unw_init_local(3)

1UNW_INIT_LOCAL(3)            Programming Library             UNW_INIT_LOCAL(3)
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NAME

6       unw_init_local -- initialize cursor for local unwinding
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SYNOPSIS

9       #include <libunwind.h>
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11       int unw_init_local(unw_cursor_t *c, unw_context_t *ctxt);
12       int unw_init_local2(unw_cursor_t *c, unw_context_t *ctxt, int flag);
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DESCRIPTION

15       The  unw_init_local()  routine initializes the unwind cursor pointed to
16       by c with the machine-state in the  context  structure  pointed  to  by
17       ctxt.   As  such,  the  machine-state pointed to by ctxt identifies the
18       initial stack frame at which unwinding  starts.  The  machine-state  is
19       expected  to  be one provided by a call to unw_getcontext; as such, the
20       instruction pointer  may  point  to  the  instruction  after  the  last
21       instruction  of  a function, and libunwind will back-up the instruction
22       pointer before beginning a walk up the call  stack.  The  machine-state
23       must remain valid for the duration for which the cursor c is in use.
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25       The  unw_init_local()  routine  can  be  used only for unwinding in the
26       address space of the current process (i.e., for local unwinding).   For
27       all  other  cases,  unw_init_remote()  must  be used instead.  However,
28       unwind performance may be better when  using  unw_init_local().   Also,
29       unw_init_local() is available even when UNW_LOCAL_ONLY has been defined
30       before including <libunwind.h>, whereas unw_init_remote() is not.
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32       If the unw_context_t is known to be a  signal  frame  (i.e.,  from  the
33       third  argument  in  a  sigaction  handler on linux), unw_init_local2()
34       should be used for correct initialization on  some  platforms,  passing
35       the UNW_INIT_SIGNAL_FRAME flag.
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RETURN VALUE

38       On  successful  completion,  unw_init_local() returns 0.  Otherwise the
39       negative value of one of the error-codes below is returned.
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THREAD AND SIGNAL SAFETY

42       unw_init_local() is thread-safe as well as safe to use  from  a  signal
43       handler.
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ERRORS

46       UNW_EINVAL
47               unw_init_local()  was  called  in  a version of libunwind which
48              supports remote unwinding only (this normally happens when call‐
49              ing unw_init_local() for a cross-platform version of libunwind).
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51       UNW_EUNSPEC
52               An unspecified error occurred.
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54       UNW_EBADREG
55               A register needed by unw_init_local() wasn't accessible.
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AUTHOR

61       David Mosberger-Tang
62       Email: dmosberger@gmail.com
63       WWW: http://www.nongnu.org/libunwind/.
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67Programming Library             16 August 2017               UNW_INIT_LOCAL(3)