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14c48b3d51
init_local, but *not* setting use_prev_instr. This is necessary to correctly unwind using ucontext argument to signal handlers.
80 lines
2.8 KiB
TeX
80 lines
2.8 KiB
TeX
\documentclass{article}
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\usepackage[fancyhdr,pdf]{latex2man}
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\input{common.tex}
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\begin{document}
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\begin{Name}{3}{unw\_init\_local}{David Mosberger-Tang}{Programming Library}{unw\_init\_local}unw\_init\_local -- initialize cursor for local unwinding
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\end{Name}
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\section{Synopsis}
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\File{\#include $<$libunwind.h$>$}\\
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\Type{int} \Func{unw\_init\_local}(\Type{unw\_cursor\_t~*}\Var{c}, \Type{unw\_context\_t~*}\Var{ctxt});\\
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\Type{int} \Func{unw\_init\_local_signal}(\Type{unw\_cursor\_t~*}\Var{c}, \Type{unw\_context\_t~*}\Var{ctxt});\\
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\section{Description}
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The \Func{unw\_init\_local}() routine initializes the unwind cursor
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pointed to by \Var{c} with the machine-state in the context structure
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pointed to by \Var{ctxt}. As such, the machine-state pointed to by
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\Var{ctxt} identifies the initial stack frame at which unwinding
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starts. The machine-state is expected to be one provided by a call to
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unw_getcontext; as such, the instruction pointer may point to the
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instruction after the last instruction of a function, and libunwind
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will back-up the instruction pointer before beginning a walk up the
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call stack. The machine-state must remain valid for the duration for
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which the cursor \Var{c} is in use.
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The \Func{unw\_init\_local}() routine can be used only for unwinding in
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the address space of the current process (i.e., for local unwinding).
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For all other cases, \Func{unw\_init\_remote}() must be used instead.
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However, unwind performance may be better when using
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\Func{unw\_init\_local}(). Also, \Func{unw\_init\_local}() is
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available even when \Const{UNW\_LOCAL\_ONLY} has been defined before
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including \File{$<$libunwind.h$>$}, whereas \Func{unw\_init\_remote}()
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is not.
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If the unw_context_t is known to be a signal frame (i.e., from the
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third argument in a sigaction handler on linux),
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\Func{unw\_init\_local\_signal}() should be used for correct
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initialization on some platforms.
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\section{Return Value}
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On successful completion, \Func{unw\_init\_local}() returns 0.
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Otherwise the negative value of one of the error-codes below is
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returned.
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\section{Thread and Signal Safety}
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\Func{unw\_init\_local}() is thread-safe as well as safe to use from a
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signal handler.
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\section{Errors}
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\begin{Description}
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\item[\Const{UNW\_EINVAL}] \Func{unw\_init\_local}() was called in a
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version of \Prog{libunwind} which supports remote unwinding only
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(this normally happens when calling \Func{unw\_init\_local}() for a
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cross-platform version of \Prog{libunwind}).
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\item[\Const{UNW\_EUNSPEC}] An unspecified error occurred.
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\item[\Const{UNW\_EBADREG}] A register needed by \Func{unw\_init\_local}()
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wasn't accessible.
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\end{Description}
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\section{See Also}
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\SeeAlso{libunwind(3)}, \SeeAlso{unw\_init\_remote(3)}
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\section{Author}
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\noindent
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David Mosberger-Tang\\
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Email: \Email{dmosberger@gmail.com}\\
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WWW: \URL{http://www.nongnu.org/libunwind/}.
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\LatexManEnd
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\end{document}
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