Visual Basic Programming Code Examples

List and delete files in the internet cache (inc. cookies) The following code can be used to query and delete files in the internet cache (including cookies). A demonstration routine can be found at the bottom of this post. Note, the enumerated type eCacheType is not supported in Excel 97, but can be changed to a list of Public Constants eg. Public Const eNormal = &H1&. Option Explicit '--------------------------Types, consts and structures Private Const ERROR_CACHE_FIND_FAIL As Long = 0 Private Const ERROR_CACHE_FIND_SUCCESS As Long = 1 Private Const ERROR_FILE_NOT_FOUND As Long = 2 Private Const ERROR_ACCESS_DENIED As Long = 5 Private Const ERROR_INSUFFICIENT_BUFFER As Long = 122 Private Const MAX_CACHE_ENTRY_INFO_SIZE As Long = 4096 Private Const LMEM_FIXED As Long = &H0 Private Const LMEM_ZEROINIT As Long = &H40 Public Enum eCacheType eNormal = &H1& eEdited = &H8& eTrackOffline = &H10& eTrackOnline = &H20& eSticky = &H40& eSparse = &H10000 eCookie = &H100000 eURLHistory = &H200000 eURLFindDefaultFilter = 0& End Enum Private Type FILETIME dwLowDateTime As Long dwHighDateTime As Long End Type Private Type INTERNET_CACHE_ENTRY_INFO dwStructSize As Long lpszSourceUrlName As Long lpszLocalFileName As Long CacheEntryType As Long 'Type of entry returned dwUseCount As Long dwHitRate As Long dwSizeLow As Long dwSizeHigh As Long LastModifiedTime As FILETIME ExpireTime As FILETIME LastAccessTime As FILETIME LastSyncTime As FILETIME lpHeaderInfo As Long dwHeaderInfoSize As Long lpszFileExtension As Long dwExemptDelta As Long End Type '--------------------------Internet Cache API Private Declare Function FindFirstUrlCacheEntry Lib "Wininet.dll" Alias "FindFirstUrlCacheEntryA" (ByVal lpszUrlSearchPattern As String, lpFirstCacheEntryInfo As Any, lpdwFirstCacheEntryInfoBufferSize As Long) As Long Private Declare Function FindNextUrlCacheEntry Lib "Wininet.dll" Alias "FindNextUrlCacheEntryA" (ByVal hEnumHandle As Long, lpNextCacheEntryInfo As Any, lpdwNextCacheEntryInfoBufferSize As Long) As Long Private Declare Function FindCloseUrlCache Lib "Wininet.dll" (ByVal hEnumHandle As Long) As Long Private Declare Function DeleteUrlCacheEntry Lib "Wininet.dll" Alias "DeleteUrlCacheEntryA" (ByVal lpszUrlName As String) As Long '--------------------------Memory API Private Declare Function LocalAlloc Lib "kernel32" (ByVal uFlags As Long, ByVal uBytes As Long) As Long Private Declare Function LocalFree Lib "kernel32" (ByVal hMem As Long) As Long Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (pDest As Any, pSource As Any, ByVal dwLength As Long) Private Declare Function lstrcpyA Lib "kernel32" (ByVal RetVal As String, ByVal Ptr As Long) As Long Private Declare Function lstrlenA Lib "kernel32" (ByVal Ptr As Any) As Long 'Purpose : Deletes the specified internet cache file 'Inputs : sCacheFile The name of the cache file 'Outputs : Returns True on success. Function InternetDeleteCache(sCacheFile As String) As Boolean InternetDeleteCache = CBool(DeleteUrlCacheEntry(sCacheFile)) End Function 'Purpose : Returns an array of files stored in the internet cache 'Inputs : eFilterType An enum which filters the files returned by their type 'Outputs : A one dimensional, one based, string array containing the names of the files Function InternetCacheList(Optional eFilterType As eCacheType = eNormal) As Variant Dim ICEI As INTERNET_CACHE_ENTRY_INFO Dim lhFile As Long, lBufferSize As Long, lptrBuffer As Long Dim sCacheFile As String Dim asURLs() As String, lNumEntries As Long 'Determine required buffer size lBufferSize = 0 lhFile = FindFirstUrlCacheEntry(0&, ByVal 0&, lBufferSize) If (lhFile = ERROR_CACHE_FIND_FAIL) And (Err.LastDllError = ERROR_INSUFFICIENT_BUFFER) Then 'Allocate memory for ICEI structure lptrBuffer = LocalAlloc(LMEM_FIXED, lBufferSize) If lptrBuffer Then 'Set a Long pointer to the memory location CopyMemory ByVal lptrBuffer, lBufferSize, 4 'Call first find API passing it the pointer to the allocated memory lhFile = FindFirstUrlCacheEntry(vbNullString, ByVal lptrBuffer, lBufferSize) '1 = success If lhFile <> ERROR_CACHE_FIND_FAIL Then 'Loop through the cache Do 'Copy data back to structure CopyMemory ICEI, ByVal lptrBuffer, Len(ICEI) If ICEI.CacheEntryType And eFilterType Then sCacheFile = StrFromPtrA(ICEI.lpszSourceUrlName) lNumEntries = lNumEntries + 1 If lNumEntries = 1 Then ReDim asURLs(1 To 1) Else ReDim Preserve asURLs(1 To lNumEntries) End If asURLs(lNumEntries) = sCacheFile End If 'Free memory associated with the last-retrieved file Call LocalFree(lptrBuffer) 'Call FindNextUrlCacheEntry with buffer size set to 0. 'Call will fail and return required buffer size. lBufferSize = 0 Call FindNextUrlCacheEntry(lhFile, ByVal 0&, lBufferSize) 'Allocate and assign the memory to the pointer lptrBuffer = LocalAlloc(LMEM_FIXED, lBufferSize) CopyMemory ByVal lptrBuffer, lBufferSize, 4& Loop While FindNextUrlCacheEntry(lhFile, ByVal lptrBuffer, lBufferSize) End If End If End If 'Free memory Call LocalFree(lptrBuffer) Call FindCloseUrlCache(lhFile) InternetCacheList = asURLs End Function 'Purpose : Converts a pointer an ansi string into a string. 'Inputs : lptrString A long pointer to a string held in memory 'Outputs : The string held at the specified memory address Function StrFromPtrA(ByVal lptrString As Long) As String 'Create buffer StrFromPtrA = String$(lstrlenA(ByVal lptrString), 0) 'Copy memory Call lstrcpyA(ByVal StrFromPtrA, ByVal lptrString) End Function 'Demonstration routine Sub Test() Dim avURLs As Variant, vThisValue As Variant On Error Resume Next 'Return an array of all internet cache files avURLs = InternetCacheList For Each vThisValue In avURLs 'Print files Debug.Print CStr(vThisValue) Next 'Return the an array of all cookies avURLs = InternetCacheList(eCookie) If MsgBox("Delete cookies?", vbQuestion + vbYesNo) = vbYes Then For Each vThisValue In avURLs 'Delete cookies InternetDeleteCache CStr(vThisValue) Debug.Print "Deleted " & vThisValue Next Else For Each vThisValue In avURLs 'Print cookie files Debug.Print vThisValue Next End If End Sub