Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
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 arguments
     provided.	The argc argument must be equal	to the number of additional
     arguments provided	to makecontext() and also equal	to the number of argu-
     ments 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

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=makecontext&sektion=3&manpath=FreeBSD+7.2-RELEASE>

home | help