Code Gem

WTF the difference is?!

Today I got a task to refine an application to make it check the file access at more detailed level. I ran into the problem of the difference of GENERIC_READ and FILE_GENERIC_READ. In MSDN the definition of GENERIC_READ is:

GENERIC_READ

FILE_READ_ATTRIBUTES

FILE_READ_DATA

FILE_READ_EA

STANDARD_RIGHTS_READ

SYNCHRONIZE

But in WinNT.h it is:

#define GENERIC_READ                     (0x80000000L)

And there is another definition on WinNT.h:

#define FILE_GENERIC_READ         (STANDARD_RIGHTS_READ     |\
                                   FILE_READ_DATA           |\
                                   FILE_READ_ATTRIBUTES     |\
                                   FILE_READ_EA             |\
                                   SYNCHRONIZE)

Which one should I use?!! Damn, this is a typical case of unfriendly API, and misguiding document!

Anyway actually I can use either. The FILE_GENERIC_READ is specific to the file kernel object, while the GENERIC_READ can apply to all kinds of kernel objects.

There are a series of great article in CodeProject which explained the topic in very much detail:

The Windows Access Control Model

• Part 1 – Background and Core Concepts. The Access Control Structures
• Part 2 – Basic Access Control programming
• Part 3 – Access Control programming with .NET v2.0
• Part 4 – The Windows 2000-style Access Control editor

March 13th, 2009 | Category: Uncategorized | Subscribe to comments | Leave a comment | Trackback URL