IMAGE_DOS_HEADER STRUCT小记

IMAGE_DOS_HEADER STRUCT {
+00h WORD e_magic // Magic DOS signature MZ(4Dh 5Ah) DOS可执行文件标记
+02h WORD e_cblp // Bytes on last page of file
+04h WORD e_cp // Pages in file
+06h WORD e_crlc // Relocations
+08h WORD e_cparhdr // Size of header in paragraphs
+0ah WORD e_minalloc // Minimun extra paragraphs needs
+0ch WORD e_maxalloc // Maximun extra paragraphs needs
+0eh WORD e_ss // intial(relative)SS value DOS代码的初始化堆栈SS
+10h WORD e_sp // intial SP value DOS代码的初始化堆栈指针SP
+12h WORD e_csum // Checksum
+14h WORD e_ip // intial IP value DOS代码的初始化指令入口[指针IP]
+16h WORD e_cs // intial(relative)CS value DOS代码的初始堆栈入口
+18h WORD e_lfarlc // File Address of relocation table
+1ah WORD e_ovno // Overlay number
+1ch WORD e_res[4] // Reserved words
+24h WORD e_oemid // OEM identifier(for e_oeminfo)
+26h WORD e_oeminfo // OEM information;e_oemid specific
+29h WORD e_res2[10] // Reserved words
+3ch LONG e_lfanew // Offset to start of PE header 指向PE文件头
} IMAGE_DOS_HEADER ENDS

1.该结构有两个重要的成员，DWORD e_magic和LONG e_lfanew。DWORD e_magic为"MZ",定义为IMAGE_DOS_SIGNATURE。LONG e_lfanew存放PE头的文件偏移量。
#define IMAGE_DOS_SIGNATURE 0x4D5A // MZ
#define IMAGE_OS2_SIGNATURE 0x4E45 // NE
#define IMAGE_OS2_SIGNATURE_LE 0x4C45 // LE
#define IMAGE_NT_SIGNATURE 0x50450000 // PE00

2.DOS Stub
它是一个总是由大约100个字节所组成的和MS-DOS 2.0兼容的可执行体，用来输出象
“this program needs windows NT”之类的错误信息。win32系统都直接跳过DOS Stub定
位到PE头。