Add ChildPortServer, a MachMessageServer::Interface implementation for the child_port subsystem

util/mach/mach_message_util.h

+// 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_UTIL_H_

[Mark Mentovai, 2014/11/25 17:27:31]

I renamed this file from mig.h because I have another utility function I’d like
to add soon, MachMessageTrailerFromHeader(), and it seemed sensible to me to
group it with these functions. It didn’t work well with the MIG naming, though.

+#define CRASHPAD_UTIL_MACH_MACH_MESSAGE_UTIL_H_
+
+#include <mach/mach.h>
+
+namespace crashpad {
+
+//! \brief Initializes a reply message for a MIG server routine based on its
+//!     corresponding request.
+//!
+//! If a request is handled by a server routine, it may be necessary to revise
+//! some of the fields set by this function, such as `msgh_size` and any fields
+//! defined in a routine’s reply structure type.
+//!
+//! \param[in] in_header The request message to base the reply on.
+//! \param[out] out_header The reply message to initialize. \a out_header will
+//!     be treated as a `mig_reply_error_t*` and all of its fields will be set
+//!     except for `RetCode`, which must be set by SetMIGReplyError(). This
+//!     argument is accepted as a `mach_msg_header_t*` instead of a
+//!     `mig_reply_error_t*` because that is the type that callers are expected
+//!     to possess in the C API.
+void PrepareMIGReplyFromRequest(const mach_msg_header_t* in_header,
+                                mach_msg_header_t* out_header);
+
+//! \brief Sets the error code in a reply message for a MIG server routine.
+//!
+//! \param[inout] out_header The reply message to operate on. \a out_header will
+//!     be treated as a `mig_reply_error_t*` and its `RetCode` field will be
+//!     set. This argument is accepted as a `mach_msg_header_t*` instead of a
+//!     `mig_reply_error_t*` because that is the type that callers are expected
+//!     to possess in the C API.
+//! \param[in] error The error code to store in \a out_header.
+//!
+//! \sa PrepareMIGReplyFromRequest()
+void SetMIGReplyError(mach_msg_header_t* out_header, kern_return_t error);
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_MACH_MACH_MESSAGE_UTIL_H_