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## Copyright (C) 2017 Jeremiah Orians
## This file is part of stage0.
##
## stage0 is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## stage0 is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with stage0. If not, see <http://www.gnu.org/licenses/>.
DEFINE POP_RAX 58
DEFINE POP_RDI 5F
DEFINE CMP_RAX_TO_IMMEDIATE8 4883f8
DEFINE JNE8 75
DEFINE LOADI32_RSI 48C7C6
DEFINE LOADI32_RAX 48C7C0
DEFINE LOADI32_RDI 48C7C7
DEFINE LOADI32_RDX 48C7C2
DEFINE SYSCALL 0F05
:_start
# first check that we got the correct number of inputs
POP_RAX # Get the number of arguments
POP_RDI # Get the program name
POP_RDI # Get the actual argument
# Check if we have the correct number of inputs
CMP_RAX_TO_IMMEDIATE8 !02
# Jump to Bail if the number is not correct
JNE8 !Bail
# Load our preferred mode (0777)
LOADI32_RSI %0x1ff
# Load the syscall number for chmod
LOADI32_RAX %90
# Call the kernel
SYSCALL
:Done
# program completed Successfully
LOADI32_RDI %0 # All is well
LOADI32_RAX %60 # put the exit syscall number in rax
SYSCALL # Call it a good day
:Bail
# first let the user know what was wrong
LOADI32_RDX %0x1a # third argument: message length
LOADI32_RSI &message # second argument: pointer to message to write
LOADI32_RDI %1 # first argument: file handle (stdout)
LOADI32_RAX %1 # system call number (sys_write)
SYSCALL # call kernel
# Second terminate with an error
LOADI32_RDI %1 # there was an error
LOADI32_RAX %60 # put the exit syscall number in eax
SYSCALL # bail out
:message
"needs a proper file name
"
:ELF_end
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