96 lines
3.3 KiB
JavaScript
96 lines
3.3 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// Heap snapshots are always saved in the temp directory, and have a regular
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// naming convention. This module provides helpers for working with heap
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// snapshot files in a safe manner. Because we attempt to avoid unnecessary
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// copies of the heap snapshot files by checking the local filesystem for a heap
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// snapshot file with the given snapshot id, we want to ensure that we are only
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// attempting to open heap snapshot files and not `~/.ssh/id_rsa`, for
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// example. Therefore, the RDP only talks about snapshot ids, or transfering the
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// bulk file data. A file path can be recovered from a snapshot id, which allows
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// one to check for the presence of the heap snapshot file on the local file
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// system, but we don't have to worry about opening arbitrary files.
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//
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// The heap snapshot file path conventions permits the following forms:
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//
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// $TEMP_DIRECTORY/XXXXXXXXXX.fxsnapshot
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// $TEMP_DIRECTORY/XXXXXXXXXX-XXXXX.fxsnapshot
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//
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// Where the strings of "X" are zero or more digits.
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"use strict";
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const { Ci } = require("chrome");
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loader.lazyRequireGetter(this, "FileUtils",
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"resource://gre/modules/FileUtils.jsm", true);
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loader.lazyRequireGetter(this, "OS", "resource://gre/modules/osfile.jsm", true);
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function getHeapSnapshotFileTemplate() {
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return OS.Path.join(OS.Constants.Path.tmpDir, `${Date.now()}.fxsnapshot`);
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}
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/**
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* Get a unique temp file path for a new heap snapshot. The file is guaranteed
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* not to exist before this call.
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*
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* @returns String
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*/
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exports.getNewUniqueHeapSnapshotTempFilePath = function () {
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let file = new FileUtils.File(getHeapSnapshotFileTemplate());
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// The call to createUnique will append "-N" after the leaf name (but before
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// the extension) until a new file is found and create it. This guarantees we
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// won't accidentally choose the same file twice.
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file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0o666);
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return file.path;
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};
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function isValidSnapshotFileId(snapshotId) {
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return /^\d+(\-\d+)?$/.test(snapshotId);
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}
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/**
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* Get the file path for the given snapshot id.
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*
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* @param {String} snapshotId
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*
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* @returns String | null
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*/
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exports.getHeapSnapshotTempFilePath = function (snapshotId) {
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// Don't want anyone sneaking "../../../.." strings into the snapshot id and
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// trying to make us open arbitrary files.
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if (!isValidSnapshotFileId(snapshotId)) {
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return null;
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}
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return OS.Path.join(OS.Constants.Path.tmpDir, snapshotId + ".fxsnapshot");
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};
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/**
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* Return true if we have the heap snapshot file for the given snapshot id on
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* the local file system. False is returned otherwise.
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*
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* @returns Promise<Boolean>
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*/
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exports.haveHeapSnapshotTempFile = function (snapshotId) {
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const path = exports.getHeapSnapshotTempFilePath(snapshotId);
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if (!path) {
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return Promise.resolve(false);
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}
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return OS.File.stat(path).then(() => true,
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() => false);
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};
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/**
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* Given a heap snapshot's file path, extricate the snapshot id.
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*
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* @param {String} path
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*
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* @returns String
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*/
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exports.getSnapshotIdFromPath = function (path) {
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return path.slice(OS.Constants.Path.tmpDir.length + 1,
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path.length - ".fxsnapshot".length);
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};
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