From 1e9110b76343ede316e045ca8ccf4439e9863eef Mon Sep 17 00:00:00 2001
From: Jakob Borg <jakob@nym.se>
Date: Tue, 30 Dec 2014 15:44:05 +0100
Subject: [PATCH] Add debugging utility for manual directory comparison

---
 cmd/stcompdirs/main.go | 177 +++++++++++++++++++++++++++++++++++++++++
 test/util.go           |   4 +
 2 files changed, 181 insertions(+)
 create mode 100644 cmd/stcompdirs/main.go

diff --git a/cmd/stcompdirs/main.go b/cmd/stcompdirs/main.go
new file mode 100644
index 000000000..0c98a0bac
--- /dev/null
+++ b/cmd/stcompdirs/main.go
@@ -0,0 +1,177 @@
+// Copyright (C) 2014 The Syncthing Authors.
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"crypto/md5"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/syncthing/syncthing/internal/symlinks"
+)
+
+func main() {
+	flag.Parse()
+	log.Println(compareDirectories(flag.Args()...))
+}
+
+// Compare a number of directories. Returns nil if the contents are identical,
+// otherwise an error describing the first found difference.
+func compareDirectories(dirs ...string) error {
+	chans := make([]chan fileInfo, len(dirs))
+	for i := range chans {
+		chans[i] = make(chan fileInfo)
+	}
+	errcs := make([]chan error, len(dirs))
+	abort := make(chan struct{})
+
+	for i := range dirs {
+		errcs[i] = startWalker(dirs[i], chans[i], abort)
+	}
+
+	res := make([]fileInfo, len(dirs))
+	for {
+		numDone := 0
+		for i := range chans {
+			fi, ok := <-chans[i]
+			if !ok {
+				err, hasError := <-errcs[i]
+				if hasError {
+					close(abort)
+					return err
+				}
+				numDone++
+			}
+			res[i] = fi
+		}
+
+		for i := 1; i < len(res); i++ {
+			if res[i] != res[0] {
+				close(abort)
+				if res[i].name < res[0].name {
+					return fmt.Errorf("%s missing %v (present in %s)", dirs[0], res[i], dirs[i])
+				} else if res[i].name > res[0].name {
+					return fmt.Errorf("%s missing %v (present in %s)", dirs[i], res[0], dirs[0])
+				}
+				return fmt.Errorf("Mismatch; %v (%s) != %v (%s)", res[i], dirs[i], res[0], dirs[0])
+			}
+		}
+
+		if numDone == len(dirs) {
+			return nil
+		}
+	}
+}
+
+type fileInfo struct {
+	name string
+	mode os.FileMode
+	mod  int64
+	hash [16]byte
+}
+
+func (f fileInfo) String() string {
+	return fmt.Sprintf("%s %04o %d %x", f.name, f.mode, f.mod, f.hash)
+}
+
+func startWalker(dir string, res chan<- fileInfo, abort <-chan struct{}) chan error {
+	walker := func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		rn, _ := filepath.Rel(dir, path)
+		if rn == "." || rn == ".stfolder" {
+			return nil
+		}
+		if rn == ".stversions" {
+			return filepath.SkipDir
+		}
+
+		var f fileInfo
+		if info.Mode()&os.ModeSymlink != 0 {
+			f = fileInfo{
+				name: rn,
+				mode: os.ModeSymlink,
+			}
+
+			tgt, _, err := symlinks.Read(path)
+			if err != nil {
+				return err
+			}
+			h := md5.New()
+			h.Write([]byte(tgt))
+			hash := h.Sum(nil)
+
+			copy(f.hash[:], hash)
+		} else if info.IsDir() {
+			f = fileInfo{
+				name: rn,
+				mode: info.Mode(),
+				// hash and modtime zero for directories
+			}
+		} else {
+			f = fileInfo{
+				name: rn,
+				mode: info.Mode(),
+				mod:  info.ModTime().Unix(),
+			}
+			sum, err := md5file(path)
+			if err != nil {
+				return err
+			}
+			f.hash = sum
+		}
+
+		select {
+		case res <- f:
+			return nil
+		case <-abort:
+			return errors.New("abort")
+		}
+	}
+
+	errc := make(chan error)
+	go func() {
+		err := filepath.Walk(dir, walker)
+		close(res)
+		if err != nil {
+			errc <- err
+		}
+		close(errc)
+	}()
+	return errc
+}
+
+func md5file(fname string) (hash [16]byte, err error) {
+	f, err := os.Open(fname)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+
+	h := md5.New()
+	io.Copy(h, f)
+	hb := h.Sum(nil)
+	copy(hash[:], hb)
+
+	return
+}
diff --git a/test/util.go b/test/util.go
index 441433959..4342ceba3 100644
--- a/test/util.go
+++ b/test/util.go
@@ -317,6 +317,10 @@ type fileInfo struct {
 	hash [16]byte
 }
 
+func (f fileInfo) String() string {
+	return fmt.Sprintf("%s %04o %d %x", f.name, f.mode, f.mod, f.hash)
+}
+
 type fileInfoList []fileInfo
 
 func (l fileInfoList) Len() int {