C语言与汇编语言混合编程..doc

C与汇编混合语言编程
1、先准备两个程序,一个汇编、一个C语言
在汇编中没有定义变量,因为在一个模块中不会有问题;
在C中定义了两个函数,一些局部变量,一些全局变量;
这样我们要考虑的内容都完备了。
ms.asm mc2.c
.386 int sum(int i{
.model flat int k = i;
extrn c m:near int j = 0;
public _start int s = 0;
.code for(j=1;j<=k;j++ s+=j;
_start: return s;
mov ax,cs }
mov ds,ax
call m int e = 1;
stop: int f = 2;
jmp stop int ar[6000000L];
end _start
extern void m({
int d;
long c;
c=1;
2、分别编译成obj文件
ml /c /coff ms.asm //指定生成coff格式的obj文件
cl /c /Fomc.obj mc2.c //指定生成的obj文件名为mc.obj
link /subsystem:windows ms.obj mc.obj //这里使用32位的链接器,要设好lib路径
现在得到ms.obj mc.obj ms.exe 三个文件
3、分析一下源代码,显然程序入口点是_start(在使用/coff参数进行编译时必须有下划线,在汇编中调用了C中的m函数,这是需要重定位的。在C中m调用了sum函数,这也是要重定位的。
4、现在利用VC6自带的dumpbin.exe工具,生成解析文件:
dumpbin /all ms.obj>msobj.txt
dumpbin /all mc.obj>mcobj.txt
dumpbin /all ms.exe>msexe.txt
现在得到三个解析文件,下面逐个分析
*******************************************************************************
*msobj.txt
******************************************************************************* Microsoft (R COFF Binary File Dumper Version 5.12.8078
Copyright (C Microsoft Corp 1992-1998. All rights reserved.
Dump of file ms.obj
File Type: COFF OBJECT
FILE HEADER valueS
14C machine (i386 //机器类型为386
3 number of sections //ms.obj文件有三节
41AABB57 time date stamp Mon Nov 29 14:01:59 2004
B2 file pointer to symbol table //符号表的文件偏移是 0B2H
B number of symbols //共 0BH=11 个符号
0 size of optional header
0 characteristics
//第一节的头部
SECTION HEADER #1
.text name
0 physical address
0 virtual address
D size of raw data //原始数据长度为 0DH=13 个字节
8C file pointer to raw data //其在文件内的偏移为 8Ch
9A file pointer to relocation table //其重定位表在文件内的偏移为9Ah
0 file pointer to line numbers
1 number of relocations //需重定位的项有 1 项
0 number of line numbers
60300020 flags
Code //这是一个代码段
4 byte align
Execute Read
RAW DATA #1 //这里列出了原始数据,恰好 13=0DH 个字节00000000: 66 8C C8 66 8E D8 E8 00 00 00 00 EB FE f..f.........
|-->这是偏移7的位置,查下面的重定位表知道它需要重定位。
当前值是 00 00 00 00 ,E8代表call
RELOCATIONS #1 //这是重定位表
Symbol Symbol
Offset Type Applied To Index Name
-------- ---------------- ----------------- -------- ------
00000007 REL32 00000000 7 _m //清楚的指出_m需要重定位 \\ \\
\\-->在原始数据内的偏移是7 \\
\\-->7表示_m在符号表中的索引号
//第二节的头部
SECTION HEADER #2
.data name
D physical address
0 virtual address
0 size of raw data
0 file pointer to raw data
0 file pointer to relocation table
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
C0300040 flags
Initialized Data //这节是初始化的数据段,也就是全局变量段,
4 byte align //上面所有的项都是0,说明汇编中没有定义全局变量
Read Write //注意,汇编中定义的_start是全局标号,并不是变量!!!
//第三节的头部
SECTION HEADER #3
.drectve name
D physical address
0 virtual address
D size of raw data //原始数据共 0Dh
A4 file pointer to raw data //在obj文件中的偏移为0A4h
0 file pointer to relocation table
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
A00 flags
Info //表明这只是一个信息段,即不是数据也不是代码,
Remove //只是用来说明某种支持信息
(no align specified
RAW DATA #3 //看一下原始数据,原来是说明程序的入口点是_start,完全正确00000000: 2D 65 6E 74 72 79 3A 73 74 61 72 74 20 -entry:start
Linker Directives
-----------------
-entry:start
//符号表
COFF SYMBOL TABLE
000 00000000 DEBUG notype Filename | .file
ms.asm
002 001220FC ABS notype Static | @comp.id
003 00000000 SECT1 notype Static | .text
Section length D, #relocs 1, #linenums 0, checksum 0
005 00000000 SECT2 notype Static | .data
Section length 0, #relocs 0, #linenums 0, checksum 0
007 00000000 UNDEF notype ( External | _m
008 00000000 SECT1 notype ( External | start
009 00000000 SECT3 notype Static | .drectve
Section length D, #relocs 0, #linenums 0, checksum 0
//可以看到_m被说明为未定义(UNDEF、外部变量(External、是个函数 ( (
//start定义在节1中(SECT1、是个函数((、可供外部使用(External
//字符串信息为0,即不存在
String Table Size = 0x0 bytes
Summary
0 .data
D .drectve
D .text
****************************************************************************** *mc.obj
****************************************************************************** Microsoft (R COFF Binary File Dumper Version 5.12.8078
Copyright (C Microsoft Corp 1992-1998. All rights reserved.
Dump of file mc.obj
File Type: COFF OBJECT
FILE HEADER valueS
14C machine (i386 //机器类型为386
2 number of sections //mc.obj文件有2节
41AABA2D time date stamp Mon Nov 29 13:57:01 2004
158 file pointer to symbol table //符号表的文件偏移是 158H
C number of symbols //共 0CH=12 个符号
0 size of optional header
0 characteristics
//第一节的头部
SECTION HEADER #1
.drectve name
0 physical address
0 virtual address
26 size of raw data //原始数据长充为 26H=38 个字节
64 file pointer to raw data //其在文件内的偏移为 64h
0 file pointer to relocation table
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
100A00 flags
Info //这是一个信息段
Remove
1 byte align
//第一节的原始数据
RAW DATA #1 //原来是说明默认库的信息00000000: 2D 64 65 66 61 75 6C 74 6C 69 62 3A 4C 49 42 43 -defaultlib:LIBC 00000010: 20 2D 64 65 66 61 75 6C 74 6C 69 62 3A 4F 4C 44 -defaultlib:OLD 00000020: 4E 41 4D 45 53 20 NAMES
Linker Directives
-----------------
-defaultlib:LIBC
-defaultlib:OLDNAMES
//第二节的头部
SECTION HEADER #2
.text name
0 physical address
0 virtual address
A6 size of raw data //原始数据长充为 0A6H=166 个字节
8A file pointer to raw data //其在文件内的偏移为 8Ah
130 file pointer to relocation table //其重定位表在文件内的偏移为130h
0 file pointer to line numbers
4 number of relocations //需重定位的项有4项
0 number of line numbers
60500020 flags
Code //这是一个代码段
16 byte align //对齐方式是以16个字节的小段边缘对齐
Execute Read //该代码可读、可执行
//这点可通过编译参数/SECTION来改变
//第二节的原始数据
//使用W32Dasm打开mc.obj文件,输入偏移地址为8Ah(见第二节的头部说明,反编译下面这段
//与汇编生成的lst文件对比,可以看出下面的数据从偏移0开始的55 8B到偏移44H的5D C3是sum //函数的数据。紧跟其后直至最后的是函数 m 的代码
//这里可以看出,32位编译器把所有的代码按它们在源代码中出现的顺序“堆积”在obj文件中
RAW DATA #2
00000000: 55 8B EC 83 EC 0C 8B 45 08 89 45 F4 C7 45 F8 00 U......E..E..E..
00000010: 00 00 00 C7 45 FC 00 00 00 00 C7 45 F8 01 00 00 ....E......E....
00000020: 00 EB 09 8B 4D F8 83 C1 01 89 4D F8 8B 55 F8 3B ....M.....M..U.;
00000030: 55 F4 7F 0B 8B 45 FC 03 45 F8 89 45 FC EB E4 8B U....E..E..E....
00000040: 45 FC 8B E5 5D C3 55 8B EC 83 EC 08 C7 45 FC 01 E...].U......E..
00000050: 00 00 00 C7 45 F8 01 00 00 00 C7 05 00 00 00 00 ....E...........
00000060: 01 00 00 00 C7 05 00 00 00 00 01 00 00 00 6A 05 ..............j.
00000070: E8 00 00 00 00 83 C4 04 C7 45 FC 00 00 00 00 EB .........E......
00000080: 09 8B 45 FC 83 C0 01 89 45 FC 81 7D FC 80 5B ..E.....E..}.€.[
00000090: 00 7D 0F 8B 4D FC 8B 55 FC 89 14 00 00 00 00 .}..M..U........
000000A0: EB DF 8B E5 5D C3 ....].
//第二节的重定位表
RELOCATIONS #2
Symbol Symbol
Offset Type Applied To Index Name
-------- ---------------- ----------------- -------- ------
0000005C DIR32 00000000 7 _e
00000066 DIR32 00000000 6 _f
00000071 REL32 00000000 A _sum
0000009C DIR32 00000000 5 _ar
//可以看到_sum要重定位,所有的全局变量也要重定位,它们各自在上面原始数据中的位置都正确的记录着
COFF SYMBOL TABLE
000 00000000 DEBUG notype Filename | .file
mc2.c
002 000A1FE8 ABS notype Static | @comp.id
003 00000000 SECT1 notype Static | .drectve
Section length 26, #relocs 0, #linenums 0, checksum 0
005 016E3600 UNDEF notype External | _ar
006 00000004 UNDEF notype External | _f
007 00000004 UNDEF notype External | _e
008 00000000 SECT2 notype Static | .text
Section length A6, #relocs 4, #linenums 0, checksum DB3BC338
00A 00000000 SECT2 notype ( External | _sum
00B 00000046 SECT2 notype ( External | _m
String Table Size = 0x0 bytes
Summary
26 .drectve
A6 .text
******************************************************************************* *ms.exe
******************************************************************************* Microsoft (R COFF Binary File Dumper Version 5.12.8078
Copyright (C Microsoft Corp 1992-1998. All rights reserved.
//因为ms.exe实际上是一个可执行文件了,这里的结构就是Windows的PE头结构
Dump of file ms.exe
PE signature found
File Type: EXECUTABLE IMAGE
FILE HEADER valueS
14C machine (i386 //机器类型为386
2 number of sections //ms.exe文件有2节
41AABAC2 time date stamp Mon Nov 29 13:59:30 2004
0 file pointer to symbol table
0 number of symbols
E0 size of optional header //这里有个可选头
10F characteristics
Relocations stripped
Executable
Line numbers stripped
Symbols stripped
32 bit word machine
OPTIONAL HEADER valueS //可选头说明程序的基本情况,告诉操作系统如何加载它
10B magic #
6.00 linker version
1000 size of code
16E4000 size of initialized data //初始化数据大小,也就是为全局变量分配的空间
0 size of uninitialized data
1000 RVA of entry point //入口点在文件中的偏移,打开ms.exe,查看一下1000h 处,呵呵,确实是汇编部分的代码
1000 base of code //代码段在文件内的偏移
2000 base of data //数据段在文件内的偏移
400000 image base //告诉操作系统将程序到内存线性地址时,应以止为基址 1000 section alignment //段对齐方式
1000 file alignment //文件对齐方式
4.00 operating system version
0.00 image version
4.00 subsystem version
0 Win32 version
16E6000 size of image //文件镜像大小
1000 size of headers //PE头大小,说明真正的文件内容从1000h开始,与前面的各处吻合
0 checksum
2 subsystem (Windows GUI
0 DLL characteristics
100000 size of stack reserve
1000 size of stack commit
100000 size of heap reserve
1000 size of heap commit
0 loader flags
10 number of directories
0 [ 0] RVA [size] of Export Directory
0 [ 0] RVA [size] of Import Directory
0 [ 0] RVA [size] of Resource Directory
0 [ 0] RVA [size] of Exception Directory
0 [ 0] RVA [size] of Certificates Directory
0 [ 0] RVA [size] of Base Relocation Directory
0 [ 0] RVA [size] of Debug Directory
0 [ 0] RVA [size] of Architecture Directory
0 [ 0] RVA [size] of Special Directory
0 [ 0] RVA [size] of Thread Storage Directory
0 [ 0] RVA [size] of Load Configuration Directory
0 [ 0] RVA [size] of Bound Import Directory
0 [ 0] RVA [size] of Import Address Table Directory
0 [ 0] RVA [size] of Delay Import Directory
0 [ 0] RVA [size] of Reserved Directory
0 [ 0] RVA [size] of Reserved Directory
//第一节的头部
SECTION HEADER #1
.text name
B6 virtual size
1000 virtual address
1000 size of raw data
1000 file pointer to raw data //在文件内的偏移是 1000h
0 file pointer to relocation table //可执行文件无重定位表
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
60000020 flags
Code //这是代码段
Execute Read
//原始数据
//对照lst文件可知,从偏移0开始的66 8C到偏移0Ch的FE结束的是ms.asm编译的结果,后面//3 个字节的CC CC CC,是以16字节小段对齐的结果,在正常情况下,不可能执行
//到这3个字节。
//从偏移10h开始的55 8B到54h的5D C3是sum(编译的结果,56h开始到结束是m(编译的结果。//下面看一下应该重定位的项当前的值:
RAW DATA #1
00401000: 66 8C C8 66 8E D8 E8 4B 00 00 00 EB FE CC CC CC f..f...K........ 00401010: 55 8B EC 83 EC 0C 8B 45 08 89 45 F4 C7 45 F8 00 U......E..E..E.. 00401020: 00 00 00 C7 45 FC 00 00 00 00 C7 45 F8 01 00 00 ....E......E.... 00401030: 00 EB 09 8B 4D F8 83 C1 01 89 4D F8 8B 55 F8 3B ....M.....M..U.; 00401040: 55 F4 7F 0B 8B 45 FC 03 45 F8 89 45 FC EB E4 8B U....E..E..E.... 00401050: 45 FC 8B E5 5D C3 55 8B EC 83 EC 08 C7 45 FC 01 E...].U......E.. 00401060: 00 00 00 C7 45 F8 01 00 00 00 C7 05 00 20 40 00 ....E........ @. 00401070: 01 00 00 00 C7 05 04 20 40 00 01 00 00 00 6A 05 ....... @.....j. 00401080: E8 8B FF FF FF 83 C4 04 C7 45 FC 00 00 00 00 EB .........E...... 00401090: 09 8B 45 FC 83 C0 01 89 45 FC 81 7D FC 80 5B ..E.....E..}.€.[
004010A0: 00 7D 0F 8B 4D FC 8B 55 FC 89 14 20 20 40 00 .}..M..U.... @.
004010B0: EB DF 8B E5 5D C3 ....].
//下面为了分析,对上面的代码进行了多次拷贝
//1、对照msobj.txt的重定位指示
//00000007 REL32 ... _m -->这是msobj.txt中的重定位指示
/ 现在它是00 00 00 4B,计算一下:m(开始于56H,
/ EB 4B 00 00 00是call 4B的意思,它的下一条指令
/ 开始于0Bh处,所以call _m转换计算如下:
/ 56H - 0BH = 4Bh 即为call 4B完全正确!!!
/
RAW DATA #1 / /-->这里的偏移是0BH
00401000: 66 8C C8 66 8E D8 E8 4B 00 00 00 EB FE CC CC CC f..f...K........
00401010: 55 8B EC 83 EC 0C 8B 45 08 89 45 F4 C7 45 F8 00 U......E..E..E..
00401020: 00 00 00 C7 45 FC 00 00 00 00 C7 45 F8 01 00 00 ....E......E....
00401030: 00 EB 09 8B 4D F8 83 C1 01 89 4D F8 8B 55 F8 3B ....M.....M..U.;
00401040: 55 F4 7F 0B 8B 45 FC 03 45 F8 89 45 FC EB E4 8B U....E..E..E....
00401050: 45 FC 8B E5 5D C3 55 8B------------55 是m(的开始,该处偏移是56H
//2、对照mcobj.txt的重定位指示
//0000005C DIR32 00000000 7 _e
//00000066 DIR32 00000000 6 _f
//00000071 REL32 00000000 A _sum
//0000009C DIR32 00000000 5 _ar
//因为mc2.c中代码编译结果在ms.exe的代码段中是从偏移10H处开始的,所以上面的重定位偏移相应//的都要加上10H成为 6CH 76H 81H ACH
//先看三个与数据段有关的重定位
-->偏移 6CH处现为00 20 40 00,即地址402000H
/ C7 05 00 20 40 00 01 00 00 00 = mov [402000H],1
/ 也就是C程序中的 e = 1 ,其中的e是一个全局变量
/ 注意这里用了绝对地址402000H,这意味着如果代码段不是初始化在 / 402000H处的话,程序将出错!!!!!!!!
//a、00401060: .... C7 05 00 20 40 00
// 00401070: 01 00 00 00
//b、00401074: C7 05 04 20 40 00 01 00 00 00 //mov word prt [402000H],1
//c、004010A9: 89 14 20 20 40 00 //movDWORD PTR [402020][ecx*4], edx
//b、 c同a ,如果数据段的加载地址不是402000H时将出错
//再看一下与函数sum(相关的重定位
//00401080: E8 8B FF FF FF //call FF FF FF 8B
//我们知道FF FF FF 8B其实就是-75H的补码表示法,好,算一下
//call FF FF FF 8B的下一条指令开始于85H
//85H + (-75H= 10 H
//从前面的分析已经看到,sum(开始于10H,所以这里就是call _sum //完全正确,因为是相对位置,所以无论代码段初始化在什么地方都不会出错
SECTION HEADER #2
.data name
16E3620 virtual size
2000 virtual address
1000 size of raw data //原始数据大小为1000H=4096字节
2000 file pointer to raw data //开始于文件偏移2000H处
0 file pointer to relocation table
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
C0000040 flags
Initialized Data //初始化的数据段
Read Write
/-->int e = 1;
/
/ /-->int f = 2;
/ /
/ /
/ / /-->int ar[6000000L];这里很大的空间
RAW DATA #2 / / /
00402000: 01 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00 ................
00402010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
004020A0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
004020B0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
004020C0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
004020D0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
004020E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00402100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00402190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................