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_set.h"
  11
  12 #if defined(OS_POSIX)
  13 #include "base/file_descriptor_posix.h"
  14 #endif
  15
  16 namespace {
  17
  18 base::StaticAtomicSequenceNumber g_ref_num;
  19
  20 // Create a reference number for identifying IPC messages in traces. The return
  21 // values has the reference number stored in the upper 24 bits, leaving the low
  22 // 8 bits set to 0 for use as flags.
  23 inline uint32 GetRefNumUpper24() {
  24   base::debug::TraceLog* trace_log = base::debug::TraceLog::GetInstance();
  25   uint32 pid = trace_log ? trace_log->process_id() : 0;
  26   uint32 count = g_ref_num.GetNext();
  27   // The 24 bit hash is composed of 14 bits of the count and 10 bits of the
  28   // Process ID. With the current trace event buffer cap, the 14-bit count did
  29   // not appear to wrap during a trace. Note that it is not a big deal if
  30   // collisions occur, as this is only used for debugging and trace analysis.
  31   return ((pid << 14) | (count & 0x3fff)) << 8;
  32 }
  33
  34 }  // namespace
  35
  36 namespace IPC {
  37
  38 //------------------------------------------------------------------------------
  39
  40 Message::~Message() {
  41 }
  42
  43 Message::Message()
  44     : Pickle(sizeof(Header)) {
  45   header()->routing = header()->type = 0;
  46   header()->flags = GetRefNumUpper24();
  47 #if defined(OS_POSIX)
  48   header()->num_fds = 0;
  49   header()->pad = 0;
  50 #endif
  51   Init();
  52 }
  53
  54 Message::Message(int32 routing_id, uint32 type, PriorityValue priority)
  55     : Pickle(sizeof(Header)) {
  56   header()->routing = routing_id;
  57   header()->type = type;
  58   DCHECK((priority & 0xffffff00) == 0);
  59   header()->flags = priority | GetRefNumUpper24();
  60 #if defined(OS_POSIX)
  61   header()->num_fds = 0;
  62   header()->pad = 0;
  63 #endif
  64   Init();
  65 }
  66
  67 Message::Message(const char* data, int data_len) : Pickle(data, data_len) {
  68   Init();
  69 }
  70
  71 Message::Message(const Message& other) : Pickle(other) {
  72   Init();
  73 #if defined(OS_POSIX)
  74   attachment_set_ = other.attachment_set_;
  75 #endif
  76 }
  77
  78 void Message::Init() {
  79   dispatch_error_ = false;
  80 #ifdef IPC_MESSAGE_LOG_ENABLED
  81   received_time_ = 0;
  82   dont_log_ = false;
  83   log_data_ = NULL;
  84 #endif
  85 }
  86
  87 Message& Message::operator=(const Message& other) {
  88   *static_cast<Pickle*>(this) = other;
  89 #if defined(OS_POSIX)
  90   attachment_set_ = other.attachment_set_;
  91 #endif
  92   return *this;
  93 }
  94
  95 void Message::SetHeaderValues(int32 routing, uint32 type, uint32 flags) {
  96   // This should only be called when the message is already empty.
  97   DCHECK(payload_size() == 0);
  98
  99   header()->routing = routing;
 100   header()->type = type;
 101   header()->flags = flags;
 102 }
 103
 104 void Message::EnsureMessageAttachmentSet() {
 105   if (attachment_set_.get() == NULL)
 106     attachment_set_ = new MessageAttachmentSet;
 107 }
 108
 109 #ifdef IPC_MESSAGE_LOG_ENABLED
 110 void Message::set_sent_time(int64 time) {
 111   DCHECK((header()->flags & HAS_SENT_TIME_BIT) == 0);
 112   header()->flags |= HAS_SENT_TIME_BIT;
 113   WriteInt64(time);
 114 }
 115
 116 int64 Message::sent_time() const {
 117   if ((header()->flags & HAS_SENT_TIME_BIT) == 0)
 118     return 0;
 119
 120   const char* data = end_of_payload();
 121   data -= sizeof(int64);
 122   return *(reinterpret_cast<const int64*>(data));
 123 }
 124
 125 void Message::set_received_time(int64 time) const {
 126   received_time_ = time;
 127 }
 128 #endif
 129
 130 #if defined(OS_POSIX)
 131 bool Message::WriteFile(base::ScopedFD descriptor) {
 132   // We write the index of the descriptor so that we don't have to
 133   // keep the current descriptor as extra decoding state when deserialising.
 134   WriteInt(attachment_set()->size());
 135   return attachment_set()->AddToOwn(descriptor.Pass());
 136 }
 137
 138 bool Message::WriteBorrowingFile(const base::PlatformFile& descriptor) {
 139   // We write the index of the descriptor so that we don't have to
 140   // keep the current descriptor as extra decoding state when deserialising.
 141   WriteInt(attachment_set()->size());
 142   return attachment_set()->AddToBorrow(descriptor);
 143 }
 144
 145 bool Message::ReadFile(PickleIterator* iter, base::ScopedFD* descriptor) const {
 146   int descriptor_index;
 147   if (!iter->ReadInt(&descriptor_index))
 148     return false;
 149
 150   MessageAttachmentSet* attachment_set = attachment_set_.get();
 151   if (!attachment_set)
 152     return false;
 153
 154   base::PlatformFile file = attachment_set->TakeDescriptorAt(descriptor_index);
 155   if (file < 0)
 156     return false;
 157
 158   descriptor->reset(file);
 159   return true;
 160 }
 161
 162 bool Message::HasFileDescriptors() const {
 163   return attachment_set_.get() && !attachment_set_->empty();
 164 }
 165
 166 #endif
 167
 168 }  // namespace IPC