Add native support for serializing char arrays without FLATDATA

Support is added to serialize arrays of type char or unsigned char directly,
without any wrappers. All invocations of the FLATDATA wrappers that are
obsoleted by this are removed.

This includes a patch by Russell Yanofsky to make char casting type safe.

The serialization of CSubNet is changed to serialize a bool directly rather
than though FLATDATA. This makes the serialization independent of the size
of the bool type (and will use 1 byte everywhere).

8 files changed, 40 insertions, 26 deletions

diff --git a/src/addrdb.cpp b/src/addrdb.cpp
index 675f3c28af..e4620e63c6 100644
--- a/src/addrdb.cpp
+++ b/src/addrdb.cpp
@@ -22,8 +22,8 @@ bool SerializeDB(Stream& stream, const Data& data)
     // Write and commit header, data
     try {
         CHashWriter hasher(SER_DISK, CLIENT_VERSION);
-        stream << FLATDATA(Params().MessageStart()) << data;
-        hasher << FLATDATA(Params().MessageStart()) << data;
+        stream << Params().MessageStart() << data;
+        hasher << Params().MessageStart() << data;
         stream << hasher.GetHash();
     } catch (const std::exception& e) {
         return error("%s: Serialize or I/O error - %s", __func__, e.what());
@@ -66,7 +66,7 @@ bool DeserializeDB(Stream& stream, Data& data, bool fCheckSum = true)
         CHashVerifier<Stream> verifier(&stream);
         // de-serialize file header (network specific magic number) and ..
         unsigned char pchMsgTmp[4];
-        verifier >> FLATDATA(pchMsgTmp);
+        verifier >> pchMsgTmp;
         // ... verify the network matches ours
         if (memcmp(pchMsgTmp, Params().MessageStart(), sizeof(pchMsgTmp)))
             return error("%s: Invalid network magic number", __func__);
diff --git a/src/netaddress.h b/src/netaddress.h
index 93bbb66491..ad6b55eb58 100644
--- a/src/netaddress.h
+++ b/src/netaddress.h
@@ -93,7 +93,7 @@ class CNetAddr
 
         template <typename Stream, typename Operation>
         inline void SerializationOp(Stream& s, Operation ser_action) {
-            READWRITE(FLATDATA(ip));
+            READWRITE(ip);
         }
 
         friend class CSubNet;
@@ -131,8 +131,8 @@ class CSubNet
         template <typename Stream, typename Operation>
         inline void SerializationOp(Stream& s, Operation ser_action) {
             READWRITE(network);
-            READWRITE(FLATDATA(netmask));
-            READWRITE(FLATDATA(valid));
+            READWRITE(netmask);
+            READWRITE(valid);
         }
 };
 
@@ -166,7 +166,7 @@ class CService : public CNetAddr
 
         template <typename Stream, typename Operation>
         inline void SerializationOp(Stream& s, Operation ser_action) {
-            READWRITE(FLATDATA(ip));
+            READWRITE(ip);
             unsigned short portN = htons(port);
             READWRITE(FLATDATA(portN));
             if (ser_action.ForRead())
diff --git a/src/protocol.h b/src/protocol.h
index e518d11944..a07c5ea862 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -48,10 +48,10 @@ public:
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream& s, Operation ser_action)
     {
-        READWRITE(FLATDATA(pchMessageStart));
-        READWRITE(FLATDATA(pchCommand));
+        READWRITE(pchMessageStart);
+        READWRITE(pchCommand);
         READWRITE(nMessageSize);
-        READWRITE(FLATDATA(pchChecksum));
+        READWRITE(pchChecksum);
     }
 
     char pchMessageStart[MESSAGE_START_SIZE];
diff --git a/src/serialize.h b/src/serialize.h
index 91da6b0f80..247e915298 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -59,6 +59,12 @@ inline T* NCONST_PTR(const T* val)
     return const_cast<T*>(val);
 }
 
+//! Safely convert odd char pointer types to standard ones.
+inline char* CharCast(char* c) { return c; }
+inline char* CharCast(unsigned char* c) { return (char*)c; }
+inline const char* CharCast(const char* c) { return c; }
+inline const char* CharCast(const unsigned char* c) { return (const char*)c; }
+
 /*
  * Lowest-level serialization and conversion.
  * @note Sizes of these types are verified in the tests
@@ -177,6 +183,8 @@ template<typename Stream> inline void Serialize(Stream& s, int64_t a ) { ser_wri
 template<typename Stream> inline void Serialize(Stream& s, uint64_t a) { ser_writedata64(s, a); }
 template<typename Stream> inline void Serialize(Stream& s, float a   ) { ser_writedata32(s, ser_float_to_uint32(a)); }
 template<typename Stream> inline void Serialize(Stream& s, double a  ) { ser_writedata64(s, ser_double_to_uint64(a)); }
+template<typename Stream, int N> inline void Serialize(Stream& s, const char (&a)[N]) { s.write(a, N); }
+template<typename Stream, int N> inline void Serialize(Stream& s, const unsigned char (&a)[N]) { s.write(CharCast(a), N); }
 
 template<typename Stream> inline void Unserialize(Stream& s, char& a    ) { a = ser_readdata8(s); } // TODO Get rid of bare char
 template<typename Stream> inline void Unserialize(Stream& s, int8_t& a  ) { a = ser_readdata8(s); }
@@ -189,6 +197,8 @@ template<typename Stream> inline void Unserialize(Stream& s, int64_t& a ) { a =
 template<typename Stream> inline void Unserialize(Stream& s, uint64_t& a) { a = ser_readdata64(s); }
 template<typename Stream> inline void Unserialize(Stream& s, float& a   ) { a = ser_uint32_to_float(ser_readdata32(s)); }
 template<typename Stream> inline void Unserialize(Stream& s, double& a  ) { a = ser_uint64_to_double(ser_readdata64(s)); }
+template<typename Stream, int N> inline void Unserialize(Stream& s, char (&a)[N]) { s.read(a, N); }
+template<typename Stream, int N> inline void Unserialize(Stream& s, unsigned char (&a)[N]) { s.read(CharCast(a), N); }
 
 template<typename Stream> inline void Serialize(Stream& s, bool a)    { char f=a; ser_writedata8(s, f); }
 template<typename Stream> inline void Unserialize(Stream& s, bool& a) { char f=ser_readdata8(s); a=f; }
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
index e03234060d..6552613c04 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -64,7 +64,7 @@ public:
 CDataStream AddrmanToStream(CAddrManSerializationMock& _addrman)
 {
     CDataStream ssPeersIn(SER_DISK, CLIENT_VERSION);
-    ssPeersIn << FLATDATA(Params().MessageStart());
+    ssPeersIn << Params().MessageStart();
     ssPeersIn << _addrman;
     std::string str = ssPeersIn.str();
     std::vector<unsigned char> vchData(str.begin(), str.end());
@@ -110,7 +110,7 @@ BOOST_AUTO_TEST_CASE(caddrdb_read)
     BOOST_CHECK(addrman1.size() == 0);
     try {
         unsigned char pchMsgTmp[4];
-        ssPeers1 >> FLATDATA(pchMsgTmp);
+        ssPeers1 >> pchMsgTmp;
         ssPeers1 >> addrman1;
     } catch (const std::exception& e) {
         exceptionThrown = true;
@@ -142,7 +142,7 @@ BOOST_AUTO_TEST_CASE(caddrdb_read_corrupted)
     BOOST_CHECK(addrman1.size() == 0);
     try {
         unsigned char pchMsgTmp[4];
-        ssPeers1 >> FLATDATA(pchMsgTmp);
+        ssPeers1 >> pchMsgTmp;
         ssPeers1 >> addrman1;
     } catch (const std::exception& e) {
         exceptionThrown = true;
diff --git a/src/test/serialize_tests.cpp b/src/test/serialize_tests.cpp
index 7a79a77e8b..9b8b7bdc56 100644
--- a/src/test/serialize_tests.cpp
+++ b/src/test/serialize_tests.cpp
@@ -19,11 +19,15 @@ protected:
     int intval;
     bool boolval;
     std::string stringval;
-    const char* charstrval;
+    char charstrval[16];
     CTransactionRef txval;
 public:
     CSerializeMethodsTestSingle() = default;
-    CSerializeMethodsTestSingle(int intvalin, bool boolvalin, std::string stringvalin, const char* charstrvalin, CTransaction txvalin) : intval(intvalin), boolval(boolvalin), stringval(std::move(stringvalin)), charstrval(charstrvalin), txval(MakeTransactionRef(txvalin)){}
+    CSerializeMethodsTestSingle(int intvalin, bool boolvalin, std::string stringvalin, const char* charstrvalin, CTransaction txvalin) : intval(intvalin), boolval(boolvalin), stringval(std::move(stringvalin)), txval(MakeTransactionRef(txvalin))
+    {
+        memcpy(charstrval, charstrvalin, sizeof(charstrval));
+    }
+
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
@@ -31,7 +35,7 @@ public:
         READWRITE(intval);
         READWRITE(boolval);
         READWRITE(stringval);
-        READWRITE(FLATDATA(charstrval));
+        READWRITE(charstrval);
         READWRITE(txval);
     }
 
@@ -53,7 +57,7 @@ public:
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream& s, Operation ser_action) {
-        READWRITE(intval, boolval, stringval, FLATDATA(charstrval), txval);
+        READWRITE(intval, boolval, stringval, charstrval, txval);
     }
 };
 
@@ -344,7 +348,7 @@ BOOST_AUTO_TEST_CASE(class_methods)
     int intval(100);
     bool boolval(true);
     std::string stringval("testing");
-    const char* charstrval("testing charstr");
+    const char charstrval[16] = "testing charstr";
     CMutableTransaction txval;
     CSerializeMethodsTestSingle methodtest1(intval, boolval, stringval, charstrval, txval);
     CSerializeMethodsTestMany methodtest2(intval, boolval, stringval, charstrval, txval);
@@ -360,7 +364,7 @@ BOOST_AUTO_TEST_CASE(class_methods)
     BOOST_CHECK(methodtest2 == methodtest3);
     BOOST_CHECK(methodtest3 == methodtest4);
 
-    CDataStream ss2(SER_DISK, PROTOCOL_VERSION, intval, boolval, stringval, FLATDATA(charstrval), txval);
+    CDataStream ss2(SER_DISK, PROTOCOL_VERSION, intval, boolval, stringval, charstrval, txval);
     ss2 >> methodtest3;
     BOOST_CHECK(methodtest3 == methodtest4);
 }
diff --git a/src/test/streams_tests.cpp b/src/test/streams_tests.cpp
index 1108dab584..5d057108b1 100644
--- a/src/test/streams_tests.cpp
+++ b/src/test/streams_tests.cpp
@@ -57,16 +57,16 @@ BOOST_AUTO_TEST_CASE(streams_vector_writer)
     BOOST_CHECK((vch == std::vector<unsigned char>{{0, 0, 0, 0, 1, 2}}));
     vch.clear();
 
-    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 0, FLATDATA(bytes));
+    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 0, bytes);
     BOOST_CHECK((vch == std::vector<unsigned char>{{3, 4, 5, 6}}));
-    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 0, FLATDATA(bytes));
+    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 0, bytes);
     BOOST_CHECK((vch == std::vector<unsigned char>{{3, 4, 5, 6}}));
     vch.clear();
 
     vch.resize(4, 8);
-    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 2, a, FLATDATA(bytes), b);
+    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 2, a, bytes, b);
     BOOST_CHECK((vch == std::vector<unsigned char>{{8, 8, 1, 3, 4, 5, 6, 2}}));
-    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 2, a, FLATDATA(bytes), b);
+    CVectorWriter(SER_NETWORK, INIT_PROTO_VERSION, vch, 2, a, bytes, b);
     BOOST_CHECK((vch == std::vector<unsigned char>{{8, 8, 1, 3, 4, 5, 6, 2}}));
     vch.clear();
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index bee890437e..368caef62c 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1077,7 +1077,7 @@ static bool WriteBlockToDisk(const CBlock& block, CDiskBlockPos& pos, const CMes
 
     // Write index header
     unsigned int nSize = GetSerializeSize(fileout, block);
-    fileout << FLATDATA(messageStart) << nSize;
+    fileout << messageStart << nSize;
 
     // Write block
     long fileOutPos = ftell(fileout.Get());
@@ -1441,7 +1441,7 @@ bool UndoWriteToDisk(const CBlockUndo& blockundo, CDiskBlockPos& pos, const uint
 
     // Write index header
     unsigned int nSize = GetSerializeSize(fileout, blockundo);
-    fileout << FLATDATA(messageStart) << nSize;
+    fileout << messageStart << nSize;
 
     // Write undo data
     long fileOutPos = ftell(fileout.Get());
@@ -4283,7 +4283,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
                 unsigned char buf[CMessageHeader::MESSAGE_START_SIZE];
                 blkdat.FindByte(chainparams.MessageStart()[0]);
                 nRewind = blkdat.GetPos()+1;
-                blkdat >> FLATDATA(buf);
+                blkdat >> buf;
                 if (memcmp(buf, chainparams.MessageStart(), CMessageHeader::MESSAGE_START_SIZE))
                     continue;
                 // read size