NAME

       unw_set_reg -- set register contents

SYNOPSIS

       #include <libunwind.h>

       int unw_set_reg(unw_cursor_t *cp, unw_regnum_t reg, unw_word_t val);

DESCRIPTION

       The  unw_set_reg()  routine  sets the value of register reg in the stack frame identified by cursor cp to
       the value passed in val.

       The  register  numbering  is  target-dependent  and   described   in   separate   manual   pages   (e.g.,
       libunwind-ia64(3)  for  the IA-64 target).  Furthermore, the exact set of accessible registers may depend
       on the type of frame that cp is referring to. For ordinary stack  frames,  it  is  normally  possible  to
       access  only  the  preserved  (``callee-saved'')  registers  and  frame-related  registers  (such  as the
       stack-pointer). However, for signal frames (see unw_is_signal_frame(3)), it is usually possible to access
       all registers.

       Note  that  unw_set_reg() can only write the contents of registers whose values fit in a single word. See
       unw_set_fpreg(3) for a way to write registers which do not fit this constraint.

RETURN VALUE

       On successful completion,  unw_set_reg()  returns  0.   Otherwise  the  negative  value  of  one  of  the
       error-codes below is returned.

THREAD AND SIGNAL SAFETY

       unw_set_reg() is thread-safe as well as safe to use from a signal handler.

ERRORS

       UNW_EUNSPEC
               An unspecified error occurred.

       UNW_EBADREG
               An  attempt  was made to write a register that is either invalid or not accessible in the current
              frame.

       UNW_EREADONLY
               An attempt was made to write to a read-only register.

       In addition, unw_set_reg()  may  return  any  error  returned  by  the  access_mem(),  access_reg(),  and
       access_fpreg() call-backs (see unw_create_addr_space(3)).

SEE ALSO

       libunwind(3), libunwind-ia64(3), unw_get_reg(3), unw_is_signal_frame(3), unw_set_fpreg(3)

AUTHOR

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