Linux temios non-canonical sys_call getch() doesn't work - linux

Question

I recently make input using Linux assembly (x86_64) i got this code and i try it eventually the code are doesn't work like what i expected, i should wait a keystroke but it auto input from no where, i suspect termios flags... code are in below :
;Get current settings
Mov EAX, 16 ; SYS_ioctl
Mov EDI, 0 ; STDIN_FILENO
Mov ESI, 0x5401 ; TCGETS
Mov RDX, termios
Int 80h
And dword [c_cflag], 0xFD ; Clear ICANON to disable canonical mode
; Write termios structure back
Mov EAX, 16 ; SYS_ioctl
Mov EDI, 0 ; STDIN_FILENO
Mov ESI, 0x5402 ; TCSETS
Mov RDX, termios
Int 80h
Mov EAX,0 ;sys_read kernel call
Mov EBX,0 ;stdin trap (standart input)
Mov ECX,Nada ;Masukkan offset/jumlah byte yang akan di baca
Mov EDX,1 ;Jumlah byte yang dibaca
Int 80h ;Call Kernel
for the termios struct :
SECTION .bss ;deklarasi untuk variable yang belum terdefinisi
Enter: Resb 1 ;Pesan 1 byte untuk Enter
Nada: Resb 1
termios:
c_iflag Resd 1 ; input mode flags
c_oflag Resd 1 ; output mode flags
c_cflag Resd 1 ; control mode flags
c_lflag Resd 1 ; local mode flags
c_line Resb 1 ; line discipline
c_cc Resb 64 ; control characters
for the output :
nasm -f elf64 -g -F stabs key.asm
ld -o KeyPress key.o
./KeyPress
Untuk memulai tekan tombol enter:
Tekan tombol untuk memainkan satu not: (1,2,3,4,5,6,7,8)
//this part are the error occur,i have to check if user inputed right value
if not it will jump to error label and printed below message//
Error note not found please contact the app developer !!
reference : Linux Getch(), My Github Repo
PS: For the newest code i already push on my repository i use ubuntu 20.04 and Intel i7 (64-bit), thanks for the help

Answer 1

... i got this code and i try it eventually the code are doesn't work like what i expected ...
Mov ESI, 0x5401
Mov RDX, termios
Int 80h
This won't work:
Int 80h is the 32-bit system call used in 32-bit programs. The first three arguments are passed in EBX, ECX and EDX, and definitely not in ESI.
And the values of EAX required for Int 80h differ from the method used in 64-bit programs: read() would be EAX=3, not EAX=0.
Int 80h seems to work in 64-bit programs, too, however, passing 64-bit values wont work; so you cannot use Int 80h for system calls that take addresses (in the example: the address of termios) as argument.
Either you assemble and link your code as 32-bit program, use int 80h, pass the arguments in EBX, ECX and EDX and use the values in EAX required for 32-bit programs (for example: EAX=3 for read()):
mov eax, 54 ; sys_ioctl when using "int 80h"
mov ebx, 0 ; stdin
mov ecx, 0x5402 ; TCSETS
mov edx, termios
int 80h
Or you build a 64-bit program and use the syscall instruction to call system calls (see this question):
mov eax, 0 ; sys_read when using "syscall"
; note that this instruction will actually set RAX to 0
mov edi, 0 ; set RDI to stdin (implicitly sets rdi)
mov rsi, Nada ; Address of the buffer (see below)
; we explicitly have to use "rsi" here!
mov edx, 1 ; number of bytes
syscall
mov ecx, Nada
I don't use "nasm" but another assembler; so maybe I am wrong. But as far as I know the instruction above would be interpreted by "nasm" as:
Read the value stored in the RAM at the address Nada and write that value to the ecx register.
However, you want the address of Nada to be written to the ecx register.
As far as I know, this instruction would be written as: mov ecx, offset Nada in "masm".
If this is true, the corresponding line in my example above must be: mov rsi, offset Nada.
And dword [c_cflag], 0xFD ; Clear ICANON to disable canonical mode
This line contains two errors:
ICANON is located in C_LFLAG, not in C_CFLAG.
And this instruction would be identical to the C/C++ instruction: c_cflag &= ~0xFFFFFF02, but you want to do: c_cflag &= ~2.
To clear bit 1 only, you have two possibilities:
And byte [c_lflag], 0xFD
; OR:
And dword [c_lflag], 0xFFFFFFFD