The unw_step()
routine advances the unwind cursor cp
to
the next older, less deeply nested stack frame.
RETURN VALUE
On successful completion, unw_step()
returns a positive value
if the updated cursor refers to a valid stack frame, or 0 if the
previous stack frame was the last frame in the chain. On error, the
negative value of one of the error-codes below is returned.
THREAD AND SIGNAL SAFETY
unw_step()
is thread-safe. If cursor cp
is in the local
address-space, this routine is also safe to use from a signal handler.
ERRORS
UNW_EUNSPEC
An unspecified error occurred.
UNW_ENOINFO
Libunwind
was unable to locate the
unwind-info needed to complete the operation.
UNW_EBADVERSION
The unwind-info needed to complete the
operation has a version or a format that is not understood by
libunwind.
UNW_EINVALIDIP
The instruction-pointer
(``program-counter'') of the next stack frame is invalid (e.g., not
properly aligned).
UNW_EBADFRAME
The next stack frame is invalid.
UNW_ESTOPUNWIND
Returned if a call to
find_proc_info()
returned -UNW_ESTOPUNWIND.
In addition, unw_step()
may return any error returned by the
find_proc_info(),
get_dyn_info_list_addr(),
access_mem(),
access_reg(),
or access_fpreg()
call-backs (see unw_create_addr_space(3)).