android/libwvdrmengine/cdm/util/include/file_store.h

// Copyright 2018 Google LLC. All Rights Reserved. This file and proprietary
// source code may only be used and distributed under the Widevine License
// Agreement.
//
// File - Platform independent interface for a File class
//
#ifndef WVCDM_UTIL_FILE_STORE_H_
#define WVCDM_UTIL_FILE_STORE_H_

#include <stddef.h>

#include <memory>
#include <string>
#include <vector>

#include "disallow_copy_and_assign.h"
#include "platform.h"
#include "util_common.h"

namespace wvutil {

// Fixed filename for ATSC DRM certificate pre-installed
// on ATSC devices for ATSC licenses.
static const std::string kAtscCertificateFileName = "atsccert.bin";
// General filename for either global or unmapped app-origin
// DRM certificates.
static const std::string kCertificateFileName = "cert1.bin";
// File extension for DRM and OEM certificate files.
static const std::string kCertificateFileNameExt = ".bin";
// Filename prefix for mapped (scoped) DRM certificate filenames
// specific to a particular app-origin.
static const std::string kScopedCertificateFilenamePrefix = "cert1_";
// TODO(b/376533901): Replace this constant with
// kScopedCertificateFilenamePrefix in source code..
static const std::string kCertificateFileNamePrefix =
    kScopedCertificateFilenamePrefix;
// Legacy general filename for either global or unmapped app-origin
// DRM certificates.
static const std::string kLegacyCertificateFileName = "cert.bin";
// Legacy filename prefix for mapped (scoped) DRM certificate filenames
// specific to a particular app-origin.
static const std::string kLegacyScopedCertificateFilenamePrefix = "cert";
// TODO(b/376533901): Replace this constant with
// kLegacyScopedCertificateFilenamePrefix in source code..
static const std::string kLegacyCertificateFileNamePrefix =
    kLegacyScopedCertificateFilenamePrefix;
// Filename for global OEM certificates.
static const std::string kOemCertificateFileName = "oemcert.bin";

// File interface. The implementation is platform dependent.
class File {
 public:
  File() {}
  virtual ~File() {}
  virtual ssize_t Read(char* buffer, size_t bytes) = 0;
  virtual ssize_t Write(const char* buffer, size_t bytes) = 0;

  CORE_DISALLOW_COPY_AND_ASSIGN(File);
};

// File system base class.  The implementation is platform dependent.
class FileSystem {
 public:
  FileSystem();
  FileSystem(const std::string& origin, void* extra_data);
  virtual ~FileSystem();

  // Concreate implementation of FileSystem.
  // Depending on the platform, this may be vendor or Widevine implemented.
  class Impl;

  // Flags for calls to Open.
  static constexpr int kNoFlags = 0;
  // Create file if does not already exist, open file if it does exist.
  static constexpr int kCreate = (1 << 0);
  // Open file as read-only; typically should not be used with kCreate.
  static constexpr int kReadOnly = (1 << 1);
  // Open file and truncated.  May be used with kCreate; should not
  // be used with kReadOnly.
  static constexpr int kTruncate = (1 << 2);

  virtual std::unique_ptr<File> Open(const std::string& file_path, int flags);

  // Checks if the |path| exists.  The |path| may be a file or directory.
  // Return true if an entry in the file system exists; false otherwise.
  virtual bool Exists(const std::string& path);
  // Same as above, except the optional parameter of |errno_value| should
  // be set to 0 or the value of C errno when attempting to check
  // the existence of a file.
  virtual bool Exists(const std::string& path, int* errno_value);

  // Removes the specified |path|.
  //
  // If |path| is a regular file, the file should be removed.
  // If |path| is a directory, both the directory and the directory
  // contents should be removed.
  //
  // Implementation must support a |path| containing a single wildcard
  // character in the filename component of the path.
  //
  // Return value:
  // - true : File/directory was removed, or file/directory did not exist
  // - false : File/directory could not be removed, or other error.
  virtual bool Remove(const std::string& path);

  // Obtain the size of a file in bytes.  |file_path| must be a file,
  // and not a directory.
  //
  // Return value:
  // - non-negative : size of file in bytes if file exists
  // - negative : file does not exist, or error occurred.
  virtual ssize_t FileSize(const std::string& file_path);

  // Return the entries stored at |dir_path| (includes both files
  // and directories).
  //
  // Return value:
  // - true : Directory exists, and directory entry names are stored
  //          in |names|; |names| may be empty if directory was empty.
  // - false : Directory does not exist, |dir_path| is not a directory,
  //           or error was encountered.
  virtual bool List(const std::string& dir_path,
                    std::vector<std::string>* names);

  const std::string& origin() const { return origin_; }
  void set_origin(const std::string& origin);

  const std::string& identifier() const { return identifier_; }
  void set_identifier(const std::string& identifier);
  bool IsGlobal() const { return identifier_.empty(); }

 private:
  std::unique_ptr<FileSystem::Impl> impl_;
  std::string origin_;
  std::string identifier_;

  CORE_DISALLOW_COPY_AND_ASSIGN(FileSystem);
};

}  // namespace wvutil

#endif  // WVCDM_UTIL_FILE_STORE_H_