对象文件结构的分析：VC

我们在Windows下编程时，如我们在VC下开发C/C++程序，程序写完后再经编译、链接生成可运行的程序。在编译时通常会生成一个obj对象文件，这个obj对象文件是什么文件呢？它里边包括哪些信息？

 

该obj对象实际上是一个COFF格式的文件，它是一种公共对象文件格式文件（Common Object File Format）。

 

一个简单的例子

写道

>od -A x -t x1 simpletest.obj

 

 

 

000000 4c 01 02 00 fb 50 f1 5c 8f 00 00 00 08 00 00 00

000010 00 00 00 00 2e 64 72 65 63 74 76 65 00 00 00 00

000020 00 00 00 00 26 00 00 00 64 00 00 00 00 00 00 00

000030 00 00 00 00 00 00 00 00 00 0a 10 00 2e 74 65 78

000040 74 00 00 00 00 00 00 00 00 00 00 00 05 00 00 00

000050 8a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

000060 20 00 50 60 2d 64 65 66 61 75 6c 74 6c 69 62 3a

000070 4c 49 42 43 20 2d 64 65 66 61 75 6c 74 6c 69 62

000080 3a 4f 4c 44 4e 41 4d 45 53 20 55 8b ec 5d c3 2e

000090 66 69 6c 65 00 00 00 00 00 00 00 fe ff 00 00 67

0000a0 01 73 69 6d 70 6c 65 74 65 73 74 2e 63 00 00 00

0000b0 00 00 00 40 63 6f 6d 70 2e 69 64 e8 1f 0a 00 ff

0000c0 ff 00 00 03 00 2e 64 72 65 63 74 76 65 00 00 00

0000d0 00 01 00 00 00 03 01 26 00 00 00 00 00 00 00 00

0000e0 00 00 00 00 00 00 00 00 00 2e 74 65 78 74 00 00

0000f0 00 00 00 00 00 02 00 00 00 03 01 05 00 00 00 00

000100 00 00 00 56 e8 2b 67 00 00 00 00 00 00 5f 6d 61

000110 69 6e 00 00 00 00 00 00 00 02 00 20 00 02 00 04

000120 00 00 00

 

0-1 4C 01 表示机器类型：Intel 386 or later processors and compatible processors 

2-3 02 00  段（section）的个数、

5-7 FB 50 F1 5C  从00:00 January 1, 1970 (a C run-time time_t value)到现在的秒数（低32位）

8-11 8F 00 00 00 COFF符号表的起始偏移位置

12-15 08 00 00 00 符号的个数

16-17 00 00  Optional头部的大小

18-19 00 00 文件属性

 

20-59

2E 64 72 65  63 74 76 65 00 00 00 00

00 00 00 00 26 00 00 00  64 00 00 00 00 00 00 00

 

00 00 00 00 00 00 00 00  00 0A 10 00 

第1个段（section）

20-27

2E 64 72 65  63 74 76 65  段名称（.drectve）

28-31

 

00 00 00 00 段加载到内存的大小

 

60-99

2E 74 65 78

74 00 00 00 00 00 00 00  00 00 00 00 05 00 00 00

8A 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00

 

20 00 50 60 

第2个段（section）