Implement new puller routine (fixes #33)

model/filemonitor.go

@@ -0,0 +1,154 @@
+package model
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"sync"
+	"time"
+
+	"github.com/calmh/syncthing/buffers"
+)
+
+type fileMonitor struct {
+	name        string // in-repo name
+	path        string // full path
+	writeDone   sync.WaitGroup
+	model       *Model
+	global      File
+	localBlocks []Block
+	copyError   error
+	writeError  error
+}
+
+func (m *fileMonitor) FileBegins(cc <-chan content) error {
+	tmp := tempName(m.path, m.global.Modified)
+
+	dir := path.Dir(tmp)
+	_, err := os.Stat(dir)
+	if err != nil && os.IsNotExist(err) {
+		os.MkdirAll(dir, 0777)
+	}
+
+	outFile, err := os.Create(tmp)
+	if err != nil {
+		return err
+	}
+
+	m.writeDone.Add(1)
+
+	var writeWg sync.WaitGroup
+	if len(m.localBlocks) > 0 {
+		writeWg.Add(1)
+		inFile, err := os.Open(m.path)
+		if err != nil {
+			return err
+		}
+
+		// Copy local blocks, close infile when done
+		go m.copyLocalBlocks(inFile, outFile, &writeWg)
+	}
+
+	// Write remote blocks,
+	writeWg.Add(1)
+	go m.copyRemoteBlocks(cc, outFile, &writeWg)
+
+	// Wait for both writing routines, then close the outfile
+	go func() {
+		writeWg.Wait()
+		outFile.Close()
+		m.writeDone.Done()
+	}()
+
+	return nil
+}
+
+func (m *fileMonitor) copyLocalBlocks(inFile, outFile *os.File, writeWg *sync.WaitGroup) {
+	defer inFile.Close()
+	defer writeWg.Done()
+
+	var buf = buffers.Get(BlockSize)
+	defer buffers.Put(buf)
+
+	for _, lb := range m.localBlocks {
+		buf = buf[:lb.Size]
+		_, err := inFile.ReadAt(buf, lb.Offset)
+		if err != nil {
+			m.copyError = err
+			return
+		}
+		_, err = outFile.WriteAt(buf, lb.Offset)
+		if err != nil {
+			m.copyError = err
+			return
+		}
+	}
+}
+
+func (m *fileMonitor) copyRemoteBlocks(cc <-chan content, outFile *os.File, writeWg *sync.WaitGroup) {
+	defer writeWg.Done()
+
+	for content := range cc {
+		_, err := outFile.WriteAt(content.data, content.offset)
+		buffers.Put(content.data)
+		if err != nil {
+			m.writeError = err
+			return
+		}
+	}
+}
+
+func (m *fileMonitor) FileDone() error {
+	m.writeDone.Wait()
+
+	tmp := tempName(m.path, m.global.Modified)
+	defer os.Remove(tmp)
+
+	err := hashCheck(tmp, m.global.Blocks)
+	if err != nil {
+		return fmt.Errorf("%s: %s (tmp) (deleting)", path.Base(m.name), err.Error())
+	}
+
+	err = os.Chtimes(tmp, time.Unix(m.global.Modified, 0), time.Unix(m.global.Modified, 0))
+	if err != nil {
+		return err
+	}
+
+	err = os.Chmod(tmp, os.FileMode(m.global.Flags&0777))
+	if err != nil {
+		return err
+	}
+
+	err = os.Rename(tmp, m.path)
+	if err != nil {
+		return err
+	}
+
+	go m.model.updateLocalLocked(m.global)
+	return nil
+}
+
+func hashCheck(name string, correct []Block) error {
+	rf, err := os.Open(name)
+	if err != nil {
+		return err
+	}
+	defer rf.Close()
+
+	current, err := Blocks(rf, BlockSize)
+	if err != nil {
+		return err
+	}
+	if len(current) != len(correct) {
+		return errors.New("incorrect number of blocks")
+	}
+	for i := range current {
+		if bytes.Compare(current[i].Hash, correct[i].Hash) != 0 {
+			return fmt.Errorf("hash mismatch: %x != %x", current[i], correct[i])
+		}
+	}
+
+	return nil
+}