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\begin{Name}{3}{unw\_get\_proc\_info\_by\_ip}{David Mosberger-Tang}{Programming Library}{unw\_get\_proc\_info\_by\_ip}unw\_get\_proc\_info\_by\_ip -- get procedure info by IP
\end{Name}

\section{Synopsis}

\File{\#include $<$libunwind.h$>$}\\

\Type{int} \Func{unw\_get\_proc\_info\_by\_ip}(\Type{unw\_addr\_space\_t~}\Var{as}, \Type{unw\_word\_t~}\Var{ip}, \Type{unw\_proc\_info\_t~*}\Var{pip}, \Type{void~*}\Var{arg});\\

\section{Description}

The \Func{unw\_get\_proc\_info\_by\_ip}() routine returns the same
kind of auxiliary information about a procedure as
\Func{unw\_get\_proc\_info}(), except that the info is looked up by
instruction-pointer (IP) instead of a cursor.  This is more flexible
because it is possible to look up the info for an arbitrary procedure,
even if it is not part of the current call-chain.  However, since it
is more flexible, it also tends to run slower (and often much slower)
than \Func{unw\_get\_proc\_info}().

The routine expects the followins arguments: \Var{as} is the
address-space in which the instruction-pointer should be looked up.
For a look-up in the local address-space,
\Var{unw\_local\_addr\_space} can be passed for this argument.
Argument \Var{ip} is the instruction-pointer for which the procedure
info should be looked up and \Var{pip} is a pointer to a structure of
type \Type{unw\_proc\_info\_t} which is used to return the info.
Lastly, \Var{arg} is the address-space argument that should be used
when accessing the address-space.  It has the same purpose as the
argument of the same name for \Func{unw\_init\_remote}().  When
accessing the local address-space (first argument is
\Var{unw\_local\_addr\_space}), \Const{NULL} must be passed for this
argument.

Note that for the purposes of \Prog{libunwind}, the code of a
procedure is assumed to occupy a single, contiguous range of
addresses.  For this reason, it is alwas possible to describe the
extent of a procedure with the \Var{start\_ip} and \Var{end\_ip}
members.  If a single function/routine is split into multiple,
discontiguous pieces, \Prog{libunwind} will treat each piece as a
separate procedure.

\section{Return Value}

On successful completion, \Func{unw\_get\_proc\_info\_by\_ip}()
returns 0.  Otherwise the negative value of one of the error-codes
below is returned.

\section{Thread and Signal Safety}

\Func{unw\_get\_proc\_info}() is thread-safe.  If the local
address-space is passed in argument \Var{as}, this routine is also
safe to use from a signal handler.

\section{Errors}

\begin{Description}
\item[\Const{UNW\_EUNSPEC}] An unspecified error occurred.
\item[\Const{UNW\_ENOINFO}] \Prog{Libunwind} was unable to locate
  unwind-info for the procedure.
\item[\Const{UNW\_EBADVERSION}] The unwind-info for the procedure has
  version or format that is not understood by \Prog{libunwind}.
\end{Description}
In addition, \Func{unw\_get\_proc\_info}() may return any error
returned by the \Func{access\_mem}() call-back (see
\Func{unw\_create\_addr\_space}(3)).

\section{See Also}

\SeeAlso{libunwind(3)},
\SeeAlso{unw\_create\_addr\_space(3)},
\SeeAlso{unw\_get\_proc\_name(3)},
\SeeAlso{unw\_get\_proc\_info(3)},
\SeeAlso{unw\_init\_remote(3)}

\section{Author}

\noindent
David Mosberger-Tang\\
Hewlett-Packard Labs\\
Palo-Alto, CA 94304\\
Email: \Email{davidm@hpl.hp.com}\\
WWW: \URL{http://www.hpl.hp.com/research/linux/libunwind/}.
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