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Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html. 6 .\" This notice shall appear on any product containing this material. 7 .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). 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If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] 10 .TH GETCONTEXT 2 "Feb 5, 2001" 11 .SH NAME 12 getcontext, setcontext \- get and set current user context 13 .SH SYNOPSIS 14 .LP 15 .nf 16 #include <ucontext.h> 17 18 \fBint\fR \fBgetcontext\fR(\fBucontext_t *\fR\fIucp\fR); 19 .fi 20 21 .LP 22 .nf 23 \fBint\fR \fBsetcontext\fR(\fBconst ucontext_t *\fR\fIucp\fR); 24 .fi 25 26 .SH DESCRIPTION 27 .sp 28 .LP 29 The \fBgetcontext()\fR function initializes the structure pointed to by 30 \fIucp\fR to the current user context of the calling process. The 31 \fBucontext_t\fR type that \fIucp\fR points to defines the user context and 32 includes the contents of the calling process' machine registers, the signal 33 mask, and the current execution stack. 34 .sp 35 .LP 36 The \fBsetcontext()\fR function restores the user context pointed to by 37 \fIucp\fR. A successful call to \fBsetcontext()\fR does not return; program 38 execution resumes at the point specified by the \fIucp\fR argument passed to 39 \fBsetcontext()\fR. The \fIucp\fR argument should be created either by a prior 40 call to \fBgetcontext()\fR, or by being passed as an argument to a signal 41 handler. If the \fIucp\fR argument was created with \fBgetcontext()\fR, program 42 execution continues as if the corresponding call of \fBgetcontext()\fR had just 43 returned. If the \fIucp\fR argument was created with \fBmakecontext\fR(3C), 44 program execution continues with the function passed to \fBmakecontext\fR(3C). 45 When that function returns, the process continues as if after a call to 46 \fBsetcontext()\fR with the \fIucp\fR argument that was input to 47 \fBmakecontext\fR(3C). If the \fIucp\fR argument was passed to a signal 48 handler, program execution continues with the program instruction following the 49 instruction interrupted by the signal. If the \fBuc_link\fR member of the 50 \fBucontext_t\fR structure pointed to by the \fIucp\fR argument is equal to 0, 51 then this context is the main context, and the process will exit when this 52 context returns. The effects of passing a \fIucp\fR argument obtained from any 53 other source are unspecified. 54 .SH RETURN VALUES 55 .sp 56 .LP 57 On successful completion, \fBsetcontext()\fR does not return and 58 \fBgetcontext()\fR returns \fB0\fR. Otherwise, \fB\(mi1\fR is returned. 59 .SH ERRORS 60 .sp 61 .LP 62 No errors are defined. 63 .SH USAGE 64 .sp 65 .LP 66 When a signal handler is executed, the current user context is saved and a new 67 context is created. If the thread leaves the signal handler via 68 \fBlongjmp\fR(3UCB), then it is unspecified whether the context at the time of 69 the corresponding \fBsetjmp\fR(3UCB) call is restored and thus whether future 70 calls to \fBgetcontext()\fR will provide an accurate representation of the 71 current context, since the context restored by \fBlongjmp\fR(3UCB) may not 72 contain all the information that \fBsetcontext()\fR requires. Signal handlers 73 should use \fBsiglongjmp\fR(3C) instead. 74 .sp 75 .LP 76 Portable applications should not modify or access the \fBuc_mcontext\fR member 77 of \fBucontext_t\fR. A portable application cannot assume that context 78 includes any process-wide static data, possibly including \fBerrno\fR. Users 79 manipulating contexts should take care to handle these explicitly when 80 required. 81 .SH ATTRIBUTES 82 .sp 83 .LP 84 See \fBattributes\fR(5) for descriptions of the following attributes: 85 .sp 86 87 .sp 88 .TS 89 box; 90 c | c 91 l | l . 92 ATTRIBUTE TYPE ATTRIBUTE VALUE 93 _ 94 Interface Stability Standard 95 .TE 96 97 .SH SEE ALSO 98 .sp 99 .LP 100 \fBsigaction\fR(2), \fBsigaltstack\fR(2), \fBsigprocmask\fR(2), 101 \fBbsd_signal\fR(3C), \fBmakecontext\fR(3C), \fBsetjmp\fR(3UCB), 102 \fBsigsetjmp\fR(3C), \fBucontext.h\fR(3HEAD), \fBattributes\fR(5), 103 \fBstandards\fR(5)