Merge bitcoin/bitcoin#26649: refactor: Use AutoFile and HashVerifier (without ser-type and ser-version) where possible

eeee610 Use AutoFile and HashVerifier where possible (MarcoFalke)
fa96114 Add HashVerifier (MarcoFalke)

Pull request description:

  This was done in the context of bitcoin/bitcoin#25284 , but I think it also makes sense standalone.

  The basic idea is that serialization type should not be initialized when it is not needed. Same for the serialization version.

  So do this here for `AutoFile` and `HashVerifier`. `CAutoFile` and `CHashVerifier` remain in places where it is not yet possible.

ACKs for top commit:
  stickies-v:
    ACK eeee610

Tree-SHA512: 93786778c309ecfdc1ed43552d24ff9d966954d69a47f66faaa6de24daacd25c651f3f62bde5abbb362700298fb3c04ffbd3207a0dd13d0bd8bff7fd6d07dcf8

Author: fanquake

src/hash.h

@@ -167,6 +167,39 @@ class CHashWriter : public HashWriter
 };
 
 /** Reads data from an underlying stream, while hashing the read data. */
+template <typename Source>
+class HashVerifier : public HashWriter
+{
+private:
+    Source& m_source;
+
+public:
+    explicit HashVerifier(Source& source LIFETIMEBOUND) : m_source{source} {}
+
+    void read(Span<std::byte> dst)
+    {
+        m_source.read(dst);
+        this->write(dst);
+    }
+
+    void ignore(size_t num_bytes)
+    {
+        std::byte data[1024];
+        while (num_bytes > 0) {
+            size_t now = std::min<size_t>(num_bytes, 1024);
+            read({data, now});
+            num_bytes -= now;
+        }
+    }
+
+    template <typename T>
+    HashVerifier<Source>& operator>>(T&& obj)
+    {
+        ::Unserialize(*this, obj);
+        return *this;
+    }
+};
+
 template<typename Source>
 class CHashVerifier : public CHashWriter
 {

src/node/blockstorage.cpp

@@ -352,7 +352,7 @@ bool BlockManager::LoadBlockIndexDB(const Consensus::Params& consensus_params)
     }
     for (std::set<int>::iterator it = setBlkDataFiles.begin(); it != setBlkDataFiles.end(); it++) {
         FlatFilePos pos(*it, 0);
-        if (CAutoFile(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION).IsNull()) {
+        if (AutoFile{OpenBlockFile(pos, true)}.IsNull()) {
             return false;
         }
     }
@@ -454,13 +454,13 @@ CBlockFileInfo* BlockManager::GetBlockFileInfo(size_t n)
 static bool UndoWriteToDisk(const CBlockUndo& blockundo, FlatFilePos& pos, const uint256& hashBlock, const CMessageHeader::MessageStartChars& messageStart)
 {
     // Open history file to append
-    CAutoFile fileout(OpenUndoFile(pos), SER_DISK, CLIENT_VERSION);
+    AutoFile fileout{OpenUndoFile(pos)};
     if (fileout.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
 
     // Write index header
-    unsigned int nSize = GetSerializeSize(blockundo, fileout.GetVersion());
+    unsigned int nSize = GetSerializeSize(blockundo, CLIENT_VERSION);
     fileout << messageStart << nSize;
 
     // Write undo data
@@ -489,14 +489,14 @@ bool UndoReadFromDisk(CBlockUndo& blockundo, const CBlockIndex* pindex)
     }
 
     // Open history file to read
-    CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
+    AutoFile filein{OpenUndoFile(pos, true)};
     if (filein.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
 
     // Read block
     uint256 hashChecksum;
-    CHashVerifier<CAutoFile> verifier(&filein); // We need a CHashVerifier as reserializing may lose data
+    HashVerifier verifier{filein}; // Use HashVerifier as reserializing may lose data, c.f. commit d342424301013ec47dc146a4beb49d5c9319d80a
     try {
         verifier << pindex->pprev->GetBlockHash();
         verifier >> blockundo;
@@ -768,7 +768,7 @@ bool ReadRawBlockFromDisk(std::vector<uint8_t>& block, const FlatFilePos& pos, c
 {
     FlatFilePos hpos = pos;
     hpos.nPos -= 8; // Seek back 8 bytes for meta header
-    CAutoFile filein(OpenBlockFile(hpos, true), SER_DISK, CLIENT_VERSION);
+    AutoFile filein{OpenBlockFile(hpos, true)};
     if (filein.IsNull()) {
         return error("%s: OpenBlockFile failed for %s", __func__, pos.ToString());
     }