2.3.67 FSCTL_SET_COMPRESSION Request
The FSCTL_SET_COMPRESSION request message requests that the server set the compression state of the file or directory associated with the handle on which this FSCTL was invoked. The message contains a 16-bit unsigned integer.
The CompressionState element is as follows.
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CompressionState |
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CompressionState (2 bytes): MUST be one of the following standard values.
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Value
Meaning
COMPRESSION_FORMAT_NONE
0x0000
The file or directory is not compressed.
COMPRESSION_FORMAT_DEFAULT
0x0001
The file or directory is compressed by using the default compression algorithm.<62>
COMPRESSION_FORMAT_LZNT1
0x0002
The file or directory is compressed by using the LZNT1 compression algorithm. For more information, see [UASDC].
All other values
Reserved for future use and MUST NOT be used.
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The actual file or directory compression performed when a server receives a request for COMPRESSION_FORMAT_DEFAULT and COMPRESSION_FORMAT_LZNT1 is implementation-dependent.<63>
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If the file system of the volume containing the specified file or directory does not support per-file or per-directory compression, the request MUST NOT succeed. The error code returned in this situation is specified in section 2.2.