restic ls --json: print "size":0 for empty files

changelog/unreleased/issue-3247

@@ -0,0 +1,8 @@
+Change: Empty files now have size of 0 in restic ls --json output
+
+Restic ls --json used to omit the sizes of empty files in its output. It now
+reports "size":0 explicitly for regular files, while omitting the size field
+for all other types.
+
+https://github.com/restic/restic/issues/3247
+https://github.com/restic/restic/pull/3257

cmd/restic/cmd_ls.go

@@ -74,18 +74,42 @@ type lsSnapshot struct {
 	StructType string     `json:"struct_type"` // "snapshot"
 }
 
-type lsNode struct {
+// Print node in our custom JSON format, followed by a newline.
-	Name       string      `json:"name"`
+func lsNodeJSON(enc *json.Encoder, path string, node *restic.Node) error {
-	Type       string      `json:"type"`
+	n := &struct {
-	Path       string      `json:"path"`
+		Name       string      `json:"name"`
-	UID        uint32      `json:"uid"`
+		Type       string      `json:"type"`
-	GID        uint32      `json:"gid"`
+		Path       string      `json:"path"`
-	Size       uint64      `json:"size,omitempty"`
+		UID        uint32      `json:"uid"`
-	Mode       os.FileMode `json:"mode,omitempty"`
+		GID        uint32      `json:"gid"`
-	ModTime    time.Time   `json:"mtime,omitempty"`
+		Size       *uint64     `json:"size,omitempty"`
-	AccessTime time.Time   `json:"atime,omitempty"`
+		Mode       os.FileMode `json:"mode,omitempty"`
-	ChangeTime time.Time   `json:"ctime,omitempty"`
+		ModTime    time.Time   `json:"mtime,omitempty"`
-	StructType string      `json:"struct_type"` // "node"
+		AccessTime time.Time   `json:"atime,omitempty"`
+		ChangeTime time.Time   `json:"ctime,omitempty"`
+		StructType string      `json:"struct_type"` // "node"
+
+		size uint64 // Target for Size pointer.
+	}{
+		Name:       node.Name,
+		Type:       node.Type,
+		Path:       path,
+		UID:        node.UID,
+		GID:        node.GID,
+		size:       node.Size,
+		Mode:       node.Mode,
+		ModTime:    node.ModTime,
+		AccessTime: node.AccessTime,
+		ChangeTime: node.ChangeTime,
+		StructType: "node",
+	}
+	// Always print size for regular files, even when empty,
+	// but never for other types.
+	if node.Type == "file" {
+		n.Size = &n.size
+	}
+
+	return enc.Encode(n)
 }
 
 func runLs(opts LsOptions, gopts GlobalOptions, args []string) error {
@@ -159,7 +183,7 @@ func runLs(opts LsOptions, gopts GlobalOptions, args []string) error {
 		enc := json.NewEncoder(gopts.stdout)
 
 		printSnapshot = func(sn *restic.Snapshot) {
-			err = enc.Encode(lsSnapshot{
+			err := enc.Encode(lsSnapshot{
 				Snapshot:   sn,
 				ID:         sn.ID(),
 				ShortID:    sn.ID().Str(),
@@ -171,19 +195,7 @@ func runLs(opts LsOptions, gopts GlobalOptions, args []string) error {
 		}
 
 		printNode = func(path string, node *restic.Node) {
-			err = enc.Encode(lsNode{
+			err := lsNodeJSON(enc, path, node)
-				Name:       node.Name,
-				Type:       node.Type,
-				Path:       path,
-				UID:        node.UID,
-				GID:        node.GID,
-				Size:       node.Size,
-				Mode:       node.Mode,
-				ModTime:    node.ModTime,
-				AccessTime: node.AccessTime,
-				ChangeTime: node.ChangeTime,
-				StructType: "node",
-			})
 			if err != nil {
 				Warnf("JSON encode failed: %v\n", err)
 			}

cmd/restic/cmd_ls_test.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/restic/restic/internal/restic"
+	rtest "github.com/restic/restic/internal/test"
+)
+
+func TestLsNodeJSON(t *testing.T) {
+	for _, c := range []struct {
+		path string
+		restic.Node
+		expect string
+	}{
+		// Mode is omitted when zero.
+		{
+			path: "/bar/baz",
+			Node: restic.Node{
+				Name: "baz",
+				Type: "file",
+				Size: 12345,
+				UID:  10000000,
+				GID:  20000000,
+
+				User:  "nobody",
+				Group: "nobodies",
+				Links: 1,
+			},
+			expect: `{"name":"baz","type":"file","path":"/bar/baz","uid":10000000,"gid":20000000,"size":12345,"mtime":"0001-01-01T00:00:00Z","atime":"0001-01-01T00:00:00Z","ctime":"0001-01-01T00:00:00Z","struct_type":"node"}`,
+		},
+
+		// Even empty files get an explicit size.
+		{
+			path: "/foo/empty",
+			Node: restic.Node{
+				Name: "empty",
+				Type: "file",
+				Size: 0,
+				UID:  1001,
+				GID:  1001,
+
+				User:  "not printed",
+				Group: "not printed",
+				Links: 0xF00,
+			},
+			expect: `{"name":"empty","type":"file","path":"/foo/empty","uid":1001,"gid":1001,"size":0,"mtime":"0001-01-01T00:00:00Z","atime":"0001-01-01T00:00:00Z","ctime":"0001-01-01T00:00:00Z","struct_type":"node"}`,
+		},
+
+		// Non-regular files do not get a size.
+		// Mode is printed in decimal, including the type bits.
+		{
+			path: "/foo/link",
+			Node: restic.Node{
+				Name:       "link",
+				Type:       "symlink",
+				Mode:       os.ModeSymlink | 0777,
+				LinkTarget: "not printed",
+			},
+			expect: `{"name":"link","type":"symlink","path":"/foo/link","uid":0,"gid":0,"mode":134218239,"mtime":"0001-01-01T00:00:00Z","atime":"0001-01-01T00:00:00Z","ctime":"0001-01-01T00:00:00Z","struct_type":"node"}`,
+		},
+
+		{
+			path: "/some/directory",
+			Node: restic.Node{
+				Name:       "directory",
+				Type:       "dir",
+				Mode:       os.ModeDir | 0755,
+				ModTime:    time.Date(2020, 1, 2, 3, 4, 5, 0, time.UTC),
+				AccessTime: time.Date(2021, 2, 3, 4, 5, 6, 7, time.UTC),
+				ChangeTime: time.Date(2022, 3, 4, 5, 6, 7, 8, time.UTC),
+			},
+			expect: `{"name":"directory","type":"dir","path":"/some/directory","uid":0,"gid":0,"mode":2147484141,"mtime":"2020-01-02T03:04:05Z","atime":"2021-02-03T04:05:06.000000007Z","ctime":"2022-03-04T05:06:07.000000008Z","struct_type":"node"}`,
+		},
+	} {
+		buf := new(bytes.Buffer)
+		enc := json.NewEncoder(buf)
+		err := lsNodeJSON(enc, c.path, &c.Node)
+		rtest.OK(t, err)
+		rtest.Equals(t, c.expect+"\n", buf.String())
+
+		// Sanity check: output must be valid JSON.
+		var v interface{}
+		err = json.NewDecoder(buf).Decode(&v)
+		rtest.OK(t, err)
+	}
+}