SUMMARY
Win32 applications can use the
SetupDixxx APIs to enumerate all of the devices that are available on a
computer.
The EnumCD sample provided by means of this article does
the following:
- Demonstrates SetupDixxx by enumerating all the CD drives regardless of their bus type.
- Obtains a handle to the device to send IOCTL commands to
get the adapter and device properties.
- Uses SCSI pass-through commands to get the inquiry data and
the drive capabilities.
Note You can obtain drive capabilities only for drives that support
SCSI-3 multimedia commands (MMC).
MORE INFORMATION
The
following file is available for download from the Microsoft Download
Center:
Release Date: 08-Oct-2002
For more information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591 How to obtain Microsoft support files from online services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.
The EnumCD.exe file contains the following files.
|
| EnumCD.c | implements the Win32 application to
enumerate the CD drives |
| EnumCD.h | header file for EnumCD.c |
| EnumCD.htm | documentation for these samples (this
file) |
| EnumCD.exe | Windows 2000 executable program (free
build) |
| Sources | DDK build instructions |
Device enumeration
The EnumCD sample uses the device
Setup class GUID (globally unique identifier) GUID_DEVCLASS_CDROM to
enumerate all the CD drives that are installed on the computer. The sample then
obtains the device ID by getting the registry properties.
To send
IOCTLs from a Win32 application, you must have the handle of the device. To
obtain the device handle, use the device interface name to open the device. The
CD-ROM class driver exposes this interface by registering the device interface.
It uses the
CdRomClassGuid interface GUID for device registration.
A Win32
application can obtain all the registered CD-ROM interfaces by using the
SetupDixxx APIs with the same interface GUID in a loop. Because the
interface registration is done by the CD-ROM class driver, this technique works
for all types of CD drives, such as SCSI, IDE, USB, and 1394.
Device properties
You can use IOCTL_STORAGE_QUERY_PROPERTY to get the adapter and
device properties. This IOCTL takes the STORAGE_PROPERTY_QUERY data structure
as an argument. However, before you call IOCTL_STORAGE_QUERY_PROPERTY, you must
correctly set the STORAGE_PROPERTY_ID and STORAGE_QUERY_TYPE members.
The STORAGE_PROPERTY_ID determines the property to be returned. Set it to
either
StorageAdapterProperty or
StorageDeviceProperty:
- StorageAdapterProperty returns the
STORAGE_ADAPTER_DESCRIPTOR data structure, which contains adapter properties
such as the bus type, maximum transfer length, alignment mask, and others.
- StorageDeviceProperty returns the STORAGE_DEVICE_DESCRIPTOR
data structure, which contains the device type, vendor ID, product ID, and
others. This information is obtained from the respective port drivers.
For more information about this IOCTL and data structures,
visit the following Web site:
IOCTL_STORAGE_GET_MEDIA_TYPES_EX is used to get information about
types of media supported by a CD drive (whether it is a CD-ROM or DVD drive).
It does not tell whether it is a reader/writer, or what types of discs it
supports. However, you can obtain this information from the Mode Sense page.
SCSI pass-through interface
The device handle obtained is also used to send SCSI pass-through
commands to the device. The sample sends the
Inquiry command to the device to get the Inquiry data.
The
sample also sends a
Mode Sense command to read the "CD Capabilities and Mechanical Status"
parameter page from the device. This page contains (among other things)
information about the capabilities of the CD drive, including whether it is a
CD or DVD drive, whether it supports reading or writing, and the media types it
supports (such as CD-R/RW or DVD-ROM/R/RAM). As mentioned earlier, this
parameter page is defined only in the SCSI-3 MMC specification. Devices that do
not support this specification will return an error.
For more
information about the SCSI pass-through interface, see the SPTI sample, which
is available in the Windows 2000 DDK.
Building the sample
- Under the Development Kits program group, click either the Free Build Environment icon or the Checked Build Environment icon to set the basic environment variables that are needed by
the Build utility.
- Change to the folder that contains the device source code,
for example:
- Run the Build utility: either type build
-ceZ, or use the BLD macro.
This method invokes the
Microsoft Make routines that produce log files named as follows (where
xxx is "fre" or "chk", depending on the environment
you choose) if there are any warnings or errors:- Buildxxx.log
- Buildxxx.err
- Buildxxx.wrn
Note If the build succeeds, the executable EnumCD.exe file is placed
in a platform-specific subfolder of your TargetPath
folder that is specified in the Sources file.
Running the EnumCD.exe sample
This sample does not require any arguments. Run the sample from a
command prompt. Properties of all the CD drives will be listed.
