140 lines
4.0 KiB
C++
140 lines
4.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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 "mozilla/UniquePtr.h"
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#ifdef XP_WIN
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// Need the HANDLE typedef.
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#include <winnt.h>
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#else
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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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{
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public:
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typedef base::ProcessId ProcessId;
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#ifdef XP_WIN
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typedef HANDLE PlatformHandleType;
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typedef HANDLE PickleType;
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#else
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typedef int PlatformHandleType;
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typedef base::FileDescriptor PickleType;
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#endif
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struct PlatformHandleHelper
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{
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MOZ_IMPLICIT PlatformHandleHelper(PlatformHandleType aHandle);
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MOZ_IMPLICIT PlatformHandleHelper(std::nullptr_t);
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bool operator != (std::nullptr_t) const;
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operator PlatformHandleType () const;
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#ifdef XP_WIN
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operator std::intptr_t () const;
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#endif
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private:
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PlatformHandleType mHandle;
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};
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struct PlatformHandleDeleter
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{
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typedef PlatformHandleHelper pointer;
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void operator () (PlatformHandleHelper aHelper);
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};
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typedef UniquePtr<PlatformHandleType, PlatformHandleDeleter> UniquePlatformHandle;
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// This should only ever be created by IPDL.
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struct IPDLPrivate
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{};
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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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// 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&
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operator=(const FileDescriptor& aOther);
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FileDescriptor&
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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
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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
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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
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ClonePlatformHandle() const;
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// Only used in nsTArray.
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bool
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operator==(const FileDescriptor& aOther) const;
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private:
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friend struct PlatformHandleTrait;
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void
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Assign(const FileDescriptor& aOther);
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void
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Close();
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static bool
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IsValid(PlatformHandleType aHandle);
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static PlatformHandleType
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Clone(PlatformHandleType aHandle);
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static void
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Close(PlatformHandleType aHandle);
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PlatformHandleType mHandle;
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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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