2003-02-08 11:10:59 +01:00
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.\" Manual page created with latex2man on Sat Feb 8 01:31:56 PST 2003
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.\" NOTE: This file is generated, DO NOT EDIT.
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.de Vb
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.ft CW
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.nf
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..
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.de Ve
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.ft R
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.fi
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..
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.TH "LIBUNWIND\-SETJMP" "3" "08 February 2003" "Programming Library " "Programming Library "
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.SH NAME
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libunwind\-setjmp \-\- libunwind\-based non\-local gotos
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.PP
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.SH SYNOPSIS
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.PP
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#include <setjmp.h>
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.br
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.PP
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int
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setjmp(jmp_buf env);
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.br
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void
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longjmp(jmp_buf env,
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int val);
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.br
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int
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_setjmp(jmp_buf env);
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.br
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void
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_longjmp(jmp_buf env,
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int val);
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.br
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int
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setjmp(sigjmp_buf env,
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int savemask);
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.br
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void
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siglongjmp(sigjmp_buf env,
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int val);
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.br
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.PP
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.SH DESCRIPTION
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.PP
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The unwind\-setjmp
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library offers a libunwind\-based
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implementation of non\-local gotos. This implementation is intended to
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be a drop\-in replacement for the normal, system\-provided routines of
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the same name. The main advantage of using the unwind\-setjmp
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library is that setting up a non\-local goto via one of the
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setjmp()
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routines is very fast. Typically, just 2 or 3 words
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need to be saved in the jump\-buffer (plus one call to
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sigprocmask(2),
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in the case of sigsetjmp).
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On the
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other hand, executing a non\-local goto by calling one of the
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longjmp()
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routines tends to be much slower than with the
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system\-provided routines. In fact, the time spent on a
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longjmp()
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will be proportional to the number of call frames
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that exist between the points where setjmp()
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and
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longjmp()
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were called. For this reason, the
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unwind\-setjmp
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library is beneficial primarily in applications
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that frequently call setjmp()
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but only rarely call
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longjmp().
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.PP
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.SH CAVEATS
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.PP
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.TP
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.B *
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The correct operation of this library depends on the presence of
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correct unwind information. On newer platforms, this is rarely an
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issue. On older platforms, care needs to be taken to
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ensure that each of the functions whose stack frames may have to be
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unwound during a longjmp()
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have correct unwind information
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(on those platforms, there is usually a compiler\-switch, such as
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\fB\-funwind\-tables\fP,
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to request the generation of unwind
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information).
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.TP
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.B *
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The contents of jmp_buf and sigjmp_buf as setup
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and used by these routines is completely different from the ones
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used by the system\-provided routines. Thus, a jump\-buffer created
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by the libunwind\-based setjmp()/_setjmp
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may only be
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used in a call to the libunwind\-based
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longjmp()/_longjmp().
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The analogous applies for
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sigjmp_buf
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with sigsetjmp()
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and siglongjmp().
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.PP
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.SH FILES
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.PP
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.TP
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\fB\-l\fPunwind\-setjmp
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The library an application should
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be linked against to ensure it uses the libunwind\-based non\-local
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goto routines.
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.PP
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.SH SEE ALSO
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.PP
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libunwind(3),
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setjmp(3), longjmp(3),
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_setjmp(3), _longjmp(3),
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sigsetjmp(3), siglongjmp(3)
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.PP
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.SH AUTHOR
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.PP
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David Mosberger\-Tang
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.br
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Hewlett\-Packard Labs
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.br
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Palo\-Alto, CA 94304
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.br
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Email: \fBdavidm@hpl.hp.com\fP
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.br
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WWW: \fBhttp://www.hpl.hp.com/research/linux/libunwind/\fP\&.
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.\" NOTE: This file is generated, DO NOT EDIT.
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