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restic/internal/backend/local/local.go
Andrea Gelmini 241916d55b
Fix typos
2023-12-06 13:11:55 +01:00

365 lines
8.9 KiB
Go

package local
import (
"context"
"hash"
"io"
"os"
"path/filepath"
"syscall"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/backend/layout"
"github.com/restic/restic/internal/backend/limiter"
"github.com/restic/restic/internal/backend/location"
"github.com/restic/restic/internal/backend/util"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/fs"
"github.com/cenkalti/backoff/v4"
)
// Local is a backend in a local directory.
type Local struct {
Config
layout.Layout
util.Modes
}
// ensure statically that *Local implements backend.Backend.
var _ backend.Backend = &Local{}
func NewFactory() location.Factory {
return location.NewLimitedBackendFactory("local", ParseConfig, location.NoPassword, limiter.WrapBackendConstructor(Create), limiter.WrapBackendConstructor(Open))
}
const defaultLayout = "default"
func open(ctx context.Context, cfg Config) (*Local, error) {
l, err := layout.ParseLayout(ctx, &layout.LocalFilesystem{}, cfg.Layout, defaultLayout, cfg.Path)
if err != nil {
return nil, err
}
fi, err := fs.Stat(l.Filename(backend.Handle{Type: backend.ConfigFile}))
m := util.DeriveModesFromFileInfo(fi, err)
debug.Log("using (%03O file, %03O dir) permissions", m.File, m.Dir)
return &Local{
Config: cfg,
Layout: l,
Modes: m,
}, nil
}
// Open opens the local backend as specified by config.
func Open(ctx context.Context, cfg Config) (*Local, error) {
debug.Log("open local backend at %v (layout %q)", cfg.Path, cfg.Layout)
return open(ctx, cfg)
}
// Create creates all the necessary files and directories for a new local
// backend at dir. Afterwards a new config blob should be created.
func Create(ctx context.Context, cfg Config) (*Local, error) {
debug.Log("create local backend at %v (layout %q)", cfg.Path, cfg.Layout)
be, err := open(ctx, cfg)
if err != nil {
return nil, err
}
// test if config file already exists
_, err = fs.Lstat(be.Filename(backend.Handle{Type: backend.ConfigFile}))
if err == nil {
return nil, errors.New("config file already exists")
}
// create paths for data and refs
for _, d := range be.Paths() {
err := fs.MkdirAll(d, be.Modes.Dir)
if err != nil {
return nil, errors.WithStack(err)
}
}
return be, nil
}
func (b *Local) Connections() uint {
return b.Config.Connections
}
// Location returns this backend's location (the directory name).
func (b *Local) Location() string {
return b.Path
}
// Hasher may return a hash function for calculating a content hash for the backend
func (b *Local) Hasher() hash.Hash {
return nil
}
// HasAtomicReplace returns whether Save() can atomically replace files
func (b *Local) HasAtomicReplace() bool {
return true
}
// IsNotExist returns true if the error is caused by a non existing file.
func (b *Local) IsNotExist(err error) bool {
return errors.Is(err, os.ErrNotExist)
}
// Save stores data in the backend at the handle.
func (b *Local) Save(_ context.Context, h backend.Handle, rd backend.RewindReader) (err error) {
finalname := b.Filename(h)
dir := filepath.Dir(finalname)
defer func() {
// Mark non-retriable errors as such
if errors.Is(err, syscall.ENOSPC) || os.IsPermission(err) {
err = backoff.Permanent(err)
}
}()
// Create new file with a temporary name.
tmpname := filepath.Base(finalname) + "-tmp-"
f, err := tempFile(dir, tmpname)
if b.IsNotExist(err) {
debug.Log("error %v: creating dir", err)
// error is caused by a missing directory, try to create it
mkdirErr := fs.MkdirAll(dir, b.Modes.Dir)
if mkdirErr != nil {
debug.Log("error creating dir %v: %v", dir, mkdirErr)
} else {
// try again
f, err = tempFile(dir, tmpname)
}
}
if err != nil {
return errors.WithStack(err)
}
defer func(f *os.File) {
if err != nil {
_ = f.Close() // Double Close is harmless.
// Remove after Rename is harmless: we embed the final name in the
// temporary's name and no other goroutine will get the same data to
// Save, so the temporary name should never be reused by another
// goroutine.
_ = fs.Remove(f.Name())
}
}(f)
// preallocate disk space
if size := rd.Length(); size > 0 {
if err := fs.PreallocateFile(f, size); err != nil {
debug.Log("Failed to preallocate %v with size %v: %v", finalname, size, err)
}
}
// save data, then sync
wbytes, err := io.Copy(f, rd)
if err != nil {
return errors.WithStack(err)
}
// sanity check
if wbytes != rd.Length() {
return errors.Errorf("wrote %d bytes instead of the expected %d bytes", wbytes, rd.Length())
}
// Ignore error if filesystem does not support fsync.
err = f.Sync()
syncNotSup := err != nil && (errors.Is(err, syscall.ENOTSUP) || isMacENOTTY(err))
if err != nil && !syncNotSup {
return errors.WithStack(err)
}
// Close, then rename. Windows doesn't like the reverse order.
if err = f.Close(); err != nil {
return errors.WithStack(err)
}
if err = os.Rename(f.Name(), finalname); err != nil {
return errors.WithStack(err)
}
// Now sync the directory to commit the Rename.
if !syncNotSup {
err = fsyncDir(dir)
if err != nil {
return errors.WithStack(err)
}
}
// try to mark file as read-only to avoid accidental modifications
// ignore if the operation fails as some filesystems don't allow the chmod call
// e.g. exfat and network file systems with certain mount options
err = setFileReadonly(finalname, b.Modes.File)
if err != nil && !os.IsPermission(err) {
return errors.WithStack(err)
}
return nil
}
var tempFile = os.CreateTemp // Overridden by test.
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (b *Local) Load(ctx context.Context, h backend.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return util.DefaultLoad(ctx, h, length, offset, b.openReader, fn)
}
func (b *Local) openReader(_ context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error) {
f, err := fs.Open(b.Filename(h))
if err != nil {
return nil, err
}
if offset > 0 {
_, err = f.Seek(offset, 0)
if err != nil {
_ = f.Close()
return nil, err
}
}
if length > 0 {
return backend.LimitReadCloser(f, int64(length)), nil
}
return f, nil
}
// Stat returns information about a blob.
func (b *Local) Stat(_ context.Context, h backend.Handle) (backend.FileInfo, error) {
fi, err := fs.Stat(b.Filename(h))
if err != nil {
return backend.FileInfo{}, errors.WithStack(err)
}
return backend.FileInfo{Size: fi.Size(), Name: h.Name}, nil
}
// Remove removes the blob with the given name and type.
func (b *Local) Remove(_ context.Context, h backend.Handle) error {
fn := b.Filename(h)
// reset read-only flag
err := fs.Chmod(fn, 0666)
if err != nil && !os.IsPermission(err) {
return errors.WithStack(err)
}
return fs.Remove(fn)
}
// List runs fn for each file in the backend which has the type t. When an
// error occurs (or fn returns an error), List stops and returns it.
func (b *Local) List(ctx context.Context, t backend.FileType, fn func(backend.FileInfo) error) (err error) {
basedir, subdirs := b.Basedir(t)
if subdirs {
err = visitDirs(ctx, basedir, fn)
} else {
err = visitFiles(ctx, basedir, fn, false)
}
if b.IsNotExist(err) {
debug.Log("ignoring non-existing directory")
return nil
}
return err
}
// The following two functions are like filepath.Walk, but visit only one or
// two levels of directory structure (including dir itself as the first level).
// Also, visitDirs assumes it sees a directory full of directories, while
// visitFiles wants a directory full or regular files.
func visitDirs(ctx context.Context, dir string, fn func(backend.FileInfo) error) error {
d, err := fs.Open(dir)
if err != nil {
return err
}
sub, err := d.Readdirnames(-1)
if err != nil {
// ignore subsequent errors
_ = d.Close()
return err
}
err = d.Close()
if err != nil {
return err
}
for _, f := range sub {
err = visitFiles(ctx, filepath.Join(dir, f), fn, true)
if err != nil {
return err
}
}
return ctx.Err()
}
func visitFiles(ctx context.Context, dir string, fn func(backend.FileInfo) error, ignoreNotADirectory bool) error {
d, err := fs.Open(dir)
if err != nil {
return err
}
if ignoreNotADirectory {
fi, err := d.Stat()
if err != nil || !fi.IsDir() {
// ignore subsequent errors
_ = d.Close()
return err
}
}
sub, err := d.Readdir(-1)
if err != nil {
// ignore subsequent errors
_ = d.Close()
return err
}
err = d.Close()
if err != nil {
return err
}
for _, fi := range sub {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
err := fn(backend.FileInfo{
Name: fi.Name(),
Size: fi.Size(),
})
if err != nil {
return err
}
}
return nil
}
// Delete removes the repository and all files.
func (b *Local) Delete(_ context.Context) error {
return fs.RemoveAll(b.Path)
}
// Close closes all open files.
func (b *Local) Close() error {
// this does not need to do anything, all open files are closed within the
// same function.
return nil
}