ipc/ipc_message.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ipc/ipc_message.h"
   6
   7 #include "base/atomic_sequence_num.h"
   8 #include "base/logging.h"
   9 #include "build/build_config.h"
  10 #include "ipc/ipc_message_attachment.h"
  11 #include "ipc/ipc_message_attachment_set.h"
  12
  13 #if defined(OS_POSIX)
  14 #include "base/file_descriptor_posix.h"
  15 #include "ipc/ipc_platform_file_attachment_posix.h"
  16 #endif
  17
  18 namespace {
  19
  20 base::StaticAtomicSequenceNumber g_ref_num;
  21
  22 // Create a reference number for identifying IPC messages in traces. The return
  23 // values has the reference number stored in the upper 24 bits, leaving the low
  24 // 8 bits set to 0 for use as flags.
  25 inline uint32 GetRefNumUpper24() {
  26   base::trace_event::TraceLog* trace_log =
  27       base::trace_event::TraceLog::GetInstance();
  28   uint32 pid = trace_log ? trace_log->process_id() : 0;
  29   uint32 count = g_ref_num.GetNext();
  30   // The 24 bit hash is composed of 14 bits of the count and 10 bits of the
  31   // Process ID. With the current trace event buffer cap, the 14-bit count did
  32   // not appear to wrap during a trace. Note that it is not a big deal if
  33   // collisions occur, as this is only used for debugging and trace analysis.
  34   return ((pid << 14) | (count & 0x3fff)) << 8;
  35 }
  36
  37 }  // namespace
  38
  39 namespace IPC {
  40
  41 //------------------------------------------------------------------------------
  42
  43 Message::~Message() {
  44 }
  45
  46 Message::Message()
  47     : Pickle(sizeof(Header)) {
  48   header()->routing = header()->type = 0;
  49   header()->flags = GetRefNumUpper24();
  50 #if defined(OS_POSIX)
  51   header()->num_fds = 0;
  52   header()->pad = 0;
  53 #endif
  54   Init();
  55 }
  56
  57 Message::Message(int32 routing_id, uint32 type, PriorityValue priority)
  58     : Pickle(sizeof(Header)) {
  59   header()->routing = routing_id;
  60   header()->type = type;
  61   DCHECK((priority & 0xffffff00) == 0);
  62   header()->flags = priority | GetRefNumUpper24();
  63 #if defined(OS_POSIX)
  64   header()->num_fds = 0;
  65   header()->pad = 0;
  66 #endif
  67   Init();
  68 }
  69
  70 Message::Message(const char* data, int data_len) : Pickle(data, data_len) {
  71   Init();
  72 }
  73
  74 Message::Message(const Message& other) : Pickle(other) {
  75   Init();
  76 #if defined(OS_POSIX)
  77   attachment_set_ = other.attachment_set_;
  78 #endif
  79 }
  80
  81 void Message::Init() {
  82   dispatch_error_ = false;
  83 #ifdef IPC_MESSAGE_LOG_ENABLED
  84   received_time_ = 0;
  85   dont_log_ = false;
  86   log_data_ = NULL;
  87 #endif
  88 }
  89
  90 Message& Message::operator=(const Message& other) {
  91   *static_cast<Pickle*>(this) = other;
  92 #if defined(OS_POSIX)
  93   attachment_set_ = other.attachment_set_;
  94 #endif
  95   return *this;
  96 }
  97
  98 void Message::SetHeaderValues(int32 routing, uint32 type, uint32 flags) {
  99   // This should only be called when the message is already empty.
 100   DCHECK(payload_size() == 0);
 101
 102   header()->routing = routing;
 103   header()->type = type;
 104   header()->flags = flags;
 105 }
 106
 107 void Message::EnsureMessageAttachmentSet() {
 108   if (attachment_set_.get() == NULL)
 109     attachment_set_ = new MessageAttachmentSet;
 110 }
 111
 112 #ifdef IPC_MESSAGE_LOG_ENABLED
 113 void Message::set_sent_time(int64 time) {
 114   DCHECK((header()->flags & HAS_SENT_TIME_BIT) == 0);
 115   header()->flags |= HAS_SENT_TIME_BIT;
 116   WriteInt64(time);
 117 }
 118
 119 int64 Message::sent_time() const {
 120   if ((header()->flags & HAS_SENT_TIME_BIT) == 0)
 121     return 0;
 122
 123   const char* data = end_of_payload();
 124   data -= sizeof(int64);
 125   return *(reinterpret_cast<const int64*>(data));
 126 }
 127
 128 void Message::set_received_time(int64 time) const {
 129   received_time_ = time;
 130 }
 131 #endif
 132
 133 bool Message::WriteAttachment(scoped_refptr<MessageAttachment> attachment) {
 134   // We write the index of the descriptor so that we don't have to
 135   // keep the current descriptor as extra decoding state when deserialising.
 136   WriteInt(attachment_set()->size());
 137   return attachment_set()->AddAttachment(attachment);
 138 }
 139
 140 bool Message::ReadAttachment(
 141     PickleIterator* iter,
 142     scoped_refptr<MessageAttachment>* attachment) const {
 143   int descriptor_index;
 144   if (!iter->ReadInt(&descriptor_index))
 145     return false;
 146
 147   MessageAttachmentSet* attachment_set = attachment_set_.get();
 148   if (!attachment_set)
 149     return false;
 150
 151   *attachment = attachment_set->GetAttachmentAt(descriptor_index);
 152   return nullptr != attachment->get();
 153 }
 154
 155 bool Message::HasAttachments() const {
 156   return attachment_set_.get() && !attachment_set_->empty();
 157 }
 158
 159 bool Message::HasMojoHandles() const {
 160   return attachment_set_.get() && 0 < attachment_set_->num_mojo_handles();
 161 }
 162
 163 }  // namespace IPC