text are reprinted and reproduced in electronic form +.\" from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- +.\" Portable Operating System Interface (POSIX), The Open Group Base +.\" Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of +.\" Electrical and Electronics Engineers, Inc and The Open Group. In the +.\" event of any discrepancy between this version and the original IEEE and +.\" The Open Group Standard, the original IEEE and The Open Group Standard is +.\" the referee document. The original Standard can be obtained online at +.\" http://www.opengroup.org/unix/online.html. +.\" +.\" $FreeBSD$ +.\" +.Dd March 3, 2008 +.Dt SEM_TIMEDWAIT 3 +.Os +.Sh NAME +.Nm sem_timedwait +.Nd "lock a semaphore" +.Sh LIBRARY +.Lb libpthread +.Sh SYNOPSIS +.In semaphore.h +.Ft int +.Fn sem_timedwait "sem_t *sem" "const struct timespec *abs_timeout" +.Sh DESCRIPTION +The +.Fn sem_timedwait +function locks the semaphore referenced by +.Fa sem , +as in the +.Xr sem_wait 3 +function. +However, if the semaphore cannot be locked without waiting for +another process or thread to unlock the semaphore by performing +a +.Xr sem_post 3 +function, this wait will be terminated when the specified timeout expires. +.Pp +The timeout will expire when the absolute time specified by +.Fa abs_timeout +passes, as measured by the clock on which timeouts are based (that is, +when the value of that clock equals or exceeds +.Fa abs_timeout ) , +or if the +absolute time specified by +.Fa abs_timeout +has already been passed at the time of the call. +.Pp +Note that the timeout is based on the +.Dv CLOCK_REALTIME +clock. +.Pp +The validity of the +.Fa abs_timeout +is not checked if the semaphore can be locked immediately. +.Sh RETURN VALUES +The +.Fn sem_timedwait +function returns zero if the calling process successfully performed the +semaphore lock operation on the semaphore designated by +.Fa sem . +If the call was unsuccessful, the state of the semaphore is unchanged, +and the function returns a value of \-1 and sets the global variable +.Va errno +to indicate the error. +.Sh ERRORS +The +.Fn sem_timedwait +function will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +The +.Fa sem +argument does not refer to a valid semaphore, or the process or thread would +have blocked, and the +.Fa abs_timeout +parameter specified a nanoseconds field value less than zero or greater than +or equal to 1000 million. +.It Bq Er ETIMEDOUT +The semaphore could not be locked before the specified timeout expired. +.It Bq Er EINTR +A signal interrupted this function. +.El +.Sh SEE ALSO +.Xr semctl 2 , +.Xr semget 2 , +.Xr semop 2 +.Xr sem_post 3 , +.Xr sem_trywait 3 , +.Xr sem_wait 3 +.Sh STANDARDS +The +.Fn sem_timedwait +function conforms to +.St -p1003.1-2004 . +.Sh HISTORY +The function first appeared in +.Fx 5.0 . |