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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-24 04:52:22 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-24 04:52:22 +0000 |
commit | 3d08cd331c1adcf0d917392f7e527b3f00511748 (patch) | |
tree | 312f0d1e1632f48862f044b8bb87e602dcffb5f9 /man/man3/sem_open.3 | |
parent | Adding debian version 6.7-2. (diff) | |
download | manpages-3d08cd331c1adcf0d917392f7e527b3f00511748.tar.xz manpages-3d08cd331c1adcf0d917392f7e527b3f00511748.zip |
Merging upstream version 6.8.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'man/man3/sem_open.3')
-rw-r--r-- | man/man3/sem_open.3 | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/man/man3/sem_open.3 b/man/man3/sem_open.3 new file mode 100644 index 0000000..0f29dcf --- /dev/null +++ b/man/man3/sem_open.3 @@ -0,0 +1,175 @@ +'\" t +.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH sem_open 3 2024-05-02 "Linux man-pages (unreleased)" +.SH NAME +sem_open \- initialize and open a named semaphore +.SH LIBRARY +POSIX threads library +.RI ( libpthread ", " \-lpthread ) +.SH SYNOPSIS +.nf +.BR "#include <fcntl.h>" " /* For O_* constants */" +.BR "#include <sys/stat.h>" " /* For mode constants */" +.B #include <semaphore.h> +.P +.BI "sem_t *sem_open(const char *" name ", int " oflag ); +.BI "sem_t *sem_open(const char *" name ", int " oflag , +.BI " mode_t " mode ", unsigned int " value ); +.fi +.SH DESCRIPTION +.BR sem_open () +creates a new POSIX semaphore or opens an existing semaphore. +The semaphore is identified by +.IR name . +For details of the construction of +.IR name , +see +.BR sem_overview (7). +.P +The +.I oflag +argument specifies flags that control the operation of the call. +(Definitions of the flags values can be obtained by including +.IR <fcntl.h> .) +If +.B O_CREAT +is specified in +.IR oflag , +then the semaphore is created if +it does not already exist. +The owner (user ID) of the semaphore is set to the effective +user ID of the calling process. +The group ownership (group ID) is set to the effective group ID +of the calling process. +.\" In reality the filesystem IDs are used on Linux. +If both +.B O_CREAT +and +.B O_EXCL +are specified in +.IR oflag , +then an error is returned if a semaphore with the given +.I name +already exists. +.P +If +.B O_CREAT +is specified in +.IR oflag , +then two additional arguments must be supplied. +The +.I mode +argument specifies the permissions to be placed on the new semaphore, +as for +.BR open (2). +(Symbolic definitions for the permissions bits can be obtained by including +.IR <sys/stat.h> .) +The permissions settings are masked against the process umask. +Both read and write permission should be granted to each class of +user that will access the semaphore. +The +.I value +argument specifies the initial value for the new semaphore. +If +.B O_CREAT +is specified, and a semaphore with the given +.I name +already exists, then +.I mode +and +.I value +are ignored. +.SH RETURN VALUE +On success, +.BR sem_open () +returns the address of the new semaphore; +this address is used when calling other semaphore-related functions. +On error, +.BR sem_open () +returns +.BR SEM_FAILED , +with +.I errno +set to indicate the error. +.SH ERRORS +.TP +.B EACCES +The semaphore exists, but the caller does not have permission to +open it. +.TP +.B EEXIST +Both +.B O_CREAT +and +.B O_EXCL +were specified in +.IR oflag , +but a semaphore with this +.I name +already exists. +.TP +.B EINVAL +.I value +was greater than +.BR SEM_VALUE_MAX . +.TP +.B EINVAL +.I name +consists of just "/", followed by no other characters. +.TP +.B EMFILE +The per-process limit on the number of open file descriptors has been reached. +.TP +.B ENAMETOOLONG +.I name +was too long. +.TP +.B ENFILE +The system-wide limit on the total number of open files has been reached. +.TP +.B ENOENT +The +.B O_CREAT +flag was not specified in +.I oflag +and no semaphore with this +.I name +exists; +or, +.\" this error can occur if we have a name of the (nonportable) form +.\" /dir/name, and the directory /dev/shm/dir does not exist. +.B O_CREAT +was specified, but +.I name +wasn't well formed. +.TP +.B ENOMEM +Insufficient memory. +.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_open () +T} Thread safety MT-Safe +.TE +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001. +.SH SEE ALSO +.BR sem_close (3), +.BR sem_getvalue (3), +.BR sem_post (3), +.BR sem_unlink (3), +.BR sem_wait (3), +.BR sem_overview (7) |