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How to Test Autorun.inf Files

This article was previously published under Q136214
Retired KB Content Disclaimer
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.
AutoPlay is enabled by the new 32-bit, protected-mode driver architecturein Microsoft Windows 95 and Microsoft Windows 98. Because the operating system can now detect the insertion ofmedia in a CD-ROM drive, it has the opportunity to do some intelligentprocessing whenever this occurs.

By default, Windows 95 and Windows 98 only check for an Autorun.inf file when a CD-ROM disc is inserted into the CD-ROM drive. However, you may want to test for syntax and logic errors before burning a CD-ROM disc. This article explains how.
In Windows 9x, whenever a CD-ROM disc is inserted, the shell immediately checks to see if the CD-ROM disc has a PC filesystem. If it does, Windows 9x looks for a file named Autorun.inf. If the file exists, Windows 9xfollows the instructions contained in the file, which usuallyinvolves running a setup application of some sort.

However, by changing a setting in the Windows 9x registry, you can have theShell use AutoPlay on any media, including shared network drives and floppydisks.

The registry key that needs to be modified is:
HKEY_CURRENT_USER\    Software\       Microsoft\          Windows\             CurrentVersion\                Policies\                   Explorer\                      "NoDriveTypeAutoRun"				
This key, which is of type REG_BINARY, consists of four bytes. The firstbyte is a bitmask defining which drive types should be AutoRun. Theother three bytes should be set to zero (0).

The bits in the bitmask correspond to these constants:
Type                BitDRIVE_UNKNOWN       0DRIVE_NO_ROOT_DIR   1DRIVE_REMOVABLE     2DRIVE_FIXED         3DRIVE_REMOTE        4DRIVE_CDROM         5DRIVE_RAMDISK       6				
Setting a bit in the bitmask prevents you from using AutoPlay with thecorresponding drive type. By default, the value in the registry is 0x95.Bits 0, 2, 4 and 7 are therefore set, which means that drive typesDRIVE_UNKNOWN, DRIVE_REMOVEABLE, and DRIVE_REMOTE don't use AutoPlayinformation. (Bit 7 is set to cover future device types.) Altering thisregistry value thus allows you to test Autorun.inf files from a floppy disk(DRIVE_REMOVEABLE), network drive (DRIVE_REMOTE), and so on. For example,to be able to test AutoPlay from a floppy disk, set the value of the firstbyte to 0x91 to enable AutoPlay for floppy disks.

NOTE: Most floppy disk drive controllers do not currently recognize when afloppy disk has been inserted. To test AutoPlay on a floppy disk, firstalter the registry setting so that bit DRIVE_REMOVEABLE is not set, startthe Windows Explorer, insert the floppy disk, and press the F5 key torefresh the display.

To test the Autorun.inf file on a given disk, using the right mouse button,click the icon for the drive in the Windows Explorer. The effects of theAutorun.inf file should be visible in the context menu.

Article ID: 136214 - Last Review: 05/11/2007 17:43:56 - Revision: 2.3

  • Microsoft Win32 Software Development Kit (SDK) 4.0
  • kbfaq KB136214