58 lines
2.1 KiB
NASM
58 lines
2.1 KiB
NASM
; define some macros
|
|
%define O_RDONLY 00000000o
|
|
%define O_WRONLY 00000001o
|
|
%define O_RDWR 00000002o
|
|
%define O_CREAT 00000100o
|
|
%define O_TRUNC 00001000o
|
|
%define S_IRUSR 00000400o
|
|
%define S_IWUSR 00000200o
|
|
|
|
|
|
section .data
|
|
path: db "/home/user/nachricht", 0
|
|
greeting: db "hidad!", 0
|
|
|
|
; https://stackoverflow.com/a/45386640
|
|
length equ $ - greeting ; Length of greeting message
|
|
|
|
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
; https://chromium.googlesource.com/chromiumos/docs/+/master/constants/syscalls.md#x86-32_bit;
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
section .text
|
|
global _start
|
|
_start:
|
|
call _open ; open file
|
|
call _write ; write to file
|
|
call _close ; close file
|
|
call _exit ; exit without errors
|
|
|
|
; https://www.man7.org/linux/man-pages/man2/open.2.html
|
|
_open:
|
|
mov eax, 0x05 ; syscall number for 'open'
|
|
mov ebx, path ; pointer to the path string
|
|
mov ecx, O_CREAT ; open the file if it doesn't exist
|
|
xor ecx, O_WRONLY ; open the file in write-only mode
|
|
mov edx, S_IRUSR ; permissions for the file
|
|
int 0x80 ; call kernel
|
|
|
|
; https://man7.org/linux/man-pages/man2/write.2.html
|
|
_write:
|
|
mov ebx, eax ; file descriptor returned by 'open'
|
|
mov eax, 0x04 ; syscall number for 'write'
|
|
mov ecx, greeting ; pointer to the greeting message
|
|
mov edx, length ; length of the greeting message
|
|
sub edx, 0x01 ; length of the greeting message without null byte
|
|
int 0x80 ; call kernel
|
|
|
|
; https://man7.org/linux/man-pages/man2/close.2.html
|
|
_close:
|
|
mov eax, 0x06 ; syscall number for 'close'
|
|
int 0x80 ; call kernel
|
|
|
|
; https://man7.org/linux/man-pages/man2/exit.2.html
|
|
_exit:
|
|
mov eax, 1 ; syscall number for 'exit'
|
|
mov ebx, 0 ; exit status
|
|
int 0x80 ; call kernel
|
|
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|