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/.