syncthing/lib/fs/walkfs.go

152 lines
4.3 KiB
Go
Raw Normal View History

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This part copied directly from golang.org/src/path/filepath/path.go (Go
// 1.6) and lightly modified to be methods on BasicFilesystem.
// In our Walk() all paths given to a WalkFunc() are relative to the
// filesystem root.
package fs
import (
"errors"
"path/filepath"
)
var ErrInfiniteRecursion = errors.New("infinite filesystem recursion detected")
type ancestorDirList struct {
list []FileInfo
fs Filesystem
}
func (ancestors *ancestorDirList) Push(info FileInfo) {
l.Debugf("ancestorDirList: Push '%s'", info.Name())
ancestors.list = append(ancestors.list, info)
}
func (ancestors *ancestorDirList) Pop() FileInfo {
aLen := len(ancestors.list)
info := ancestors.list[aLen-1]
l.Debugf("ancestorDirList: Pop '%s'", info.Name())
ancestors.list = ancestors.list[:aLen-1]
return info
}
func (ancestors *ancestorDirList) Contains(info FileInfo) bool {
l.Debugf("ancestorDirList: Contains '%s'", info.Name())
for _, ancestor := range ancestors.list {
if ancestors.fs.SameFile(info, ancestor) {
return true
}
}
return false
}
// WalkFunc is the type of the function called for each file or directory
// visited by Walk. The path argument contains the argument to Walk as a
// prefix; that is, if Walk is called with "dir", which is a directory
// containing the file "a", the walk function will be called with argument
// "dir/a". The info argument is the FileInfo for the named path.
//
// If there was a problem walking to the file or directory named by path, the
// incoming error will describe the problem and the function can decide how
// to handle that error (and Walk will not descend into that directory). If
// an error is returned, processing stops. The sole exception is when the function
// returns the special value SkipDir. If the function returns SkipDir when invoked
// on a directory, Walk skips the directory's contents entirely.
// If the function returns SkipDir when invoked on a non-directory file,
// Walk skips the remaining files in the containing directory.
type WalkFunc func(path string, info FileInfo, err error) error
type walkFilesystem struct {
Filesystem
checkInfiniteRecursion bool
}
func NewWalkFilesystem(next Filesystem) Filesystem {
fs := &walkFilesystem{
Filesystem: next,
}
for _, opt := range next.Options() {
if _, ok := opt.(*OptionJunctionsAsDirs); ok {
fs.checkInfiniteRecursion = true
break
}
}
return fs
}
// walk recursively descends path, calling walkFn.
func (f *walkFilesystem) walk(path string, info FileInfo, walkFn WalkFunc, ancestors *ancestorDirList) error {
l.Debugf("walk: path=%s", path)
path, err := Canonicalize(path)
if err != nil {
return err
}
err = walkFn(path, info, nil)
if err != nil {
if info.IsDir() && err == SkipDir {
return nil
}
return err
}
if !info.IsDir() && path != "." {
return nil
}
if f.checkInfiniteRecursion {
if !ancestors.Contains(info) {
ancestors.Push(info)
defer ancestors.Pop()
} else {
return walkFn(path, info, ErrInfiniteRecursion)
}
}
names, err := f.DirNames(path)
if err != nil {
return walkFn(path, info, err)
}
for _, name := range names {
filename := filepath.Join(path, name)
fileInfo, err := f.Lstat(filename)
if err != nil {
if err := walkFn(filename, fileInfo, err); err != nil && err != SkipDir {
return err
}
} else {
err = f.walk(filename, fileInfo, walkFn, ancestors)
if err != nil {
if !fileInfo.IsDir() || err != SkipDir {
return err
}
}
}
}
return nil
}
// Walk walks the file tree rooted at root, calling walkFn for each file or
// directory in the tree, including root. All errors that arise visiting files
// and directories are filtered by walkFn. The files are walked in lexical
// order, which makes the output deterministic but means that for very
// large directories Walk can be inefficient.
// Walk does not follow symbolic links.
func (f *walkFilesystem) Walk(root string, walkFn WalkFunc) error {
info, err := f.Lstat(root)
if err != nil {
return walkFn(root, nil, err)
}
var ancestors *ancestorDirList
if f.checkInfiniteRecursion {
ancestors = &ancestorDirList{fs: f.Filesystem}
}
return f.walk(root, info, walkFn, ancestors)
}