Quelle SharedMemoryPlatform_android.cpp Sprache: C

/* -*- 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/. */

/* This source code was derived from Chromium code, and as such is also subject
* to the [Chromium license](ipc/chromium/src/LICENSE). */

#include "SharedMemoryPlatform.h"

#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

#include "mozilla/Ashmem.h"

#ifdef MOZ_VALGRIND
#  include <valgrind/valgrind.h>
#endif

#include "mozilla/Maybe.h"
#include "mozilla/UniquePtrExtensions.h"
#include "prenv.h"

namespace mozilla::ipc::shared_memory {

// Right now we do nothing different for freezable shared memory on Android.
static Maybe<PlatformHandle> CreateImpl(size_t aSize, bool aFreezable) {
  MOZ_ASSERT(aSize > 0);

  int fd = mozilla::android::ashmem_create(nullptr, aSize);
  if (fd < 0) {
    MOZ_LOG_FMT(gSharedMemoryLog, LogLevel::Warning, "failed to open shm: {}",
                strerror(errno));
    return Nothing();
  }

  return Some(fd);
}

bool Platform::Create(Handle& aHandle, size_t aSize) {
  if (auto ph = CreateImpl(aSize, false)) {
    aHandle.mHandle = std::move(*ph);
    aHandle.mSize = aSize;
    return true;
  }
  return false;
}

bool Platform::CreateFreezable(FreezableHandle& aHandle, size_t aSize) {
  if (auto ph = CreateImpl(aSize, true)) {
    aHandle.mHandle = std::move(*ph);
    aHandle.mSize = aSize;
    return true;
  }
  return false;
}

PlatformHandle Platform::CloneHandle(const PlatformHandle& aHandle) {
  const int new_fd = dup(aHandle.get());
  if (new_fd < 0) {
    MOZ_LOG_FMT(gSharedMemoryLog, LogLevel::Warning,
                "failed to duplicate file descriptor: {}", strerror(errno));
    return nullptr;
  }
  return mozilla::UniqueFileHandle(new_fd);
}

bool Platform::Freeze(FreezableHandle& aHandle) {
  if (mozilla::android::ashmem_setProt(aHandle.mHandle.get(), PROT_READ) != 0) {
    MOZ_LOG_FMT(gSharedMemoryLog, LogLevel::Warning,
                "failed to set ashmem read-only: {}", strerror(errno));
    return false;
  }
  return true;
}

Maybe<void*> Platform::Map(const HandleBase& aHandle, void* aFixedAddress,
                           bool aReadOnly) {
  // Don't use MAP_FIXED when a fixed_address was specified, since that can
  // replace pages that are alread mapped at that address.
  void* mem = mmap(aFixedAddress, aHandle.Size(),
                   PROT_READ | (aReadOnly ? 0 : PROT_WRITE), MAP_SHARED,
                   aHandle.mHandle.get(), 0);

  if (mem == MAP_FAILED) {
    MOZ_LOG_FMT(gSharedMemoryLog, LogLevel::Warning, "call to mmap failed: {}",
                strerror(errno));
    return Nothing();
  }

  if (aFixedAddress && mem != aFixedAddress) {
    DebugOnly<bool> munmap_succeeded = munmap(mem, aHandle.Size()) == 0;
    MOZ_ASSERT(munmap_succeeded, "call to munmap failed");
    return Nothing();
  }

  return Some(mem);
}

void Platform::Unmap(void* aMemory, size_t aSize) { munmap(aMemory, aSize); }

bool Platform::Protect(char* aAddr, size_t aSize, Access aAccess) {
  int flags = PROT_NONE;
  if (aAccess & AccessRead) flags |= PROT_READ;
  if (aAccess & AccessWrite) flags |= PROT_WRITE;

  return 0 == mprotect(aAddr, aSize, flags);
}

void* Platform::FindFreeAddressSpace(size_t aSize) {
  void* memory = mmap(nullptr, aSize, PROT_NONE,
                      MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
  if (memory == MAP_FAILED) {
    return nullptr;
  }
  munmap(memory, aSize);
  return memory;
}

size_t Platform::PageSize() { return sysconf(_SC_PAGESIZE); }

bool Platform::IsSafeToMap(const PlatformHandle&) { return true; }

}  // namespace mozilla::ipc::shared_memory

quality100%

¤ Dauer der Verarbeitung: 0.16 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.