Bug 1707853 - Add always-skipped unit test for documentation purposes r=necko-reviewers,dragana

This test is for documentation purposes. You may run it locally on Windows by removing the skip-if = true from xpcshell.ini
As sharing  folders on windows requires elevated priviledges, you will need to execute some commands in a separate cmd.exe instance with Admin priviledges.

Differential Revision: https://phabricator.services.mozilla.com/D113498

modules/libjar/test/unit/test_fault_handler.js

@@ -0,0 +1,138 @@
+/* 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/. */
+
+"use strict";
+
+// This test checks that we properly handle exceptions occuring when a
+// network mapped drive is disconnected while we're reading from mmaped
+// file on that drive.
+// Because sharing folders requires network priviledges, this test cannot
+// be completely automated. It will create the necessary files and wait
+// while you run a `net share sharedfolder=...path...` in a CMD terminal
+// with Administator priviledges.
+// See bug 1551562 and bug 1707853
+
+/* import-globals-from ../../zipwriter/test/unit/head_zipwriter.js */
+
+function wrapInputStream(input) {
+  let wrapper = Cc["@mozilla.org/scriptableinputstream;1"].createInstance(
+    Ci.nsIScriptableInputStream
+  );
+  wrapper.init(input);
+  return wrapper;
+}
+
+const { Subprocess } = ChromeUtils.import(
+  "resource://gre/modules/Subprocess.jsm"
+);
+
+const XPI_NAME = "testjar.xpi";
+const SHARE_NAME = "sharedfolder";
+
+async function net(args, silent = false) {
+  if (!silent) {
+    info(`Executing "net ${args.join(" ")}"`);
+  }
+  let proc = await Subprocess.call({
+    command: "C:\\Windows\\System32\\net.exe",
+    arguments: args,
+    environmentAppend: true,
+    stderr: "stdout",
+  });
+  let { exitCode } = await proc.wait();
+  let stdout = await proc.stdout.readString();
+  if (!silent) {
+    info(`stdout: ${stdout}`);
+    equal(exitCode, 0);
+  }
+
+  // Introduce a small delay so we're sure the command effects are visible
+  await new Promise(resolve => do_timeout(500, resolve));
+  return stdout;
+}
+
+const time = 1199145600000; // Jan 1st 2008
+
+add_task(async function test() {
+  let tmpFile = do_get_profile().clone();
+  tmpFile.append("sharedfolder");
+  tmpFile.create(Ci.nsIFile.DIRECTORY_TYPE, 0o755);
+  let tmpDir = tmpFile.clone();
+  tmpFile.append(XPI_NAME);
+
+  let DATA = "a".repeat(1024 * 1024 * 10); // 10Mb
+
+  zipW.open(tmpFile, PR_RDWR | PR_CREATE_FILE | PR_TRUNCATE);
+  let stream = Cc["@mozilla.org/io/string-input-stream;1"].createInstance(
+    Ci.nsIStringInputStream
+  );
+  stream.setData(DATA, DATA.length);
+  zipW.addEntryStream(
+    "data",
+    time * PR_USEC_PER_MSEC,
+    Ci.nsIZipWriter.COMPRESSION_NONE,
+    stream,
+    false
+  );
+  zipW.close();
+
+  // find the computer name
+  let lines = await net(["config", "workstation"], true);
+  let COMPUTER_NAME;
+  for (let l of lines.split("\n")) {
+    if (l.startsWith("Computer name")) {
+      COMPUTER_NAME = l.split("\\\\")[1].trim();
+    }
+  }
+  ok(COMPUTER_NAME);
+
+  dump(
+    `\n\n-------\nNow in a CMD with Administrator priviledges please run:\nnet share ${SHARE_NAME}=${tmpDir.path.replaceAll(
+      "\\\\",
+      "\\"
+    )} /grant:everyone,READ\n\n-------\n`
+  );
+
+  info("waiting while you run command");
+  while (true) {
+    let output = await net(["share"], true);
+    if (output.includes(SHARE_NAME)) {
+      break;
+    }
+  }
+
+  // Map the network share to a X: drive
+  await net(["use", "x:", `\\\\${COMPUTER_NAME}\\${SHARE_NAME}`]);
+
+  // the build script have created the zip we can test on in the current dir.
+  let file = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
+  file.initWithPath(`X:\\${XPI_NAME}`);
+  info(file.path);
+  ok(file.exists());
+
+  let zipreader = Cc["@mozilla.org/libjar/zip-reader;1"].createInstance(
+    Ci.nsIZipReader
+  );
+  zipreader.open(file);
+  stream = wrapInputStream(zipreader.getInputStream("data"));
+
+  // Delete the X: drive
+  await net(["use", "x:", "/delete", "/y"]);
+
+  // Checks that we get the expected failure
+  Assert.throws(
+    () => {
+      while (true) {
+        Assert.ok(stream.read(1024).length > 0);
+      }
+    },
+    /NS_ERROR_FAILURE/,
+    "Got fault handler exception"
+  );
+
+  // This part is optional, but it's good to clean up.
+  dump(
+    `\n\n-------\nNow in a CMD with Administrator priviledges please run:\nnet share ${SHARE_NAME} /delete\n\n-------\n`
+  );
+});

modules/libjar/test/unit/xpcshell.ini

@@ -46,3 +46,8 @@ skip-if = os == "mac"
 # recovering from SIGBUS is temporarily disabled by bug 1583735
 skip-if = true
 [test_empty_jar_telemetry.js]
+[test_fault_handler.js]
+head = ../../zipwriter/test/unit/head_zipwriter.js
+skip-if =
+  os != "win" # tests windows specific exception handling
+  true # Requires elevated priviledges. See bug 1707853 and comments in test