зеркало из https://github.com/mozilla/gecko-dev.git
115 строки
3.8 KiB
C++
115 строки
3.8 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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#ifndef mozilla_ipc_FileDescriptor_h
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#define mozilla_ipc_FileDescriptor_h
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#include "base/basictypes.h"
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#include "base/process.h"
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#include "ipc/IPCMessageUtils.h"
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#include "mozilla/UniquePtrExtensions.h"
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#include "mozilla/ipc/IPDLParamTraits.h"
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#ifdef XP_UNIX
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# include "base/file_descriptor_posix.h"
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#endif
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namespace mozilla {
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namespace ipc {
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// This class is used by IPDL to share file descriptors across processes. When
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// sending a FileDescriptor IPDL will first duplicate a platform-specific file
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// handle type ('PlatformHandleType') into a handle that is valid in the other
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// process. Then IPDL will convert the duplicated handle into a type suitable
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// for pickling ('PickleType') and then send that through the IPC pipe. In the
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// receiving process the pickled data is converted into a platform-specific file
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// handle and then returned to the receiver.
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//
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// To use this class add 'FileDescriptor' as an argument in the IPDL protocol
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// and then pass a file descriptor from C++ to the Call/Send method. The
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// Answer/Recv method will receive a FileDescriptor& on which PlatformHandle()
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// can be called to return the platform file handle.
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class FileDescriptor {
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public:
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typedef base::ProcessId ProcessId;
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using UniquePlatformHandle = mozilla::UniqueFileHandle;
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using PlatformHandleType = UniquePlatformHandle::ElementType;
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#ifdef XP_WIN
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typedef PlatformHandleType PickleType;
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#else
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typedef base::FileDescriptor PickleType;
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#endif
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// This should only ever be created by IPDL.
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struct IPDLPrivate {};
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// Represents an invalid handle.
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FileDescriptor();
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// Copy constructor will duplicate a new handle.
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FileDescriptor(const FileDescriptor& aOther);
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FileDescriptor(FileDescriptor&& aOther);
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// This constructor will duplicate a new handle.
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// The caller still have to close aHandle.
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explicit FileDescriptor(PlatformHandleType aHandle);
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explicit FileDescriptor(UniquePlatformHandle&& aHandle);
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// This constructor WILL NOT duplicate the handle.
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// FileDescriptor takes the ownership from IPC message.
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FileDescriptor(const IPDLPrivate&, const PickleType& aPickle);
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~FileDescriptor();
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FileDescriptor& operator=(const FileDescriptor& aOther);
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FileDescriptor& operator=(FileDescriptor&& aOther);
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// Performs platform-specific actions to duplicate mHandle in the other
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// process (e.g. dup() on POSIX, DuplicateHandle() on Windows). Returns a
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// pickled value that can be passed to the other process via IPC.
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PickleType ShareTo(const IPDLPrivate&, ProcessId aTargetPid) const;
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// Tests mHandle against a well-known invalid platform-specific file handle
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// (e.g. -1 on POSIX, INVALID_HANDLE_VALUE on Windows).
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bool IsValid() const;
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// Returns a duplicated handle, it is caller's responsibility to close the
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// handle.
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UniquePlatformHandle ClonePlatformHandle() const;
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// Extracts the underlying handle and makes this object an invalid handle.
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// (Compare UniquePtr::release.)
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UniquePlatformHandle TakePlatformHandle();
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// Only used in nsTArray.
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bool operator==(const FileDescriptor& aOther) const;
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private:
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static UniqueFileHandle Clone(PlatformHandleType aHandle);
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UniquePlatformHandle mHandle;
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};
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template <>
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struct IPDLParamTraits<FileDescriptor> {
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typedef FileDescriptor paramType;
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static void Write(IPC::Message* aMsg, IProtocol* aActor,
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const paramType& aParam);
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static bool Read(const IPC::Message* aMsg, PickleIterator* aIter,
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IProtocol* aActor, paramType* aResult);
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};
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} // namespace ipc
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} // namespace mozilla
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#endif // mozilla_ipc_FileDescriptor_h
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