all: Implement variable sized blocks (fixes #4807)

lib/scanner/virtualfs_test.go

@@ -0,0 +1,146 @@
+// Copyright (C) 2017 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package scanner
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/syncthing/syncthing/lib/fs"
+)
+
+type infiniteFS struct {
+	fs.Filesystem
+	width    int   // number of files and directories per level
+	depth    int   // number of tree levels to simulate
+	filesize int64 // size of each file in bytes
+}
+
+var errNotSupp = errors.New("not supported")
+
+func (i infiniteFS) Lstat(name string) (fs.FileInfo, error) {
+	return fakeInfo{name, i.filesize}, nil
+}
+
+func (i infiniteFS) Stat(name string) (fs.FileInfo, error) {
+	return fakeInfo{name, i.filesize}, nil
+}
+
+func (i infiniteFS) DirNames(name string) ([]string, error) {
+	// Returns a list of fake files and directories. Names are such that
+	// files appear before directories - this makes it so the scanner will
+	// actually see a few files without having to reach the max depth.
+	var names []string
+	for j := 0; j < i.width; j++ {
+		names = append(names, fmt.Sprintf("aa-file-%d", j))
+	}
+	if len(strings.Split(name, string(os.PathSeparator))) < i.depth {
+		for j := 0; j < i.width; j++ {
+			names = append(names, fmt.Sprintf("zz-dir-%d", j))
+		}
+	}
+	return names, nil
+}
+
+func (i infiniteFS) Open(name string) (fs.File, error) {
+	return &fakeFile{name, i.filesize, 0}, nil
+}
+
+type singleFileFS struct {
+	fs.Filesystem
+	name     string
+	filesize int64
+}
+
+func (s singleFileFS) Lstat(name string) (fs.FileInfo, error) {
+	switch name {
+	case ".":
+		return fakeInfo{".", 0}, nil
+	case s.name:
+		return fakeInfo{s.name, s.filesize}, nil
+	default:
+		return nil, errors.New("no such file")
+	}
+}
+
+func (s singleFileFS) Stat(name string) (fs.FileInfo, error) {
+	switch name {
+	case ".":
+		return fakeInfo{".", 0}, nil
+	case s.name:
+		return fakeInfo{s.name, s.filesize}, nil
+	default:
+		return nil, errors.New("no such file")
+	}
+}
+
+func (s singleFileFS) DirNames(name string) ([]string, error) {
+	if name != "." {
+		return nil, errors.New("no such file")
+	}
+	return []string{s.name}, nil
+}
+
+func (s singleFileFS) Open(name string) (fs.File, error) {
+	if name != s.name {
+		return nil, errors.New("no such file")
+	}
+	return &fakeFile{s.name, s.filesize, 0}, nil
+}
+
+type fakeInfo struct {
+	name string
+	size int64
+}
+
+func (f fakeInfo) Name() string       { return f.name }
+func (f fakeInfo) Mode() fs.FileMode  { return 0755 }
+func (f fakeInfo) Size() int64        { return f.size }
+func (f fakeInfo) ModTime() time.Time { return time.Unix(1234567890, 0) }
+func (f fakeInfo) IsDir() bool        { return strings.Contains(filepath.Base(f.name), "dir") || f.name == "." }
+func (f fakeInfo) IsRegular() bool    { return !f.IsDir() }
+func (f fakeInfo) IsSymlink() bool    { return false }
+
+type fakeFile struct {
+	name       string
+	size       int64
+	readOffset int64
+}
+
+func (f *fakeFile) Name() string {
+	return f.name
+}
+
+func (f *fakeFile) Read(bs []byte) (int, error) {
+	remaining := f.size - f.readOffset
+	if remaining == 0 {
+		return 0, io.EOF
+	}
+	if remaining < int64(len(bs)) {
+		f.readOffset = f.size
+		return int(remaining), nil
+	}
+	f.readOffset += int64(len(bs))
+	return len(bs), nil
+}
+
+func (f *fakeFile) Stat() (fs.FileInfo, error) {
+	return fakeInfo{f.name, f.size}, nil
+}
+
+func (f *fakeFile) Write([]byte) (int, error)          { return 0, errNotSupp }
+func (f *fakeFile) WriteAt([]byte, int64) (int, error) { return 0, errNotSupp }
+func (f *fakeFile) Close() error                       { return nil }
+func (f *fakeFile) Truncate(size int64) error          { return errNotSupp }
+func (f *fakeFile) ReadAt([]byte, int64) (int, error)  { return 0, errNotSupp }
+func (f *fakeFile) Seek(int64, int) (int64, error)     { return 0, errNotSupp }
+func (f *fakeFile) Sync() error                        { return nil }