debian man page for unw_getcontext

UNW_GETCONTEXT(3)					       Programming Library						 UNW_GETCONTEXT(3)

NAME
       unw_getcontext -- get initial machine-state

SYNOPSIS
       #include <libunwind.h>

       int unw_getcontext(unw_context_t *ucp);

DESCRIPTION
       The  unw_getcontext() routine initializes the context structure pointed to by ucp with the machine-state of the call-site. The exact set of
       registers stored by unw_getcontext() is platform-specific, but, in general, at least all preserved (``callee-saved'') and all frame-related
       registers, such as the stack-pointer, will be stored.

       This routine is normally implemented as a macro and applications should not attempt to take its address.

PLATFORM-SPECIFIC NOTES
       On  IA-64,  unw_context_t  has a layout that is compatible with that of ucontext_t and such structures can be initialized with getcontext()
       instead of unw_getcontext().  However, the reverse is not true and it is not safe to use  structures  initialized  by  unw_getcontext()	in
       places  where  a structure initialized by getcontext() is expected. The reason for this asymmetry is that unw_getcontext() is optimized for
       maximum performance and does not, for example, save the signal mask.

RETURN VALUE
       On successful completion, unw_getcontext() returns 0.  Otherwise, a value of -1 is returned.

THREAD AND SIGNAL SAFETY
       unw_getcontext() is thread-safe as well as safe to use from a signal handler.

SEE ALSO
       libunwind(3), unw_init_local(3)

AUTHOR
       David Mosberger-Tang
       Email: dmosberger@gmail.com
       WWW: http://www.nongnu.org/libunwind/.

Programming Library						  16 August 2007						 UNW_GETCONTEXT(3)