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.
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/.
