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 gen-
eral, 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() in-
stead 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)
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