ucontext(5)

ucontext -- user context

Synopsis

   #include <ucontext.h>

Description

The ucontext structure defines the context of a thread of control within an executing process.

This structure includes at least the following members:

   ucontext_t  *uc_link
   sigset_t    uc_sigmask
   stack_t     uc_stack
   mcontext_t  uc_mcontext

uc_link is a pointer to the context that is to be resumed when this context returns. If uc_link is equal to 0, then this context is the main context, and the process exits when this context returns. The uc_link field is only meaningful for contexts created using makecontext.

uc_sigmask defines the set of signals that are blocked when this context is active [see sigprocmask(2)].

uc_stack defines the stack used by this context [see sigaltstack(2)].

uc_mcontext contains the saved set of machine registers and any implementation specific context data. Portable applications should not modify or access uc_mcontext.

The ucontext structure has been enhanced to handle floating point context information for Pentium III processors. See ``Pentium III extended floating point support'' in New features for more information.

References

getcontext(2), makecontext(3C), sigaction(2), sigaltstack(2), sigprocmask(2)