rclone/fs/walk/walk.go

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// Package walk walks directories
package walk
import (
"context"
"errors"
"fmt"
"path"
"sort"
"strings"
"sync"
"time"
"github.com/rclone/rclone/fs"
"github.com/rclone/rclone/fs/dirtree"
"github.com/rclone/rclone/fs/filter"
"github.com/rclone/rclone/fs/list"
)
// ErrorSkipDir is used as a return value from Walk to indicate that the
// directory named in the call is to be skipped. It is not returned as
// an error by any function.
var ErrorSkipDir = errors.New("skip this directory")
// ErrorCantListR is returned by WalkR if the underlying Fs isn't
// capable of doing a recursive listing.
var ErrorCantListR = errors.New("recursive directory listing not available")
// Func is the type of the function called for directory
// visited by Walk. The path argument contains remote path to the directory.
//
// If there was a problem walking to 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
// ErrorSkipDir. If the function returns ErrorSkipDir, Walk skips the
// directory's contents entirely.
type Func func(path string, entries fs.DirEntries, err error) error
// Walk lists the directory.
//
// If includeAll is not set it will use the filters defined.
//
// If maxLevel is < 0 then it will recurse indefinitely, else it will
// only do maxLevel levels.
//
// It calls fn for each tranche of DirEntries read.
//
// Note that fn will not be called concurrently whereas the directory
// listing will proceed concurrently.
//
// Parent directories are always listed before their children.
//
// This is implemented by WalkR if Config.UseListR is true
// and f supports it and level > 1, or WalkN otherwise.
//
// If --files-from and --no-traverse is set then a DirTree will be
// constructed with just those files in and then walked with WalkR
//
// Note: this will flag filter-aware backends!
//
// NB (f, path) to be replaced by fs.Dir at some point
func Walk(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, fn Func) error {
ci := fs.GetConfig(ctx)
fi := filter.GetConfig(ctx)
ctx = filter.SetUseFilter(ctx, f.Features().FilterAware && !includeAll) // make filter-aware backends constrain List
if ci.NoTraverse && fi.HaveFilesFrom() {
return walkR(ctx, f, path, includeAll, maxLevel, fn, fi.MakeListR(ctx, f.NewObject))
}
// FIXME should this just be maxLevel < 0 - why the maxLevel > 1
if (maxLevel < 0 || maxLevel > 1) && ci.UseListR && f.Features().ListR != nil {
return walkListR(ctx, f, path, includeAll, maxLevel, fn)
}
return walkListDirSorted(ctx, f, path, includeAll, maxLevel, fn)
}
// ListType is uses to choose which combination of files or directories is requires
type ListType byte
// Types of listing for ListR
const (
ListObjects ListType = 1 << iota // list objects only
ListDirs // list dirs only
ListAll = ListObjects | ListDirs // list files and dirs
)
// Objects returns true if the list type specifies objects
func (l ListType) Objects() bool {
return (l & ListObjects) != 0
}
// Dirs returns true if the list type specifies dirs
func (l ListType) Dirs() bool {
return (l & ListDirs) != 0
}
// Filter in (inplace) to only contain the type of list entry required
func (l ListType) Filter(in *fs.DirEntries) {
if l == ListAll {
return
}
out := (*in)[:0]
for _, entry := range *in {
switch entry.(type) {
case fs.Object:
if l.Objects() {
out = append(out, entry)
}
case fs.Directory:
if l.Dirs() {
out = append(out, entry)
}
default:
fs.Errorf(nil, "Unknown object type %T", entry)
}
}
*in = out
}
// ListR lists the directory recursively.
//
// If includeAll is not set it will use the filters defined.
//
// If maxLevel is < 0 then it will recurse indefinitely, else it will
// only do maxLevel levels.
//
// If synthesizeDirs is set then for bucket-based remotes it will
// synthesize directories from the file structure. This uses extra
// memory so don't set this if you don't need directories, likewise do
// set this if you are interested in directories.
//
// It calls fn for each tranche of DirEntries read. Note that these
// don't necessarily represent a directory
//
// Note that fn will not be called concurrently whereas the directory
// listing will proceed concurrently.
//
// Directories are not listed in any particular order so you can't
// rely on parents coming before children or alphabetical ordering
//
// This is implemented by using ListR on the backend if possible and
// efficient, otherwise by Walk.
//
// Note: this will flag filter-aware backends
//
// NB (f, path) to be replaced by fs.Dir at some point
func ListR(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, listType ListType, fn fs.ListRCallback) error {
fi := filter.GetConfig(ctx)
// FIXME disable this with --no-fast-list ??? `--disable ListR` will do it...
doListR := f.Features().ListR
// Can't use ListR if...
if doListR == nil || // ...no ListR
fi.HaveFilesFrom() || // ...using --files-from
maxLevel >= 0 || // ...using bounded recursion
len(fi.Opt.ExcludeFile) > 0 || // ...using --exclude-file
fi.UsesDirectoryFilters() { // ...using any directory filters
return listRwalk(ctx, f, path, includeAll, maxLevel, listType, fn)
}
ctx = filter.SetUseFilter(ctx, f.Features().FilterAware && !includeAll) // make filter-aware backends constrain List
return listR(ctx, f, path, includeAll, listType, fn, doListR, listType.Dirs() && f.Features().BucketBased)
}
// listRwalk walks the file tree for ListR using Walk
// Note: this will flag filter-aware backends (via Walk)
func listRwalk(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, listType ListType, fn fs.ListRCallback) error {
var listErr error
walkErr := Walk(ctx, f, path, includeAll, maxLevel, func(path string, entries fs.DirEntries, err error) error {
// Carry on listing but return the error at the end
if err != nil {
listErr = err
err = fs.CountError(err)
fs.Errorf(path, "error listing: %v", err)
return nil
}
listType.Filter(&entries)
return fn(entries)
})
if listErr != nil {
return listErr
}
return walkErr
}
// dirMap keeps track of directories made for bucket-based remotes.
// true => directory has been sent
// false => directory has been seen but not sent
type dirMap struct {
mu sync.Mutex
m map[string]bool
root string
}
// make a new dirMap
func newDirMap(root string) *dirMap {
return &dirMap{
m: make(map[string]bool),
root: root,
}
}
// add adds a directory and parents with sent
func (dm *dirMap) add(dir string, sent bool) {
for {
if dir == dm.root || dir == "" {
return
}
currentSent, found := dm.m[dir]
if found {
// If it has been sent already then nothing more to do
if currentSent {
return
}
// If not sent already don't override
if !sent {
return
}
// currentSent == false && sent == true so needs overriding
}
dm.m[dir] = sent
// Add parents in as unsent
dir = parentDir(dir)
sent = false
}
}
// parentDir finds the parent directory of path
func parentDir(entryPath string) string {
dirPath := path.Dir(entryPath)
if dirPath == "." {
dirPath = ""
}
return dirPath
}
// add all the directories in entries and their parents to the dirMap
func (dm *dirMap) addEntries(entries fs.DirEntries) error {
dm.mu.Lock()
defer dm.mu.Unlock()
for _, entry := range entries {
switch x := entry.(type) {
case fs.Object:
dm.add(parentDir(x.Remote()), false)
case fs.Directory:
dm.add(x.Remote(), true)
default:
return fmt.Errorf("unknown object type %T", entry)
}
}
return nil
}
// send any missing parents to fn
func (dm *dirMap) sendEntries(fn fs.ListRCallback) (err error) {
// Count the strings first so we allocate the minimum memory
n := 0
for _, sent := range dm.m {
if !sent {
n++
}
}
if n == 0 {
return nil
}
dirs := make([]string, 0, n)
// Fill the dirs up then sort it
for dir, sent := range dm.m {
if !sent {
dirs = append(dirs, dir)
}
}
sort.Strings(dirs)
// Now convert to bulkier Dir in batches and send
now := time.Now()
list := NewListRHelper(fn)
for _, dir := range dirs {
err = list.Add(fs.NewDir(dir, now))
if err != nil {
return err
}
}
return list.Flush()
}
// listR walks the file tree using ListR
func listR(ctx context.Context, f fs.Fs, path string, includeAll bool, listType ListType, fn fs.ListRCallback, doListR fs.ListRFn, synthesizeDirs bool) error {
fi := filter.GetConfig(ctx)
includeDirectory := fi.IncludeDirectory(ctx, f)
if !includeAll {
includeAll = fi.InActive()
}
var dm *dirMap
if synthesizeDirs {
dm = newDirMap(path)
}
var mu sync.Mutex
err := doListR(ctx, path, func(entries fs.DirEntries) (err error) {
if synthesizeDirs {
err = dm.addEntries(entries)
if err != nil {
return err
}
}
listType.Filter(&entries)
if !includeAll {
filteredEntries := entries[:0]
for _, entry := range entries {
var include bool
switch x := entry.(type) {
case fs.Object:
include = fi.IncludeObject(ctx, x)
case fs.Directory:
include, err = includeDirectory(x.Remote())
if err != nil {
return err
}
default:
return fmt.Errorf("unknown object type %T", entry)
}
if include {
filteredEntries = append(filteredEntries, entry)
}
}
entries = filteredEntries
}
mu.Lock()
defer mu.Unlock()
return fn(entries)
})
if err != nil {
return err
}
if synthesizeDirs {
err = dm.sendEntries(fn)
if err != nil {
return err
}
}
return nil
}
// walkListDirSorted lists the directory.
//
// It implements Walk using non recursive directory listing.
func walkListDirSorted(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, fn Func) error {
return walk(ctx, f, path, includeAll, maxLevel, fn, list.DirSorted)
}
// walkListR lists the directory.
//
// It implements Walk using recursive directory listing if
// available, or returns ErrorCantListR if not.
func walkListR(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, fn Func) error {
listR := f.Features().ListR
if listR == nil {
return ErrorCantListR
}
return walkR(ctx, f, path, includeAll, maxLevel, fn, listR)
}
type listDirFunc func(ctx context.Context, fs fs.Fs, includeAll bool, dir string) (entries fs.DirEntries, err error)
func walk(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, fn Func, listDir listDirFunc) error {
var (
wg sync.WaitGroup // sync closing of go routines
traversing sync.WaitGroup // running directory traversals
doClose sync.Once // close the channel once
mu sync.Mutex // stop fn being called concurrently
ci = fs.GetConfig(ctx) // current config
)
// listJob describe a directory listing that needs to be done
type listJob struct {
remote string
depth int
}
in := make(chan listJob, ci.Checkers)
errs := make(chan error, 1)
quit := make(chan struct{})
closeQuit := func() {
doClose.Do(func() {
close(quit)
go func() {
for range in {
traversing.Done()
}
}()
})
}
for i := 0; i < ci.Checkers; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for {
select {
case job, ok := <-in:
if !ok {
return
}
entries, err := listDir(ctx, f, includeAll, job.remote)
var jobs []listJob
if err == nil && job.depth != 0 {
entries.ForDir(func(dir fs.Directory) {
// Recurse for the directory
jobs = append(jobs, listJob{
remote: dir.Remote(),
depth: job.depth - 1,
})
})
}
mu.Lock()
err = fn(job.remote, entries, err)
mu.Unlock()
// NB once we have passed entries to fn we mustn't touch it again
if err != nil && err != ErrorSkipDir {
traversing.Done()
err = fs.CountError(err)
fs.Errorf(job.remote, "error listing: %v", err)
closeQuit()
// Send error to error channel if space
select {
case errs <- err:
default:
}
continue
}
if err == nil && len(jobs) > 0 {
traversing.Add(len(jobs))
go func() {
// Now we have traversed this directory, send these
// jobs off for traversal in the background
for _, newJob := range jobs {
in <- newJob
}
}()
}
traversing.Done()
case <-quit:
return
}
}
}()
}
// Start the process
traversing.Add(1)
in <- listJob{
remote: path,
depth: maxLevel - 1,
}
traversing.Wait()
close(in)
wg.Wait()
close(errs)
// return the first error returned or nil
return <-errs
}
func walkRDirTree(ctx context.Context, f fs.Fs, startPath string, includeAll bool, maxLevel int, listR fs.ListRFn) (dirtree.DirTree, error) {
fi := filter.GetConfig(ctx)
dirs := dirtree.New()
// Entries can come in arbitrary order. We use toPrune to keep
// all directories to exclude later.
toPrune := make(map[string]bool)
includeDirectory := fi.IncludeDirectory(ctx, f)
var mu sync.Mutex
err := listR(ctx, startPath, func(entries fs.DirEntries) error {
mu.Lock()
defer mu.Unlock()
for _, entry := range entries {
slashes := strings.Count(entry.Remote(), "/")
excluded := true
switch x := entry.(type) {
case fs.Object:
// Make sure we don't delete excluded files if not required
if includeAll || fi.IncludeObject(ctx, x) {
if maxLevel < 0 || slashes <= maxLevel-1 {
dirs.Add(x)
excluded = false
}
}
// Make sure we include any parent directories of excluded objects
if excluded {
dirPath := parentDir(x.Remote())
slashes--
if maxLevel >= 0 {
for ; slashes > maxLevel-1; slashes-- {
dirPath = parentDir(dirPath)
}
}
inc, err := includeDirectory(dirPath)
if err != nil {
return err
}
if inc || includeAll {
// If the directory doesn't exist already, create it
_, obj := dirs.Find(dirPath)
if obj == nil {
dirs.AddDir(fs.NewDir(dirPath, time.Now()))
}
}
}
// Check if we need to prune a directory later.
if !includeAll && len(fi.Opt.ExcludeFile) > 0 {
basename := path.Base(x.Remote())
for _, excludeFile := range fi.Opt.ExcludeFile {
if basename == excludeFile {
excludeDir := parentDir(x.Remote())
toPrune[excludeDir] = true
}
}
}
case fs.Directory:
inc, err := includeDirectory(x.Remote())
if err != nil {
return err
}
if includeAll || inc {
if maxLevel < 0 || slashes <= maxLevel-1 {
if slashes == maxLevel-1 {
// Just add the object if at maxLevel
dirs.Add(x)
} else {
dirs.AddDir(x)
}
}
}
default:
return fmt.Errorf("unknown object type %T", entry)
}
}
return nil
})
if err != nil {
return nil, err
}
dirs.CheckParents(startPath)
if len(dirs) == 0 {
dirs[startPath] = nil
}
err = dirs.Prune(toPrune)
if err != nil {
return nil, err
}
dirs.Sort()
return dirs, nil
}
// Create a DirTree using List
func walkNDirTree(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, listDir listDirFunc) (dirtree.DirTree, error) {
dirs := make(dirtree.DirTree)
fn := func(dirPath string, entries fs.DirEntries, err error) error {
if err == nil {
dirs[dirPath] = entries
}
return err
}
err := walk(ctx, f, path, includeAll, maxLevel, fn, listDir)
if err != nil {
return nil, err
}
return dirs, nil
}
// NewDirTree returns a DirTree filled with the directory listing
// using the parameters supplied.
//
// If includeAll is not set it will use the filters defined.
//
// If maxLevel is < 0 then it will recurse indefinitely, else it will
// only do maxLevel levels.
//
// This is implemented by WalkR if f supports ListR and level > 1, or
// WalkN otherwise.
//
// If --files-from and --no-traverse is set then a DirTree will be
// constructed with just those files in.
//
// NB (f, path) to be replaced by fs.Dir at some point
func NewDirTree(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int) (dirtree.DirTree, error) {
ci := fs.GetConfig(ctx)
fi := filter.GetConfig(ctx)
// if --no-traverse and --files-from build DirTree just from files
if ci.NoTraverse && fi.HaveFilesFrom() {
return walkRDirTree(ctx, f, path, includeAll, maxLevel, fi.MakeListR(ctx, f.NewObject))
}
// if have ListR; and recursing; and not using --files-from; then build a DirTree with ListR
if ListR := f.Features().ListR; (maxLevel < 0 || maxLevel > 1) && ListR != nil && !fi.HaveFilesFrom() {
return walkRDirTree(ctx, f, path, includeAll, maxLevel, ListR)
}
// otherwise just use List
return walkNDirTree(ctx, f, path, includeAll, maxLevel, list.DirSorted)
}
func walkR(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int, fn Func, listR fs.ListRFn) error {
dirs, err := walkRDirTree(ctx, f, path, includeAll, maxLevel, listR)
if err != nil {
return err
}
skipping := false
skipPrefix := ""
emptyDir := fs.DirEntries{}
for _, dirPath := range dirs.Dirs() {
if skipping {
// Skip over directories as required
if strings.HasPrefix(dirPath, skipPrefix) {
continue
}
skipping = false
}
entries := dirs[dirPath]
if entries == nil {
entries = emptyDir
}
err = fn(dirPath, entries, nil)
if err == ErrorSkipDir {
skipping = true
skipPrefix = dirPath
if skipPrefix != "" {
skipPrefix += "/"
}
} else if err != nil {
return err
}
}
return nil
}
// GetAll runs ListR getting all the results
func GetAll(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int) (objs []fs.Object, dirs []fs.Directory, err error) {
err = ListR(ctx, f, path, includeAll, maxLevel, ListAll, func(entries fs.DirEntries) error {
for _, entry := range entries {
switch x := entry.(type) {
case fs.Object:
objs = append(objs, x)
case fs.Directory:
dirs = append(dirs, x)
}
}
return nil
})
return
}
// ListRHelper is used in the implementation of ListR to accumulate DirEntries
type ListRHelper struct {
callback fs.ListRCallback
entries fs.DirEntries
}
// NewListRHelper should be called from ListR with the callback passed in
func NewListRHelper(callback fs.ListRCallback) *ListRHelper {
return &ListRHelper{
callback: callback,
}
}
// send sends the stored entries to the callback if there are >= max
// entries.
func (lh *ListRHelper) send(max int) (err error) {
if len(lh.entries) >= max {
err = lh.callback(lh.entries)
lh.entries = lh.entries[:0]
}
return err
}
// Add an entry to the stored entries and send them if there are more
// than a certain amount
func (lh *ListRHelper) Add(entry fs.DirEntry) error {
if entry == nil {
return nil
}
lh.entries = append(lh.entries, entry)
return lh.send(100)
}
// Flush the stored entries (if any) sending them to the callback
func (lh *ListRHelper) Flush() error {
return lh.send(1)
}