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// Copyright 2024 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package blob
import (
"encoding/base64"
"fmt"
"io"
"os"
"path/filepath"
"strings"
)
// Storage is not assumed to be used for partciularly large objects (e.g. GB of size),
// but rather for blobs that risk overwhelming Spanner column size limits.
type Storage interface {
// Write stores the object uniquely identified by a set of IDs (parts).
// If it already exists, it will be overwritten.
// The first argument is the URI which can be used to later retrieve it with Read.
Write(source io.Reader, parts ...string) (string, error)
Read(uri string) (io.ReadCloser, error)
}
var _ Storage = (*LocalStorage)(nil)
// LocalStorage keeps objets in the specified local directory.
// It's intended to be used only for unit tests.
type LocalStorage struct {
baseFolder string
}
func NewLocalStorage(baseFolder string) *LocalStorage {
return &LocalStorage{baseFolder: baseFolder}
}
const localStoragePrefix = "local://"
func (ls *LocalStorage) Write(source io.Reader, parts ...string) (string, error) {
// A whatever approach that can handle arbitrary inputs.
name := base64.StdEncoding.EncodeToString([]byte(filepath.Join(parts...)))
file, err := os.Create(filepath.Join(ls.baseFolder, name))
if err != nil {
return "", err
}
defer file.Close()
_, err = io.Copy(file, source)
if err != nil {
return "", fmt.Errorf("failed to save data: %w", err)
}
return localStoragePrefix + name, nil
}
func (ls *LocalStorage) Read(uri string) (io.ReadCloser, error) {
if !strings.HasPrefix(uri, localStoragePrefix) {
return nil, fmt.Errorf("unsupported URI type")
}
// TODO: add some other URI validation checks?
path := filepath.Join(ls.baseFolder, strings.TrimPrefix(uri, localStoragePrefix))
return os.Open(path)
}
func ReadAllBytes(storage Storage, uri string) ([]byte, error) {
if uri == "" {
return nil, nil
}
reader, err := storage.Read(uri)
if err != nil {
return nil, err
}
defer reader.Close()
return io.ReadAll(reader)
}
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