widget/LSBUtils.cpp
author Kris Maglione <maglione.k@gmail.com>
Thu, 12 Jul 2018 23:13:04 -0700
changeset 817896 2000ede41108d6312734d8df7db98272b33528fa
parent 697673 f53d4e3b563526a4191ea488d374cb0ebc7b597e
permissions -rw-r--r--
Bug 1475612: Fix double file close on background thread. r?erahm LSBUtils closes a file descriptor twice, once with fclose and then again with close. It also does this on a background thread, during startup, which means it tends to race with main thread code which opens files. This patch fixes that, and also removes a work-around for the issue in the MemMapSnapshot code. MozReview-Commit-ID: JdDHt9ayFEl

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * 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/. */

#include "LSBUtils.h"

#include <unistd.h>
#include "base/process_util.h"
#include "mozilla/FileUtils.h"

namespace mozilla {
namespace widget {
namespace lsb {

static const char* gLsbReleasePath = "/usr/bin/lsb_release";

bool
GetLSBRelease(nsACString& aDistributor,
              nsACString& aDescription,
              nsACString& aRelease,
              nsACString& aCodename)
{
  if (access(gLsbReleasePath, R_OK) != 0)
    return false;

  int pipefd[2];
  if (pipe(pipefd) == -1) {
    NS_WARNING("pipe() failed!");
    return false;
  }

  std::vector<std::string> argv = {
    gLsbReleasePath, "-idrc"
  };

  base::LaunchOptions options;
  options.fds_to_remap.push_back({ pipefd[1], STDOUT_FILENO });
  options.wait = true;

  base::ProcessHandle process;
  bool ok = base::LaunchApp(argv, options, &process);
  close(pipefd[1]);
  if (!ok) {
    NS_WARNING("Failed to spawn lsb_release!");
    close(pipefd[0]);
    return false;
  }

  ScopedCloseFile stream(fdopen(pipefd[0], "r"));
  if (!stream) {
    NS_WARNING("Could not wrap fd!");
    close(pipefd[0]);
    return false;
  }

  char dist[256], desc[256], release[256], codename[256];
  if (fscanf(stream, "Distributor ID:\t%255[^\n]\n"
                     "Description:\t%255[^\n]\n"
                     "Release:\t%255[^\n]\n"
                     "Codename:\t%255[^\n]\n",
             dist, desc, release, codename) != 4)
  {
    NS_WARNING("Failed to parse lsb_release!");
    return false;
  }

  aDistributor.Assign(dist);
  aDescription.Assign(desc);
  aRelease.Assign(release);
  aCodename.Assign(codename);
  return true;
}

}  // namespace lsb
}  // namespace widget
}  // namespace mozilla