Author: Jonas Bilinkevicius

How to determine file and tree sizes larger 2 GB

Answer:

Solve 1:

You will need to use the FindFirstFile, FindNextFile and FindClose functions, e.g.:

1   function GetFileSize(const FileName: string): Int64;
2   var
3     F: TWin32FindData;
4     H: THandle;
5   begin
6     H := FindFirstFile(PChar(FileName), F);
7     if H = INVALID_HANDLE_VALUE then
8       RaiseLastWin32Error;
9     try
10      Result := F.nFileSizeHigh shl 32 + F.nFileSizeLow;
11    finally
12      Windows.FindClose(H);
13    end;
14  end;
15  
16  function GetTreeSize(FileName: string): Int64;
17  
18    procedure TreeSize(const FileName: string);
19    var
20      F: TWin32FindData;
21      H: THandle;
22    begin
23      H := FindFirstFile(PChar(FileName), F);
24      if H = INVALID_HANDLE_VALUE then
25        RaiseLastWin32Error;
26      try
27        repeat
28          if ((F.dwFileAttributes and FILE_ATTRIBUTE_DIRECTORY) > 0) and 
29  (F.cFileName[0]
30            <> '.') then
31            TreeSize(ExtractFilePath(FileName) + F.cFileName + '\*.*')
32          else
33            Result := Result + F.nFileSizeHigh shl 32 + F.nFileSizeLow;
34        until not FindNextFile(H, F);
35      finally
36        Windows.FindClose(H);
37      end;
38    end;
39  
40  begin
41    Result := 0;
42    TreeSize(IncludeTrailingBackslash(ExtractFilePath(FileName)) + '*.*');
43  end;


I would add one little detail to your function. By calculating the filesize, you 
should cast the values to Int64. In the helpfile you can read, that this is 
necessary, because the operation would normally return an integer. In this case, 
(F.nFileSizeHigh shl 32) would return an Integer and not an Int64.

Result := Int64(F.nFileSizeHigh) shl 32 + Int64(F.nFileSizeLow);

I think, casting "nFileSizeLow" is not necessary, but better to make it safe.


Solve 2:

Use the WinAPI version of the function GetFileSize() as follows:
44  
45  procedure CardinalsToI64(var I: Int64; const LowPart, HighPart: Cardinal);
46  begin
47    TULargeInteger(I).LowPart := LowPart;
48    TULargeInteger(I).HighPart := HighPart;
49  end;
50  
51  { ... }
52  var
53    fLOdword: dword;
54    fHIdword: dword;
55    FFilesize: Int64;
56    FFileHandle: THandle;
57  begin
58    FFileHandle := CreateFile(PChar(FFileName), GENERIC_READ, FILE_SHARE_READ, nil,
59      OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
60    fLOdword := GetFileSize(FFileHandle, @fHIdword);
61    CardinalsToI64(FFilesize, fLOdword, fHIdword);



Solve 3:

62  function GetFileSize(const FileName: string): Int64;
63  var
64    SizeLow, SizeHigh: DWord;
65    hFile: THandle;
66  begin
67    Result := 0;
68    hFile := FileOpen(FileName, fmOpenRead);
69    try
70      if hFile <> 0 then
71      begin
72        SizeLow := Windows.GetFileSize(hFile, @SizeHigh);
73        Result := (SizeHigh shl 32) + SizeLow;
74      end;
75    finally
76      FileClose(hFile);
77    end;
78  end;