global main
extern printf
+extern fflush
+extern stdout
+
+; macros
+%macro write_str 2
+ mov eax, 4
+ mov ebx, 1
+ mov ecx, %1
+ mov edx, %2
+ int 0x80
+%endmacro
section .data
banner_str db `SPED - the stupidly pointless editor\n`, 0x00
nofile_str db `no file provided\n`, 0x00
+ readlines_str db `opened file with %i lines\n`, 0x00
+ 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
+ cur_line resb 4
section .text
main:
push DWORD [ebx]
call readFile
+ mov [buffer], eax
+ mov [buffer_lines], ecx
+ mov DWORD [cur_line], 0x00
+
+ push DWORD [buffer_lines]
+ push readlines_str
+ call printf
+
+ call repl
+
mov eax, 0
jmp _main_exit
pop ebp
ret
+; prompt for user
+; no args - reads from globals
+repl:
+
+ %define CMDSTR 4 ; the previous line read from user
+
+ push ebp
+ mov ebp, esp
+
+ sub esp, 4
+
+ _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:
+
+
+ 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 CMDSTR
+
+ mov esp, ebp
+ pop ebp
+ ret
+
