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diff --git a/man3p/makecontext.3p b/man3p/makecontext.3p new file mode 100644 index 000000000..f7cd844d6 --- /dev/null +++ b/man3p/makecontext.3p @@ -0,0 +1,142 @@ +.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved +.TH "MAKECONTEXT" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" makecontext +.SH NAME +makecontext, swapcontext \- manipulate user contexts +.SH SYNOPSIS +.LP +\fB#include <ucontext.h> +.br +.sp +void makecontext(ucontext_t *\fP\fIucp\fP\fB, void (*\fP\fIfunc\fP\fB)(void), +.br +\ \ \ \ \ \ int\fP \fIargc\fP\fB, ...); +.br +int swapcontext(ucontext_t *restrict\fP \fIoucp\fP\fB, +.br +\ \ \ \ \ \ const ucontext_t *restrict\fP \fIucp\fP\fB); \fP +\fB +.br +\fP +.SH DESCRIPTION +.LP +The \fImakecontext\fP() function shall modify the context specified +by \fIucp\fP, which has been initialized using \fIgetcontext\fP(). +When this context is resumed using \fIswapcontext\fP() or \fIsetcontext\fP(), +program execution shall continue by calling \fIfunc\fP, passing it +the +arguments that follow \fIargc\fP in the \fImakecontext\fP() call. +.LP +Before a call is made to \fImakecontext\fP(), the application shall +ensure that the context being modified has a stack +allocated for it. The application shall ensure that the value of \fIargc\fP +matches the number of arguments of type \fBint\fP +passed to \fIfunc\fP; otherwise, the behavior is undefined. +.LP +The \fIuc_link\fP member is used to determine the context that shall +be resumed when the context being modified by +\fImakecontext\fP() returns. The application shall ensure that the +\fIuc_link\fP member is initialized prior to the call to +\fImakecontext\fP(). +.LP +The \fIswapcontext\fP() function shall save the current context in +the context structure pointed to by \fIoucp\fP and shall +set the context to the context structure pointed to by \fIucp\fP. +.SH RETURN VALUE +.LP +Upon successful completion, \fIswapcontext\fP() shall return 0. Otherwise, +-1 shall be returned and \fIerrno\fP set to +indicate the error. +.SH ERRORS +.LP +The \fIswapcontext\fP() function shall fail if: +.TP 7 +.B ENOMEM +The \fIucp\fP argument does not have enough stack left to complete +the operation. +.sp +.LP +\fIThe following sections are informative.\fP +.SH EXAMPLES +.LP +The following example illustrates the use of \fImakecontext\fP(): +.sp +.RS +.nf + +\fB#include <stdio.h> +#include <ucontext.h> +.sp + +static ucontext_t ctx[3]; +.sp + +static void +f1 (void) +{ + puts("start f1"); + swapcontext(&ctx[1], &ctx[2]); + puts("finish f1"); +} +.sp + +static void +f2 (void) +{ + puts("start f2"); + swapcontext(&ctx[2], &ctx[1]); + puts("finish f2"); +} +.sp + +int +main (void) +{ + char st1[8192]; + char st2[8192]; +.sp + + getcontext(&ctx[1]); + ctx[1].uc_stack.ss_sp = st1; + ctx[1].uc_stack.ss_size = sizeof st1; + ctx[1].uc_link = &ctx[0]; + makecontext(&ctx[1], f1, 0); +.sp + + getcontext(&ctx[2]); + ctx[2].uc_stack.ss_sp = st2; + ctx[2].uc_stack.ss_size = sizeof st2; + ctx[2].uc_link = &ctx[1]; + makecontext(&ctx[2], f2, 0); +.sp + + swapcontext(&ctx[0], &ctx[2]); + return 0; +} +\fP +.fi +.RE +.SH APPLICATION USAGE +.LP +None. +.SH RATIONALE +.LP +None. +.SH FUTURE DIRECTIONS +.LP +None. +.SH SEE ALSO +.LP +\fIexit\fP() , \fIgetcontext\fP() , \fIsigaction\fP() , \fIsigprocmask\fP() +, the Base Definitions volume of +IEEE\ Std\ 1003.1-2001, \fI<ucontext.h>\fP +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. In the +event of any discrepancy between this version 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 . |