+
+%include "fileutils.S"
+
+extern printf
+extern fflush
+extern stdout
+extern free
+
+global repl
+
+section .data
+ prompt_str db `sped > `, 0x00
+ invalidcmd_str db `invalid command\n`, 0x00
+ invalidaddr_str db `invalid address\n`, 0x00
+ charcount_str db `read %i chars\n`, 0x00
+ currentline_str db `current line: %i\n`, 0x00
+ echo_str db `%s`, 0x00 ; print strings without format exploit
+
+section .bss
+ buffer resb 4
+ buffer_lines resb 4
+ buffer_filename resb 4
+ cur_line resb 4
+
+section .text
+
+; prompt for user
+; args: buffer, buffer_lines, buffer_filename
+repl:
+
+ %define _BUFFER 16
+ %define _BUFFER_LINES 12
+ %define _BUFFER_FILENAME 8
+ %define CMDSTR 4 ; the previous line read from user
+
+ push ebp
+ mov ebp, esp
+
+ sub esp, 4
+
+ ; set bss vars
+ mov eax, [ebp+_BUFFER]
+ mov [buffer], eax
+ mov eax, [ebp+_BUFFER_LINES]
+ mov [buffer_lines], eax
+ mov eax, [ebp+_BUFFER_FILENAME]
+ mov [buffer_filename], eax
+ mov DWORD [cur_line], 0x00
+
+ _repl_loop:
+
+ ; print the prompt
+ push prompt_str
+ call printf
+ push DWORD [stdout]
+ call fflush
+
+ ; read line from stdin
+ push 0
+ call readLine
+
+ mov DWORD [ebp-CMDSTR], eax
+
+ ; commands are single char for now
+ cmp ecx, 1
+ jne _repl_invalid_cmd
+
+ ; parse commands
+ mov eax, DWORD [ebp-CMDSTR]
+ mov eax, [eax]
+
+ ; q exists program =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'q'
+ jne _repl_cmd_quit_end
+ jmp _repl_exit
+ _repl_cmd_quit_end:
+
+ ; p prints current line =-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'p'
+ jne _repl_cmd_print_end
+
+ mov eax, DWORD [cur_line]
+ mov ecx, 4
+ mul ecx
+ add eax, [buffer]
+ push DWORD [eax]
+ push echo_str
+ call printf
+ jmp _repl_continue
+ _repl_cmd_print_end:
+
+ ; n prints the current line number =-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'n'
+ jne _repl_cmd_number_end
+
+ push DWORD [cur_line]
+ push currentline_str
+ call printf
+
+ jmp _repl_continue
+ _repl_cmd_number_end:
+
+ ; - goes to prev line =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], '-'
+ jne _repl_cmd_decline_end
+
+ ; make sure we are within bounds
+ mov eax, DWORD [cur_line]
+ sub eax, 1
+ cmp eax, 0
+ jl _repl_invalid_addr
+
+ sub DWORD [cur_line], 1
+
+ jmp _repl_continue
+ _repl_cmd_decline_end:
+
+ ; + goes to next line =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], '+'
+ jne _repl_cmd_incline_end
+
+ ; make sure we are within bounds
+ mov eax, DWORD [cur_line]
+ add eax, 1
+ cmp eax, [buffer_lines]
+ jge _repl_invalid_addr
+
+ add DWORD [cur_line], 1
+
+ jmp _repl_continue
+ _repl_cmd_incline_end:
+
+ ; g goes to first line =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'g'
+ jne _repl_cmd_jumptop_end
+
+ mov DWORD [cur_line], 0x00
+
+ jmp _repl_continue
+ _repl_cmd_jumptop_end:
+
+ ; G goes to last line =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'G'
+ jne _repl_cmd_jumpbot_end
+
+ mov eax, DWORD [buffer_lines]
+ sub eax, 1
+ mov DWORD [cur_line], eax
+
+ jmp _repl_continue
+ _repl_cmd_jumpbot_end:
+
+ ; c changes the current line =-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'c'
+ jne _repl_cmd_change_end
+
+ ; read a new line to use
+ push 0
+ call readLine
+
+ mov esi, eax
+
+ ; free old string
+ mov eax, [cur_line]
+ mov ecx, 4
+ mul ecx
+ add eax, [buffer]
+ push DWORD [eax]
+ call free
+
+ ; insert new string
+ mov eax, [cur_line]
+ mov ecx, 4
+ mul ecx
+ add eax, DWORD [buffer]
+ mov [eax], esi
+
+ jmp _repl_continue
+ _repl_cmd_change_end:
+
+ ; d delete line =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'd'
+ jne _repl_cmd_delete_end
+
+
+
+ jmp _repl_continue
+ _repl_cmd_delete_end:
+
+ ; w writes file =-=-=-=-=-=-=-=-=-=-=-=-=
+ mov eax, DWORD [ebp-CMDSTR]
+ cmp BYTE [eax], 'w'
+ jne _repl_cmd_write_end
+
+ push DWORD [buffer_filename]
+ push DWORD [buffer]
+ push DWORD [buffer_lines]
+ call writeFile
+
+ jmp _repl_continue
+ _repl_cmd_write_end:
+
+
+ ; if no commands were matched, it's an error
+ jmp _repl_invalid_cmd
+
+ ; some error messages
+ _repl_invalid_cmd:
+ push invalidcmd_str
+ call printf
+ jmp _repl_continue
+
+ _repl_invalid_addr:
+ push invalidaddr_str
+ call printf
+ jmp _repl_continue
+
+ _repl_continue:
+ jmp _repl_loop
+
+ _repl_exit:
+
+ %undef _BUFFER
+ %undef _BUFFER_LINES
+ %undef _BUFFER_FILENAME
+ %undef CMDSTR
+
+ mov esp, ebp
+ pop ebp
+ ret
+
