mfbt/Unused.h
author Jed Davis <jld@mozilla.com>
Mon, 20 Nov 2017 10:47:54 -0700
changeset 447508 3b11a0bf7ae7a7fe0ed508583cf07441b68bab78
parent 413998 57b1aa6bfa2e43322cc2318916352a3fea19d19d
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1409895 - Deny getcwd in the Linux content process sandbox. r=gcp getcwd won't do anything useful once we start chroot()ing to remove filesystem access; with this patch it will at least fail the same way regardless of whether user namespaces are available or if other factors prevent complete FS isolation. Bonus fix: improve the comments for this group of syscalls. MozReview-Commit-ID: KueZzly2mlO

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#ifndef mozilla_unused_h
#define mozilla_unused_h

#include "mozilla/Attributes.h"
#include "mozilla/Types.h"

#ifdef __cplusplus

namespace mozilla {

//
// Suppress GCC warnings about unused return values with
//   Unused << SomeFuncDeclaredWarnUnusedReturnValue();
//
struct unused_t
{
  template<typename T>
  MOZ_ALWAYS_INLINE_EVEN_DEBUG void
  operator<<(const T& /*unused*/) const {}
};

extern MFBT_DATA const unused_t Unused;

} // namespace mozilla

#endif // __cplusplus

// An alternative to mozilla::Unused for use in (a) C code and (b) code where
// linking with unused.o is difficult.
#define MOZ_UNUSED(expr) \
  do { if (expr) { (void)0; } } while (0)

#endif // mozilla_unused_h