/// <summary>
/// Clears the cache of the web browser
/// </summary>
public static void ClearCache()
{
const int errorInsufficientBuffer = 0x7A;
DeleteGroups();
// Start to delete URLs that do not belong to any group.
var cacheEntryInfoBufferSizeInitial = 0;
ClearCacheNativeMethods.FindFirstUrlCacheEntry(null, IntPtr.Zero, ref cacheEntryInfoBufferSizeInitial);
// should always fail because buffer is too small
if (Marshal.GetLastWin32Error() != errorInsufficientBuffer)
{
return;
}
var cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
var cacheEntryInfoBuffer = Marshal.AllocHGlobal(cacheEntryInfoBufferSize);
try
{
var enumHandle = ClearCacheNativeMethods.FindFirstUrlCacheEntry(null, cacheEntryInfoBuffer,
ref cacheEntryInfoBufferSizeInitial);
if (enumHandle != IntPtr.Zero)
{
bool more;
do
{
var internetCacheEntry =
Marshal.PtrToStructure <ClearCacheNativeMethods.InternetCacheEntryInfoA>(cacheEntryInfoBuffer);
cacheEntryInfoBufferSizeInitial = cacheEntryInfoBufferSize;
ClearCacheNativeMethods.DeleteUrlCacheEntry(internetCacheEntry.SourceUrlName);
more = ClearCacheNativeMethods.FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer,
ref cacheEntryInfoBufferSizeInitial);
if (!more && Marshal.GetLastWin32Error() == errorInsufficientBuffer)
{
cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
cacheEntryInfoBuffer = Marshal.ReAllocHGlobal(cacheEntryInfoBuffer,
(IntPtr)cacheEntryInfoBufferSize);
more = ClearCacheNativeMethods.FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer,
ref cacheEntryInfoBufferSizeInitial);
}
} while (more);
}
}
finally
{
Marshal.FreeHGlobal(cacheEntryInfoBuffer);
}
}
/// <summary>
/// Delete the groups first.
/// Groups may not always exist on the system.
/// For more information, visit the following Microsoft Web site:
/// http://msdn.microsoft.com/library/?url=/workshop/networking/wininet/overview/cache.asp
/// By default, a URL does not belong to any group. Therefore, that cache may become
/// empty even when the CacheGroup APIs are not used because the existing URL does not belong to any group.
/// </summary>
private static void DeleteGroups()
{
// Indicates that all of the cache groups in the user's system should be enumerated
const int cacheGroupSearchAll = 0x0;
// Indicates that all the cache entries that are associated with the cache group
// should be deleted, unless the entry belongs to another cache group.
const int cacheGroupFlagFlushUrlOnDelete = 0x2;
long groupId = 0;
var enumHandle = ClearCacheNativeMethods.FindFirstUrlCacheGroup(0, cacheGroupSearchAll, IntPtr.Zero, 0,
ref groupId,
IntPtr.Zero);
if (enumHandle == IntPtr.Zero)
{
return;
}
do
{
ClearCacheNativeMethods.DeleteUrlCacheGroup(groupId, cacheGroupFlagFlushUrlOnDelete, IntPtr.Zero);
} while (ClearCacheNativeMethods.FindNextUrlCacheGroup(enumHandle, ref groupId, IntPtr.Zero));
}
