1 .TH SETJMP 3
2 .SH NAME
3 setjmp, longjmp, notejmp \- non-local goto
4 .SH SYNOPSIS
5 .B #include <u.h>
6 .br
7 .B #include <libc.h>
8 .PP
9 .ta \w'\fLvoid 'u
10 .B
11 int	setjmp(jmp_buf env)
12 .PP
13 .B
14 void	longjmp(jmp_buf env, int val)
15 .PP
16 .B
17 void	notejmp(void *uregs, jmp_buf env, int val)
18 .SH DESCRIPTION
19 These routines are useful for dealing with errors
20 and interrupts encountered in
21 a low-level subroutine of a program.
22 .PP
23 .I Setjmp
24 saves its stack environment in
25 .I env
26 for later use by
27 .IR longjmp .
28 It returns value 0.
29 .PP
30 .I Longjmp
31 restores the environment saved by the last call of
32 .IR setjmp .
33 It then causes execution to
34 continue as if the call of
35 .I setjmp
36 had just returned with value
37 .IR val .
38 The invoker of
39 .I setjmp
40 must not itself have returned in the interim.
41 All accessible data have values as of the time
42 .I longjmp
43 was called.
44 .PP
45 .I Notejmp
46 is the same as
47 .I longjmp
48 except that it is to be called from within a note handler (see
49 .MR notify (3) ).
50 The
51 .I uregs
52 argument should be the first argument passed to the note handler.
53 .PP
54 .I Setjmp
55 and
56 .I longjmp
57 can also be used to switch stacks.
58 .SH SOURCE
59 .B \*9/src/lib9/jmp.c
60 .SH SEE ALSO
61 .MR notify (3)
62 .SH BUGS
63 .PP
64 .I Notejmp
65 cannot recover from an address trap or bus error (page fault) on the 680x0
66 architectures.
67 .PP
68 To avoid name conflicts with the underlying system,
69 .IR setjmp ,
70 .IR longjmp ,
71 .IR notejmp ,
72 and
73 .I jmp_buf
74 are preprocessor macros defined as
75 .IR p9setjmp ,
76 .IR p9longjmp ,
77 .IR p9notejmp ,
78 and
79 .IR p9jmp_buf ;
80 see
81 .MR intro (3) .
82 .PP
83 .I P9setjmp
84 is implemented as a preprocessor macro that calls
85 .I sigsetjmp
86 (see
87 Unix's
88 .IR setjmp (3)).