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\begin{Name}{3}{unw\_step}{David Mosberger-Tang}{Programming Library}{unw\_step}unw\_step -- advance to next stack frame
\File{\#include $<$libunwind.h$>$}\\
\Type{int} \Func{unw\_step}(\Type{unw\_cursor\_t~*}\Var{cp});\\
The \Func{unw\_step}() routine advances the unwind cursor \Var{cp} to
the next older, less deeply nested stack frame.
\section{Return Value}
On successful completion, \Func{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.
\section{Thread and Signal Safety}
\Func{unw\_step}() is thread-safe. If cursor \Var{cp} is in the local
address-space, this routine is also safe to use from a signal handler.
\item[\Const{UNW\_EUNSPEC}] An unspecified error occurred.
\item[\Const{UNW\_ENOINFO}] \Prog{Libunwind} was unable to locate the
unwind-info needed to complete the operation.
\item[\Const{UNW\_EBADVERSION}] The unwind-info needed to complete the
operation has a version or a format that is not understood by
\item[\Const{UNW\_EINVALIDIP}] The instruction-pointer
(``program-counter'') of the next stack frame is invalid (e.g., not
properly aligned).
\item[\Const{UNW\_EBADFRAME}] The next stack frame is invalid.
\item[\Const{UNW\_ESTOPUNWIND}] Returned if a call to
\Func{find\_proc\_info}() returned -\Const{UNW\_ESTOPUNWIND}.
In addition, \Func{unw\_step}() may return any error returned by the
\Func{find\_proc\_info}(), \Func{get\_dyn\_info\_list\_addr}(),
\Func{access\_mem}(), \Func{access\_reg}(), or \Func{access\_fpreg}()
call-backs (see \Func{unw\_create\_addr\_space}(3)).
\section{See Also}
David Mosberger-Tang\\
Email: \Email{}\\
WWW: \URL{}.