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88 lines
1.6 KiB
Groff
88 lines
1.6 KiB
Groff
.TH SETJMP 3
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.SH NAME
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setjmp, longjmp, notejmp \- non-local goto
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.ta \w'\fLvoid 'u
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.B
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int setjmp(jmp_buf env)
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.PP
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.B
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void longjmp(jmp_buf env, int val)
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.PP
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.B
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void notejmp(void *uregs, jmp_buf env, int val)
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.SH DESCRIPTION
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These routines are useful for dealing with errors
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and interrupts encountered in
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a low-level subroutine of a program.
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.PP
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.I Setjmp
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saves its stack environment in
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.I env
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for later use by
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.IR longjmp .
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It returns value 0.
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.PP
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.I Longjmp
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restores the environment saved by the last call of
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.IR setjmp .
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It then causes execution to
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continue as if the call of
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.I setjmp
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had just returned with value
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.IR val .
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The invoker of
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.I setjmp
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must not itself have returned in the interim.
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All accessible data have values as of the time
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.I longjmp
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was called.
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.PP
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.I Notejmp
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is the same as
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.I longjmp
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except that it is to be called from within a note handler (see
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.MR notify (3) ).
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The
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.I uregs
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argument should be the first argument passed to the note handler.
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.PP
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.I Setjmp
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and
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.I longjmp
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can also be used to switch stacks.
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.SH SOURCE
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.B \*9/src/lib9/jmp.c
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.SH SEE ALSO
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.MR notify (3)
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.SH BUGS
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.PP
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.I Notejmp
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cannot recover from an address trap or bus error (page fault) on the 680x0
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architectures.
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.PP
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To avoid name conflicts with the underlying system,
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.IR setjmp ,
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.IR longjmp ,
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.IR notejmp ,
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and
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.I jmp_buf
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are preprocessor macros defined as
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.IR p9setjmp ,
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.IR p9longjmp ,
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.IR p9notejmp ,
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and
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.IR p9jmp_buf ;
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see
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.MR intro (3) .
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.PP
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.I P9setjmp
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is implemented as a preprocessor macro that calls
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.I sigsetjmp
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(see
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Unix's
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.IR setjmp (3)).
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