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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:40:15 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:40:15 +0000 |
commit | 399644e47874bff147afb19c89228901ac39340e (patch) | |
tree | 1c4c0b733f4c16b5783b41bebb19194a9ef62ad1 /man3/sem_getvalue.3 | |
parent | Initial commit. (diff) | |
download | manpages-399644e47874bff147afb19c89228901ac39340e.tar.xz manpages-399644e47874bff147afb19c89228901ac39340e.zip |
Adding upstream version 6.05.01.upstream/6.05.01
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'man3/sem_getvalue.3')
-rw-r--r-- | man3/sem_getvalue.3 | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/man3/sem_getvalue.3 b/man3/sem_getvalue.3 new file mode 100644 index 0000000..6e529ba --- /dev/null +++ b/man3/sem_getvalue.3 @@ -0,0 +1,75 @@ +'\" t +.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH sem_getvalue 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +sem_getvalue \- get the value of a semaphore +.SH LIBRARY +POSIX threads library +.RI ( libpthread ", " \-lpthread ) +.SH SYNOPSIS +.nf +.B #include <semaphore.h> +.PP +.BI "int sem_getvalue(sem_t *restrict " sem ", int *restrict " sval ); +.fi +.SH DESCRIPTION +.BR sem_getvalue () +places the current value of the semaphore pointed to +.I sem +into the integer pointed to by +.IR sval . +.PP +If one or more processes or threads are blocked +waiting to lock the semaphore with +.BR sem_wait (3), +POSIX.1 permits two possibilities for the value returned in +.IR sval : +either 0 is returned; +or a negative number whose absolute value is the count +of the number of processes and threads currently blocked in +.BR sem_wait (3). +Linux adopts the former behavior. +.SH RETURN VALUE +.BR sem_getvalue () +returns 0 on success; +on error, \-1 is returned and +.I errno +is set to indicate the error. +.SH ERRORS +.TP +.B EINVAL +.I sem +is not a valid semaphore. +(The glibc implementation currently does not check whether +.I sem +is valid.) +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR sem_getvalue () +T} Thread safety MT-Safe +.TE +.sp 1 +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001. +.SH NOTES +The value of the semaphore may already have changed by the time +.BR sem_getvalue () +returns. +.SH SEE ALSO +.BR sem_post (3), +.BR sem_wait (3), +.BR sem_overview (7) |