libxrdeveloper's documentation
void xr_call_set_error ( xr_call call,
int  code,
const char *  msg,
  ... 
)

Set retval to be stadard XML-RPC error structure.

If error is set and retval is set too, error gets preference on serialize response.

Parameters
callCall obejct.
codeError code.
msgError message.
Documentation for libxr, Wed Apr 27 2016 22:07:49.