doc/unw_init_remote.tex

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\begin{Name}{3}{unw\_init\_remote}{David Mosberger-Tang}{Programming Library}{unw\_init\_remote}unw\_init\_remote -- initialize cursor for remote unwinding
\end{Name}

\section{Synopsis}

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

\Type{int} \Func{unw\_init\_remote}(\Type{unw\_cursor\_t~*}\Var{c}, \Type{unw\_addr\_space\_t~}\Var{as}, \Type{void~*}\Var{arg});\\

\section{Description}

The \Func{unw\_init\_remote}() routine initializes the unwind cursor
pointed to by \Var{c} for unwinding in the address space identified by
\Var{as}.  The \Var{as} argument can either be set to
\Var{unw\_local\_addr\_space} (local address space) or to an arbitrary
address space created with \Func{unw\_create\_addr\_space}().

The \Var{arg} void-pointer tells the address space exactly what entity
should be unwound.  For example, if \Var{unw\_local\_addr\_space} is
passed in \Var{as}, then \Var{arg} needs to be a pointer to a context
structure containing the machine-state of the initial stack frame.
However, other address-spaces may instead expect a process-id, a
thread-id, or a pointer to an arbitrary structure which identifies the
stack-frame chain to be unwound.  In other words, the interpretation
of \Var{arg} is entirely dependent on the address-space in use;
\Prog{libunwind} never interprets the argument in any way on its own.

Note that \Func{unw\_init\_remote}() can be used to initiate unwinding
in \emph{any} process, including the local process in which the
unwinder itself is running.  However, for local unwinding, it is
generally preferable to use \Func{unw\_init\_local}() instead, because
it is easier to use and because it may perform better.

\section{Return Value}

On successful completion, \Func{unw\_init\_remote}() returns 0.
Otherwise the negative value of one of the error-codes below is
returned.

\section{Thread and Signal Safety}

\Func{unw\_init\_remote}() 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\_EINVAL}] \Func{unw\_init\_remote}() was called in a
  version of \Prog{libunwind} which supports local unwinding only
  (this normally happens when defining \Const{UNW\_LOCAL\_ONLY} before
  including \File{$<$libunwind.h$>$} and then calling
  \Func{unw\_init\_remote}()).
\item[\Const{UNW\_EUNSPEC}] An unspecified error occurred.
\item[\Const{UNW\_EBADREG}] A register needed by \Func{unw\_init\_remote}()
  wasn't accessible.
\end{Description}

\section{See Also}

\SeeAlso{libunwind(3)}, \SeeAlso{unw\_create\_addr\_space(3)},
\SeeAlso{unw\_init\_local(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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