xref: /external/libunwind/doc/unw_is_signal_frame.tex

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\begin{Name}{3}{unw\_is\_signal\_frame}{David Mosberger-Tang}{Programming Library}{unw\_is\_signal\_frame}unw\_is\_signal\_frame -- check if current frame is a signal frame
\end{Name}

\section{Synopsis}

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

\Type{int} \Func{unw\_is\_signal\_frame}(\Type{unw\_cursor\_t~*}\Var{cp});\\

\section{Description}

The \Func{unw\_is\_signal\_frame}() routine returns a positive value
if the current frame identified by \Var{cp} is a signal frame, and a
value of 0 otherwise.  For the purpose of this discussion, a signal
frame is a frame that was created in response to a potentially
asynchronous interruption.  For UNIX and UNIX-like platforms, such
frames are normally created by the kernel when delivering a signal.
In a kernel-environment, a signal frame might, for example, correspond
to a frame created in response to a device interrupt.

Signal frames are somewhat unusual because the asynchronous nature of
the events that create them require storing the contents of registers
that are normally treated as scratch (``caller-saved'') registers.

\section{Return Value}

On successful completion, \Func{unw\_is\_signal\_frame}() returns a
positive value if the current frame is a signal frame, or 0 if it is
not.  Otherwise, a negative value of one of the error-codes below is
returned.

\section{Thread and Signal Safety}

\Func{unw\_is\_signal\_frame}() is thread-safe as well as safe to use
from a signal handler.

\section{Errors}

\begin{Description}
\item[\Const{UNW\_ENOINFO}] \Prog{Libunwind} is unable to determine
  whether or not the current frame is a signal frame.
\end{Description}

\section{See Also}

\SeeAlso{libunwind(3)},
\SeeAlso{unw\_get\_reg(3)},
\SeeAlso{unw\_set\_reg(3)},
\SeeAlso{unw\_get\_fpreg(3)},
\SeeAlso{unw\_set\_fpreg(3)}

\section{Author}

\noindent
David Mosberger-Tang\\
Email: \Email{dmosberger@gmail.com}\\
WWW: \URL{http://www.nongnu.org/libunwind/}.
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