Files
distributor/internal/adapters/local/backend.go

372 lines
11 KiB
Go

package local
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"io/fs"
"os"
"path/filepath"
"strings"
"gitea.maximumdirect.net/eric/distributor/internal/storage"
)
const backendName = "local"
type Backend struct {
root string
}
func New(root string) (*Backend, error) {
if root == "" {
return nil, storage.NewError(storage.OpOpenBackend, backendName, "", storage.ErrInvalidPath, nil)
}
absRoot, err := filepath.Abs(root)
if err != nil {
return nil, storage.NewError(storage.OpOpenBackend, backendName, root, storage.ErrInvalidPath, err)
}
return &Backend{root: filepath.Clean(absRoot)}, nil
}
func (b *Backend) ReadFile(ctx context.Context, path string) ([]byte, error) {
reader, err := b.OpenReader(ctx, path)
if err != nil {
return nil, err
}
defer reader.Close()
data, err := io.ReadAll(reader)
if err != nil {
return nil, storage.NewError(storage.OpReadFile, backendName, path, storage.ErrUnknown, err)
}
return data, nil
}
func (b *Backend) OpenReader(ctx context.Context, path string) (io.ReadCloser, error) {
if err := ctx.Err(); err != nil {
return nil, err
}
nativePath, err := b.nativePath(path, false)
if err != nil {
return nil, err
}
if err := b.rejectSymlinkAncestors(nativePath, true); err != nil {
return nil, err
}
info, err := os.Lstat(nativePath)
if err != nil {
return nil, b.translateError(storage.OpOpenReader, path, err)
}
if !info.Mode().IsRegular() {
return nil, storage.NewError(storage.OpOpenReader, backendName, path, storage.ErrUnsupported, nil)
}
file, err := os.Open(nativePath)
if err != nil {
return nil, b.translateError(storage.OpOpenReader, path, err)
}
return file, nil
}
func (b *Backend) WriteFile(ctx context.Context, path string, data []byte, opts storage.WriteOptions) (storage.Entry, error) {
opts.Size = int64(len(data))
opts.SizeKnown = true
return b.WriteFrom(ctx, path, bytes.NewReader(data), opts)
}
func (b *Backend) WriteFrom(ctx context.Context, path string, r io.Reader, opts storage.WriteOptions) (storage.Entry, error) {
if err := ctx.Err(); err != nil {
return storage.Entry{}, err
}
nativePath, err := b.nativePath(path, false)
if err != nil {
return storage.Entry{}, err
}
parent := filepath.Dir(nativePath)
if err := b.rejectSymlinkAncestors(parent, true); err != nil {
return storage.Entry{}, err
}
if info, err := os.Lstat(nativePath); err == nil {
if !opts.Overwrite {
return storage.Entry{}, storage.NewError(storage.OpWriteFrom, backendName, path, storage.ErrAlreadyExist, nil)
}
if !info.Mode().IsRegular() {
return storage.Entry{}, storage.NewError(storage.OpWriteFrom, backendName, path, storage.ErrConflict, nil)
}
} else if !errors.Is(err, fs.ErrNotExist) {
return storage.Entry{}, b.translateError(storage.OpWriteFrom, path, err)
}
if err := os.MkdirAll(parent, 0o755); err != nil {
return storage.Entry{}, b.translateError(storage.OpWriteFrom, path, err)
}
temp, err := os.CreateTemp(parent, ".distributor-write-*")
if err != nil {
return storage.Entry{}, b.translateError(storage.OpWriteFrom, path, err)
}
tempPath := temp.Name()
cleanup := true
defer func() {
if cleanup {
_ = os.Remove(tempPath)
}
}()
written, copyErr := io.Copy(temp, r)
closeErr := temp.Close()
if copyErr != nil {
return storage.Entry{}, storage.NewError(storage.OpWriteFrom, backendName, path, storage.ErrUnknown, copyErr)
}
if closeErr != nil {
return storage.Entry{}, storage.NewError(storage.OpWriteFrom, backendName, path, storage.ErrUnknown, closeErr)
}
if opts.SizeKnown && written != opts.Size {
return storage.Entry{}, storage.NewError(storage.OpWriteFrom, backendName, path, storage.ErrConflict, fmt.Errorf("stream size %d does not match expected size %d", written, opts.Size))
}
if err := os.Rename(tempPath, nativePath); err != nil {
return storage.Entry{}, b.translateError(storage.OpWriteFrom, path, err)
}
cleanup = false
return b.Stat(ctx, path)
}
func (b *Backend) Stat(ctx context.Context, path string) (storage.Entry, error) {
if err := ctx.Err(); err != nil {
return storage.Entry{}, err
}
nativePath, err := b.nativePath(path, true)
if err != nil {
return storage.Entry{}, err
}
info, err := os.Lstat(nativePath)
if err != nil {
return storage.Entry{}, b.translateError(storage.OpStat, path, err)
}
return entryFromInfo(path, info), nil
}
func (b *Backend) Walk(ctx context.Context, prefix string, opts storage.WalkOptions, fn storage.WalkFunc) error {
if err := ctx.Err(); err != nil {
return err
}
nativePrefix, err := b.nativePath(prefix, true)
if err != nil {
return err
}
info, err := os.Lstat(nativePrefix)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
return nil
}
return b.translateError(storage.OpWalk, prefix, err)
}
emitter := storage.NewWalkEmitter(ctx, backendName, opts, fn)
if !info.IsDir() {
return storage.FinishWalk(emitter.Emit(entryFromInfo(prefix, info)))
}
walkErr := filepath.WalkDir(nativePrefix, func(nativePath string, dirEntry fs.DirEntry, err error) error {
if err != nil {
return b.translateError(storage.OpWalk, prefix, err)
}
if nativePath == nativePrefix {
return nil
}
relPath, err := filepath.Rel(b.root, nativePath)
if err != nil {
return b.translateError(storage.OpWalk, prefix, err)
}
logicalPath := filepath.ToSlash(relPath)
if !opts.Recursive && filepath.Dir(nativePath) != nativePrefix {
if dirEntry.IsDir() {
return filepath.SkipDir
}
return nil
}
info, err := dirEntry.Info()
if err != nil {
return b.translateError(storage.OpWalk, logicalPath, err)
}
return emitter.Emit(entryFromInfo(logicalPath, info))
})
return storage.FinishWalk(walkErr)
}
func (b *Backend) HasAny(ctx context.Context, prefix string) (bool, error) {
return storage.HasAny(ctx, b, prefix)
}
func (b *Backend) DeleteManagedBundle(ctx context.Context, bundlePath string, managedOutputPaths []string, opts storage.DeleteOptions) error {
if err := ctx.Err(); err != nil {
return err
}
targets, err := storage.ManagedBundleTargets(bundlePath, managedOutputPaths)
if err != nil {
return err
}
for _, logicalPath := range targets {
nativePath, err := b.nativePath(logicalPath, false)
if err != nil {
return err
}
if nativePath == b.root {
return storage.NewError(storage.OpDeleteManagedBundle, backendName, logicalPath, storage.ErrInvalidPath, nil)
}
info, err := os.Lstat(nativePath)
if err != nil {
if opts.IgnoreMissing && errors.Is(err, fs.ErrNotExist) {
continue
}
return b.translateError(storage.OpDeleteManagedBundle, logicalPath, err)
}
if info.IsDir() {
return storage.NewError(storage.OpDeleteManagedBundle, backendName, logicalPath, storage.ErrUnsupported, nil)
}
if err := os.Remove(nativePath); err != nil {
return b.translateError(storage.OpDeleteManagedBundle, logicalPath, err)
}
if opts.PruneEmptyDirs {
b.pruneEmptyParents(filepath.Dir(nativePath))
}
}
return nil
}
func (b *Backend) DeletePrefix(ctx context.Context, prefix string, opts storage.DeleteOptions) error {
if err := ctx.Err(); err != nil {
return err
}
nativePrefix, err := b.nativePath(prefix, true)
if err != nil {
return err
}
if err := b.rejectSymlinkAncestors(nativePrefix, false); err != nil {
return err
}
if prefix == "" {
entries, err := os.ReadDir(nativePrefix)
if err != nil {
if opts.IgnoreMissing && errors.Is(err, fs.ErrNotExist) {
return nil
}
return b.translateError(storage.OpDeletePrefix, prefix, err)
}
for _, entry := range entries {
if err := ctx.Err(); err != nil {
return err
}
child := filepath.Join(nativePrefix, entry.Name())
if err := os.RemoveAll(child); err != nil {
return b.translateError(storage.OpDeletePrefix, entry.Name(), err)
}
}
return nil
}
if _, err := os.Lstat(nativePrefix); err != nil {
if opts.IgnoreMissing && errors.Is(err, fs.ErrNotExist) {
return nil
}
return b.translateError(storage.OpDeletePrefix, prefix, err)
}
if err := os.RemoveAll(nativePrefix); err != nil {
return b.translateError(storage.OpDeletePrefix, prefix, err)
}
if opts.PruneEmptyDirs {
b.pruneEmptyParents(filepath.Dir(nativePrefix))
}
return nil
}
func (b *Backend) nativePath(logicalPath string, allowEmpty bool) (string, error) {
if logicalPath == "" {
if !allowEmpty {
return "", storage.NewError(storage.OpValidatePath, backendName, logicalPath, storage.ErrInvalidPath, nil)
}
return b.root, nil
}
if err := storage.ValidatePath(logicalPath); err != nil {
return "", err
}
nativePath := filepath.Clean(filepath.Join(b.root, filepath.FromSlash(logicalPath)))
rel, err := filepath.Rel(b.root, nativePath)
if err != nil {
return "", storage.NewError(storage.OpValidatePath, backendName, logicalPath, storage.ErrInvalidPath, err)
}
if rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) || filepath.IsAbs(rel) {
return "", storage.NewError(storage.OpValidatePath, backendName, logicalPath, storage.ErrInvalidPath, nil)
}
return nativePath, nil
}
func (b *Backend) rejectSymlinkAncestors(nativePath string, includeFinal bool) error {
rel, err := filepath.Rel(b.root, nativePath)
if err != nil {
return storage.NewError(storage.OpValidatePath, backendName, nativePath, storage.ErrInvalidPath, err)
}
if rel == "." {
return nil
}
segments := strings.Split(rel, string(filepath.Separator))
limit := len(segments)
if !includeFinal {
limit--
}
current := b.root
for i := 0; i < limit; i++ {
current = filepath.Join(current, segments[i])
info, err := os.Lstat(current)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
return nil
}
return b.translateError(storage.OpStat, filepath.ToSlash(filepath.Join(segments[:i+1]...)), err)
}
if info.Mode()&os.ModeSymlink != 0 {
return storage.NewError(storage.OpStat, backendName, filepath.ToSlash(filepath.Join(segments[:i+1]...)), storage.ErrUnsupported, nil)
}
}
return nil
}
func (b *Backend) pruneEmptyParents(start string) {
for current := start; current != b.root && strings.HasPrefix(current, b.root); current = filepath.Dir(current) {
err := os.Remove(current)
if err != nil {
return
}
}
}
func (b *Backend) translateError(op, path string, err error) error {
kind := storage.ErrUnknown
switch {
case errors.Is(err, fs.ErrNotExist):
kind = storage.ErrNotFound
case errors.Is(err, fs.ErrExist):
kind = storage.ErrAlreadyExist
case errors.Is(err, fs.ErrPermission):
kind = storage.ErrPermission
}
return storage.NewError(op, backendName, path, kind, err)
}
func entryFromInfo(path string, info fs.FileInfo) storage.Entry {
entryType := storage.EntryTypeOther
switch {
case info.Mode()&os.ModeSymlink != 0:
entryType = storage.EntryTypeSymlink
case info.Mode().IsRegular():
entryType = storage.EntryTypeFile
case info.IsDir():
entryType = storage.EntryTypeDirectory
}
return storage.Entry{
Path: path,
Type: entryType,
Size: info.Size(),
}
}