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global _start
%macro write 3
mov rdi, %1
mov rsi, %2
mov rdx, %3
mov rax, 1
syscall
%endmacro
%macro read 3
mov rdi, %1
mov rsi, %2
mov rdx, %3
xor rax, rax
syscall
%endmacro
%macro mmap 6
mov rdi, %1
mov rsi, %2
mov rdx, %3
mov r10, %4
mov r8, %5
mov r9, %6
mov rax, 9
syscall
%endmacro
%macro munmap 2
mov rdi, %1
mov rsi, %2
mov rax, 11
syscall
%endmacro
%macro exit 1
mov rdi, %1
mov rax, 60
syscall
%endmacro
section .text
_start:
pop qword [argc]
pop rcx
cmp dword [argc], 1
jg skip_stdin
stdin_loop:
read 0, buf, 4000
cmp rax, 1
jle end
mov rdx, buf
mov rcx, [argc]
jmp count_start
clear_pos:
cmp rbx, rax
je arg_loop
mov byte [pos + rax], 0
inc rax
jmp clear_pos
skip_stdin:
mov rcx, [argc]
arg_loop:
cmp rcx, 1
jle end
pop rdx
count_start:
xor rax, rax
xor rbx, rbx
count_loop:
cmp byte [rdx + rax], '~'
je found
cmp byte [rdx + rax], '`'
je found
cmp byte [rdx + rax], '_'
je found
cmp byte [rdx + rax], '*'
je found
cmp byte [rdx + rax], '|'
je found
cmp byte [rdx + rax], '\'
je found
cmp byte [rdx + rax], 0
je escape
inc rax
jmp count_loop
found:
inc rbx
mov byte [pos + rax], 1
inc rax
jmp count_loop
escape:
push rcx ; argc counter
push rax ; string length
push rbx ; number of extra characters needed
push rdx ; string memory address
add rbx, rax
inc rbx
mmap 0, rbx, 3, 34, -1, 0 ; 3 = PROT_READ | PROT_WRITE, 34 = MAP_PRIVATE | MAP_ANONYMOUS
pop rdx
pop rbx
pop rsi
add rsi, rbx
xor r8, r8
xor r9, r9
escape_loop:
cmp r9, rsi
je escape_loop_end
cmp byte [pos + r8], 1
jne skip_backslash
mov byte [rax + r9], '\'
inc r9
skip_backslash:
mov r10b, byte [rdx + r8]
mov byte [rax + r9], r10b
inc r8
inc r9
jmp escape_loop
escape_loop_end:
mov byte [rax + r9], 10
inc r9
push rax
write 1, rax, r9
pop rax
munmap rax, r9
pop rcx
next_arg:
dec rcx
xor rax, rax
jmp clear_pos
end:
exit 0
section .bss
argc: resq 1
buf: resb 4001
pos: resb 4000
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