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