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UNW_STEP(3)                  Programming Library                   UNW_STEP(3)

NAME
       unw_step -- advance to next stack frame

SYNOPSIS
       #include <libunwind.h>

       int unw_step(unw_cursor_t *cp);

DESCRIPTION
       The unw_step() routine advances the unwind cursor cp to the next older,
       less deeply nested stack frame.

RETURN VALUE
       On successful completion, unw_step() returns a positive value if the
       updated cursor refers to a valid stack frame, or 0 if the previous
       stack frame was the last frame in the chain. On error, the negative
       value of one of the error-codes below is returned.

THREAD AND SIGNAL SAFETY
       unw_step() is thread-safe. If cursor cp is in the local address-space,
       this routine is also safe to use from a signal handler.

ERRORS
       UNW_EUNSPEC
               An unspecified error occurred.

       UNW_ENOINFO
               Libunwind was unable to locate the unwind-info needed to
              complete the operation.

       UNW_EBADVERSION
               The unwind-info needed to complete the operation has a version
              or a format that is not understood by libunwind.

       UNW_EINVALIDIP
               The instruction-pointer (``program-counter'') of the next stack
              frame is invalid (e.g., not properly aligned).

       UNW_EBADFRAME
               The next stack frame is invalid.

       UNW_ESTOPUNWIND
               Returned if a call to find_proc_info() returned
              -UNW_ESTOPUNWIND.

       In addition, unw_step() may return any error returned by the
       find_proc_info(), get_dyn_info_list_addr(), access_mem(), access_reg(),
       or access_fpreg() call-backs (see unw_create_addr_space(3)).

SEE ALSO
       libunwind(3), unw_create_addr_space(3)

AUTHOR
       David Mosberger-Tang
       Email: dmosberger@gmail.com
       WWW: http://www.nongnu.org/libunwind/.

Programming Library             16 August 2007                     UNW_STEP(3)