Add new archiver code

internal/archiver/scanner.go

@@ -0,0 +1,112 @@
+package archiver
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+
+	"github.com/restic/restic/internal/fs"
+)
+
+// Scanner  traverses the targets and calls the function Result with cumulated
+// stats concerning the files and folders found. Select is used to decide which
+// items should be included. Error is called when an error occurs.
+type Scanner struct {
+	FS     fs.FS
+	Select SelectFunc
+	Error  ErrorFunc
+	Result func(item string, s ScanStats)
+}
+
+// NewScanner initializes a new Scanner.
+func NewScanner(fs fs.FS) *Scanner {
+	return &Scanner{
+		FS: fs,
+		Select: func(item string, fi os.FileInfo) bool {
+			return true
+		},
+		Error: func(item string, fi os.FileInfo, err error) error {
+			return err
+		},
+		Result: func(item string, s ScanStats) {},
+	}
+}
+
+// ScanStats collect statistics.
+type ScanStats struct {
+	Files, Dirs, Others uint
+	Bytes               uint64
+}
+
+// Scan traverses the targets. The function Result is called for each new item
+// found, the complete result is also returned by Scan.
+func (s *Scanner) Scan(ctx context.Context, targets []string) error {
+	var stats ScanStats
+	for _, target := range targets {
+		abstarget, err := s.FS.Abs(target)
+		if err != nil {
+			return err
+		}
+
+		stats, err = s.scan(ctx, stats, abstarget)
+		if err != nil {
+			return err
+		}
+
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+	}
+
+	s.Result("", stats)
+	return nil
+}
+
+func (s *Scanner) scan(ctx context.Context, stats ScanStats, target string) (ScanStats, error) {
+	if ctx.Err() != nil {
+		return stats, ctx.Err()
+	}
+
+	fi, err := s.FS.Lstat(target)
+	if err != nil {
+		// ignore error if the target is to be excluded anyway
+		if !s.Select(target, nil) {
+			return stats, nil
+		}
+
+		// else return filtered error
+		return stats, s.Error(target, fi, err)
+	}
+
+	if !s.Select(target, fi) {
+		return stats, nil
+	}
+
+	switch {
+	case fi.Mode().IsRegular():
+		stats.Files++
+		stats.Bytes += uint64(fi.Size())
+	case fi.Mode().IsDir():
+		if ctx.Err() != nil {
+			return stats, ctx.Err()
+		}
+
+		names, err := readdirnames(s.FS, target)
+		if err != nil {
+			return stats, s.Error(target, fi, err)
+		}
+
+		for _, name := range names {
+			stats, err = s.scan(ctx, stats, filepath.Join(target, name))
+			if err != nil {
+				return stats, err
+			}
+		}
+		stats.Dirs++
+	default:
+		stats.Others++
+	}
+
+	s.Result(target, stats)
+	return stats, nil
+}