MAKECONTEXT(3)						   BSD Library Functions Manual 					    MAKECONTEXT(3)

NAME

     makecontext, swapcontext -- modify and exchange user thread contexts

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <ucontext.h>

     void
     makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...);

     int
     swapcontext(ucontext_t *oucp, const ucontext_t *ucp);

DESCRIPTION

     The makecontext() function modifies the user thread context pointed to by ucp, which must have previously been initialized by a call to
     getcontext(3) and had a stack allocated for it.  The context is modified so that it will continue execution by invoking func() with the argu-
     ments provided.  The argc argument must be equal to the number of additional arguments provided to makecontext() and also equal to the number
     of arguments to func(), or else the behavior is undefined.

     The ucp->uc_link argument must be initialized before calling makecontext() and determines the action to take when func() returns: if equal to
     NULL, the process exits; otherwise, setcontext(ucp->uc_link) is implicitly invoked.

     The swapcontext() function saves the current thread context in *oucp and makes *ucp the currently active context.

RETURN VALUES

     If successful, swapcontext() returns zero; otherwise -1 is returned and the global variable errno is set appropriately.

ERRORS

     The swapcontext() function will fail if:

     [ENOMEM]		There is not enough stack space in ucp to complete the operation.

SEE ALSO

     setcontext(3), ucontext(3)

BSD
								September 10, 2002							       BSD