зеркало из https://github.com/mozilla/gecko-dev.git
152 строки
4.0 KiB
C++
152 строки
4.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "MemMapSnapshot.h"
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#include "base/eintr_wrapper.h"
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#include "base/file_util.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/ResultExtensions.h"
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#include "mozilla/ScopeExit.h"
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#include "mozilla/ipc/FileDescriptorUtils.h"
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#include "nsIFile.h"
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#ifdef XP_WIN
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# include "mozilla/RandomNum.h"
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# include "mozilla/WindowsVersion.h"
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# include "nsDebug.h"
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# include "nsString.h"
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# include <windows.h>
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#endif
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#ifdef XP_UNIX
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# include <sys/stat.h>
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#endif
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namespace mozilla {
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using loader::AutoMemMap;
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namespace ipc {
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Result<Ok, nsresult> MemMapSnapshot::Init(size_t aSize) {
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MOZ_ASSERT(!mInitialized);
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MOZ_TRY(Create(aSize));
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mInitialized = true;
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return Ok();
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}
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Result<Ok, nsresult> MemMapSnapshot::Finalize(AutoMemMap& aMem) {
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MOZ_ASSERT(mInitialized);
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MOZ_TRY(Freeze(aMem));
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mInitialized = false;
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return Ok();
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}
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#if defined(XP_WIN)
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Result<Ok, nsresult> MemMapSnapshot::Create(size_t aSize) {
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SECURITY_ATTRIBUTES sa;
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SECURITY_DESCRIPTOR sd;
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ACL dacl;
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sa.nLength = sizeof(sa);
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sa.lpSecurityDescriptor = &sd;
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sa.bInheritHandle = FALSE;
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if (NS_WARN_IF(!InitializeAcl(&dacl, sizeof(dacl), ACL_REVISION)) ||
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NS_WARN_IF(
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!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) ||
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NS_WARN_IF(!SetSecurityDescriptorDacl(&sd, TRUE, &dacl, FALSE))) {
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return Err(NS_ERROR_FAILURE);
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}
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nsAutoStringN<sizeof("MozSharedMem_") + 16 * 4> name;
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if (!IsWin8Point1OrLater()) {
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name.AssignLiteral("MozSharedMem_");
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for (size_t i = 0; i < 4; ++i) {
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Maybe<uint64_t> randomNum = RandomUint64();
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if (NS_WARN_IF(randomNum.isNothing())) {
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return Err(NS_ERROR_UNEXPECTED);
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}
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name.AppendPrintf("%016llx", *randomNum);
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}
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}
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HANDLE handle =
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CreateFileMapping(INVALID_HANDLE_VALUE, &sa, PAGE_READWRITE, 0,
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DWORD(aSize), name.IsEmpty() ? nullptr : name.get());
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if (!handle) {
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return Err(NS_ERROR_FAILURE);
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}
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mFile.emplace(handle);
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return mMem.initWithHandle(mFile.ref(), aSize, PR_PROT_READWRITE);
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}
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Result<Ok, nsresult> MemMapSnapshot::Freeze(AutoMemMap& aMem) {
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auto orig = mFile.ref().ClonePlatformHandle();
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mFile.reset();
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HANDLE handle;
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if (!::DuplicateHandle(
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GetCurrentProcess(), orig.release(), GetCurrentProcess(), &handle,
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GENERIC_READ | FILE_MAP_READ, false, DUPLICATE_CLOSE_SOURCE)) {
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return Err(NS_ERROR_FAILURE);
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}
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return aMem.initWithHandle(FileDescriptor(handle), mMem.size());
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}
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#elif defined(XP_UNIX)
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Result<Ok, nsresult> MemMapSnapshot::Create(size_t aSize) {
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FilePath path;
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ScopedCloseFile fd(file_util::CreateAndOpenTemporaryShmemFile(&path));
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if (!fd) {
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return Err(NS_ERROR_FAILURE);
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}
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if (HANDLE_EINTR(ftruncate(fileno(fd), aSize)) != 0) {
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return Err(NS_ERROR_FAILURE);
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}
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MOZ_TRY(mMem.init(FILEToFileDescriptor(fd), PR_PROT_READWRITE));
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mPath.Assign(path.value().data(), path.value().length());
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return Ok();
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}
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Result<Ok, nsresult> MemMapSnapshot::Freeze(AutoMemMap& aMem) {
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// Delete the shm file after we're done here, whether we succeed or not. The
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// open file descriptor will keep it alive until all remaining references
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// are closed, at which point it will be automatically freed.
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auto cleanup = MakeScopeExit([&]() { PR_Delete(mPath.get()); });
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// Make the shm file readonly. This doesn't make a difference in practice,
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// since we open and share a read-only file descriptor, and then delete the
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// file. But it doesn't hurt, either.
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chmod(mPath.get(), 0400);
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nsCOMPtr<nsIFile> file;
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MOZ_TRY(NS_NewNativeLocalFile(mPath, /* followLinks = */ false,
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getter_AddRefs(file)));
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return aMem.init(file);
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}
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#else
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# error "Unsupported build configuration"
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#endif
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} // namespace ipc
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} // namespace mozilla
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