1 files changed, 109 insertions, 0 deletions
diff --git a/browser/components/backup/resources/BackupResource.sys.mjs b/browser/components/backup/resources/BackupResource.sys.mjs
new file mode 100644
index 0000000000..bde3f0669c
--- /dev/null
+++ b/browser/components/backup/resources/BackupResource.sys.mjs
@@ -0,0 +1,109 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+// Convert from bytes to kilobytes (not kibibytes).
+const BYTES_IN_KB = 1000;
+
+/**
+ * An abstract class representing a set of data within a user profile
+ * that can be persisted to a separate backup archive file, and restored
+ * to a new user profile from that backup archive file.
+ */
+export class BackupResource {
+  /**
+   * This must be overridden to return a simple string identifier for the
+   * resource, for example "places" or "extensions". This key is used as
+   * a unique identifier for the resource.
+   *
+   * @type {string}
+   */
+  static get key() {
+    throw new Error("BackupResource::key needs to be overridden.");
+  }
+
+  /**
+   * Get the size of a file.
+   *
+   * @param {string} filePath - path to a file.
+   * @returns {Promise<number|null>} - the size of the file in kilobytes, or null if the
+   * file does not exist, the path is a directory or the size is unknown.
+   */
+  static async getFileSize(filePath) {
+    if (!(await IOUtils.exists(filePath))) {
+      return null;
+    }
+
+    let { size } = await IOUtils.stat(filePath);
+
+    if (size < 0) {
+      return null;
+    }
+
+    let sizeInKb = Math.ceil(size / BYTES_IN_KB);
+    // Make the measurement fuzzier by rounding to the nearest 10kb.
+    let nearestTenthKb = Math.round(sizeInKb / 10) * 10;
+
+    return Math.max(nearestTenthKb, 1);
+  }
+
+  /**
+   * Get the total size of a directory.
+   *
+   * @param {string} directoryPath - path to a directory.
+   * @returns {Promise<number|null>} - the size of all descendants of the directory in kilobytes, or null if the
+   * directory does not exist, the path is not a directory or the size is unknown.
+   */
+  static async getDirectorySize(directoryPath) {
+    if (!(await IOUtils.exists(directoryPath))) {
+      return null;
+    }
+
+    let { type } = await IOUtils.stat(directoryPath);
+
+    if (type != "directory") {
+      return null;
+    }
+
+    let children = await IOUtils.getChildren(directoryPath, {
+      ignoreAbsent: true,
+    });
+
+    let size = 0;
+    for (const childFilePath of children) {
+      let { size: childSize, type: childType } = await IOUtils.stat(
+        childFilePath
+      );
+
+      if (childSize >= 0) {
+        let sizeInKb = Math.ceil(childSize / BYTES_IN_KB);
+        // Make the measurement fuzzier by rounding to the nearest 10kb.
+        let nearestTenthKb = Math.round(sizeInKb / 10) * 10;
+        size += Math.max(nearestTenthKb, 1);
+      }
+
+      if (childType == "directory") {
+        let childDirectorySize = await this.getDirectorySize(childFilePath);
+        if (Number.isInteger(childDirectorySize)) {
+          size += childDirectorySize;
+        }
+      }
+    }
+
+    return size;
+  }
+
+  constructor() {}
+
+  /**
+   * This must be overridden to record telemetry on the size of any
+   * data associated with this BackupResource.
+   *
+   * @param {string} profilePath - path to a profile directory.
+   * @returns {Promise<undefined>}
+   */
+  // eslint-disable-next-line no-unused-vars
+  async measure(profilePath) {
+    throw new Error("BackupResource::measure needs to be overridden.");
+  }
+}