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-.TH GETCONTEXT 3 2009-03-15 "Linux" "Linux Programmer's Manual"
+.TH GETCONTEXT 3 2014-04-08 "Linux" "Linux Programmer's Manual"
.SH NAME
getcontext, setcontext \- get or set the user context
.SH SYNOPSIS
.BI "int setcontext(const ucontext_t *" ucp );
.SH DESCRIPTION
In a System V-like environment, one has the two types
-\fImcontext_t\fP and \fIucontext_t\fP defined in
+.I mcontext_t
+and
+.I ucontext_t
+defined in
.I <ucontext.h>
and the four functions
.BR getcontext (),
.BR setcontext (),
-.BR makecontext (3)
+.BR makecontext (3),
and
.BR swapcontext (3)
that allow user-level context switching between multiple
threads of control within a process.
.LP
-The \fImcontext_t\fP type is machine-dependent and opaque.
-The \fIucontext_t\fP type is a structure that has at least
+The
+.I mcontext_t
+type is machine-dependent and opaque.
+The
+.I ucontext_t
+type is a structure that has at least
the following fields:
.in +4
.nf
.fi
.in
-with \fIsigset_t\fP and \fIstack_t\fP defined in
+with
+.IR sigset_t
+and
+.I stack_t
+defined in
.IR <signal.h> .
-Here \fIuc_link\fP points to the context that will be resumed
+Here
+.I uc_link
+points to the context that will be resumed
when the current context terminates (in case the current context
was created using
.BR makecontext (3)),
-\fIuc_sigmask\fP is the
+.I uc_sigmask
+is the
set of signals blocked in this context (see
.BR sigprocmask (2)),
-\fIuc_stack\fP is the stack used by this context (see
+.I uc_stack
+is the stack used by this context (see
.BR sigaltstack (2)),
-and \fIuc_mcontext\fP is the
+and
+.I uc_mcontext
+is the
machine-specific representation of the saved context,
that includes the calling thread's machine registers.
.LP
The function
.BR getcontext ()
initializes the structure
-pointed at by \fIucp\fP to the currently active context.
+pointed at by
+.I ucp
+to the currently active context.
.LP
The function
.BR setcontext ()
restores the user context
-pointed at by \fIucp\fP.
+pointed at by
+.IR ucp .
A successful call does not return.
The context should have been obtained by a call of
.BR getcontext (),
.LP
If the context was obtained by a call of
.BR makecontext (3),
-program execution continues by a call to the function \fIfunc\fP
+program execution continues by a call to the function
+.I func
specified as the second argument of that call to
.BR makecontext (3).
-When the function \fIfunc\fP returns, we continue with the
-\fIuc_link\fP member of the structure \fIucp\fP specified as the
+When the function
+.I func
+returns, we continue with the
+.I uc_link
+member of the structure
+.I ucp
+specified as the
first argument of that call to
.BR makecontext (3).
When this member is NULL, the thread exits.
returns 0 and
.BR setcontext ()
does not return.
-On error, both return \-1 and set \fIerrno\fP
+On error, both return \-1 and set
+.I errno
appropriately.
.SH ERRORS
None defined.
+.SH ATTRIBUTES
+.SS Multithreading (see pthreads(7))
+The
+.BR getcontext ()
+and
+.BR setcontext ()
+functions are thread-safe.
.SH CONFORMING TO
SUSv2, POSIX.1-2001.
POSIX.1-2008 removes the specification of
.BR longjmp (3),
.BR makecontext (3),
.BR sigsetjmp (3)
+.SH COLOPHON
+This page is part of release 3.79 of the Linux
+.I man-pages
+project.
+A description of the project,
+information about reporting bugs,
+and the latest version of this page,
+can be found at
+\%http://www.kernel.org/doc/man\-pages/.
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