/// <summary>
/// Creates an instance of <see cref="DirectoryMembershipFingerprintResult"/>.
/// </summary>
public DirectoryMembershipFingerprintResult(
DirectoryMembershipTrackingFingerprint fingerprint,
PathExistence pathExistence,
int memberCount)
{
Fingerprint = fingerprint;
PathExistence = pathExistence;
MemberCount = memberCount;
}
/// <summary>
/// Computes fingerprint.
/// </summary>
public static Possible <DirectoryMembershipFingerprintResult> ComputeFingerprint(
string path,
Action <string, FileAttributes> handleEntry = null,
Func <string, FileAttributes, bool> shouldIncludeEntry = null)
{
Contract.Requires(!string.IsNullOrWhiteSpace(path));
var calculator = DirectoryMembershipTrackingFingerprint.CreateCalculator();
int memberCount = 0;
EnumerateDirectoryResult enumResult = FileUtilities.EnumerateDirectoryEntries(
path,
(entryName, entryAttributes) =>
{
if (shouldIncludeEntry?.Invoke(entryName, entryAttributes) ?? true)
{
calculator = calculator.Accumulate(entryName, entryAttributes);
memberCount++;
handleEntry?.Invoke(entryName, entryAttributes);
}
});
DirectoryMembershipTrackingFingerprint fingerprint = calculator.GetFingerprint();
var existence = PathExistence.Nonexistent;
bool enumerationSucceeded = true;
switch (enumResult.Status)
{
case EnumerateDirectoryStatus.Success:
existence = PathExistence.ExistsAsDirectory;
break;
case EnumerateDirectoryStatus.CannotEnumerateFile:
// We return an empty fingerprint for a path without children, even if that is because
// the directory path was to a 'leaf' node (file).
Contract.Assume(fingerprint == DirectoryMembershipTrackingFingerprint.Zero);
existence = PathExistence.ExistsAsFile;
break;
case EnumerateDirectoryStatus.SearchDirectoryNotFound:
// The directory is expected to exist because we have a handle.
// But that handle may be for a symlink to a non-existent directory.
// Thus, directory enumeration results in directory not found.
var possibleExistence = HandleSearchDirectoryNotFoundOnDirectoryEnumerationForFingerprinting(path);
if (possibleExistence.Succeeded)
{
existence = possibleExistence.Result;
}
fingerprint = DirectoryMembershipTrackingFingerprint.Absent;
break;
case EnumerateDirectoryStatus.AccessDenied:
case EnumerateDirectoryStatus.UnknownError:
enumerationSucceeded = false;
break;
default:
throw Contract.AssertFailure("Unhandled EnumerateDirectoryStatus");
}
if (!enumerationSucceeded)
{
return(new Failure <EnumerateDirectoryStatus>(enumResult.Status).Annotate(
"Failed to enumerate a directory (unexpected since a read-access handle to it was just opened; was there a rename?)"));
}
return(new DirectoryMembershipFingerprintResult(fingerprint, existence, memberCount));
}