Add MachMessageServer and its test

util/mach/mach_message_server.cc

+// 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.
+
+#include "util/mach/mach_message_server.h"
+
+#include <mach/mach_time.h>
+
+#include <limits>
+
+#include "base/mac/mach_logging.h"
+#include "base/mac/scoped_mach_vm.h"
+
+namespace crashpad {
+
+namespace {
+
+mach_timebase_info_data_t* TimebaseInternal() {
+  mach_timebase_info_data_t* timebase_info = new mach_timebase_info_data_t;
+  kern_return_t kr = mach_timebase_info(timebase_info);
+  MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_timebase_info";
+  return timebase_info;
+}
+
+mach_timebase_info_data_t* Timebase() {
+  static mach_timebase_info_data_t* timebase_info = TimebaseInternal();
+  return timebase_info;
+}
+
+uint64_t NanosecondTicks() {
+  uint64_t absolute_time = mach_absolute_time();
+  mach_timebase_info_data_t* timebase_info = Timebase();
+  return absolute_time * timebase_info->numer / timebase_info->denom;
+}
+
+const int kNanosecondsPerMillisecond = 1E6;
+
+// TimerRunning determines whether |deadline| has passed. If |deadline| is in
+// the future, |*remaining_ms| is set to the number of milliseconds remaining,
+// which will always be a positive value, and this function returns true. If
+// |deadline| is zero (indicating that no timer is in effect), |*remaining_ms|
+// is set to zero and this function returns true. Otherwise, this function
+// returns false. |deadline| is specified on the same time base as is returned
+// by NanosecondTicks().
+bool TimerRunning(uint64_t deadline, mach_msg_timeout_t* remaining_ms) {
+  if (!deadline) {
+    *remaining_ms = MACH_MSG_TIMEOUT_NONE;
+    return true;
+  }
+
+  uint64_t now = NanosecondTicks();
+
+  if (now >= deadline) {
+    return false;
+  }
+
+  uint64_t remaining = deadline - now;
+
+  // Round to the nearest millisecond, taking care not to overflow.
+  const int kHalfMillisecondInNanoseconds = kNanosecondsPerMillisecond / 2;
+  mach_msg_timeout_t remaining_mach;
+  if (remaining <=
+      std::numeric_limits<uint64_t>::max() - kHalfMillisecondInNanoseconds) {
+    remaining_mach = (remaining + kHalfMillisecondInNanoseconds) /
+                     kNanosecondsPerMillisecond;
+  } else {
+    remaining_mach = remaining / kNanosecondsPerMillisecond;
+  }
+
+  if (remaining_mach == MACH_MSG_TIMEOUT_NONE) {
+    return false;
+  }
+
+  *remaining_ms = remaining_mach;
+  return true;
+}
+
+}  // namespace
+
+// This implementation is based on 10.9.4
+// xnu-2422.110.17/libsyscall/mach/mach_msg.c mach_msg_server_once(), but
+// adapted to local style using scopers, replacing the server callback function
+// and |max_size| parameter with a C++ interface, and with the addition of the
+// the |persistent| parameter allowing this function to serve as a stand-in for
+// mach_msg_server(), the |nonblocking| parameter to control blocking directly,
+// and the |timeout| parameter allowing this function to not block indefinitely.
+mach_msg_return_t MachMessageServer(MachMessageServerInterface* interface,
+                                    mach_port_t receive_port,
+                                    mach_msg_options_t options,
+                                    bool persistent,
+                                    bool nonblocking,
+                                    mach_msg_timeout_t timeout) {
+  options &= ~(MACH_RCV_MSG | MACH_SEND_MSG);
+
+  mach_msg_options_t timeout_options = MACH_RCV_TIMEOUT | MACH_SEND_TIMEOUT |
+                                       MACH_RCV_INTERRUPT | MACH_SEND_INTERRUPT;
+
+  uint64_t deadline;
+  if (nonblocking) {
+    options |= timeout_options;
+    deadline = 0;
+  } else if (timeout != MACH_MSG_TIMEOUT_NONE) {
+    options |= timeout_options;
+    deadline = NanosecondTicks() +
+               static_cast<uint64_t>(timeout) * kNanosecondsPerMillisecond;
+  } else {
+    options &= ~timeout_options;
+    deadline = 0;
+  }
+
+  mach_msg_size_t trailer_alloc = REQUESTED_TRAILER_SIZE(options);
+  mach_msg_size_t max_request_size = interface->MachMessageServerRequestSize();
+  mach_msg_size_t request_alloc = round_page(max_request_size + trailer_alloc);
+  mach_msg_size_t request_size = (options & MACH_RCV_LARGE)
+                                     ? request_alloc
+                                     : max_request_size + trailer_alloc;
+
+  mach_msg_size_t max_reply_size = interface->MachMessageServerReplySize();
+  mach_msg_size_t reply_alloc = round_page(
+      (options & MACH_SEND_TRAILER) ? (max_reply_size + MAX_TRAILER_SIZE)
+                                    : max_reply_size);
+
+  mach_port_t self = mach_task_self();
+
+  kern_return_t kr;
+
+  do {
+    mach_msg_size_t this_request_alloc = request_alloc;
+    mach_msg_size_t this_request_size = request_size;
+
+    base::mac::ScopedMachVM request_scoper;
+    mach_msg_header_t* request_header = NULL;
+
+    while (!request_scoper.address()) {
+      vm_address_t request_addr;
+      kr = vm_allocate(self,
+                       &request_addr,
+                       this_request_alloc,
+                       VM_FLAGS_ANYWHERE | VM_MAKE_TAG(VM_MEMORY_MACH_MSG));
+      if (kr != KERN_SUCCESS) {
+        return kr;
+      }
+      base::mac::ScopedMachVM trial_request_scoper(request_addr,
+                                                   this_request_alloc);
+      request_header = reinterpret_cast<mach_msg_header_t*>(request_addr);
+
+      do {
+        // If |options| contains MACH_RCV_INTERRUPT, retry mach_msg in a loop
+        // when it returns MACH_RCV_INTERRUPTED to recompute |remaining_ms|
+        // rather than allowing mach_msg to retry using the original timeout
+        // value. See 10.9.4 xnu-2422.110.17/libsyscall/mach/mach_msg.c
+        // mach_msg().
+        mach_msg_timeout_t remaining_ms;
+        if (!TimerRunning(deadline, &remaining_ms)) {
+          return MACH_RCV_TIMED_OUT;
+        }
+
+        kr = mach_msg(request_header,
+                      options | MACH_RCV_MSG,
+                      0,
+                      this_request_size,
+                      receive_port,
+                      remaining_ms,
+                      MACH_PORT_NULL);
+      } while (kr == MACH_RCV_INTERRUPTED);
+
+      if (kr == MACH_MSG_SUCCESS) {
+        request_scoper.swap(trial_request_scoper);
+      } else if (kr == MACH_RCV_TOO_LARGE && options & MACH_RCV_LARGE) {
+        this_request_size =
+            round_page(request_header->msgh_size + trailer_alloc);
+        this_request_alloc = this_request_size;
+      } else {
+        return kr;
+      }
+    }
+
+    vm_address_t reply_addr;
+    kr = vm_allocate(self,
+                     &reply_addr,
+                     reply_alloc,
+                     VM_FLAGS_ANYWHERE | VM_MAKE_TAG(VM_MEMORY_MACH_MSG));
+    if (kr != KERN_SUCCESS) {
+      return kr;
+    }
+
+    base::mac::ScopedMachVM reply_scoper(reply_addr, reply_alloc);
+
+    mach_msg_header_t* reply_header =
+        reinterpret_cast<mach_msg_header_t*>(reply_addr);
+    bool destroy_complex_request = false;
+    interface->MachMessageServerFunction(
+        request_header, reply_header, &destroy_complex_request);
+
+    if (!(reply_header->msgh_bits & MACH_MSGH_BITS_COMPLEX)) {
+      mig_reply_error_t* reply_mig =
+          reinterpret_cast<mig_reply_error_t*>(reply_header);
+      if (reply_mig->RetCode == MIG_NO_REPLY) {
+        reply_header->msgh_remote_port = MACH_PORT_NULL;
+      } else if (reply_mig->RetCode != KERN_SUCCESS &&
+                 request_header->msgh_bits & MACH_MSGH_BITS_COMPLEX) {
+        destroy_complex_request = true;
+      }
+    }
+
+    if (destroy_complex_request &&
+        request_header->msgh_bits & MACH_MSGH_BITS_COMPLEX) {
+      request_header->msgh_remote_port = MACH_PORT_NULL;
+      mach_msg_destroy(request_header);
+    }
+
+    if (reply_header->msgh_remote_port != MACH_PORT_NULL) {
+      mach_msg_option_t send_options =
+          options | MACH_SEND_MSG |
+          (MACH_MSGH_BITS_REMOTE(reply_header->msgh_bits) ==
+                   MACH_MSG_TYPE_MOVE_SEND_ONCE
+               ? 0
+               : MACH_SEND_TIMEOUT);

[Robert Sesek, 2014/09/08 16:28:47]

Why is SEND_ONCE a gate for SEND_TIMEOUT?

+
+      bool running;
+      do {
+        // If |options| contains MACH_SEND_INTERRUPT, retry mach_msg in a loop
+        // when it returns MACH_SEND_INTERRUPTED to recompute |remaining_ms|
+        // rather than allowing mach_msg to retry using the original timeout
+        // value. See 10.9.4 xnu-2422.110.17/libsyscall/mach/mach_msg.c
+        // mach_msg().
+        mach_msg_timeout_t remaining_ms;
+        running = TimerRunning(deadline, &remaining_ms);
+        if (!running) {
+          // Don’t return just yet. If the timer ran out in between the time the
+          // request was received and now, at least try to send the response.
+          remaining_ms = 0;
+        }
+
+        kr = mach_msg(reply_header,
+                      send_options,
+                      reply_header->msgh_size,
+                      0,
+                      MACH_PORT_NULL,
+                      remaining_ms,
+                      MACH_PORT_NULL);
+      } while (kr == MACH_SEND_INTERRUPTED);
+
+      if (kr != KERN_SUCCESS) {
+        if (kr == MACH_SEND_INVALID_DEST || kr == MACH_SEND_TIMED_OUT) {
+          mach_msg_destroy(reply_header);
+        }
+        return kr;
+      }
+
+      if (!running) {
+        // The reply message was sent successfuly, so act as though the deadline
+        // was reached before or during the subsequent receive operation when in
+        // persistent mode, and just return success when not in persistent mode.
+        return persistent ? MACH_RCV_TIMED_OUT : kr;
+      }
+    }
+  } while (persistent);
+
+  return kr;
+}
+
+}  // namespace crashpad