PureBasic Forums - English

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Declare CreateFilePreallocated(fileId, filename.s, fileSize.q)

Define big_size.q

big_size = 1024 * 1024 ; 1mb for testing
; big_size = 1024 * 1024 * 1024 * 4 ; 4gb

CreateFilePreallocated(1, "blah.bin", big_size)
; write big_size of data nonsequentially (meaning that I might write the last byte just before the first)
CloseFile(1)

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Procedure CreateFilePreallocated(fileId, filename.s, fileSize.q)
  CreateFile(fileId, filename)
  FileSeek(fileId, fileSize)
  TruncateFile(fileId)
  FileSeek(fileId, 0)
EndProcedure

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Procedure CreateFilePreallocated(fileId, filename.s, fileSize.q)
  CreateFile(fileId, filename)
  i.q
  For i = 1 To fileSize-7 Step 8
    WriteQuad(fileId, 0)
  Next
  i - 8
  For i = i To fileSize
    WriteByte(fileId, 0)
  Next
  FileSeek(fileId, 0)
EndProcedure

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#FALLOC_STEP = 1024 * 1024 ; 1mb
Procedure CreateFilePreallocated(fileId, filename.s, fileSize.q)
  CreateFile(fileId, filename)
  *buf = AllocateMemory(#FALLOC_STEP)
  While fileSize > 0
    len.q
    If fileSize > #FALLOC_STEP
      len = #FALLOC_STEP
    Else
      len = fileSize
    End

    WriteData(fileId, *buf, len)
    fileSize - len
  Wend

  FreeMemory(*buf)

  FileSeek(fileId, 0)
EndProcedure

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; by Dige 11/2011
Procedure.L OpenFileAsMemory ( file.S, maxSize.q );

  Handle = CreateFile_( file, #GENERIC_READ|#GENERIC_WRITE, 3, 0, 3, #OPEN_EXISTING,0 )
  
  If Handle <> #INVALID_HANDLE_VALUE
    ;HighOrder = (maxSize & $FFFFFFFF00000000) >> 32
    HighOrder = 0; Max. 32 Bit = 2.1GB!!
    LowOrder  = maxSize & $00000000FFFFFFFF
    
    MapHandle = CreateFileMapping_(Handle, 0, #PAGE_READWRITE,  HighOrder, LowOrder, 0)
    
    If MapHandle
      ViewHandle = MapViewOfFile_(MapHandle, #FILE_MAP_WRITE, 0, 0, 0)
       
      If ViewHandle
        ProcedureReturn ViewHandle
        UnmapViewOfFile_( ViewHandle )
      EndIf
      CloseHandle_(MapHandle)
    EndIf
    CloseHandle_(Handle)
  EndIf

  ProcedureReturn #False
EndProcedure

; Example, how to use
*mem = OpenFileAsMemory ( "MyNewBigFile.bin", $100000 )

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EnableExplicit

Macro CTL_CODE( DeviceType, Function, Method, Access )
 ( ((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method) )
EndMacro

Import "Kernel32.lib"
    SetFilePointerEx.i(*hFile,liDistanceToMove.q,*lpNewFilePointer,dwMoveMethod.l) ;As "_SetFilePointerEx@24"
EndImport

#FILE_DEVICE_FILE_SYSTEM = $00000009
#METHOD_BUFFERED         = 0
#FILE_SPECIAL_ACCESS     = 0
#FILE_WRITE_DATA         = 2
#FSCTL_SET_SPARSE        = CTL_CODE(#FILE_DEVICE_FILE_SYSTEM, 49, #METHOD_BUFFERED, #FILE_SPECIAL_ACCESS)
#FSCTL_SET_ZERO_DATA     = CTL_CODE(#FILE_DEVICE_FILE_SYSTEM, 50, #METHOD_BUFFERED, #FILE_WRITE_DATA)

Structure FILE_ZERO_DATA_INFORMATION
  FileOffset.q
  BeyondFinalZero.q
EndStructure

Structure FileSizeLowHigh
    fileSizeLow.l
    fileSizeHigh.l
EndStructure

Structure FileSizeQuad
    StructureUnion
       fileSizeAsLongs.FileSizeLowHigh
       fileSize.q
    EndStructureUnion
EndStructure

Procedure.i ZeroSparseFile(fileId,FileOffset.q,Size.q)
    Protected fzdi.FILE_ZERO_DATA_INFORMATION, bytesReturned.l
    fzdi\FileOffset      = FileOffset
    fzdi\BeyondFinalZero = FileOffset+Size+1
    ProcedureReturn DeviceIoControl_(FileID(fileId),#FSCTL_SET_ZERO_DATA,@fzdi,SizeOf(FILE_ZERO_DATA_INFORMATION),#Null,0,@bytesReturned,#Null)
EndProcedure

Procedure.q GetSparseFileSize(filename.s)
    Protected fileSize.FileSizeQuad
    fileSize\fileSizeAsLongs\fileSizeLow = GetCompressedFileSize_(filename,@fileSize\fileSizeAsLongs\fileSizeHigh)
    If fileSize\fileSizeAsLongs\fileSizeLow = -1
        If GetLastError_() <> #NO_ERROR
            ProcedureReturn -1 ; ERROR, file does not exist?
        EndIf
    EndIf
    ProcedureReturn fileSize\fileSize
EndProcedure

Procedure CreateSparseFile(fileId, filename.s, fileSize.q)
    Protected file, bytesReturned.l, fileId2
    fileId2 = fileId
    file = CreateFile(fileId,filename)
    If file
        If fileId = #PB_Any : fileId = file : EndIf
        If Not DeviceIoControl_(FileID(fileId),#FSCTL_SET_SPARSE,#Null,0,#Null,0,@bytesReturned,#Null)
            ; failed to set file to sparse file
            CloseFile(fileId)
            ;DeleteFile(filename) ; ?? remove created file on failure
            ProcedureReturn 0
        EndIf
        If Not ZeroSparseFile(fileId,0,fileSize)
            ; failed to set sparse file content to 0
            CloseFile(fileId)
            ;DeleteFile(filename) ; ?? remove created file on failure
            ProcedureReturn 0
        EndIf
        ; success
        SetFilePointerEx(FileID(fileId),fileSize,#Null,#FILE_BEGIN)
        SetEndOfFile_(FileID(fileId))
        SetFilePointerEx(FileID(fileId),0,#Null,#FILE_BEGIN)
    EndIf
    ProcedureReturn file
EndProcedure

Define file, big_size.q

;big_size = 1024 * 1024 ; 1mb for testing
big_size = 1024 * 1024 * 1024 * 4 ; 4gb
Debug big_size

OpenConsole()

file = CreateSparseFile(1, "blah.bin", big_size)
If file
    ; write big_size of data nonsequentially (meaning that I might write the last byte just before the first)
    PrintN("Lof(): "+Str(Lof(1)))
    WriteByte(1,$64)
    FileSeek(1, big_size - 100)
    WriteQuad(1,$AABBCCDDEEFF1122)
    FileSeek(1, big_size - 1)
    WriteAsciiCharacter(1,$80)

    CloseFile(1)
    PrintN("GetSparseFileSize(): "+Str(GetSparseFileSize("blah.bin")))

    If ReadFile(2,"blah.bin")
        PrintN("Lof(): "+Str(Lof(2)))

        PrintN("reading Byte: $"+Hex(ReadByte(2)))
        FileSeek(2, big_size - 100)
        PrintN("reading Quad: $"+Hex(ReadQuad(2)))
        FileSeek(2, big_size - 1)
        PrintN("reading Byte: $"+Hex(ReadAsciiCharacter(2)))

        CloseFile(2)
        PrintN("GetSparseFileSize(): "+Str(GetSparseFileSize("blah.bin")))

    EndIf
Else
    PrintN("Error: can not create sparse file")
EndIf

PrintN("press <ENTER>")
Input()