CIFS Access Mode Encoding

  • Article

Client requests and server responses, such as SMB_COM_OPEN, pass file access modes encoded into a USHORT value.

The encoding of these file access modes is as follows:

    1111 11
    5432 1098 7654 3210
    rWrC rLLL rSSS rAAA

  • W
    Write through mode.

    No read ahead or write behind allowed on this file or device. When the response is returned, data is expected to be on the disk or device.

  • S
    Sharing mode for read/write.

    Code Description
    0 Compatibility mode
    1 Deny read/write/execute (exclusive)
    2 Deny write
    3 Deny read/execute
    4 Deny none

  • A
    Access mode for read/write.

    Code Description
    0 Open for reading
    1 Open for writing
    2 Open for reading and writing
    3 Open for execute

  • C
    Cache mode.

    Code Description
    0 Normal file
    1 Do not cache this file

  • L
    Locality of reference.

    Code Description
    0 Locality unknown
    1 Mainly sequential access
    2 Mainly random access
    3 Random access with some locally
    4 to 7 Currently undefined

See Also

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