Add MachMessageServer and its test

util/mach/mach_message_server.h

Index: util/mach/mach_message_server.h
diff --git a/util/mach/mach_message_server.h b/util/mach/mach_message_server.h
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+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_MACH_MACH_MESSAGE_SERVER_H_
+#define CRASHPAD_UTIL_MACH_MACH_MESSAGE_SERVER_H_
+
+#include <mach/mach.h>
+
+#include "base/basictypes.h"
+
+namespace crashpad {
+
+//! \brief Runs a Mach message server to handle a Mach RPC request for MIG
+//!     servers.
+//!
+//! The principal entry point to this interface is the static Run() method.
+class MachMessageServer {
+ public:
+  //! \brief A Mach RPC callback interface, called by Run().
+  class Interface {
+   public:
+    //! \brief Handles a Mach RPC request.
+    //!
+    //! This method is a stand-in for a MIG-generated Mach RPC server “demux”
+    //! function such as `exc_server()` and `mach_exc_server()`. Implementations
+    //! may call such a function directly. This method is expected to behave
+    //! exactly as these functions behave.
+    //!
+    //! \param[in] in The request message, received as a Mach message.
+    //! \param[out] out The reply message. The caller allocates storage, and the
+    //!     callee is expected to populate the reply message appropriately.
+    //!     After returning, the caller will send this reply as a Mach message
+    //!     via the message’s reply port.
+    //! \param[out] destroy_complex_request `true` if a complex request message
+    //!     is to be destroyed even when handled successfully, `false`
+    //!     otherwise. The traditional behavior is `false`. In this case, the
+    //!     caller only destroys the request message in \a in when the reply
+    //!     message in \a out is not complex and when it indicates a return code
+    //!     other than `KERN_SUCCESS` or `MIG_NO_REPLY`. The assumption is that
+    //!     the rights or out-of-line data carried in a complex message may be
+    //!     retained by the server in this situation, and that it is the
+    //!     responsibility of the server to release these resources as needed.
+    //!     However, in many cases, these resources are not needed beyond the
+    //!     duration of a request-reply transaction, and in such cases, it is
+    //!     less error-prone to always have the caller,
+    //!     MachMessageServer::Run(), destroy complex request messages. To
+    //!     choose this behavior, this parameter should be set to `true`.
+    //!
+    //! \return `true` on success and `false` on failure, although the caller
+    //!     ignores the return value. However, the return code to be included in
+    //!     the reply message should be set as `mig_reply_error_t::RetCode`. The
+    //!     non-`void` return value is used for increased compatibility with
+    //!     MIG-generated functions.
+    virtual bool MachMessageServerFunction(mach_msg_header_t* in,
+                                           mach_msg_header_t* out,
+                                           bool* destroy_complex_request) = 0;
+
+    //! \return The expected or maximum size, in bytes, of a request message to
+    //!     be received as the \a in parameter of MachMessageServerFunction().
+    virtual mach_msg_size_t MachMessageServerRequestSize() = 0;
+
+    //! \return The maximum size, in bytes, of a reply message to be sent via
+    //!     the \a out parameter of MachMessageServerFunction(). This value does
+    //!     not need to include the size of any trailer to be sent with the
+    //!     message.
+    virtual mach_msg_size_t MachMessageServerReplySize() = 0;
+
+   protected:
+    ~Interface() {}
+  };
+
+  //! \brief Informs Run() whether to handle a single request-reply transaction
+  //!     or to run in a loop.
+  enum Persistent {
+    //! \brief Handle a single request-reply transaction and then return.
+    kOneShot = false,
+
+    //! \brief Run in a loop, potentially handling multiple request-reply
+    //!     transactions.
+    kPersistent,
+  };
+
+  //! \brief Informs Run() whether or not to block while waiting for requests.
+  enum Nonblocking {
+    //! \brief Wait for a request message if none is queued.
+    kBlocking = false,
+
+    //! \brief Return as soon as there no request messages queued. This may
+    //!     result in an immediate return without handling any requests.
+    kNonblocking,
+  };
+
+  //! \brief Runs a Mach message server to handle a Mach RPC request for MIG
+  //!     servers.
+  //!
+  //! This function listens for a request message and passes it to a callback
+  //! interface. A reponse is collected from that interface, and is sent back as
+  //! a reply.
+  //!
+  //! This function is similar to `mach_msg_server()` and
+  //! `mach_msg_server_once()`.
+  //!
+  //! \param[in] interface The MachMessageServerInterface that is responsible
+  //!     for handling the message. Interface::MachMessageServerRequestSize() is
+  //!     used as the receive size for the request message, and
+  //!     Interface::MachMessageServerReplySize() is used as the
+  //!     maximum size of the reply message. If \a options contains
+  //!     `MACH_RCV_LARGE`, this function will retry a receive operation that
+  //!     returns `MACH_RCV_TOO_LARGE` with an appropriately-sized buffer.
+  //!     MachMessageServerInterface::MachMessageServerFunction() is called to
+  //!     handle the request and populate the reply.
+  //! \param[in] receive_port The port on which to receive the request message.
+  //! \param[in] options Options suitable for mach_msg.
+  //! \param[in] persistent Chooses between one-shot and persistent operation.
+  //! \param[in] nonblocking Chooses between blocking and nonblocking operation.
+  //! \param[in] timeout_ms When \a nonblocking is `false`, the the maximum
+  //!     duration that this entire function will run, in milliseconds, or
+  //!     `MACH_MSG_TIMEOUT_NONE` to specify no timeout (infinite waiting). When
+  //!     \a nonblocking is `true`, this parameter has no effect. When \a
+  //!     persistent is `true`, the timeout applies to the overall duration of
+  //!     this function, not to any individual `mach_msg()` call.
+  //!
+  //! \return On success, `KERN_SUCCESS` (when \a persistent is `false`) or
+  //!     `MACH_RCV_TIMED_OUT` (when \a persistent and \a nonblocking are both
+  //!     `true`, or when \a persistent is `true`, \a nonblocking is `false`,
+  //!     and \a timeout is not `MACH_MSG_TIMEOUT_NONE`. This function has no
+  //!     successful return value when \a persistent is `true`, \a nonblocking
+  //!     is `false`, and \a timeout is `MACH_MSG_TIMEOUT_NONE`. On failure,
+  //!     returns a value identifying the nature of the error.
+  static mach_msg_return_t Run(Interface* interface,
+                               mach_port_t receive_port,
+                               mach_msg_options_t options,
+                               Persistent persistent,
+                               Nonblocking nonblocking,
+                               mach_msg_timeout_t timeout_ms);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(MachMessageServer);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_MACH_MACH_MESSAGE_SERVER_H_