2.3.18 FSCTL_GET_COMPRESSION Reply
The FSCTL_GET_COMPRESSION reply message returns the results of the FSCTL_GET_COMPRESSION request as a 16-bit unsigned integer value that indicates the current compression state of the file or directory.
The CompressionState element is as follows.
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CompressionState |
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CompressionState (2 bytes): One of the following standard values MUST be returned.
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Value |
Meaning |
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COMPRESSION_FORMAT_NONE 0x0000 |
The file or directory is not compressed. |
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COMPRESSION_FORMAT_LZNT1 0x0002 |
The file or directory is compressed by using the LZNT1 compression algorithm. For more information, see [UASDC]. |
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All other values |
Reserved for future use and MUST NOT be used. |
The actual file or directory compression format is implementation-dependent.<26>
If the file system of the volume that contains the specified file or directory does not support per-file or per-directory compression, the request MUST NOT succeed. The error code that is returned in this situation MUST be as specified in section 2.2.
This message also returns a status code as specified in section 2.2. Upon success, the status code returned by the function that processes this FSCTL is STATUS_SUCCESS. The most common error codes are listed in the following table.
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Error code |
Meaning |
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STATUS_INVALID_PARAMETER 0xC000000D |
The output buffer length is less than 2, or the handle is not to a file or directory. |
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STATUS_INVALID_DEVICE_REQUEST 0xC0000010 |
The volume does not support compression.<27> |