UCONTEXT(2)               NetBSD System Calls Manual               UCONTEXT(2)

NAME
     ucontext -- user context

SYNOPSIS
     #include <ucontext.h>

DESCRIPTION
     ucontext_t is a structure type which is used to describe the context of a
     thread of control within the execution of a process.

     ucontext_t includes the following members:

           ucontext_t *  uc_link
           sigset_t      uc_sigmask
           stack_t       uc_stack
           mcontext_t    uc_mcontext

     The uc_link member points to the context that will be resumed after the
     function specified when modifying a context using makecontext(3) has
     returned.  If uc_link is a null pointer, then the context is the main
     context, and the process will exit with an exit status of 0 upon return.

     The uc_sigmask member is the set of signals that are blocked when the
     context is activated.  Further information can be found in
     sigprocmask(2).

     The uc_stack member defines the stack used by the context.  Further
     information can be found in sigaltstack(2).

     The uc_mcontext member defines the machine state associated with the con-
     text; it may consist of general registers, floating point registers and
     other machine-specific information.  Its description is beyond the scope
     of this manual page; portable applications should not access this struc-
     ture member.

SEE ALSO
     _exit(2), getcontext(2), setcontext(2), sigaltstack(2), sigprocmask(2),
     makecontext(3), swapcontext(3)

STANDARDS
     The ucontext_t type conforms to X/Open System Interfaces and Headers
     Issue 5 (``XSH5'').

HISTORY
     The makecontext() and swapcontext() functions first appeared in AT&T
     System V.4 UNIX.

NetBSD 4.0                       June 13, 2001                      NetBSD 4.0