Windows Registry Application Developer Issues SIG North Texas PC Users Group January 11, 2003 Daniel Ogden SIG Co-Leader

Windows Registry  Windows Registry Settings (From Windows Customization presentation of )  Not for the faint of heart  Contrary to Microsoft and other’s recommendations, use “regedit.exe” rather than “regedt32.exe” for most registry operations  Permissions  Saving of keys as “Favorites”  Local run/Current User run  Default separate vdm  Current Control Set

Windows Registry  Scope of Presentation  Windows NT 4.0/2000/XP only  Registry Structure  Registry Elements  Registry in Windows Boot Process  Registry Security  Registry Customization

Windows Registry  Registry Structure  Subtree-Root Level of the Registry  Five Subtrees-  HKEY_LOCAL MACHINE Local system hardware, device drivers, services, and machine- specific application data information.Local system hardware, device drivers, services, and machine- specific application data information.  HKEY_USERS Pre-logon default user profile information and HKEY_CURRENT_USER keyPre-logon default user profile information and HKEY_CURRENT_USER key  HKEY_CURRENT_USER Currently logged on user profile informationCurrently logged on user profile information  HKEY_CLASS_ROOT Software configuration information from the HKEY_LOCAL MACHINE\SOFTWARE\Classes keySoftware configuration information from the HKEY_LOCAL MACHINE\SOFTWARE\Classes key  HKEY_CURRENT _CONFIG Hardware information from the HKEY_LOCAL MACHINE\SOFTWARE and HKEY_LOCAL MACHINE\ SYSTEM keysHardware information from the HKEY_LOCAL MACHINE\SOFTWARE and HKEY_LOCAL MACHINE\ SYSTEM keys

Windows Registry  Registry Elements  Keys/Subkeys  Defines the structure of the registry  Similar to folders in a file system  Values  Contains Registry data in specific subkeys  Five types of values String value (REG_SZ)-Single line string valueString value (REG_SZ)-Single line string value Binary value (REG_BINARY)-Binary valueBinary value (REG_BINARY)-Binary value DWORD value (REG_DWORD)-Doubleword value up to four bytes longDWORD value (REG_DWORD)-Doubleword value up to four bytes long Multi-string value (REG_MULTI_SZ)-Multiple line string valueMulti-string value (REG_MULTI_SZ)-Multiple line string value Expandable string value (REG_EXPAND_SZ)-Expandable string valueExpandable string value (REG_EXPAND_SZ)-Expandable string value  Hives  System-accessible only files containing registry database  Consist of a data file and a log file  Path- “%systemroot%\System32\config”

Windows Registry  Registry in Windows Boot Process 1.In the initial hardware detection phase, NTDETECT.COM detects the installed hardware, which information later will be stored in the HKEY_LOCAL MACHINE\HARDWARE key. 2.NTLDER then loads the information in the HKEY_LOCAL MACHINE\SYSTEM key, which contains the information regarding the device and service drivers that will be loaded. 3.NTLDR then creates the HKEY_LOCAL MACHINE\HARDWARE key and a Clone ControlSet key, which is a read-only copy of the ControlSet key created in step 2. 4.The boot process then initializes the drivers and services loaded earlier and records any errors in the Registry.

Windows Registry  Registry Security  Security is set by Registry permissions.  In Windows 2000, regedt32.exe must be used to set permissions. In Windows XP, regedit.exe can also be used.  Are two basic permission available ReadRead Full ControlFull Control  By default, only the System and Administrators have “full control” permissions  Can also create specific permissions  Inheritance behavior can be set to determine which permissions are inherited to child keys  Registry access can also be audited

Windows Registry  Registry Customization  Two native Windows Registry editors available  Regedt32.exe  Regedit.exe  While many books recommend using regedt32.exe as only it supports read-only mode and permissions (Windows 2000 only), regedit.exe is much easier to work with and is recommended for experienced Registry editors.  Can set certain keys as “Favorites” in regedit.exe  Can export keys to a text file (“regedit4” mode )

Windows Registry  Registry Customization  HKEY_CURRENT_USER  Control Panel  Software\{Various software apps}  Software\Microsoft  Software\Microsoft\Windows\Current Version  Software\Microsoft\Windows NT\Current Version  HKEY_LOCAL MACHINE  Software\Classes  Software\{Various software apps}  Software\Microsoft  Software\Microsoft\Windows\Current Version  Software\Microsoft\Windows NT\Current Version  System\CurrentControlSet

Windows Registry  Sources  Source for much of this presentation: Microsoft Windows 2000 Professional Installation and Configuration Handbook (Que Books)-Appendix A: The Registry and Registry Editors  Strongly recommend visiting as it has a collection of Registry books, Registry tips, and even a Registry tutorial