restic/internal/backend/local/local.go

322 lines
7.8 KiB
Go

package local
import (
"context"
"io"
"os"
"path/filepath"
"syscall"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/fs"
"github.com/cenkalti/backoff/v4"
)
// Local is a backend in a local directory.
type Local struct {
Config
backend.Layout
}
// ensure statically that *Local implements restic.Backend.
var _ restic.Backend = &Local{}
const defaultLayout = "default"
// 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)
l, err := backend.ParseLayout(ctx, &backend.LocalFilesystem{}, cfg.Layout, defaultLayout, cfg.Path)
if err != nil {
return nil, err
}
return &Local{Config: cfg, Layout: l}, nil
}
// 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)
l, err := backend.ParseLayout(ctx, &backend.LocalFilesystem{}, cfg.Layout, defaultLayout, cfg.Path)
if err != nil {
return nil, err
}
be := &Local{
Config: cfg,
Layout: l,
}
// test if config file already exists
_, err = fs.Lstat(be.Filename(restic.Handle{Type: restic.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, backend.Modes.Dir)
if err != nil {
return nil, errors.Wrap(err, "MkdirAll")
}
}
return be, nil
}
// Location returns this backend's location (the directory name).
func (b *Local) Location() string {
return b.Path
}
// IsNotExist returns true if the error is caused by a non existing file.
func (b *Local) IsNotExist(err error) bool {
return os.IsNotExist(errors.Cause(err))
}
// Save stores data in the backend at the handle.
func (b *Local) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) (err error) {
debug.Log("Save %v", h)
if err := h.Valid(); err != nil {
return backoff.Permanent(err)
}
filename := b.Filename(h)
defer func() {
// Mark non-retriable errors as such
if errors.Is(err, syscall.ENOSPC) || os.IsPermission(err) {
err = backoff.Permanent(err)
}
}()
// create new file
f, err := openFile(filename, os.O_CREATE|os.O_EXCL|os.O_WRONLY, backend.Modes.File)
if b.IsNotExist(err) {
debug.Log("error %v: creating dir", err)
// error is caused by a missing directory, try to create it
mkdirErr := os.MkdirAll(filepath.Dir(filename), backend.Modes.Dir)
if mkdirErr != nil {
debug.Log("error creating dir %v: %v", filepath.Dir(filename), mkdirErr)
} else {
// try again
f, err = openFile(filename, os.O_CREATE|os.O_EXCL|os.O_WRONLY, backend.Modes.File)
}
}
if err != nil {
return errors.Wrap(err, "OpenFile")
}
// save data, then sync
_, err = io.Copy(f, rd)
if err != nil {
_ = f.Close()
return errors.Wrap(err, "Write")
}
if err = f.Sync(); err != nil {
pathErr, ok := err.(*os.PathError)
isNotSupported := ok && pathErr.Op == "sync" && pathErr.Err == syscall.ENOTSUP
// ignore error if filesystem does not support the sync operation
if !isNotSupported {
_ = f.Close()
return errors.Wrap(err, "Sync")
}
}
err = f.Close()
if err != nil {
return errors.Wrap(err, "Close")
}
// try to mark file as read-only to avoid accidential 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(filename, backend.Modes.File)
if err != nil && !os.IsPermission(err) {
return errors.Wrap(err, "Chmod")
}
return nil
}
var openFile = fs.OpenFile // 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 restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return backend.DefaultLoad(ctx, h, length, offset, b.openReader, fn)
}
func (b *Local) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
debug.Log("Load %v, length %v, offset %v", h, length, offset)
if err := h.Valid(); err != nil {
return nil, backoff.Permanent(err)
}
if offset < 0 {
return nil, errors.New("offset is negative")
}
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(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
debug.Log("Stat %v", h)
if err := h.Valid(); err != nil {
return restic.FileInfo{}, backoff.Permanent(err)
}
fi, err := fs.Stat(b.Filename(h))
if err != nil {
return restic.FileInfo{}, errors.Wrap(err, "Stat")
}
return restic.FileInfo{Size: fi.Size(), Name: h.Name}, nil
}
// Test returns true if a blob of the given type and name exists in the backend.
func (b *Local) Test(ctx context.Context, h restic.Handle) (bool, error) {
debug.Log("Test %v", h)
_, err := fs.Stat(b.Filename(h))
if err != nil {
if os.IsNotExist(errors.Cause(err)) {
return false, nil
}
return false, errors.Wrap(err, "Stat")
}
return true, nil
}
// Remove removes the blob with the given name and type.
func (b *Local) Remove(ctx context.Context, h restic.Handle) error {
debug.Log("Remove %v", h)
fn := b.Filename(h)
// reset read-only flag
err := fs.Chmod(fn, 0666)
if err != nil && !os.IsPermission(err) {
return errors.Wrap(err, "Chmod")
}
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 restic.FileType, fn func(restic.FileInfo) error) (err error) {
debug.Log("List %v", t)
basedir, subdirs := b.Basedir(t)
if subdirs {
err = visitDirs(ctx, basedir, fn)
} else {
err = visitFiles(ctx, basedir, fn)
}
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(restic.FileInfo) error) error {
d, err := fs.Open(dir)
if err != nil {
return err
}
defer d.Close()
sub, err := d.Readdirnames(-1)
if err != nil {
return err
}
for _, f := range sub {
err = visitFiles(ctx, filepath.Join(dir, f), fn)
if err != nil {
return err
}
}
return ctx.Err()
}
func visitFiles(ctx context.Context, dir string, fn func(restic.FileInfo) error) error {
d, err := fs.Open(dir)
if err != nil {
return err
}
defer d.Close()
sub, err := d.Readdir(-1)
if err != nil {
return err
}
for _, fi := range sub {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
err := fn(restic.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(ctx context.Context) error {
debug.Log("Delete()")
return fs.RemoveAll(b.Path)
}
// Close closes all open files.
func (b *Local) Close() error {
debug.Log("Close()")
// this does not need to do anything, all open files are closed within the
// same function.
return nil
}