Thread: Device IO

CreateFile Function (Windows)

Google is your friend!

Originally Posted by Benji Wiebe

I have tried but it comes up with the error "file not found".

Are you formatting the drive name correctly?

In C, as a physical drive, named in a string literal you need "\\\\.\\PhysicalDrive0" to open drive C: You have to double the slashes because C uses the \ as an escape character like in \n ... so to get one slash you need 2.

Naming Files, Paths, and Namespaces (Windows)

Originally Posted by MSDN

NT Namespaces

There are also APIs that allow the use of the NT namespace convention, but the Windows Object Manager makes that unnecessary in most cases. To illustrate, it is useful to browse the Windows namespaces in the system object browser using the Windows Sysinternals WinObj tool. When you run this tool, what you see is the NT namespace beginning at the root, or "\". The subfolder called "Global??" is where the Win32 namespace resides. Named device objects reside in the NT namespace within the "Device" subdirectory. Here you may also find Serial0 and Serial1, the device objects representing the first two COM ports if present on your system. A device object representing a volume would be something like "HarddiskVolume1", although the numeric suffix may vary. The name "DR0" under subdirectory "Harddisk0" is an example of the device object representing a disk, and so on.

To make these device objects accessible by Windows applications, the device drivers create a symbolic link (symlink) in the Win32 namespace, "Global??", to their respective device objects. For example, COM0 and COM1 under the "Global??" subdirectory are simply symlinks to Serial0 and Serial1, "C:" is a symlink to HarddiskVolume1, "Physicaldrive0" is a symlink to DR0, and so on. Without a symlink, a specified device "Xxx" will not be available to any Windows application using Win32 namespace conventions as described previously. However, a handle could be opened to that device using any APIs that support the NT namespace absolute path of the format "\Device\Xxx".

If the device has a symlink in the Global?? namespace you can open it with CreateFile (with the symlink name, not the device path) assuming you have the correct user rights to open it.
If not then you have to use the NT api, like NtCreateFile, etc..