ipc/ipc_message.h

   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 #ifndef IPC_IPC_MESSAGE_H_
   6 #define IPC_IPC_MESSAGE_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/debug/trace_event.h"
  12 #include "base/pickle.h"
  13 #include "ipc/ipc_export.h"
  14
  15 #if !defined(NDEBUG)
  16 #define IPC_MESSAGE_LOG_ENABLED
  17 #endif
  18
  19 #if defined(OS_POSIX)
  20 #include "base/memory/ref_counted.h"
  21 #endif
  22
  23 namespace base {
  24 struct FileDescriptor;
  25 }
  26
  27 class FileDescriptorSet;
  28
  29 namespace IPC {
  30
  31 //------------------------------------------------------------------------------
  32
  33 struct LogData;
  34
  35 class IPC_EXPORT Message : public Pickle {
  36  public:
  37   enum PriorityValue {
  38     PRIORITY_LOW = 1,
  39     PRIORITY_NORMAL,
  40     PRIORITY_HIGH
  41   };
  42
  43   // Bit values used in the flags field.
  44   // Upper 24 bits of flags store a reference number, so this enum is limited to
  45   // 8 bits.
  46   enum {
  47     PRIORITY_MASK     = 0x03,  // Low 2 bits of store the priority value.
  48     SYNC_BIT          = 0x04,
  49     REPLY_BIT         = 0x08,
  50     REPLY_ERROR_BIT   = 0x10,
  51     UNBLOCK_BIT       = 0x20,
  52     PUMPING_MSGS_BIT  = 0x40,
  53     HAS_SENT_TIME_BIT = 0x80,
  54   };
  55
  56   virtual ~Message();
  57
  58   Message();
  59
  60   // Initialize a message with a user-defined type, priority value, and
  61   // destination WebView ID.
  62   Message(int32 routing_id, uint32 type, PriorityValue priority);
  63
  64   // Initializes a message from a const block of data.  The data is not copied;
  65   // instead the data is merely referenced by this message.  Only const methods
  66   // should be used on the message when initialized this way.
  67   Message(const char* data, int data_len);
  68
  69   Message(const Message& other);
  70   Message& operator=(const Message& other);
  71
  72   PriorityValue priority() const {
  73     return static_cast<PriorityValue>(header()->flags & PRIORITY_MASK);
  74   }
  75
  76   // True if this is a synchronous message.
  77   void set_sync() {
  78     header()->flags |= SYNC_BIT;
  79   }
  80   bool is_sync() const {
  81     return (header()->flags & SYNC_BIT) != 0;
  82   }
  83
  84   // Set this on a reply to a synchronous message.
  85   void set_reply() {
  86     header()->flags |= REPLY_BIT;
  87   }
  88
  89   bool is_reply() const {
  90     return (header()->flags & REPLY_BIT) != 0;
  91   }
  92
  93   // Set this on a reply to a synchronous message to indicate that no receiver
  94   // was found.
  95   void set_reply_error() {
  96     header()->flags |= REPLY_ERROR_BIT;
  97   }
  98
  99   bool is_reply_error() const {
 100     return (header()->flags & REPLY_ERROR_BIT) != 0;
 101   }
 102
 103   // Normally when a receiver gets a message and they're blocked on a
 104   // synchronous message Send, they buffer a message.  Setting this flag causes
 105   // the receiver to be unblocked and the message to be dispatched immediately.
 106   void set_unblock(bool unblock) {
 107     if (unblock) {
 108       header()->flags |= UNBLOCK_BIT;
 109     } else {
 110       header()->flags &= ~UNBLOCK_BIT;
 111     }
 112   }
 113
 114   bool should_unblock() const {
 115     return (header()->flags & UNBLOCK_BIT) != 0;
 116   }
 117
 118   // Tells the receiver that the caller is pumping messages while waiting
 119   // for the result.
 120   bool is_caller_pumping_messages() const {
 121     return (header()->flags & PUMPING_MSGS_BIT) != 0;
 122   }
 123
 124   uint32 type() const {
 125     return header()->type;
 126   }
 127
 128   int32 routing_id() const {
 129     return header()->routing;
 130   }
 131
 132   void set_routing_id(int32 new_id) {
 133     header()->routing = new_id;
 134   }
 135
 136   uint32 flags() const {
 137     return header()->flags;
 138   }
 139
 140   // Sets all the given header values. The message should be empty at this
 141   // call.
 142   void SetHeaderValues(int32 routing, uint32 type, uint32 flags);
 143
 144   template<class T, class S, class P>
 145   static bool Dispatch(const Message* msg, T* obj, S* sender, P* parameter,
 146                        void (T::*func)()) {
 147     (obj->*func)();
 148     return true;
 149   }
 150
 151   template<class T, class S, class P>
 152   static bool Dispatch(const Message* msg, T* obj, S* sender, P* parameter,
 153                        void (T::*func)(P*)) {
 154     (obj->*func)(parameter);
 155     return true;
 156   }
 157
 158   // Used for async messages with no parameters.
 159   static void Log(std::string* name, const Message* msg, std::string* l) {
 160   }
 161
 162   // Find the end of the message data that starts at range_start.  Returns NULL
 163   // if the entire message is not found in the given data range.
 164   static const char* FindNext(const char* range_start, const char* range_end) {
 165     return Pickle::FindNext(sizeof(Header), range_start, range_end);
 166   }
 167
 168 #if defined(OS_POSIX)
 169   // On POSIX, a message supports reading / writing FileDescriptor objects.
 170   // This is used to pass a file descriptor to the peer of an IPC channel.
 171
 172   // Add a descriptor to the end of the set. Returns false if the set is full.
 173   bool WriteFileDescriptor(const base::FileDescriptor& descriptor);
 174
 175   // Get a file descriptor from the message. Returns false on error.
 176   //   iter: a Pickle iterator to the current location in the message.
 177   bool ReadFileDescriptor(PickleIterator* iter,
 178                           base::FileDescriptor* descriptor) const;
 179
 180   // Returns true if there are any file descriptors in this message.
 181   bool HasFileDescriptors() const;
 182 #endif
 183
 184 #ifdef IPC_MESSAGE_LOG_ENABLED
 185   // Adds the outgoing time from Time::Now() at the end of the message and sets
 186   // a bit to indicate that it's been added.
 187   void set_sent_time(int64 time);
 188   int64 sent_time() const;
 189
 190   void set_received_time(int64 time) const;
 191   int64 received_time() const { return received_time_; }
 192   void set_output_params(const std::string& op) const { output_params_ = op; }
 193   const std::string& output_params() const { return output_params_; }
 194   // The following four functions are needed so we can log sync messages with
 195   // delayed replies.  We stick the log data from the sent message into the
 196   // reply message, so that when it's sent and we have the output parameters
 197   // we can log it.  As such, we set a flag on the sent message to not log it.
 198   void set_sync_log_data(LogData* data) const { log_data_ = data; }
 199   LogData* sync_log_data() const { return log_data_; }
 200   void set_dont_log() const { dont_log_ = true; }
 201   bool dont_log() const { return dont_log_; }
 202 #endif
 203
 204   // Called to trace when message is sent.
 205   void TraceMessageBegin() {
 206     TRACE_EVENT_FLOW_BEGIN0(TRACE_DISABLED_BY_DEFAULT("ipc.flow"), "IPC",
 207         header()->flags);
 208   }
 209   // Called to trace when message is received.
 210   void TraceMessageEnd() {
 211     TRACE_EVENT_FLOW_END0(TRACE_DISABLED_BY_DEFAULT("ipc.flow"), "IPC",
 212         header()->flags);
 213   }
 214
 215  protected:
 216   friend class Channel;
 217   friend class MessageReplyDeserializer;
 218   friend class SyncMessage;
 219
 220 #pragma pack(push, 4)
 221   struct Header : Pickle::Header {
 222     int32 routing;  // ID of the view that this message is destined for
 223     uint32 type;    // specifies the user-defined message type
 224     uint32 flags;   // specifies control flags for the message
 225 #if defined(OS_POSIX)
 226     uint16 num_fds; // the number of descriptors included with this message
 227     uint16 pad;     // explicitly initialize this to appease valgrind
 228 #endif
 229   };
 230 #pragma pack(pop)
 231
 232   Header* header() {
 233     return headerT<Header>();
 234   }
 235   const Header* header() const {
 236     return headerT<Header>();
 237   }
 238
 239   void InitLoggingVariables();
 240
 241 #if defined(OS_POSIX)
 242   // The set of file descriptors associated with this message.
 243   scoped_refptr<FileDescriptorSet> file_descriptor_set_;
 244
 245   // Ensure that a FileDescriptorSet is allocated
 246   void EnsureFileDescriptorSet();
 247
 248   FileDescriptorSet* file_descriptor_set() {
 249     EnsureFileDescriptorSet();
 250     return file_descriptor_set_.get();
 251   }
 252   const FileDescriptorSet* file_descriptor_set() const {
 253     return file_descriptor_set_.get();
 254   }
 255 #endif
 256
 257 #ifdef IPC_MESSAGE_LOG_ENABLED
 258   // Used for logging.
 259   mutable int64 received_time_;
 260   mutable std::string output_params_;
 261   mutable LogData* log_data_;
 262   mutable bool dont_log_;
 263 #endif
 264 };
 265
 266 //------------------------------------------------------------------------------
 267
 268 }  // namespace IPC
 269
 270 enum SpecialRoutingIDs {
 271   // indicates that we don't have a routing ID yet.
 272   MSG_ROUTING_NONE = -2,
 273
 274   // indicates a general message not sent to a particular tab.
 275   MSG_ROUTING_CONTROL = kint32max,
 276 };
 277
 278 #define IPC_REPLY_ID 0xFFFFFFF0  // Special message id for replies
 279 #define IPC_LOGGING_ID 0xFFFFFFF1  // Special message id for logging
 280
 281 #endif  // IPC_IPC_MESSAGE_H_