How to Develop a File System Filter (Windows CE 5.0)
You can develop a file system filter to export file system entry points. This allows you to encrypt, compress, or virus scan any file system loaded by the file system driver (FSD) manager. To do this, you must create an FSD that exposes the appropriate functions.
After you create a file system filter, you can debug your file system filter to verify that it is functioning properly.
Note File system filters cannot be used with the object store. For more information on the object store, see Object Store.
Hardware and Software Assumptions
- You are familiar with building a Platform Builder run-time image from the command line. For more information, see Build Tool.
To track your progress in the following table, select the check box next to each step.
| Step | Topic | |
|---|---|---|
| 1. Create an OS design. | Creating an OS Design | |
| 2. Create an FSD. | File System Driver Creation | |
| 3. Modify your FSD to expose the FSD_HookVolume and FSD_UnhookVolume functions, rather than the FSD_MountDisk and FSD_UnmountDisk functions that are supported in a generic FSD.
For more information, see File System Filter Implementation. |
Not applicable | |
| 4. Build your FSD. | Building a Device Driver from the Command Line | |
| 5. Modify the Platform.reg file for your OS design to include your file system filter. | File System Filters | |
| 6. Debug your file system filter in Platform Builder by setting a breakpoint in the entry point for FSD_HookVolume and FSD_UnhookVolume. | Setting a Breakpoint at a Source Code Line | |
| 7. Build your run-time image. | Building a Run-Time Image | |
| 8. Download your run-time image to your target device. | Downloading a Run-Time Image | |
| 9. Verify that your file system filter is being loaded correctly by running the Platform Builder debugger until you reach the breakpoints that you previously set.
If the debugger reaches the breakpoints, you have successfully added a file system filter to your run-time image. For more information, see Troubleshooting: Debugging a Driver. |
Running the Debugger Until a Breakpoint Is Reached |
See Also
File System Filters | File System Filter Implementation | File System Filter Samples | Installable File System | File System Driver Creation
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