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