Cancel FindFiles API

[littlewing1977]

I found an example using the FindFilesAPI by manavo11.

http://www.vbforums.com/showthread.php?t=244915

It works great, by the way. Is there any way to cancel it? It tried exiting the function and it pops up with my msgbox and then starts going again. I must be missing something.

'Create a form with a command button (command1), a list box (list1)
'and four text boxes (text1, text2, text3 and text4).
'Type in the first textbox a startingpath like c:\
'and in the second textbox you put a pattern like *.* or *.txt

Private Declare Function FindFirstFile Lib "kernel32" Alias "FindFirstFileA" (ByVal lpFileName As String, lpFindFileData As WIN32_FIND_DATA) As Long
Private Declare Function FindNextFile Lib "kernel32" Alias "FindNextFileA" (ByVal hFindFile As Long, lpFindFileData As WIN32_FIND_DATA) As Long
Private Declare Function GetFileAttributes Lib "kernel32" Alias "GetFileAttributesA" (ByVal lpFileName As String) As Long
Private Declare Function FindClose Lib "kernel32" (ByVal hFindFile As Long) As Long

Const MAX_PATH = 260
Const MAXDWORD = &HFFFF
Const INVALID_HANDLE_VALUE = -1
Const FILE_ATTRIBUTE_ARCHIVE = &H20
Const FILE_ATTRIBUTE_DIRECTORY = &H10
Const FILE_ATTRIBUTE_HIDDEN = &H2
Const FILE_ATTRIBUTE_NORMAL = &H80
Const FILE_ATTRIBUTE_READONLY = &H1
Const FILE_ATTRIBUTE_SYSTEM = &H4
Const FILE_ATTRIBUTE_TEMPORARY = &H100

Private Type FILETIME
    dwLowDateTime As Long
    dwHighDateTime As Long
End Type

Private Type WIN32_FIND_DATA
    dwFileAttributes As Long
    ftCreationTime As FILETIME
    ftLastAccessTime As FILETIME
    ftLastWriteTime As FILETIME
    nFileSizeHigh As Long
    nFileSizeLow As Long
    dwReserved0 As Long
    dwReserved1 As Long
    cFileName As String * MAX_PATH
    cAlternate As String * 14
End Type
Function StripNulls(OriginalStr As String) As String
    If (InStr(OriginalStr, Chr(0)) > 0) Then
        OriginalStr = Left(OriginalStr, InStr(OriginalStr, Chr(0)) - 1)
    End If
    StripNulls = OriginalStr
End Function

Function FindFilesAPI(path As String, SearchStr As String, FileCount As Integer, DirCount As Integer)
    'KPD-Team 1999
    'E-Mail: [email protected]
    'URL: http://www.allapi.net/

    Dim FileName As String ' Walking filename variable...
    Dim DirName As String ' SubDirectory Name
    Dim dirNames() As String ' Buffer for directory name entries
    Dim nDir As Integer ' Number of directories in this path
    Dim i As Integer ' For-loop counter...
    Dim hSearch As Long ' Search Handle
    Dim WFD As WIN32_FIND_DATA
    Dim Cont As Integer
    If Right(path, 1) <> "\" Then path = path & "\"
    ' Search for subdirectories.
    nDir = 0
    ReDim dirNames(nDir)
    Cont = True
    hSearch = FindFirstFile(path & "*", WFD)
    If hSearch <> INVALID_HANDLE_VALUE Then
        Do While Cont
        DirName = StripNulls(WFD.cFileName)
        ' Ignore the current and encompassing directories.
        If (DirName <> ".") And (DirName <> "..") Then
            ' Check for directory with bitwise comparison.
            If GetFileAttributes(path & DirName) And FILE_ATTRIBUTE_DIRECTORY Then
                dirNames(nDir) = DirName
                DirCount = DirCount + 1
                nDir = nDir + 1
                ReDim Preserve dirNames(nDir)
            End If
        End If
        Cont = FindNextFile(hSearch, WFD) 'Get next subdirectory.
        Loop
        Cont = FindClose(hSearch)
    End If
    ' Walk through this directory and sum file sizes.
    hSearch = FindFirstFile(path & SearchStr, WFD)
    Cont = True
    If hSearch <> INVALID_HANDLE_VALUE Then
        While Cont
            FileName = StripNulls(WFD.cFileName)
            If (FileName <> ".") And (FileName <> "..") Then
                FindFilesAPI = FindFilesAPI + (WFD.nFileSizeHigh * MAXDWORD) + WFD.nFileSizeLow
                FileCount = FileCount + 1
                List1.AddItem path & FileName
            End If
            Cont = FindNextFile(hSearch, WFD) ' Get next file
        Wend
        Cont = FindClose(hSearch)
    End If
    ' If there are sub-directories...
    If nDir > 0 Then
        ' Recursively walk into them...
        For i = 0 To nDir - 1
            FindFilesAPI = FindFilesAPI + FindFilesAPI(path & dirNames(i) & "\", SearchStr, FileCount, DirCount)
        Next i
    End If
End Function
Sub Command1_Click()
    Dim SearchPath As String, FindStr As String
    Dim FileSize As Long
    Dim NumFiles As Integer, NumDirs As Integer
    Screen.MousePointer = vbHourglass
    List1.Clear
    SearchPath = Text1.Text
    FindStr = Text2.Text
    FileSize = FindFilesAPI(SearchPath, FindStr, NumFiles, NumDirs)
    Text3.Text = NumFiles & " Files found in " & NumDirs + 1 & " Directories"
    Text4.Text = "Size of files found under " & SearchPath & " = " & Format(FileSize, "#,###,###,##0") & " Bytes"
    Screen.MousePointer = vbDefault
End Sub

[dilettante]

I don't see a single thing there you can't do by just using the built-in Dir$() function, which is a thin wrapper on these APIs anyway.

What do you mean by "cancel" here? As this is written it's all straight-line code so a Cancel button can't get a word in edgewise. Adding DoEvents() calls would just be wrong. What do you really want to do? What have you tried?

[littlewing1977]

I placed a DoEvents in there so I could click on a button. I click a cancel button and it changes a boolean to True. Then I checked the value of the boolean and exited the function if it was true. I tried that is several places. I even put a test in every loop at one point.

[dilettante]

If you read the code you'll see it makes recursive calls to itself. DoEvents() is the really wrong way to handle it, but if you insist on that instead of a rewrite you'll need to rework the code some so that it "breaks out" properly, unwinding the recursion.

[littlewing1977]

I am thinking about using Dir instead. I think I would be able to figure that out a little better. I don't completely understand everything that is going on in this code.

[dilettante]

Well even with Dir$() the code doesn't change much.

Maybe the attached example is closer to what you need.

[littlewing1977]

I may have to just leave it the way it is with no cancel. I was just told that we are getting close to the deadline and I need to get another piece working right.
Thanks for the help though.