initial commitHEADmaster

3 files changed, 155 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b95b722
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.o
+escape
+
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..deec692
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,13 @@
+SRC = escaper
+OUT = escape
+WRN = -w+all
+FMTN = elf64
+FMTL = elf_x86_64
+
+default:
+	nasm -f $(FMTN) $(WRN) $(SRC).s
+	ld -m $(FMTL) $(SRC).o -o $(OUT)
+debug:
+	nasm -g -f $(FMTN) $(WRN) $(SRC).s
+	ld -m $(FMTL) $(SRC).o -o $(OUT)
+
diff --git a/escaper.s b/escaper.s
new file mode 100644
index 0000000..19b0095
--- /dev/null
+++ b/escaper.s
@@ -0,0 +1,139 @@
+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
+