98 lines
2.6 KiB
Go
98 lines
2.6 KiB
Go
package storage
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import (
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"context"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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)
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// LocalStorage implements StorageBackend using the local filesystem.
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type LocalStorage struct {
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basePath string
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}
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// NewLocalStorage creates a LocalStorage rooted at basePath. The path is
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// resolved to an absolute path and verified to exist.
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func NewLocalStorage(basePath string) (*LocalStorage, error) {
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abs, err := filepath.Abs(basePath)
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if err != nil {
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return nil, fmt.Errorf("resolve storage path: %w", err)
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}
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return &LocalStorage{basePath: abs}, nil
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}
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// Save writes the contents of reader to path under the storage root.
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func (s *LocalStorage) Save(_ context.Context, path string, reader io.Reader) (int64, error) {
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fullPath := filepath.Join(s.basePath, path)
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if !isSubPath(s.basePath, fullPath) {
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return 0, fmt.Errorf("storage: path traversal attempt: %s", path)
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}
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if err := os.MkdirAll(filepath.Dir(fullPath), 0750); err != nil {
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return 0, fmt.Errorf("create parent directory: %w", err)
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}
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file, err := os.Create(fullPath)
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if err != nil {
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return 0, fmt.Errorf("create file: %w", err)
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}
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defer file.Close()
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written, err := io.Copy(file, reader)
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if err != nil {
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// Best-effort cleanup on write failure.
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os.Remove(fullPath)
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return 0, fmt.Errorf("write file: %w", err)
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}
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return written, nil
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}
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// Open returns a reader for the file at path under the storage root.
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func (s *LocalStorage) Open(_ context.Context, path string) (io.ReadCloser, error) {
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fullPath := filepath.Join(s.basePath, path)
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if !isSubPath(s.basePath, fullPath) {
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return nil, fmt.Errorf("storage: path traversal attempt: %s", path)
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}
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file, err := os.Open(fullPath)
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if err != nil {
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if os.IsNotExist(err) {
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return nil, fmt.Errorf("file not found on disk: %s", path)
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}
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return nil, fmt.Errorf("open file: %w", err)
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}
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return file, nil
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}
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// Delete removes the file at path under the storage root.
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func (s *LocalStorage) Delete(_ context.Context, path string) error {
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fullPath := filepath.Join(s.basePath, path)
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if !isSubPath(s.basePath, fullPath) {
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return fmt.Errorf("storage: path traversal attempt: %s", path)
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}
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err := os.Remove(fullPath)
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if os.IsNotExist(err) {
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return nil // idempotent: already gone
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}
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return err
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}
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// isSubPath returns true if target is within base (no path traversal).
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func isSubPath(base, target string) bool {
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rel, err := filepath.Rel(base, target)
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if err != nil {
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return false
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}
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if filepath.IsAbs(rel) {
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return false
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}
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// Reject paths that escape the base directory.
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// filepath.Rel returns ".." or starts with "../" for paths outside base.
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return rel != ".." && !strings.HasPrefix(rel, ".."+string(filepath.Separator))
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}
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