ucontext(2) [netbsd man page]

UCONTEXT(2)						      BSD System Calls Manual						       UCONTEXT(2)

NAME

     ucontext -- user context

SYNOPSIS

     #include <ucontext.h>

DESCRIPTION

     The ucontext_t is a structure type which is used to describe the context of a thread of control within the execution of a process.  A
     thread's context includes its stack, saved registers, and list of blocked signals.

     The ucontext_t structure 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 context; 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 structure 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'') and IEEE Std 1003.1-2001 (``POSIX.1'').  The IEEE Std
     1003.1-2008 (``POSIX.1'') revision removed the ucontext_t from the specification.

BSD
								  April 29, 2010							       BSD

<ucontext.h>(P) 					     POSIX Programmer's Manual						   <ucontext.h>(P)

NAME

       ucontext.h - user context

SYNOPSIS

       #include <ucontext.h>

DESCRIPTION

       The <ucontext.h> header shall define the mcontext_t type through typedef.

       The <ucontext.h> header shall define the ucontext_t type as a structure that shall include at least the following members:

	      ucontext_t *uc_link     Pointer to the context that is resumed
				      when this context returns.
	      sigset_t	  uc_sigmask  The set of signals that are blocked when this
				      context is active.
	      stack_t	  uc_stack    The stack used by this context.
	      mcontext_t  uc_mcontext A machine-specific representation of the saved
				      context.

       The types sigset_t and stack_t shall be defined as in <signal.h> .

       The following shall be declared as functions and may also be defined as macros, Function prototypes shall be provided.

	      int  getcontext(ucontext_t *);
	      int  setcontext(const ucontext_t *);
	      void makecontext(ucontext_t *, void (*)(void), int, ...);
	      int  swapcontext(ucontext_t *restrict, const ucontext_t *restrict);

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <signal.h> , the System Interfaces volume of IEEE Std 1003.1-2001, getcontext(), makecontext(), sigaction(), sigprocmask(), sigaltstack()

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							   <ucontext.h>(P)