mirror of https://github.com/mkerrisk/man-pages
73 lines
2.7 KiB
Groff
73 lines
2.7 KiB
Groff
.\" Written by Michael Haardt, Fri Nov 25 14:51:42 MET 1994
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, write to the Free
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.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
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.\" USA.
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.\"
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.\" Added siglongjmp, Sun Mar 2 22:03:05 EST 1997, jrv@vanzandt.mv.com
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.\" Modifications, Sun Feb 26 14:39:45 1995, faith@cs.unc.edu
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.\" "
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.TH LONGJMP 3 1997-03-02 "" "Library functions"
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.SH NAME
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longjmp, siglongjmp \- non-local jump to a saved stack context
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.SH SYNOPSIS
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.ad l
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.B #include <setjmp.h>
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.sp
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.nf
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.BI "void longjmp(jmp_buf " env ", int " val );
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.BI "void siglongjmp(sigjmp_buf " env ", int " val );
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.fi
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.ad b
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.SH DESCRIPTION
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\fBlongjmp\fP() and \fBsetjmp\fP(3) are useful for dealing with errors
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and interrupts encountered in a low-level subroutine of a program.
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\fBlongjmp\fP() restores the environment saved by the last call of
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\fBsetjmp\fP(3) with the corresponding \fIenv\fP argument.
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After
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\fBlongjmp\fP() is completed, program execution continues as if the
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corresponding call of \fBsetjmp\fP(3) had just returned the value
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\fIval\fP.
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\fBlongjmp\fP() cannot cause 0 to be returned.
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If \fBlongjmp\fP()
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is invoked with a second argument of 0, 1 will be returned instead.
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.P
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\fBsiglongjmp\fP() is similar to \fBlongjmp\fP() except for the type of
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its \fIenv\fP argument.
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If the \fBsigsetjmp\fP(3) call that set this
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\fIenv\fP used a non-zero \fIsavesigs\fP flag, \fBsiglongjmp\fP() also
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restores the set of blocked signals.
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.SH "RETURN VALUE"
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These functions never return.
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.SH "CONFORMING TO"
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C89, C99, and POSIX.1-2001 specify \fBlongjmp\fP().
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POSIX.1-2001 specifies \fBsiglongjmp\fP().
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.SH NOTES
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POSIX does not specify whether \fBlongjmp\fP() will restore the signal
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context.
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If you want to save and restore signal masks, use
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\fBsiglongjmp\fP().
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.P
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\fBlongjmp\fP() and \fBsiglongjmp\fP() make programs hard to
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understand and maintain.
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If possible an alternative should be used.
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.SH "SEE ALSO"
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.BR setjmp (3),
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.BR sigsetjmp (3)
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