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.\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
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.\"
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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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2007-04-12 22:42:49 +00:00
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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.\" manual page may be incorrect or out-of-date.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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.\"
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.\" Created Sat Aug 21 1995 Thomas K. Dyas <tdyas@eden.rutgers.edu>
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.\" Modified Tue Oct 22 22:09:03 1996 by Eric S. Raymond <esr@thyrsus.com>
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.\" 2008-06-26, mtk, added some more detail on the work done by sigreturn()
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.\"
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2008-06-27 15:51:26 +00:00
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.TH SIGRETURN 2 2008-06-26 "Linux" "Linux Programmer's Manual"
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.SH NAME
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sigreturn \- return from signal handler and cleanup stack frame
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.SH SYNOPSIS
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.BI "int sigreturn(unsigned long " __unused );
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.SH DESCRIPTION
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When the Linux kernel creates the stack frame for a signal handler, a
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call to
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.BR sigreturn ()
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is inserted into the stack frame so that upon
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return from the signal handler,
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.BR sigreturn ()
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will be called.
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2008-07-02 13:43:42 +00:00
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This
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.BR sigreturn ()
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call undoes everything that was
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done\(emchanging the process's signal mask, switching stacks (see
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.BR sigaltstack "(2))\(emin "
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order to invoke the signal handler:
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it restores the process's signal mask, switches stacks,
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and restores the process's context (registers, processor flags),
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so that the process directly resumes execution
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at the point where it was interrupted by the signal.
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.SH "RETURN VALUE"
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.BR sigreturn ()
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never returns.
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.SH FILES
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/usr/src/linux/arch/i386/kernel/signal.c
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.br
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/usr/src/linux/arch/alpha/kernel/entry.S
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.SH "CONFORMING TO"
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.BR sigreturn ()
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is specific to Linux and should not be used in programs intended to be
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portable.
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.SH NOTES
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The
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.BR sigreturn ()
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call is used by the kernel to implement signal handlers.
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It should
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.B never
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be called directly.
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Better yet, the specific use of the
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.I __unused
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argument varies depending on the architecture.
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.SH "SEE ALSO"
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.BR kill (2),
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.BR sigaltstack (2),
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.BR signal (2),
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.BR signal (7)
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