Go deep into Windows ME system files

The pursuit of stability is the goal of any operating system, and Windows Me is no exception. Unfortunately, Windows itself is a messy operating system with messy configuration and arrangement of system files: system files are not properly differentiated from general application software files (unlike Unix, distinguish the user zone from the system), and most of the application software must be combined with some system files for normal execution, therefore, the installation program of some application software has to install the system files together to the user's computer, and the problem of system instability arises ......
For example. For example, if your current Windows System uses a System file System. dll with the version 5.1, it is placed in the System directory under the Windows System directory. You have installed an application named Winkiller (for example, it is only used), but this software uses the System version 3.0. dll System file. The Winkiller installer will use the old version of System. the dll is copied to the System directory under the Windows System directory, what's more, the installer simply overwrites the system files of the new and old versions (many games and irresponsible applications do this ).
What are the consequences of overwriting system files? It is hard to say that if you are lucky enough, you may not have any problems. But in most cases, it is to make your system unstable or crash at some specific time. In this case, Microsoft engineers use the DLL Hell-the Windows system uses the Dynamic Link Library (Dynamic Link Library) to share all the system files with the application software, DLL Hell means that the whole system is like a Hell because the system file is overwritten.
Okay, after you curse Microsoft, let's take a look at Microsoft's improvement (or remedy) measures in its new version of Windows Me-System File Protection.
Strictly speaking, System File Protection (SFP) should be an enhanced version of System File Checker. Microsoft once added the System File Checker function to automatically check the System File status in Windows 98 SE, but in fact, the System File Checker does not play much role-if it is true, probably no SFP will appear now ^_^.
SFP detects system files in real time after Windows Me is started. As long as SFP detects that system files will be overwritten or deleted, it "pretends" to allow users or applications to overwrite or delete system files, however, SFP immediately backs up the system files that will be overwritten or deleted. As long as the user or application completes the overwriting or deletion process, SFP will immediately restore the system files backed up previously.
To achieve the above protection effect, SFP saves two lists. One copy records the names of all SFP-protected system files, which are stored in C: WINDOWSSYSTEMsfpsfpdb. sfp (assuming the installation directory of Windows Me is C: WINDOWS ). Sfpdb. sfp is a readable text file, which can be opened using tools such as Notepad. in sfp, a whole row of records is a protected system file (see figure 1 ).
However, sfpdb. sfp alone is not enough-if only sfpdb. sfp in text file format is available, anyone can tamper with the content of sfpdb. sfp on their own, so the protection is not protected. Therefore, Microsoft uses the "security directory" file (Suffix. cat) to store these protected digital signatures, the digital signatures of these currently protected SYSTEM files are stored in C: WINDOWSSYSTEMCatRoot {F750E6C3-38EE-11D1-85E5-00C04FC295EE} SYSTEM. in CAT. You can double-click SYSTEM. CAT file, the system will pop up the "security directory" Window of 2. If you press the "view signature" button in the lower right corner of the window, the "Digital Signature Details" Window of 3 will appear.
We can test the SFP protection function by ourselves: first, browse sfpdb. sfp content, find a system file protected by SFP, and then directly delete it in the directory where the file is stored or overwrite it with other files. If you are not comfortable with the SFP function, you can move the protected system files to other places.
Let's take a look at a test example. I deleted C: WINDOWSSYSTEM MSRATING. DLL. The SFP automatically restored the result in just a few seconds. Throughout the process, you can not only directly observe the test results in "Resource Manager", but also use the SFP system to record the file C: WINDOWSSYSTEMsfpsfplog.txt to view the operation process of SFP (see figure 4 ).
Is SFP really safe to protect users from falling into the DLL Hell? This problem should be solved in two aspects: first, SFP alone cannot completely solve the DLL Hell, SFP only passively prevents system files from being deleted or overwritten (as Windows 2000 uses Wondows File Protection to provide similar functions). program developers only need to pay attention to problems arising when using system files, in this way, you can avoid overwriting system files during software development to achieve dual protection against the entire DLL Hell problem. In addition, in some cases, some protected system files cannot be restored by SFP, so you still cannot rest assured ......