mount: factor filesystem code into mountlib and mounttest

cmd/mountlib/write.go

@@ -0,0 +1,158 @@
+package mountlib
+
+import (
+	"io"
+	"sync"
+
+	"github.com/ncw/rclone/fs"
+)
+
+// WriteFileHandle is an open for write handle on a File
+type WriteFileHandle struct {
+	mu          sync.Mutex
+	closed      bool // set if handle has been closed
+	remote      string
+	pipeReader  *io.PipeReader
+	pipeWriter  *io.PipeWriter
+	o           fs.Object
+	result      chan error
+	file        *File
+	writeCalled bool // set the first time Write() is called
+	offset      int64
+}
+
+func newWriteFileHandle(d *Dir, f *File, src fs.ObjectInfo) (*WriteFileHandle, error) {
+	fh := &WriteFileHandle{
+		remote: src.Remote(),
+		result: make(chan error, 1),
+		file:   f,
+	}
+	fh.pipeReader, fh.pipeWriter = io.Pipe()
+	r := fs.NewAccountSizeName(fh.pipeReader, 0, src.Remote()).WithBuffer() // account the transfer
+	go func() {
+		o, err := d.f.Put(r, src)
+		fh.o = o
+		fh.result <- err
+	}()
+	fh.file.addWriters(1)
+	fh.file.setSize(0)
+	fs.Stats.Transferring(fh.remote)
+	return fh, nil
+}
+
+// Node returns the Node assocuated with this - satisfies Noder interface
+func (fh *WriteFileHandle) Node() Node {
+	return fh.file
+}
+
+// Write data to the file handle
+func (fh *WriteFileHandle) Write(data []byte, offset int64) (written int64, err error) {
+	fs.Debugf(fh.remote, "WriteFileHandle.Write len=%d", len(data))
+	fh.mu.Lock()
+	defer fh.mu.Unlock()
+	if fh.offset != offset {
+		fs.Errorf(fh.remote, "WriteFileHandle.Write can't seek in file")
+		return 0, ESPIPE
+	}
+	if fh.closed {
+		fs.Errorf(fh.remote, "WriteFileHandle.Write error: %v", EBADF)
+		return 0, EBADF
+	}
+	fh.writeCalled = true
+	// FIXME should probably check the file isn't being seeked?
+	n, err := fh.pipeWriter.Write(data)
+	written = int64(n)
+	fh.offset += written
+	fh.file.setSize(fh.offset)
+	if err != nil {
+		fs.Errorf(fh.remote, "WriteFileHandle.Write error: %v", err)
+		return 0, err
+	}
+	fs.Debugf(fh.remote, "WriteFileHandle.Write OK (%d bytes written)", n)
+	return written, nil
+}
+
+// Returns the offset of the file pointer
+func (fh *WriteFileHandle) Offset() (offset int64) {
+	return fh.offset
+}
+
+// close the file handle returning EBADF if it has been
+// closed already.
+//
+// Must be called with fh.mu held
+func (fh *WriteFileHandle) close() error {
+	if fh.closed {
+		return EBADF
+	}
+	fh.closed = true
+	fs.Stats.DoneTransferring(fh.remote, true)
+	fh.file.addWriters(-1)
+	writeCloseErr := fh.pipeWriter.Close()
+	err := <-fh.result
+	readCloseErr := fh.pipeReader.Close()
+	if err == nil {
+		fh.file.setObject(fh.o)
+		err = writeCloseErr
+	}
+	if err == nil {
+		err = readCloseErr
+	}
+	return err
+}
+
+// Flush is called on each close() of a file descriptor. So if a
+// filesystem wants to return write errors in close() and the file has
+// cached dirty data, this is a good place to write back data and
+// return any errors. Since many applications ignore close() errors
+// this is not always useful.
+//
+// NOTE: The flush() method may be called more than once for each
+// open(). This happens if more than one file descriptor refers to an
+// opened file due to dup(), dup2() or fork() calls. It is not
+// possible to determine if a flush is final, so each flush should be
+// treated equally. Multiple write-flush sequences are relatively
+// rare, so this shouldn't be a problem.
+//
+// Filesystems shouldn't assume that flush will always be called after
+// some writes, or that if will be called at all.
+func (fh *WriteFileHandle) Flush() error {
+	fh.mu.Lock()
+	defer fh.mu.Unlock()
+	fs.Debugf(fh.remote, "WriteFileHandle.Flush")
+	// If Write hasn't been called then ignore the Flush - Release
+	// will pick it up
+	if !fh.writeCalled {
+		fs.Debugf(fh.remote, "WriteFileHandle.Flush ignoring flush on unwritten handle")
+		return nil
+
+	}
+	err := fh.close()
+	if err != nil {
+		fs.Errorf(fh.remote, "WriteFileHandle.Flush error: %v", err)
+	} else {
+		fs.Debugf(fh.remote, "WriteFileHandle.Flush OK")
+	}
+	return err
+}
+
+// Release is called when we are finished with the file handle
+//
+// It isn't called directly from userspace so the error is ignored by
+// the kernel
+func (fh *WriteFileHandle) Release() error {
+	fh.mu.Lock()
+	defer fh.mu.Unlock()
+	if fh.closed {
+		fs.Debugf(fh.remote, "WriteFileHandle.Release nothing to do")
+		return nil
+	}
+	fs.Debugf(fh.remote, "WriteFileHandle.Release closing")
+	err := fh.close()
+	if err != nil {
+		fs.Errorf(fh.remote, "WriteFileHandle.Release error: %v", err)
+	} else {
+		fs.Debugf(fh.remote, "WriteFileHandle.Release OK")
+	}
+	return err
+}