components/places/PlacesBackups.jsm

/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
 * vim: sw=2 ts=2 sts=2 expandtab filetype=javascript
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

var EXPORTED_SYMBOLS = ["PlacesBackups"];

const { XPCOMUtils } = ChromeUtils.import(
  "resource://gre/modules/XPCOMUtils.jsm"
);
const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");

XPCOMUtils.defineLazyModuleGetters(this, {
  PlacesUtils: "resource://gre/modules/PlacesUtils.jsm",
  BookmarkJSONUtils: "resource://gre/modules/BookmarkJSONUtils.jsm",
});

XPCOMUtils.defineLazyGetter(
  this,
  "filenamesRegex",
  () =>
    /^bookmarks-([0-9-]+)(?:_([0-9]+)){0,1}(?:_([a-z0-9=+-]{24})){0,1}\.(json(lz4)?)$/i
);

async function limitBackups(aMaxBackups, backupFiles) {
  if (
    typeof aMaxBackups == "number" &&
    aMaxBackups > -1 &&
    backupFiles.length >= aMaxBackups
  ) {
    let numberOfBackupsToDelete = backupFiles.length - aMaxBackups;
    while (numberOfBackupsToDelete--) {
      let oldestBackup = backupFiles.pop();
      await IOUtils.remove(oldestBackup);
    }
  }
}

/**
 * Appends meta-data information to a given filename.
 */
function appendMetaDataToFilename(aFilename, aMetaData) {
  let matches = aFilename.match(filenamesRegex);
  return (
    "bookmarks-" +
    matches[1] +
    "_" +
    aMetaData.count +
    "_" +
    aMetaData.hash +
    "." +
    matches[4]
  );
}

/**
 * Gets the hash from a backup filename.
 *
 * @return the extracted hash or null.
 */
function getHashFromFilename(aFilename) {
  let matches = aFilename.match(filenamesRegex);
  if (matches && matches[3]) {
    return matches[3];
  }
  return null;
}

/**
 * Given two filenames, checks if they contain the same date.
 */
function isFilenameWithSameDate(aSourceName, aTargetName) {
  let sourceMatches = aSourceName.match(filenamesRegex);
  let targetMatches = aTargetName.match(filenamesRegex);

  return sourceMatches && targetMatches && sourceMatches[1] == targetMatches[1];
}

/**
 * Given a filename, searches for another backup with the same date.
 *
 * @return path string or null.
 */
function getBackupFileForSameDate(aFilename) {
  return (async function() {
    let backupFiles = await PlacesBackups.getBackupFiles();
    for (let backupFile of backupFiles) {
      if (isFilenameWithSameDate(PathUtils.filename(backupFile), aFilename)) {
        return backupFile;
      }
    }
    return null;
  })();
}

var PlacesBackups = {
  /**
   * Matches the backup filename:
   *  0: file name
   *  1: date in form Y-m-d
   *  2: bookmarks count
   *  3: contents hash
   *  4: file extension
   */
  get filenamesRegex() {
    return filenamesRegex;
  },

  /**
   * Gets backup folder asynchronously.
   * @return {Promise}
   * @resolve the folder (the folder string path).
   */
  getBackupFolder: function PB_getBackupFolder() {
    return (async () => {
      if (this._backupFolder) {
        return this._backupFolder;
      }
      let profileDir = await PathUtils.getProfileDir();
      let backupsDirPath = PathUtils.join(
        profileDir,
        this.profileRelativeFolderPath
      );
      await IOUtils.makeDirectory(backupsDirPath);
      return (this._backupFolder = backupsDirPath);
    })();
  },

  get profileRelativeFolderPath() {
    return "bookmarkbackups";
  },

  /**
   * Cache current backups in a sorted (by date DESC) array.
   * @return {Promise}
   * @resolve a sorted array of string paths.
   */
  getBackupFiles: function PB_getBackupFiles() {
    return (async () => {
      if (this._backupFiles) {
        return this._backupFiles;
      }

      this._backupFiles = [];

      let backupFolderPath = await this.getBackupFolder();
      let children = await IOUtils.getChildren(backupFolderPath);
      let list = [];
      for (const entry of children) {
        // Since IOUtils I/O is serialized, we can safely remove .tmp files
        // without risking to remove ongoing backups.
        let filename = PathUtils.filename(entry);
        if (filename.endsWith(".tmp")) {
          list.push(IOUtils.remove(entry));
          continue;
        }

        if (filenamesRegex.test(filename)) {
          // Remove bogus backups in future dates.
          if (this.getDateForFile(entry) > new Date()) {
            list.push(IOUtils.remove(entry));
            continue;
          }
          this._backupFiles.push(entry);
        }
      }
      await Promise.all(list);

      this._backupFiles.sort((a, b) => {
        let aDate = this.getDateForFile(a);
        let bDate = this.getDateForFile(b);
        return bDate - aDate;
      });

      return this._backupFiles;
    })();
  },

  /**
   * Invalidates the internal cache for testing purposes.
   */
  invalidateCache() {
    this._backupFiles = null;
  },

  /**
   * Generates a ISO date string (YYYY-MM-DD) from a Date object.
   *
   * @param dateObj
   *        The date object to parse.
   * @return an ISO date string.
   */
  toISODateString: function toISODateString(dateObj) {
    if (!dateObj || dateObj.constructor.name != "Date" || !dateObj.getTime()) {
      throw new Error("invalid date object");
    }
    let padDate = val => ("0" + val).substr(-2, 2);
    return [
      dateObj.getFullYear(),
      padDate(dateObj.getMonth() + 1),
      padDate(dateObj.getDate()),
    ].join("-");
  },

  /**
   * Creates a filename for bookmarks backup files.
   *
   * @param [optional] aDateObj
   *                   Date object used to build the filename.
   *                   Will use current date if empty.
   * @param [optional] bool - aCompress
   *                   Determines if file extension is json or jsonlz4
                       Default is json
   * @return A bookmarks backup filename.
   */
  getFilenameForDate: function PB_getFilenameForDate(aDateObj, aCompress) {
    let dateObj = aDateObj || new Date();
    // Use YYYY-MM-DD (ISO 8601) as it doesn't contain illegal characters
    // and makes the alphabetical order of multiple backup files more useful.
    return (
      "bookmarks-" +
      PlacesBackups.toISODateString(dateObj) +
      ".json" +
      (aCompress ? "lz4" : "")
    );
  },

  /**
   * Creates a Date object from a backup file.  The date is the backup
   * creation date.
   *
   * @param {Sring} aBackupFile The path of the backup.
   * @return {Date} A Date object for the backup's creation time.
   */
  getDateForFile: function PB_getDateForFile(aBackupFile) {
    let filename = PathUtils.filename(aBackupFile);
    let matches = filename.match(filenamesRegex);
    if (!matches) {
      throw new Error(`Invalid backup file name: ${filename}`);
    }
    return new Date(matches[1].replace(/-/g, "/"));
  },

  /**
   * Get the most recent backup file.
   *
   * @return {Promise}
   * @result the path to the file.
   */
  getMostRecentBackup: function PB_getMostRecentBackup() {
    return (async () => {
      let entries = await this.getBackupFiles();
      for (let entry of entries) {
        let rx = /\.json(lz4)?$/;
        if (PathUtils.filename(entry).match(rx)) {
          return entry;
        }
      }
      return null;
    })();
  },

  /**
   * Returns whether a recent enough backup exists, using these heuristic: if
   * a backup exists, it should be newer than the last browser session date,
   * otherwise it should not be older than maxDays.
   * If the backup is older than the last session, the calculated time is
   * reported to telemetry.
   *
   * @param [maxDays] The maximum number of days a backup can be old.
   */
  async hasRecentBackup({ maxDays = 3 } = {}) {
    let lastBackupFile = await PlacesBackups.getMostRecentBackup();
    if (!lastBackupFile) {
      return false;
    }
    let lastBackupTime = PlacesBackups.getDateForFile(lastBackupFile);
    let profileLastUse = Services.appinfo.replacedLockTime || Date.now();
    if (lastBackupTime > profileLastUse) {
      return true;
    }
    let backupAge = Math.round((profileLastUse - lastBackupTime) / 86400000);
    // Telemetry the age of the last available backup.
    try {
      Services.telemetry
        .getHistogramById("PLACES_BACKUPS_DAYSFROMLAST")
        .add(backupAge);
    } catch (ex) {
      Cu.reportError(new Error("Unable to report telemetry."));
    }
    return backupAge <= maxDays;
  },

  /**
   * Serializes bookmarks using JSON, and writes to the supplied file.
   *
   * @param aFilePath
   *        path for the "bookmarks.json" file to be created.
   * @return {Promise}
   * @resolves the number of serialized uri nodes.
   */
  async saveBookmarksToJSONFile(aFilePath) {
    let { count: nodeCount, hash: hash } = await BookmarkJSONUtils.exportToFile(
      aFilePath
    );

    let backupFolderPath = await this.getBackupFolder();
    let profileDir = await PathUtils.getProfileDir();
    if (profileDir == backupFolderPath) {
      // We are creating a backup in the default backups folder,
      // so just update the internal cache.
      if (!this._backupFiles) {
        await this.getBackupFiles();
      }
      this._backupFiles.unshift(aFilePath);
    } else {
      let aMaxBackup = Services.prefs.getIntPref(
        "browser.bookmarks.max_backups"
      );
      if (aMaxBackup === 0) {
        if (!this._backupFiles) {
          await this.getBackupFiles();
        }
        limitBackups(aMaxBackup, this._backupFiles);
        return nodeCount;
      }
      // If we are saving to a folder different than our backups folder, then
      // we also want to create a new compressed version in it.
      // This way we ensure the latest valid backup is the same saved by the
      // user.  See bug 424389.
      let mostRecentBackupFile = await this.getMostRecentBackup();
      if (
        !mostRecentBackupFile ||
        hash != getHashFromFilename(PathUtils.filename(mostRecentBackupFile))
      ) {
        let name = this.getFilenameForDate(undefined, true);
        let newFilename = appendMetaDataToFilename(name, {
          count: nodeCount,
          hash,
        });
        let newFilePath = PathUtils.join(backupFolderPath, newFilename);
        let backupFile = await getBackupFileForSameDate(name);
        if (backupFile) {
          // There is already a backup for today, replace it.
          await IOUtils.remove(backupFile);
          if (!this._backupFiles) {
            await this.getBackupFiles();
          } else {
            this._backupFiles.shift();
          }
          this._backupFiles.unshift(newFilePath);
        } else {
          // There is no backup for today, add the new one.
          if (!this._backupFiles) {
            await this.getBackupFiles();
          }
          this._backupFiles.unshift(newFilePath);
        }
        let jsonString = await IOUtils.read(aFilePath);
        await IOUtils.write(newFilePath, jsonString, {
          compress: true,
        });
        await limitBackups(aMaxBackup, this._backupFiles);
      }
    }
    return nodeCount;
  },

  /**
   * Creates a dated backup in <profile>/bookmarkbackups.
   * Stores the bookmarks using a lz4 compressed JSON file.
   *
   * @param [optional] int aMaxBackups
   *                       The maximum number of backups to keep.  If set to 0
   *                       all existing backups are removed and aForceBackup is
   *                       ignored, so a new one won't be created.
   * @param [optional] bool aForceBackup
   *                        Forces creating a backup even if one was already
   *                        created that day (overwrites).
   * @return {Promise}
   */
  create: function PB_create(aMaxBackups, aForceBackup) {
    return (async () => {
      if (aMaxBackups === 0) {
        // Backups are disabled, delete any existing one and bail out.
        if (!this._backupFiles) {
          await this.getBackupFiles();
        }
        await limitBackups(0, this._backupFiles);
        return;
      }

      // Ensure to initialize _backupFiles
      if (!this._backupFiles) {
        await this.getBackupFiles();
      }
      let newBackupFilename = this.getFilenameForDate(undefined, true);
      // If we already have a backup for today we should do nothing, unless we
      // were required to enforce a new backup.
      let backupFile = await getBackupFileForSameDate(newBackupFilename);
      if (backupFile && !aForceBackup) {
        return;
      }

      if (backupFile) {
        // In case there is a backup for today we should recreate it.
        this._backupFiles.shift();
        await IOUtils.remove(backupFile);
      }

      // Now check the hash of the most recent backup, and try to create a new
      // backup, if that fails due to hash conflict, just rename the old backup.
      let mostRecentBackupFile = await this.getMostRecentBackup();
      let mostRecentHash =
        mostRecentBackupFile &&
        getHashFromFilename(PathUtils.filename(mostRecentBackupFile));

      // Save bookmarks to a backup file.
      let backupFolder = await this.getBackupFolder();
      let newBackupFile = PathUtils.join(backupFolder, newBackupFilename);
      let newFilenameWithMetaData;
      try {
        let {
          count: nodeCount,
          hash: hash,
        } = await BookmarkJSONUtils.exportToFile(newBackupFile, {
          compress: true,
          failIfHashIs: mostRecentHash,
        });
        newFilenameWithMetaData = appendMetaDataToFilename(newBackupFilename, {
          count: nodeCount,
          hash,
        });
      } catch (ex) {
        if (!ex.becauseSameHash) {
          throw ex;
        }
        // The last backup already contained up-to-date information, just
        // rename it as if it was today's backup.
        this._backupFiles.shift();
        newBackupFile = mostRecentBackupFile;
        // Ensure we retain the proper extension when renaming
        // the most recent backup file.
        if (/\.json$/.test(PathUtils.filename(mostRecentBackupFile))) {
          newBackupFilename = this.getFilenameForDate();
        }
        newFilenameWithMetaData = appendMetaDataToFilename(newBackupFilename, {
          count: this.getBookmarkCountForFile(mostRecentBackupFile),
          hash: mostRecentHash,
        });
      }

      // Append metadata to the backup filename.
      let newBackupFileWithMetadata = PathUtils.join(
        backupFolder,
        newFilenameWithMetaData
      );
      await IOUtils.move(newBackupFile, newBackupFileWithMetadata);
      this._backupFiles.unshift(newBackupFileWithMetadata);

      // Limit the number of backups.
      await limitBackups(aMaxBackups, this._backupFiles);
    })();
  },

  /**
   * Gets the bookmark count for backup file.
   *
   * @param aFilePath
   *        File path The backup file.
   *
   * @return the bookmark count or null.
   */
  getBookmarkCountForFile: function PB_getBookmarkCountForFile(aFilePath) {
    let count = null;
    let filename = PathUtils.filename(aFilePath);
    let matches = filename.match(filenamesRegex);
    if (matches && matches[2]) {
      count = matches[2];
    }
    return count;
  },

  /**
   * Gets a bookmarks tree representation usable to create backups in different
   * file formats.  The root or the tree is PlacesUtils.bookmarks.rootGuid.
   *
   * @return an object representing a tree with the places root as its root.
   *         Each bookmark is represented by an object having these properties:
   *         * id: the item id (make this not enumerable after bug 824502)
   *         * title: the title
   *         * guid: unique id
   *         * parent: item id of the parent folder, not enumerable
   *         * index: the position in the parent
   *         * dateAdded: microseconds from the epoch
   *         * lastModified: microseconds from the epoch
   *         * type: type of the originating node as defined in PlacesUtils
   *         The following properties exist only for a subset of bookmarks:
   *         * annos: array of annotations
   *         * uri: url
   *         * iconuri: favicon's url
   *         * keyword: associated keyword
   *         * charset: last known charset
   *         * tags: csv string of tags
   *         * root: string describing whether this represents a root
   *         * children: array of child items in a folder
   */
  async getBookmarksTree() {
    let startTime = Date.now();
    let root = await PlacesUtils.promiseBookmarksTree(
      PlacesUtils.bookmarks.rootGuid,
      {
        includeItemIds: true,
      }
    );

    try {
      Services.telemetry
        .getHistogramById("PLACES_BACKUPS_BOOKMARKSTREE_MS")
        .add(Date.now() - startTime);
    } catch (ex) {
      Cu.reportError("Unable to report telemetry.");
    }
    return [root, root.itemsCount];
  },
};