2.3.65 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.


0


1


2


3


4


5


6


7


8


9

1
0


1


2


3


4


5


6


7


8


9

2
0


1


2


3


4


5


6


7


8


9

3
0


1

CompressionState

CompressionState (2 bytes): MUST be one of the following standard values.

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.<60>

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.

The actual file or directory compression performed when a server receives a request for COMPRESSION_FORMAT_DEFAULT and COMPRESSION_FORMAT_LZNT1 is implementation-dependent.<61>

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.