NAME
getcontext,
setcontext —
get and set user thread
context
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<ucontext.h>
int
getcontext(ucontext_t
*ucp);
int
setcontext(const
ucontext_t *ucp);
DESCRIPTION
The
getcontext()
function saves the current thread's execution context in the structure
pointed to by ucp. This saved context may then later
be restored by calling setcontext().
The
setcontext()
function makes a previously saved thread context the current thread context,
i.e., the current context is lost and setcontext()
does not return. Instead, execution continues in the context specified by
ucp, which must have been previously initialized by a
call to getcontext(),
makecontext(3), or by being passed as an argument to a signal handler
(see sigaction(2)).
If ucp was initialized by
getcontext(),
then execution continues as if the original
getcontext() call had just returned (again).
If ucp was initialized by
makecontext(3), execution continues with the invocation of the
function specified to
makecontext(3). When that function returns,
ucp->uc_link determines what happens next: if
ucp->uc_link is NULL, the
process exits; otherwise,
setcontext(ucp->uc_link)
is implicitly invoked.
If ucp was initialized by the invocation of a signal handler, execution continues at the point the thread was interrupted by the signal.
RETURN VALUES
If successful, getcontext() returns zero
and setcontext() does not return; otherwise -1 is
returned.
ERRORS
No errors are defined for getcontext() or
setcontext().