Support hard links

Closes #152

src/cmds/restic/integration_helpers_test.go

@@ -15,6 +15,7 @@ import (
 type dirEntry struct {
 	path string
 	fi   os.FileInfo
+	link uint64
 }
 
 func walkDir(dir string) <-chan *dirEntry {
@@ -36,6 +37,7 @@ func walkDir(dir string) <-chan *dirEntry {
 			ch <- &dirEntry{
 				path: name,
 				fi:   info,
+				link: nlink(info),
 			}
 
 			return nil

src/cmds/restic/integration_helpers_unix_test.go

@@ -4,7 +4,9 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
+	"path/filepath"
 	"syscall"
 )
 
@@ -37,5 +39,37 @@ func (e *dirEntry) equals(other *dirEntry) bool {
 		return false
 	}
 
+	if stat.Nlink != stat2.Nlink {
+		fmt.Fprintf(os.Stderr, "%v: Number of links do not match (%v != %v)\n", e.path, stat.Nlink, stat2.Nlink)
+		return false
+	}
+
 	return true
 }
+
+func nlink(info os.FileInfo) uint64 {
+	stat, _ := info.Sys().(*syscall.Stat_t)
+	return uint64(stat.Nlink)
+}
+
+func inode(info os.FileInfo) uint64 {
+	stat, _ := info.Sys().(*syscall.Stat_t)
+	return uint64(stat.Ino)
+}
+
+func createFileSetPerHardlink(dir string) map[uint64][]string {
+	var stat syscall.Stat_t
+	linkTests := make(map[uint64][]string)
+	files, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return nil
+	}
+	for _, f := range files {
+
+		if err := syscall.Stat(filepath.Join(dir, f.Name()), &stat); err != nil {
+			return nil
+		}
+		linkTests[uint64(stat.Ino)] = append(linkTests[uint64(stat.Ino)], f.Name())
+	}
+	return linkTests
+}

src/cmds/restic/integration_helpers_windows_test.go

@@ -4,6 +4,7 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 )
 
@@ -25,3 +26,24 @@ func (e *dirEntry) equals(other *dirEntry) bool {
 
 	return true
 }
+
+func nlink(info os.FileInfo) uint64 {
+	return 1
+}
+
+func inode(info os.FileInfo) uint64 {
+	return uint64(0)
+}
+
+func createFileSetPerHardlink(dir string) map[uint64][]string {
+	linkTests := make(map[uint64][]string)
+	files, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return nil
+	}
+	for i, f := range files {
+		linkTests[uint64(i)] = append(linkTests[uint64(i)], f.Name())
+		i++
+	}
+	return linkTests
+}

src/cmds/restic/integration_test.go

@@ -1011,3 +1011,100 @@ func TestPrune(t *testing.T) {
 		testRunCheck(t, gopts)
 	})
 }
+
+func TestHardLink(t *testing.T) {
+	// this test assumes a test set with a single directory containing hard linked files
+	withTestEnvironment(t, func(env *testEnvironment, gopts GlobalOptions) {
+		datafile := filepath.Join("testdata", "test.hl.tar.gz")
+		fd, err := os.Open(datafile)
+		if os.IsNotExist(errors.Cause(err)) {
+			t.Skipf("unable to find data file %q, skipping", datafile)
+			return
+		}
+		OK(t, err)
+		OK(t, fd.Close())
+
+		testRunInit(t, gopts)
+
+		SetupTarTestFixture(t, env.testdata, datafile)
+
+		linkTests := createFileSetPerHardlink(env.testdata)
+
+		opts := BackupOptions{}
+
+		// first backup
+		testRunBackup(t, []string{env.testdata}, opts, gopts)
+		snapshotIDs := testRunList(t, "snapshots", gopts)
+		Assert(t, len(snapshotIDs) == 1,
+			"expected one snapshot, got %v", snapshotIDs)
+
+		testRunCheck(t, gopts)
+
+		// restore all backups and compare
+		for i, snapshotID := range snapshotIDs {
+			restoredir := filepath.Join(env.base, fmt.Sprintf("restore%d", i))
+			t.Logf("restoring snapshot %v to %v", snapshotID.Str(), restoredir)
+			testRunRestore(t, gopts, restoredir, snapshotIDs[0])
+			Assert(t, directoriesEqualContents(env.testdata, filepath.Join(restoredir, "testdata")),
+				"directories are not equal")
+
+			linkResults := createFileSetPerHardlink(filepath.Join(restoredir, "testdata"))
+			Assert(t, linksEqual(linkTests, linkResults),
+				"links are not equal")
+		}
+
+		testRunCheck(t, gopts)
+	})
+}
+
+func linksEqual(source, dest map[uint64][]string) bool {
+	for _, vs := range source {
+		found := false
+		for kd, vd := range dest {
+			if linkEqual(vs, vd) {
+				delete(dest, kd)
+				found = true
+				break
+			}
+		}
+		if !found {
+			return false
+		}
+	}
+
+	if len(dest) != 0 {
+		return false
+	}
+
+	return true
+}
+
+func linkEqual(source, dest []string) bool {
+	// equal if sliced are equal without considering order
+	if source == nil && dest == nil {
+		return true
+	}
+
+	if source == nil || dest == nil {
+		return false
+	}
+
+	if len(source) != len(dest) {
+		return false
+	}
+
+	for i := range source {
+		found := false
+		for j := range dest {
+			if source[i] == dest[j] {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return false
+		}
+	}
+
+	return true
+}