man3/sem_destroy.3

   1 .\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .TH SEM_DESTROY 3 2021-03-22 "Linux man-pages (unreleased)"
   6 .SH NAME
   7 sem_destroy \- destroy an unnamed semaphore
   8 .SH LIBRARY
   9 POSIX threads library
  10 .RI ( libpthread ", " \-lpthread )
  11 .SH SYNOPSIS
  12 .nf
  13 .B #include <semaphore.h>
  14 .PP
  15 .BI "int sem_destroy(sem_t *" sem );
  16 .fi
  17 .SH DESCRIPTION
  18 .BR sem_destroy ()
  19 destroys the unnamed semaphore at the address pointed to by
  20 .IR sem .
  21 .PP
  22 Only a semaphore that has been initialized by
  23 .BR sem_init (3)
  24 should be destroyed using
  25 .BR sem_destroy ().
  26 .PP
  27 Destroying a semaphore that other processes or threads are
  28 currently blocked on (in
  29 .BR sem_wait (3))
  30 produces undefined behavior.
  31 .PP
  32 Using a semaphore that has been destroyed produces undefined results,
  33 until the semaphore has been reinitialized using
  34 .BR sem_init (3).
  35 .SH RETURN VALUE
  36 .BR sem_destroy ()
  37 returns 0 on success;
  38 on error, \-1 is returned, and
  39 .I errno
  40 is set to indicate the error.
  41 .SH ERRORS
  42 .TP
  43 .B EINVAL
  44 .I sem
  45 is not a valid semaphore.
  46 .SH ATTRIBUTES
  47 For an explanation of the terms used in this section, see
  48 .BR attributes (7).
  49 .ad l
  50 .nh
  51 .TS
  52 allbox;
  53 lbx lb lb
  54 l l l.
  55 Interface       Attribute       Value
  56 T{
  57 .BR sem_destroy ()
  58 T}      Thread safety   MT-Safe
  59 .TE
  60 .hy
  61 .ad
  62 .sp 1
  63 .SH STANDARDS
  64 POSIX.1-2001, POSIX.1-2008.
  65 .SH NOTES
  66 An unnamed semaphore should be destroyed with
  67 .BR sem_destroy ()
  68 before the memory in which it is located is deallocated.
  69 Failure to do this can result in resource leaks on some implementations.
  70 .\" But not on NPTL, where sem_destroy () is a no-op..
  71 .SH SEE ALSO
  72 .BR sem_init (3),
  73 .BR sem_post (3),
  74 .BR sem_wait (3),
  75 .BR sem_overview (7)