path: root/ipc/chromium/src/chrome/common/ipc_message_utils.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_COMMON_IPC_MESSAGE_UTILS_H_
#define CHROME_COMMON_IPC_MESSAGE_UTILS_H_

#include <string>
#include <vector>
#include <map>

#include "base/file_path.h"
#include "base/string_util.h"
#include "base/string16.h"
#include "base/time.h"

#if defined(OS_POSIX)
#include "chrome/common/file_descriptor_set_posix.h"
#endif
#include "chrome/common/ipc_message.h"
#include "chrome/common/transport_dib.h"

namespace IPC {

//-----------------------------------------------------------------------------
// An iterator class for reading the fields contained within a Message.

class MessageIterator {
 public:
  explicit MessageIterator(const Message& m) : msg_(m), iter_(m) {
  }
  int NextInt() const {
    int val;
    if (!msg_.ReadInt(&iter_, &val))
      NOTREACHED();
    return val;
  }
  intptr_t NextIntPtr() const {
    intptr_t val;
    if (!msg_.ReadIntPtr(&iter_, &val))
      NOTREACHED();
    return val;
  }
  const std::string NextString() const {
    std::string val;
    if (!msg_.ReadString(&iter_, &val))
      NOTREACHED();
    return val;
  }
  const std::wstring NextWString() const {
    std::wstring val;
    if (!msg_.ReadWString(&iter_, &val))
      NOTREACHED();
    return val;
  }
 private:
  const Message& msg_;
  mutable PickleIterator iter_;
};

//-----------------------------------------------------------------------------
// ParamTraits specializations, etc.
//
// The full set of types ParamTraits is specialized upon contains *possibly*
// repeated types: unsigned long may be uint32_t or size_t, unsigned long long
// may be uint64_t or size_t, nsresult may be uint32_t, and so on.  You can't
// have ParamTraits<unsigned int> *and* ParamTraits<uint32_t> if unsigned int
// is uint32_t -- that's multiple definitions, and you can only have one.
//
// You could use #ifs and macro conditions to avoid duplicates, but they'd be
// hairy: heavily dependent upon OS and compiler author choices, forced to
// address all conflicts by hand.  Happily there's a better way.  The basic
// idea looks like this, where T -> U represents T inheriting from U:
//
// class ParamTraits<P>
// |
// --> class ParamTraits1<P>
//     |
//     --> class ParamTraits2<P>
//         |
//         --> class ParamTraitsN<P> // or however many levels
//
// The default specialization of ParamTraits{M}<P> is an empty class that
// inherits from ParamTraits{M + 1}<P> (or nothing in the base case).
//
// Now partition the set of parameter types into sets without duplicates.
// Assign each set of types to a level M.  Then specialize ParamTraitsM for
// each of those types.  A reference to ParamTraits<P> will consist of some
// number of empty classes inheriting in sequence, ending in a non-empty
// ParamTraits{N}<P>.  It's okay for the parameter types to be duplicative:
// either name of a type will resolve to the same ParamTraits{N}<P>.
//
// The nice thing is that because templates are instantiated lazily, if we
// indeed have uint32_t == unsigned int, say, with the former in level N and
// the latter in M > N, ParamTraitsM<unsigned int> won't be created (as long as
// nobody uses ParamTraitsM<unsigned int>, but why would you), and no duplicate
// code will be compiled or extra symbols generated.  It's as efficient at
// runtime as manually figuring out and avoiding conflicts by #ifs.
//
// The scheme we follow below names the various classes according to the types
// in them, and the number of ParamTraits levels is larger, but otherwise it's
// exactly the above idea.
//

template <class P> struct ParamTraits;

template <class P>
static inline void WriteParam(Message* m, const P& p) {
  ParamTraits<P>::Write(m, p);
}

template <class P>
static inline bool WARN_UNUSED_RESULT ReadParam(const Message* m, PickleIterator* iter,
                                                P* p) {
  return ParamTraits<P>::Read(m, iter, p);
}

template <class P>
static inline void LogParam(const P& p, std::wstring* l) {
  ParamTraits<P>::Log(p, l);
}

// Fundamental types.

template <class P>
struct ParamTraitsFundamental {};

template <>
struct ParamTraitsFundamental<bool> {
  typedef bool param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteBool(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadBool(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(p ? L"true" : L"false");
  }
};

template <>
struct ParamTraitsFundamental<int> {
  typedef int param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteInt(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadInt(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%d", p));
  }
};

template <>
struct ParamTraitsFundamental<long> {
  typedef long param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteLong(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadLong(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%l", p));
  }
};

template <>
struct ParamTraitsFundamental<unsigned long> {
  typedef unsigned long param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteULong(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadULong(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%ul", p));
  }
};

template <>
struct ParamTraitsFundamental<long long> {
  typedef long long param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteBytes(&p, sizeof(param_type));
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadBytesInto(iter, r, sizeof(*r));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%ll", p));
  }
};

template <>
struct ParamTraitsFundamental<unsigned long long> {
  typedef unsigned long long param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteBytes(&p, sizeof(param_type));
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadBytesInto(iter, r, sizeof(*r));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%ull", p));
  }
};

template <>
struct ParamTraitsFundamental<double> {
  typedef double param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteDouble(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadDouble(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"e", p));
  }
};

// Fixed-size <stdint.h> types.

template <class P>
struct ParamTraitsFixed : ParamTraitsFundamental<P> {};

template <>
struct ParamTraitsFixed<int16_t> {
  typedef int16_t param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteInt16(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadInt16(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%hd", p));
  }
};

template <>
struct ParamTraitsFixed<uint16_t> {
  typedef uint16_t param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteUInt16(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadUInt16(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%hu", p));
  }
};

template <>
struct ParamTraitsFixed<uint32_t> {
  typedef uint32_t param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteUInt32(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadUInt32(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%u", p));
  }
};

template <>
struct ParamTraitsFixed<int64_t> {
  typedef int64_t param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteInt64(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadInt64(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%" PRId64L, p));
  }
};

template <>
struct ParamTraitsFixed<uint64_t> {
  typedef uint64_t param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteInt64(static_cast<int64_t>(p));
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadInt64(iter, reinterpret_cast<int64_t*>(r));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%" PRIu64L, p));
  }
};

// Other standard C types.

template <class P>
struct ParamTraitsLibC : ParamTraitsFixed<P> {};

template <>
struct ParamTraitsLibC<size_t> {
  typedef size_t param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteSize(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadSize(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%u", p));
  }
};

// std::* types.

template <class P>
struct ParamTraitsStd : ParamTraitsLibC<P> {};

template <>
struct ParamTraitsStd<std::string> {
  typedef std::string param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteString(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadString(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(UTF8ToWide(p));
  }
};

template <>
struct ParamTraitsStd<std::wstring> {
  typedef std::wstring param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteWString(p);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadWString(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(p);
  }
};

template <class K, class V>
struct ParamTraitsStd<std::map<K, V> > {
  typedef std::map<K, V> param_type;
  static void Write(Message* m, const param_type& p) {
    WriteParam(m, static_cast<int>(p.size()));
    typename param_type::const_iterator iter;
    for (iter = p.begin(); iter != p.end(); ++iter) {
      WriteParam(m, iter->first);
      WriteParam(m, iter->second);
    }
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    int size;
    if (!ReadParam(m, iter, &size) || size < 0)
      return false;
    for (int i = 0; i < size; ++i) {
      K k;
      if (!ReadParam(m, iter, &k))
        return false;
      V& value = (*r)[k];
      if (!ReadParam(m, iter, &value))
        return false;
    }
    return true;
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(L"<std::map>");
  }
};

// Windows-specific types.

template <class P>
struct ParamTraitsWindows : ParamTraitsStd<P> {};

#if defined(OS_WIN)
template <>
struct ParamTraitsWindows<HANDLE> {
  typedef HANDLE param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteIntPtr(reinterpret_cast<intptr_t>(p));
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    DCHECK_EQ(sizeof(param_type), sizeof(intptr_t));
    return m->ReadIntPtr(iter, reinterpret_cast<intptr_t*>(r));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"0x%X", p));
  }
};

template <>
struct ParamTraitsWindows<HWND> {
  typedef HWND param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteIntPtr(reinterpret_cast<intptr_t>(p));
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    DCHECK_EQ(sizeof(param_type), sizeof(intptr_t));
    return m->ReadIntPtr(iter, reinterpret_cast<intptr_t*>(r));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"0x%X", p));
  }
};
#endif  // defined(OS_WIN)

// Various ipc/chromium types.

template <class P>
struct ParamTraitsIPC : ParamTraitsWindows<P> {};

#if defined(OS_POSIX)
// FileDescriptors may be serialised over IPC channels on POSIX. On the
// receiving side, the FileDescriptor is a valid duplicate of the file
// descriptor which was transmitted: *it is not just a copy of the integer like
// HANDLEs on Windows*. The only exception is if the file descriptor is < 0. In
// this case, the receiving end will see a value of -1. *Zero is a valid file
// descriptor*.
//
// The received file descriptor will have the |auto_close| flag set to true. The
// code which handles the message is responsible for taking ownership of it.
// File descriptors are OS resources and must be closed when no longer needed.
//
// When sending a file descriptor, the file descriptor must be valid at the time
// of transmission. Since transmission is not synchronous, one should consider
// dup()ing any file descriptors to be transmitted and setting the |auto_close|
// flag, which causes the file descriptor to be closed after writing.
template<>
struct ParamTraitsIPC<base::FileDescriptor> {
  typedef base::FileDescriptor param_type;
  static void Write(Message* m, const param_type& p) {
    const bool valid = p.fd >= 0;
    WriteParam(m, valid);

    if (valid) {
      if (!m->WriteFileDescriptor(p)) {
        NOTREACHED() << "Too many file descriptors for one message!";
      }
    }
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    bool valid;
    if (!ReadParam(m, iter, &valid))
      return false;

    if (!valid) {
      r->fd = -1;
      r->auto_close = false;
      return true;
    }

    return m->ReadFileDescriptor(iter, r);
  }
  static void Log(const param_type& p, std::wstring* l) {
    if (p.auto_close) {
      l->append(StringPrintf(L"FD(%d auto-close)", p.fd));
    } else {
      l->append(StringPrintf(L"FD(%d)", p.fd));
    }
  }
};
#endif // defined(OS_POSIX)

#if defined(OS_WIN)
template<>
struct ParamTraitsIPC<TransportDIB::Id> {
  typedef TransportDIB::Id param_type;
  static void Write(Message* m, const param_type& p) {
    WriteParam(m, p.handle);
    WriteParam(m, p.sequence_num);
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return (ReadParam(m, iter, &r->handle) &&
            ReadParam(m, iter, &r->sequence_num));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(L"TransportDIB(");
    LogParam(p.handle, l);
    l->append(L", ");
    LogParam(p.sequence_num, l);
    l->append(L")");
  }
};
#endif

// Mozilla-specific types.

template <class P>
struct ParamTraitsMozilla : ParamTraitsIPC<P> {};

template <>
struct ParamTraitsMozilla<nsresult> {
  typedef nsresult param_type;
  static void Write(Message* m, const param_type& p) {
    m->WriteUInt32(static_cast<uint32_t>(p));
  }
  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
    return m->ReadUInt32(iter, reinterpret_cast<uint32_t*>(r));
  }
  static void Log(const param_type& p, std::wstring* l) {
    l->append(StringPrintf(L"%u", static_cast<uint32_t>(p)));
  }
};

// Finally, ParamTraits itself.

template <class P> struct ParamTraits : ParamTraitsMozilla<P> {};

}  // namespace IPC

#endif  // CHROME_COMMON_IPC_MESSAGE_UTILS_H_