/// <summary>
/// Copy one file with the appropriate number of retries if it fails.
/// </summary>
private bool DoCopyWithRetries(FileState sourceFileState, FileState destinationFileState, CopyFileWithState copyFile)
{
int retries = 0;
while (!_cancellationTokenSource.IsCancellationRequested)
{
try
{
bool?result = copyFile(sourceFileState, destinationFileState);
if (result.HasValue)
{
return(result.Value);
}
}
catch (OperationCanceledException)
{
break;
}
catch (Exception e) when(ExceptionHandling.IsIoRelatedException(e))
{
if (e is ArgumentException || // Invalid chars
e is NotSupportedException || // Colon in the middle of the path
e is PathTooLongException)
{
// No use retrying these cases
throw;
}
if (e is UnauthorizedAccessException || e is IOException) // Not clear why we can get one and not the other
{
int code = Marshal.GetHRForException(e);
LogDiagnostic("Got {0} copying {1} to {2} and HR is {3}", e.ToString(), sourceFileState.Name, destinationFileState.Name, code);
if (code == NativeMethods.ERROR_ACCESS_DENIED)
{
// ERROR_ACCESS_DENIED can either mean there's an ACL preventing us, or the file has the readonly bit set.
// In either case, that's likely not a race, and retrying won't help.
// Retrying is mainly for ERROR_SHARING_VIOLATION, where someone else is using the file right now.
// However, there is a limited set of circumstances where a copy failure will show up as access denied due
// to a failure to reset the readonly bit properly, in which case retrying will succeed. This seems to be
// a pretty edge scenario, but since some of our internal builds appear to be hitting it, provide a secret
// environment variable to allow overriding the default behavior and forcing retries in this circumstance as well.
if (!s_alwaysRetryCopy)
{
throw;
}
else
{
LogDiagnostic("Retrying on ERROR_ACCESS_DENIED because MSBUILDALWAYSRETRY = 1");
}
}
}
if (e is IOException && DestinationFolder != null && FileSystems.Default.FileExists(DestinationFolder.ItemSpec))
{
// We failed to create the DestinationFolder because it's an existing file. No sense retrying.
// We don't check for this case upstream because it'd be another hit to the filesystem.
throw;
}
if (e is IOException)
{
// if this was just because the source and destination files are the
// same file, that's not a failure.
// Note -- we check this exceptional case here, not before the copy, for perf.
if (PathsAreIdentical(sourceFileState.Name, destinationFileState.Name))
{
return(true);
}
}
if (retries < Retries)
{
retries++;
Log.LogWarningWithCodeFromResources("Copy.Retrying", sourceFileState.Name,
destinationFileState.Name, retries, RetryDelayMilliseconds, e.Message,
GetLockedFileMessage(destinationFileState.Name));
// if we have to retry for some reason, wipe the state -- it may not be correct anymore.
destinationFileState.Reset();
Thread.Sleep(RetryDelayMilliseconds);
continue;
}
else if (Retries > 0)
{
// Exception message is logged in caller
Log.LogErrorWithCodeFromResources("Copy.ExceededRetries", sourceFileState.Name,
destinationFileState.Name, Retries, GetLockedFileMessage(destinationFileState.Name));
throw;
}
else
{
throw;
}
}
if (retries < Retries)
{
retries++;
Log.LogWarningWithCodeFromResources("Copy.Retrying", sourceFileState.Name,
destinationFileState.Name, retries, RetryDelayMilliseconds, String.Empty /* no details */,
GetLockedFileMessage(destinationFileState.Name));
// if we have to retry for some reason, wipe the state -- it may not be correct anymore.
destinationFileState.Reset();
Thread.Sleep(RetryDelayMilliseconds);
}
else if (Retries > 0)
{
Log.LogErrorWithCodeFromResources("Copy.ExceededRetries", sourceFileState.Name,
destinationFileState.Name, Retries, GetLockedFileMessage(destinationFileState.Name));
return(false);
}
else
{
return(false);
}
}
// Canceling
return(false);
}
/// <summary>
/// Copy one file from source to destination. Create the target directory if necessary and
/// leave the file read-write.
/// </summary>
/// <returns>Return true to indicate success, return false to indicate failure and NO retry, return NULL to indicate retry.</returns>
private bool?CopyFileWithLogging
(
FileState sourceFileState, // The source file
FileState destinationFileState // The destination file
)
{
bool destinationFileExists = false;
if (destinationFileState.DirectoryExists)
{
Log.LogErrorWithCodeFromResources("Copy.DestinationIsDirectory", sourceFileState.Name, destinationFileState.Name);
return(false);
}
if (sourceFileState.DirectoryExists)
{
// If the source file passed in is actually a directory instead of a file, log a nice
// error telling the user so. Otherwise, .NET Framework's File.Copy method will throw
// an UnauthorizedAccessException saying "access is denied", which is not very useful
// to the user.
Log.LogErrorWithCodeFromResources("Copy.SourceIsDirectory", sourceFileState.Name);
return(false);
}
if (!sourceFileState.FileExists)
{
Log.LogErrorWithCodeFromResources("Copy.SourceFileNotFound", sourceFileState.Name);
return(false);
}
string destinationFolder = Path.GetDirectoryName(destinationFileState.Name);
if (!string.IsNullOrEmpty(destinationFolder) && !_directoriesKnownToExist.ContainsKey(destinationFolder))
{
if (!FileSystems.Default.DirectoryExists(destinationFolder))
{
Log.LogMessageFromResources(MessageImportance.Normal, "Copy.CreatesDirectory", destinationFolder);
Directory.CreateDirectory(destinationFolder);
}
// It's very common for a lot of files to be copied to the same folder.
// Eg., "c:\foo\a"->"c:\bar\a", "c:\foo\b"->"c:\bar\b" and so forth.
// We don't want to check whether this folder exists for every single file we copy. So store which we've checked.
_directoriesKnownToExist.TryAdd(destinationFolder, true);
}
if (OverwriteReadOnlyFiles)
{
MakeFileWriteable(destinationFileState, true);
destinationFileExists = destinationFileState.FileExists;
}
bool linkCreated = false;
string errorMessage = string.Empty;
// If we want to create hard or symbolic links, then try that first
if (UseHardlinksIfPossible)
{
TryCopyViaLink("Copy.HardLinkComment", MessageImportance.Normal, sourceFileState, destinationFileState, ref destinationFileExists, out linkCreated, ref errorMessage, (source, destination, errMessage) => NativeMethods.MakeHardLink(destination, source, ref errorMessage));
}
else if (UseSymboliclinksIfPossible)
{
TryCopyViaLink("Copy.SymbolicLinkComment", MessageImportance.Normal, sourceFileState, destinationFileState, ref destinationFileExists, out linkCreated, ref errorMessage, (source, destination, errMessage) => NativeMethods.MakeSymbolicLink(destination, source, ref errorMessage));
}
if (ErrorIfLinkFails && !linkCreated)
{
Log.LogErrorWithCodeFromResources("Copy.LinkFailed", sourceFileState.Name, destinationFileState.Name);
return(false);
}
// If the link was not created (either because the user didn't want one, or because it couldn't be created)
// then let's copy the file
if (!linkCreated)
{
// Do not log a fake command line as well, as it's superfluous, and also potentially expensive
string sourceFilePath = FileUtilities.GetFullPathNoThrow(sourceFileState.Name);
string destinationFilePath = FileUtilities.GetFullPathNoThrow(destinationFileState.Name);
Log.LogMessageFromResources(MessageImportance.Normal, "Copy.FileComment", sourceFilePath, destinationFilePath);
File.Copy(sourceFileState.Name, destinationFileState.Name, true);
}
destinationFileState.Reset();
// If the destinationFile file exists, then make sure it's read-write.
// The File.Copy command copies attributes, but our copy needs to
// leave the file writeable.
if (sourceFileState.IsReadOnly)
{
MakeFileWriteable(destinationFileState, false);
}
return(true);
}