UNW_INIT_LOCAL(3) Programming Library UNW_INIT_LOCAL(3)
NAME
unw_init_local -- initialize cursor for local unwinding
SYNOPSIS
#include <libunwind.h>
int unw_init_local(unw_cursor_t *c, unw_context_t *ctxt);
int unw_init_local2(unw_cursor_t *c, unw_context_t *ctxt, int flag);
DESCRIPTION
The unw_init_local() routine initializes the unwind cursor pointed to
by c with the machine-state in the context structure pointed to by
ctxt. As such, the machine-state pointed to by ctxt identifies the
initial stack frame at which unwinding starts. The machine-state is ex-
pected to be one provided by a call to unw_getcontext; as such, the in-
struction pointer may point to the instruction after the last instruc-
tion of a function, and libunwind will back-up the instruction pointer
before beginning a walk up the call stack. The machine-state must re-
main valid for the duration for which the cursor c is in use.
The unw_init_local() routine can be used only for unwinding in the ad-
dress space of the current process (i.e., for local unwinding). For
all other cases, unw_init_remote() must be used instead. However, un-
wind performance may be better when using unw_init_local(). Also,
unw_init_local() is available even when UNW_LOCAL_ONLY has been defined
before including <libunwind.h>, whereas unw_init_remote() is not.
If the unw_context_t is known to be a signal frame (i.e., from the
third argument in a sigaction handler on linux), unw_init_local2()
should be used for correct initialization on some platforms, passing
the UNW_INIT_SIGNAL_FRAME flag.
RETURN VALUE
On successful completion, unw_init_local() returns 0. Otherwise the
negative value of one of the error-codes below is returned.
THREAD AND SIGNAL SAFETY
unw_init_local() is thread-safe as well as safe to use from a signal
handler.
ERRORS
UNW_EINVAL
unw_init_local() was called in a version of libunwind which
supports remote unwinding only (this normally happens when call-
ing unw_init_local() for a cross-platform version of libunwind).
UNW_EUNSPEC
An unspecified error occurred.
UNW_EBADREG
A register needed by unw_init_local() wasn't accessible.
SEE ALSO
libunwind(3), unw_init_remote(3)
AUTHOR
David Mosberger-Tang
Email: dmosberger@gmail.com
WWW: http://www.nongnu.org/libunwind/.
Programming Library 16 August 2017 UNW_INIT_LOCAL(3)
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