Work on completion of file args

tools/completion/files.go

@@ -14,35 +14,97 @@ import (
 
 var _ = fmt.Print
 
-type CompleteFilesCallback func(completion_candidate string, abspath string, d fs.DirEntry) error
+type CompleteFilesCallback func(completion_candidate, abspath string, d fs.DirEntry) error
+type Walk_callback func(path string, d fs.DirEntry, err error) error
+
+func transform_symlink(path string) string {
+	if q, err := filepath.EvalSymlinks(path); err == nil {
+		return q
+	}
+	return path
+}
+
+func needs_symlink_recurse(path string, d fs.DirEntry) bool {
+	if d.Type()&os.ModeSymlink == os.ModeSymlink {
+		if s, serr := os.Stat(path); serr == nil && s.IsDir() {
+			return true
+		}
+	}
+	return false
+}
+
+type transformed_walker struct {
+	seen               map[string]bool
+	real_callback      Walk_callback
+	transform_func     func(string) string
+	needs_recurse_func func(string, fs.DirEntry) bool
+}
+
+func (self *transformed_walker) walk(dirpath string) error {
+	resolved_path := self.transform_func(dirpath)
+	if self.seen[resolved_path] {
+		return nil
+	}
+	self.seen[resolved_path] = true
+
+	c := func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			// Happens if ReadDir on d failed, skip it in that case
+			return fs.SkipDir
+		}
+		rpath, err := filepath.Rel(resolved_path, path)
+		if err != nil {
+			return err
+		}
+		path_based_on_original_dir := filepath.Join(dirpath, rpath)
+		if self.needs_recurse_func(path, d) {
+			err = self.walk(path_based_on_original_dir)
+		} else {
+			err = self.real_callback(path_based_on_original_dir, d, err)
+		}
+		return err
+	}
+
+	return filepath.WalkDir(resolved_path, c)
+}
+
+// Walk, recursing into symlinks that point to directories. Ignores directories
+// that could not be read.
+func WalkWithSymlink(dirpath string, callback Walk_callback) error {
+	sw := transformed_walker{
+		seen: make(map[string]bool), real_callback: callback, transform_func: transform_symlink, needs_recurse_func: needs_symlink_recurse}
+	return sw.walk(dirpath)
+}
 
 func complete_files(prefix string, callback CompleteFilesCallback) error {
 	base := "."
-	base_len := len(base) + 1
 	has_cwd_prefix := strings.HasPrefix(prefix, "./")
 	is_abs_path := filepath.IsAbs(prefix)
 	wd := ""
 	if is_abs_path {
 		base = prefix
-		base_len = 0
 		if s, err := os.Stat(prefix); err != nil || !s.IsDir() {
 			base = filepath.Dir(prefix)
 		}
 	} else {
-		wd, _ = os.Getwd()
-	}
-	filepath.WalkDir(base, func(path string, d fs.DirEntry, err error) error {
-		if err != nil {
-			return nil
+		var qe error
+		wd, qe = os.Getwd()
+		if qe != nil {
+			wd = ""
 		}
-		if path == base {
+	}
+	num := 0
+	WalkWithSymlink(base, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return fs.SkipDir
+		}
+		num++
+		if num == 1 {
 			return nil
 		}
 		completion_candidate := path
 		abspath := path
-		if is_abs_path {
-			completion_candidate = path[base_len:]
-		} else {
+		if !is_abs_path {
 			abspath = filepath.Join(wd, path)
 			if has_cwd_prefix {
 				completion_candidate = "./" + completion_candidate