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

NAME
     mmaakkeeccoonntteexxtt, sswwaappccoonntteexxtt - modify and exchange user thread contexts

LLIIBBRRAARRYY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##iinncclluuddee <>

     void
     mmaakkeeccoonntteexxtt(ucontextt *ucp, void (*func)(void), int argc, ...);

     int
     sswwaappccoonntteexxtt(ucontextt *oucp, const ucontextt *ucp);

DESCRIPTION
     The mmaakkeeccoonntteexxtt() 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 ffuunncc() with the arguments
     provided.  The argc argument must be equal to the number of additional
     arguments provided to mmaakkeeccoonntteexxtt() and also equal to the number of argu-
     ments to ffuunncc(), or else the behavior is undefined.

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

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

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

EERRRROORRSS
     The sswwaappccoonntteexxtt() 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