代替データストリームのサンプル

Main.fsx

#load "NativeMethod.fsx"

open System
open System.IO
open System.Text
open NativeMethod

let nullptr = IntPtr.Zero

let write (str:string) handle =
    let bytes = (Encoding.GetEncoding("Shift_JIS")).GetBytes(str.ToCharArray())
    let length = Array.length >> uint32
    let mutable size = 0u
    NativeMethod.writeFile(handle, bytes, length bytes, &size, nullptr)

let read handle =
    let mutable size = 0
    NativeMethod.getFileSize(handle, &size) |> ignore
    let mutable buf = Array.zeroCreate (int size)
    let mutable readsize = 0u
    NativeMethod.readFile(handle, buf, uint32 size, &readsize, nullptr) |> ignore
    (Encoding.GetEncoding("Shift_JIS")).GetString(buf)

// 書き込みサンプル
let h = NativeMethod.createFile("sample.txt:foo", FileAccess.ReadWrite, FileShare.Read, nullptr, FileMode.OpenOrCreate, FileAttributes.Normal, nullptr)
if h <> nullptr then
    printfn "=== Write ==="
    write "ほげほげ" h |> ignore
    NativeMethod.closeHandle(h) |> ignore
else
    printfn "Failed"

// 読み込みサンプル
let h' = NativeMethod.createFile("sample.txt:foo", FileAccess.ReadWrite, FileShare.Read, nullptr, FileMode.OpenOrCreate, FileAttributes.Normal, nullptr)
if h' <> nullptr then
    printfn "=== Read ==="
    read h' |> printfn "read value= %s"
    NativeMethod.closeHandle(h') |> ignore
else
    printfn "Failed"

NativeMethod.fsx

module NativeMethod =

    open System
    open System.IO
    open System.Runtime.ConstrainedExecution
    open System.Runtime.InteropServices
    open System.Security
    open System.Text

    [<DllImport("kernel32.dll", CharSet=CharSet.Unicode, SetLastError=true, EntryPoint="CreateFileW");CompiledName("CreateFileW")>]
    extern nativeint createFile ( 
        [<MarshalAs(UnmanagedType.LPWStr); In>] string filename,
        [<MarshalAs(UnmanagedType.U4)>] FileAccess access,
        [<MarshalAs(UnmanagedType.U4)>] FileShare share,
        nativeint securityAttributes,
        [<MarshalAs(UnmanagedType.U4)>] FileMode creationDsiposition,
        [<MarshalAs(UnmanagedType.U4)>] FileAttributes flagsAndAttributes,
        nativeint templateFile )

    [<DllImport("kernel32.dll", SetLastError=true, EntryPoint="CloseHandle");CompiledName("CloseHandle")>]
    [<ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success);SuppressUnmanagedCodeSecurity>]
    extern [<MarshalAs(UnmanagedType.Bool)>] bool closeHandle(nativeint handle)

    [<DllImport("kernel32.dll", BestFitMapping=true, CharSet=CharSet.Ansi);CompiledName("WriteFile")>]
    extern [<MarshalAs(UnmanagedType.Bool)>] bool writeFile(
        nativeint filehandle, 
        byte[] buffer,
        uint32 numberOfBytesToWrite,
        uint32& numberOfBytesWritten,
        nativeint overlapped )

    [<DllImport("kernel32.dll", SetLastError=true, EntryPoint="ReadFile");CompiledName("ReadFile")>]
    extern [<MarshalAs(UnmanagedType.Bool)>] bool readFile(
        nativeint filehandle, 
        [<Out>] byte[] buffer,
        uint32 numberOfBytesToRead, 
        uint32& numberOfBytesRead, 
        nativeint overlapped )

    [<DllImport("kernel32.dll", EntryPoint="GetFileSizeEx");CompiledName("GetFileSize")>]
    extern [<MarshalAs(UnmanagedType.Bool)>] bool getFileSize(
        nativeint filehandle,
        [<Out>] int32& filesize);