mirror of https://github.com/mkerrisk/man-pages
148 lines
4.0 KiB
Groff
148 lines
4.0 KiB
Groff
.\" Copyright (c) 2005 Michael Kerrisk
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.\" based on earlier work by faith@cs.unc.edu and
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.\" Mike Battersby <mib@deakin.edu.au>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
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.\"
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.TH SIGSUSPEND 2 2019-03-06 "Linux" "Linux Programmer's Manual"
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.SH NAME
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sigsuspend, rt_sigsuspend \- wait for a signal
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.SH SYNOPSIS
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.nf
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.B #include <signal.h>
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.PP
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.BI "int sigsuspend(const sigset_t *" mask );
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.fi
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.PP
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.RS -4
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.RE
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.PP
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.BR sigsuspend ():
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.nf
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_POSIX_C_SOURCE
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.fi
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.SH DESCRIPTION
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.BR sigsuspend ()
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temporarily replaces the signal mask of the calling thread with the
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mask given by
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.I mask
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and then suspends the thread until delivery of a signal whose
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action is to invoke a signal handler or to terminate a process.
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.PP
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If the signal terminates the process, then
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.BR sigsuspend ()
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does not return.
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If the signal is caught, then
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.BR sigsuspend ()
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returns after the signal handler returns,
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and the signal mask is restored to the state before the call to
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.BR sigsuspend ().
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.PP
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It is not possible to block
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.B SIGKILL
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or
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.BR SIGSTOP ;
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specifying these signals in
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.IR mask ,
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has no effect on the thread's signal mask.
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.SH RETURN VALUE
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.BR sigsuspend ()
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always returns \-1, with
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.I errno
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set to indicate the error (normally,
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.BR EINTR ).
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.SH ERRORS
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.TP
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.B EFAULT
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.I mask
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points to memory which is not a valid part of the process address space.
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.TP
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.B EINTR
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The call was interrupted by a signal;
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.BR signal (7).
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008.
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.SH NOTES
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Normally,
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.BR sigsuspend ()
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is used in conjunction with
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.BR sigprocmask (2)
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in order to prevent delivery of a signal during the execution of a
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critical code section.
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The caller first blocks the signals with
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.BR sigprocmask (2).
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When the critical code has completed, the caller then waits for the
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signals by calling
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.BR sigsuspend ()
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with the signal mask that was returned by
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.BR sigprocmask (2)
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(in the
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.I oldset
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argument).
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.PP
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See
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.BR sigsetops (3)
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for details on manipulating signal sets.
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.\"
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.SS C library/kernel differences
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The original Linux system call was named
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.BR sigsuspend ().
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However, with the addition of real-time signals in Linux 2.2,
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the fixed-size, 32-bit
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.IR sigset_t
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type supported by that system call was no longer fit for purpose.
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Consequently, a new system call,
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.BR rt_sigsuspend (),
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was added to support an enlarged
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.IR sigset_t
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type.
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The new system call takes a second argument,
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.IR "size_t sigsetsize" ,
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which specifies the size in bytes of the signal set in
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.IR mask .
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This argument is currently required to have the value
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.IR sizeof(sigset_t)
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(or the error
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.B EINVAL
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results).
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The glibc
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.BR sigsuspend ()
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wrapper function hides these details from us, transparently calling
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.BR rt_sigsuspend ()
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when the kernel provides it.
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.\"
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.SH SEE ALSO
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.BR kill (2),
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.BR pause (2),
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.BR sigaction (2),
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.BR signal (2),
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.BR sigprocmask (2),
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.BR sigwaitinfo (2),
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.BR sigsetops (3),
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.BR sigwait (3),
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.BR signal (7)
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