linux – 如何调试需要用户输入的NASM汇编程序?
发布时间:2020-12-13 22:49:37 所属栏目:Linux 来源:网络整理
导读:我正在阅读杰夫的惊人书籍 assembly step by step,我在第8章,他展示了一个汇编程序的例子,它以这种方式从用户那里获取文件: SECTION .bss ; Section containing uninitialized data BUFFLEN equ 1024 ; Length of buffer Buff: resb BUFFLEN ; Text buffer
我正在阅读杰夫的惊人书籍
assembly step by step,我在第8章,他展示了一个汇编程序的例子,它以这种方式从用户那里获取文件:
SECTION .bss ; Section containing uninitialized data BUFFLEN equ 1024 ; Length of buffer Buff: resb BUFFLEN ; Text buffer itself 它将文件文本读入Buff,并将ALL CAPS中该文本的一个版本输出到另一个文件. 我想在调试模式下运行该程序,以逐步分析所有寄存器的情况. 我正在使用INSIGHT在ubuntu上运行它. 我是一个完全的初学者.我知道如何使用Insight来逐步完成,但用户运行此程序的方式是: myProgram > outputfile.txt < inputfile.txt 我如何在调试器中模仿这个? 这里是完整的来源: ; Executable name : uppercaser2 ; Version : 1.0 ; Created date : 3/25/2009 ; Last update : 3/25/2009 ; Author : Jeff Duntemann ; Description : A simple program in assembly for Linux,using NASM 2.05,; demonstrating simple text file I/O (through redirection) for reading an ; input file to a buffer in blocks,forcing lowercase characters to ; uppercase,and writing the modified buffer to an output file. ; ; Run it this way: ; uppercaser2 > (output file) < (input file) ; ; Build using these commands: ; nasm -f elf -g -F stabs uppercaser2.asm ; ld -o uppercaser2 uppercaser2.o ; SECTION .bss ; Section containing uninitialized data BUFFLEN equ 1024 ; Length of buffer Buff: resb BUFFLEN ; Text buffer itself SECTION .data ; Section containing initialised data SECTION .text ; Section containing code global _start ; Linker needs this to find the entry point! _start: nop ; This no-op keeps gdb happy... ; Read a buffer full of text from stdin: read: mov eax,3 ; Specify sys_read call mov ebx,0 ; Specify File Descriptor 0: Standard Input mov ecx,Buff ; Pass offset of the buffer to read to mov edx,BUFFLEN ; Pass number of bytes to read at one pass int 80h ; Call sys_read to fill the buffer mov esi,eax ; Copy sys_read return value for safekeeping cmp eax,0 ; If eax=0,sys_read reached EOF on stdin je Done ; Jump If Equal (to 0,from compare) ; Set up the registers for the process buffer step: mov ecx,esi ; Place the number of bytes read into ecx mov ebp,Buff ; Place address of buffer into ebp dec ebp ; Adjust count to offset ; Go through the buffer and convert lowercase to uppercase characters: Scan: cmp byte [ebp+ecx],61h ; Test input char against lowercase 'a' jb Next ; If below 'a' in ASCII,not lowercase cmp byte [ebp+ecx],7Ah ; Test input char against lowercase 'z' ja Next ; If above 'z' in ASCII,not lowercase ; At this point,we have a lowercase char sub byte [ebp+ecx],20h ; Subtract 20h to give uppercase... Next: dec ecx ; Decrement counter jnz Scan ; If characters remain,loop back ; Write the buffer full of processed text to stdout: Write: mov eax,4 ; Specify sys_write call mov ebx,1 ; Specify File Descriptor 1: Standard output mov ecx,Buff ; Pass offset of the buffer mov edx,esi ; Pass the # of bytes of data in the buffer int 80h ; Make kernel call jmp read ; Loop back and load another buffer full ; All done! Let's end this party: Done: mov eax,1 ; Code for Exit Syscall mov ebx,0 ; Return a code of zero int 80H ; Make kernel call 解决方法
听起来你想将进程附加到GDB.你可以试试这个.
shell$gdb ./uppercaser2 gdb> list gdb> break read gdb> run > ouput.txt < input.txt gdb> x/5i $eip 在shell提示符下,启动GDB并将uppercaser2附加到GDB.应加载调试符号,您可以使用列表来检查来源.通过行号或功能名称在所需位置创建断点.使用GDB的运行来启动输入和输出文件的程序.从这里,您可以使用GDB命令分析寄存器并逐步执行内存. (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |