import idautils
import idc

REGISTERS = {
    1: 'R0',
    2: 'R1',
    3: 'R2',
    4: 'R3',
}

def get_debug_func_ea(function_str):
    for f in Functions():
        name = idaapi.get_func_name(f)
        if name == function_str:
            return f
    return None

def get_nth_arg(start_ea, end_ea, n=0):
    for addr in range(start_ea, end_ea, 4)[::-1]:
        if not DecodeInstruction(addr):
            continue
        if DecodeInstruction(addr).get_canon_mnem() == 'LDR' and idc.print_operand(addr, 0) == REGISTERS[n]:
            return idc.get_operand_value(addr, 1)
    return None

ea = get_debug_func_ea('ProcUserLog')
for ref in CodeRefsTo(ea, 1):
    caller_name = idaapi.get_func_name(ref)
    caller_address = idc.get_name_ea_simple(caller_name)
    if not caller_name:
        continue
    if caller_name.startswith('sub_'):
        if not ref:
            continue
        ea = get_nth_arg(ref - 0x20, ref, 3)
        if ea:
            if get_segm_name(ea) == '.text':
                ea = idc.get_wide_dword(ea)
            if get_segm_name(ea) == '.rodata':
                fn_name = idc.get_strlit_contents(ea)
                if fn_name:
                    print '--------------------------------------------------------'
                    print 'Function Address:  ' + hex(caller_address)
                    print 'Function Old Name: ' + caller_name
                    print 'Function New Name: ' + fn_name
                    print '---------------------------------------------------------'
                    idc.set_name(caller_address, fn_name, 0x800)