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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 previ-ously previously
     ously 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 arguments 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