1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
## 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_eax 58
DEFINE POP_ebx 5B
DEFINE CMP_EAX_TO_IMMEDIATE8 83F8
DEFINE JNE8 75
DEFINE LOADI32_ECX B9
DEFINE LOADI32_EAX B8
DEFINE LOADI32_EBX BB
DEFINE LOADI32_EDX BA
DEFINE INT_80 CD80
:_start
# first check that we got the correct number of inputs
POP_eax # Get the number of arguments
POP_ebx # Get the program name
POP_ebx # Get the actual argument
# Check if we have the correct number of inputs
CMP_EAX_TO_IMMEDIATE8 !02
# Jump to Bail if the number is not correct
JNE8 !Bail
# Load our preferred mode (0777)
LOADI32_ECX %0x1ff
# Load the syscall number for chmod
LOADI32_EAX %15
# Call the kernel
INT_80
:Done
# program completed Successfully
LOADI32_EBX %0 # All is well
LOADI32_EAX %1 # put the exit syscall number in eax
INT_80 # Call it a good day
:Bail
# first let the user know what was wrong
LOADI32_EDX %0x1a # third argument: message length
LOADI32_ECX &msg # second argument: pointer to message to write
LOADI32_EBX %1 # first argument: file handle (stdout)
LOADI32_EAX %4 # system call number (sys_write)
INT_80 # call kernel
# Second terminate with an error
LOADI32_EBX %1 # there was an error
LOADI32_EAX %1 # put the exit syscall number in eax
INT_80 # bail out
:msg
"needs a proper file name
"
:ELF_end
|
