The Portable Executable File Format

This chapter gives you a comprehensive picture of the Portable Executable file format for Windows NT. The PE format is portable across all Microsoft 32-bit operating systems.

MICROSOFT INTRODUCED A NEW executable file format with Windows NT. This format is called the Portable Executable (PE) format because it is supposed to be portable across all 32-bit operating systems by Microsoft. The same PE format executable can be executed on any version of Windows NT, Windows 95, and Win32s. Also, the same format is used for executables for Windows NT running on processors other than Intel x86, such as MIPS, Alpha, and Power PC. The 32-bit DLLs and Windows NT device drivers also follow the same PE format.

It is helpful to understand the PE file format because PE files are almost identical on disk and in RAM. Learning about the PE format is also helpful for understanding many operating system concepts. For example, how operating system loader works to support dynamic linking of DLL functions, the data structures involved in dynamic linking such as import table, export table, and so on.

The PE format is not really undocumented. The WINNT.H file has several structure definitions representing the PE format. The Microsoft Developer's Network (MSDN) CD-ROMs contain several descriptions of the PE format. However, these descriptions are in bits and pieces, and are by no means complete. In this chapter, we try to give you a comprehensive picture of the PE format.

Microsoft also provides a DLL with the SDK that has utility functions for interpreting PE files. We also discuss these functions and correlate them with other information about the PE format.