feat: links to folders open as folders, on machines and SSH hosts, with their own icon; deleting a link leaves what it leads to

internal/agent/fs.go

@@ -114,13 +114,21 @@ func fsList(path string) (proto.FSListResult, error) {
 		if err != nil {
 			continue
 		}
-		out = append(out, proto.FSEntry{
+		ent := proto.FSEntry{
 			Name:  e.Name(),
 			IsDir: e.IsDir(),
 			Size:  info.Size(),
 			Mode:  info.Mode().String(),
 			MTime: info.ModTime().Unix(),
-		})
+		}
+		// A link to a folder opens like one.
+		if info.Mode()&os.ModeSymlink != 0 {
+			ent.Link = true
+			if t, err := os.Stat(filepath.Join(abs, e.Name())); err == nil && t.IsDir() {
+				ent.IsDir = true
+			}
+		}
+		out = append(out, ent)
 	}
 	// Directories first, then alphabetical.
 	sort.Slice(out, func(i, j int) bool {

internal/agent/sshfs.go

@@ -72,7 +72,9 @@ var (
 // statCommand lists dir's entries as "type|size|mtime|mode|name" lines.
 func statCommand(flavour, dir string) string {
 	d := shq(strings.TrimSuffix(dir, "/") + "/")
-	loop := "cd " + d + " && for f in .[!.]* ..?* *; do [ -e \"$f\" ] || [ -L \"$f\" ] || continue; "
+	// Each line starts with LD for a link to a folder, so it opens like one.
+	loop := "cd " + d + " && for f in .[!.]* ..?* *; do [ -e \"$f\" ] || [ -L \"$f\" ] || continue; " +
+		"t=; [ -L \"$f\" ] && [ -d \"$f\" ] && t=LD; printf '%s|' \"$t\"; "
 	switch flavour {
 	case "bsd":
 		return loop + "stat -f '%HT|%z|%m|%Sp|%N' -- \"$f\"; done"
@@ -84,6 +86,11 @@ func statCommand(flavour, dir string) string {
 
 // parseStatLine reads one line of statCommand's output.
 func parseStatLine(line string) (proto.FSEntry, bool) {
+	// The LD mark of statCommand: empty, or LD for a link to a folder.
+	mark := ""
+	if i := strings.IndexByte(line, '|'); i >= 0 && (line[:i] == "" || line[:i] == "LD") {
+		mark, line = line[:i], line[i+1:]
+	}
 	p := strings.SplitN(line, "|", 5)
 	if len(p) != 5 {
 		return proto.FSEntry{}, false
@@ -94,7 +101,8 @@ func parseStatLine(line string) (proto.FSEntry, bool) {
 		return proto.FSEntry{}, false
 	}
 	t := strings.ToLower(p[0])
-	return proto.FSEntry{Name: p[4], IsDir: strings.Contains(t, "directory"), Size: size, MTime: mt, Mode: p[3]}, true
+	return proto.FSEntry{Name: p[4], IsDir: strings.Contains(t, "directory") || mark == "LD", Size: size, MTime: mt, Mode: p[3],
+		Link: strings.Contains(t, "link")}, true
 }
 
 // parseLsLine reads a line of "ls -la" for a host with no stat: no times.

internal/agent/sshfs_test.go

@@ -4,6 +4,8 @@ import (
 	"archive/tar"
 	"bytes"
 	"io"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -193,3 +195,33 @@ func TestUnpackCommandReplaces(t *testing.T) {
 		t.Fatalf("error: %s", cmd)
 	}
 }
+
+// A link to a folder lists as a folder (marked as a link), so it opens.
+func TestParseStatLineFolderLink(t *testing.T) {
+	e, ok := parseStatLine("LD|symbolic link|7|1700000000|lrwxrwxrwx|www")
+	if !ok || !e.IsDir || !e.Link || e.Name != "www" {
+		t.Fatalf("%+v %v", e, ok)
+	}
+	e, ok = parseStatLine("|regular file|5|1700000000|-rw-r--r--|a|b")
+	if !ok || e.IsDir || e.Name != "a|b" {
+		t.Fatalf("plain: %+v %v", e, ok)
+	}
+	if !strings.Contains(statCommand("gnu", "/x"), `[ -L "$f" ] && [ -d "$f" ]`) {
+		t.Fatal("the command does not mark folder links")
+	}
+}
+
+func TestListFolderLink(t *testing.T) {
+	d := t.TempDir()
+	_ = os.Mkdir(filepath.Join(d, "real"), 0o755)
+	_ = os.Symlink(filepath.Join(d, "real"), filepath.Join(d, "ln"))
+	r, err := fsList(d)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, e := range r.Entries {
+		if e.Name == "ln" && (!e.IsDir || !e.Link) {
+			t.Fatalf("link: %+v", e)
+		}
+	}
+}