94 lines
3.1 KiB
Groff
94 lines
3.1 KiB
Groff
.\" Copyright (c) 1985, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)sigreturn.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd June 4, 1993
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.Dt SIGRETURN 2
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.Os
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.Sh NAME
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.Nm sigreturn
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.Nd return from signal
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In signal.h
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.Ft int
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.Fn sigreturn "const ucontext_t *scp"
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.Sh DESCRIPTION
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The
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.Fn sigreturn
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system call
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allows users to atomically unmask, switch stacks,
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and return from a signal context.
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The processes signal mask and stack status are
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restored from the context structure pointed to by
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.Fa scp .
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The system call does not return;
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the users stack pointer, frame pointer, argument pointer,
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and processor status longword are restored from the context.
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Execution resumes at the specified pc.
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This system call is used by the trampoline code and
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.Xr longjmp 3
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when returning from a signal to the previously executing program.
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.Sh NOTES
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This system call is not available in
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.Bx 4.2
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hence it should not be used if backward compatibility is needed.
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.Sh RETURN VALUES
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If successful, the system call does not return.
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Otherwise, a value of -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn sigreturn
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system call
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will fail and the process context will remain unchanged
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if one of the following occurs.
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.Bl -tag -width Er
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.It Bq Er EFAULT
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The
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.Fa scp
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argument
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points to memory that is not a valid part of the process
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address space.
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.It Bq Er EINVAL
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The process status longword is invalid or would improperly
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raise the privilege level of the process.
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.El
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.Sh SEE ALSO
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.Xr sigvec 2 ,
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.Xr setjmp 3 ,
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.Xr ucontext 3
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.Sh HISTORY
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The
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.Fn sigreturn
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system call appeared in
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.Bx 4.3 .
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