man3/pthread_mutexattr_getpshared.3

   1 .\" Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .TH PTHREAD_MUTEXATTR_GETPSHARED 3 2021-03-22 "Linux man-pages (unreleased)"
   6 .SH NAME
   7 pthread_mutexattr_getpshared, pthread_mutexattr_setpshared \- get/set
   8 process-shared mutex attribute
   9 .SH LIBRARY
  10 POSIX threads library
  11 .RI ( libpthread ", " \-lpthread )
  12 .SH SYNOPSIS
  13 .nf
  14 .B #include <pthread.h>
  15 .PP
  16 .B int pthread_mutexattr_getpshared(
  17 .BI "                      const pthread_mutexattr_t *restrict " attr ,
  18 .BI "                      int *restrict " pshared );
  19 .BI "int pthread_mutexattr_setpshared(pthread_mutexattr_t *" attr ,
  20 .BI "                      int " pshared );
  21 .fi
  22 .SH DESCRIPTION
  23 These functions get and set the process-shared attribute
  24 in a mutex attributes object.
  25 This attribute must be appropriately set to ensure correct,
  26 efficient operation of a mutex created using this attributes object.
  27 .PP
  28 The process-shared attribute can have one of the following values:
  29 .TP
  30 .B PTHREAD_PROCESS_PRIVATE
  31 Mutexes created with this attributes object are to be shared
  32 only among threads in the same process that initialized the mutex.
  33 This is the default value for the process-shared mutex attribute.
  34 .TP
  35 .B PTHREAD_PROCESS_SHARED
  36 Mutexes created with this attributes object can be shared between
  37 any threads that have access to the memory containing the object,
  38 including threads in different processes.
  39 .PP
  40 .BR pthread_mutexattr_getpshared ()
  41 places the value of the process-shared attribute of
  42 the mutex attributes object referred to by
  43 .I attr
  44 in the location pointed to by
  45 .IR pshared .
  46 .PP
  47 .BR pthread_mutexattr_setpshared ()
  48 sets the value of the process-shared attribute of
  49 the mutex attributes object referred to by
  50 .I attr
  51 to the value specified in
  52 .BR pshared .
  53 .PP
  54 If
  55 .I attr
  56 does not refer to an initialized mutex attributes object,
  57 the behavior is undefined.
  58 .SH RETURN VALUE
  59 On success, these functions return 0.
  60 On error, they return a positive error number.
  61 .SH ERRORS
  62 .BR pthread_mutexattr_setpshared ()
  63 can fail with the following errors:
  64 .TP
  65 .B EINVAL
  66 The value specified in
  67 .I pshared
  68 is invalid.
  69 .TP
  70 .B ENOTSUP
  71 .I pshared is
  72 .B PTHREAD_PROCESS_SHARED
  73 but the implementation does not support process-shared mutexes.
  74 .SH STANDARDS
  75 POSIX.1-2001, POSIX.1-2008.
  76 .SH SEE ALSO
  77 .ad l
  78 .nh
  79 .BR pthread_mutexattr_init (3),
  80 .BR pthreads (7)