Merge bitcoin/bitcoin#28483: refactor: Return CAutoFile from BlockManager::Open*File()

fa56c421be04af846f479c30749b17e6663ab418 Return CAutoFile from BlockManager::Open*File() (MarcoFalke)
9999b89cd37fb2a23c5ebcd91d9cb31d69375933 Make BufferedFile to be a CAutoFile wrapper (MarcoFalke)
fa389d902fbf5fac19fba8c5d0c5e0a25f15ca63 refactor: Drop unused fclose() from BufferedFile (MarcoFalke)

Pull request description:

  This is required for https://github.com/bitcoin/bitcoin/pull/28052, but makes sense on its own, because offloading logic to `CAutoFile` instead of re-implementing it allows to delete code and complexity.

ACKs for top commit:
  TheCharlatan:
    Re-ACK fa56c421be04af846f479c30749b17e6663ab418
  willcl-ark:
    tACK fa56c421be

Tree-SHA512: fe4638f3a6bd3f9d968cfb9ae3259c9d6cd278fe2912cbc90289851311c8c781099db4c160e775960975c4739098d9af801a8d2d12603f371f8edfe134d8f85a

12 files changed, 66 insertions, 84 deletions

diff --git a/src/bench/load_external.cpp b/src/bench/load_external.cpp
index 252cbb163b..3b100d97b0 100644
--- a/src/bench/load_external.cpp
+++ b/src/bench/load_external.cpp
@@ -5,6 +5,7 @@
 #include <bench/bench.h>
 #include <bench/data.h>
 #include <chainparams.h>
+#include <clientversion.h>
 #include <test/util/setup_common.h>
 #include <util/chaintype.h>
 #include <validation.h>
@@ -54,7 +55,7 @@ static void LoadExternalBlockFile(benchmark::Bench& bench)
     bench.run([&] {
         // "rb" is "binary, O_RDONLY", positioned to the start of the file.
         // The file will be closed by LoadExternalBlockFile().
-        FILE* file{fsbridge::fopen(blkfile, "rb")};
+        CAutoFile file{fsbridge::fopen(blkfile, "rb"), CLIENT_VERSION};
         testing_setup->m_node.chainman->LoadExternalBlockFile(file, &pos, &blocks_with_unknown_parent);
     });
     fs::remove(blkfile);
diff --git a/src/bench/streams_findbyte.cpp b/src/bench/streams_findbyte.cpp
index 22b8f1b356..4aaccb2af8 100644
--- a/src/bench/streams_findbyte.cpp
+++ b/src/bench/streams_findbyte.cpp
@@ -4,19 +4,23 @@
 
 #include <bench/bench.h>
 
-#include <util/fs.h>
 #include <streams.h>
+#include <util/fs.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
 
 static void FindByte(benchmark::Bench& bench)
 {
     // Setup
-    FILE* file = fsbridge::fopen("streams_tmp", "w+b");
+    CAutoFile file{fsbridge::fopen("streams_tmp", "w+b"), 0};
     const size_t file_size = 200;
     uint8_t data[file_size] = {0};
     data[file_size-1] = 1;
-    fwrite(&data, sizeof(uint8_t), file_size, file);
-    rewind(file);
-    BufferedFile bf{file, /*nBufSize=*/file_size + 1, /*nRewindIn=*/file_size, 0};
+    file << data;
+    std::rewind(file.Get());
+    BufferedFile bf{file, /*nBufSize=*/file_size + 1, /*nRewindIn=*/file_size};
 
     bench.run([&] {
         bf.SetPos(0);
@@ -24,7 +28,7 @@ static void FindByte(benchmark::Bench& bench)
     });
 
     // Cleanup
-    bf.fclose();
+    file.fclose();
     fs::remove("streams_tmp");
 }
 
diff --git a/src/index/txindex.cpp b/src/index/txindex.cpp
index 6b38e19d81..e16dd0f8bd 100644
--- a/src/index/txindex.cpp
+++ b/src/index/txindex.cpp
@@ -79,7 +79,7 @@ bool TxIndex::FindTx(const uint256& tx_hash, uint256& block_hash, CTransactionRe
         return false;
     }
 
-    CAutoFile file{m_chainstate->m_blockman.OpenBlockFile(postx, true), CLIENT_VERSION};
+    CAutoFile file{m_chainstate->m_blockman.OpenBlockFile(postx, true)};
     if (file.IsNull()) {
         return error("%s: OpenBlockFile failed", __func__);
     }
diff --git a/src/node/blockstorage.cpp b/src/node/blockstorage.cpp
index f21c94c0a0..ae63d12ef7 100644
--- a/src/node/blockstorage.cpp
+++ b/src/node/blockstorage.cpp
@@ -459,7 +459,7 @@ bool BlockManager::LoadBlockIndexDB()
     }
     for (std::set<int>::iterator it = setBlkDataFiles.begin(); it != setBlkDataFiles.end(); it++) {
         FlatFilePos pos(*it, 0);
-        if (AutoFile{OpenBlockFile(pos, true)}.IsNull()) {
+        if (OpenBlockFile(pos, true).IsNull()) {
             return false;
         }
     }
@@ -592,7 +592,7 @@ CBlockFileInfo* BlockManager::GetBlockFileInfo(size_t n)
 bool BlockManager::UndoWriteToDisk(const CBlockUndo& blockundo, FlatFilePos& pos, const uint256& hashBlock) const
 {
     // Open history file to append
-    AutoFile fileout{OpenUndoFile(pos)};
+    CAutoFile fileout{OpenUndoFile(pos)};
     if (fileout.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
@@ -627,7 +627,7 @@ bool BlockManager::UndoReadFromDisk(CBlockUndo& blockundo, const CBlockIndex& in
     }
 
     // Open history file to read
-    AutoFile filein{OpenUndoFile(pos, true)};
+    CAutoFile filein{OpenUndoFile(pos, true)};
     if (filein.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
@@ -715,15 +715,15 @@ FlatFileSeq BlockManager::UndoFileSeq() const
     return FlatFileSeq(m_opts.blocks_dir, "rev", UNDOFILE_CHUNK_SIZE);
 }
 
-FILE* BlockManager::OpenBlockFile(const FlatFilePos& pos, bool fReadOnly) const
+CAutoFile BlockManager::OpenBlockFile(const FlatFilePos& pos, bool fReadOnly) const
 {
-    return BlockFileSeq().Open(pos, fReadOnly);
+    return CAutoFile{BlockFileSeq().Open(pos, fReadOnly), CLIENT_VERSION};
 }
 
 /** Open an undo file (rev?????.dat) */
-FILE* BlockManager::OpenUndoFile(const FlatFilePos& pos, bool fReadOnly) const
+CAutoFile BlockManager::OpenUndoFile(const FlatFilePos& pos, bool fReadOnly) const
 {
-    return UndoFileSeq().Open(pos, fReadOnly);
+    return CAutoFile{UndoFileSeq().Open(pos, fReadOnly), CLIENT_VERSION};
 }
 
 fs::path BlockManager::GetBlockPosFilename(const FlatFilePos& pos) const
@@ -824,7 +824,7 @@ bool BlockManager::FindUndoPos(BlockValidationState& state, int nFile, FlatFileP
 bool BlockManager::WriteBlockToDisk(const CBlock& block, FlatFilePos& pos) const
 {
     // Open history file to append
-    CAutoFile fileout{OpenBlockFile(pos), CLIENT_VERSION};
+    CAutoFile fileout{OpenBlockFile(pos)};
     if (fileout.IsNull()) {
         return error("WriteBlockToDisk: OpenBlockFile failed");
     }
@@ -880,7 +880,7 @@ bool BlockManager::ReadBlockFromDisk(CBlock& block, const FlatFilePos& pos) cons
     block.SetNull();
 
     // Open history file to read
-    CAutoFile filein{OpenBlockFile(pos, true), CLIENT_VERSION};
+    CAutoFile filein{OpenBlockFile(pos, true)};
     if (filein.IsNull()) {
         return error("ReadBlockFromDisk: OpenBlockFile failed for %s", pos.ToString());
     }
@@ -923,7 +923,7 @@ bool BlockManager::ReadRawBlockFromDisk(std::vector<uint8_t>& block, const FlatF
 {
     FlatFilePos hpos = pos;
     hpos.nPos -= 8; // Seek back 8 bytes for meta header
-    AutoFile filein{OpenBlockFile(hpos, true)};
+    CAutoFile filein{OpenBlockFile(hpos, true)};
     if (filein.IsNull()) {
         return error("%s: OpenBlockFile failed for %s", __func__, pos.ToString());
     }
@@ -1015,8 +1015,8 @@ void ImportBlocks(ChainstateManager& chainman, std::vector<fs::path> vImportFile
                 if (!fs::exists(chainman.m_blockman.GetBlockPosFilename(pos))) {
                     break; // No block files left to reindex
                 }
-                FILE* file = chainman.m_blockman.OpenBlockFile(pos, true);
-                if (!file) {
+                CAutoFile file{chainman.m_blockman.OpenBlockFile(pos, true)};
+                if (file.IsNull()) {
                     break; // This error is logged in OpenBlockFile
                 }
                 LogPrintf("Reindexing block file blk%05u.dat...\n", (unsigned int)nFile);
@@ -1036,8 +1036,8 @@ void ImportBlocks(ChainstateManager& chainman, std::vector<fs::path> vImportFile
 
         // -loadblock=
         for (const fs::path& path : vImportFiles) {
-            FILE* file = fsbridge::fopen(path, "rb");
-            if (file) {
+            CAutoFile file{fsbridge::fopen(path, "rb"), CLIENT_VERSION};
+            if (!file.IsNull()) {
                 LogPrintf("Importing blocks file %s...\n", fs::PathToString(path));
                 chainman.LoadExternalBlockFile(file);
                 if (chainman.m_interrupt) {
diff --git a/src/node/blockstorage.h b/src/node/blockstorage.h
index b251ece31f..a89fa7f76e 100644
--- a/src/node/blockstorage.h
+++ b/src/node/blockstorage.h
@@ -29,6 +29,7 @@
 #include <vector>
 
 class BlockValidationState;
+class CAutoFile;
 class CBlock;
 class CBlockFileInfo;
 class CBlockUndo;
@@ -126,7 +127,7 @@ private:
     FlatFileSeq BlockFileSeq() const;
     FlatFileSeq UndoFileSeq() const;
 
-    FILE* OpenUndoFile(const FlatFilePos& pos, bool fReadOnly = false) const;
+    CAutoFile OpenUndoFile(const FlatFilePos& pos, bool fReadOnly = false) const;
 
     bool WriteBlockToDisk(const CBlock& block, FlatFilePos& pos) const;
     bool UndoWriteToDisk(const CBlockUndo& blockundo, FlatFilePos& pos, const uint256& hashBlock) const;
@@ -278,7 +279,7 @@ public:
     void UpdatePruneLock(const std::string& name, const PruneLockInfo& lock_info) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
     /** Open a block file (blk?????.dat) */
-    FILE* OpenBlockFile(const FlatFilePos& pos, bool fReadOnly = false) const;
+    CAutoFile OpenBlockFile(const FlatFilePos& pos, bool fReadOnly = false) const;
 
     /** Translation to a filesystem path */
     fs::path GetBlockPosFilename(const FlatFilePos& pos) const;
diff --git a/src/streams.h b/src/streams.h
index f9a817c9b6..e069719d89 100644
--- a/src/streams.h
+++ b/src/streams.h
@@ -571,7 +571,7 @@ public:
     }
 };
 
-/** Non-refcounted RAII wrapper around a FILE* that implements a ring buffer to
+/** Wrapper around a CAutoFile& that implements a ring buffer to
  *  deserialize from. It guarantees the ability to rewind a given number of bytes.
  *
  *  Will automatically close the file when it goes out of scope if not null.
@@ -580,9 +580,7 @@ public:
 class BufferedFile
 {
 private:
-    const int nVersion;
-
-    FILE *src;            //!< source file
+    CAutoFile& m_src;
     uint64_t nSrcPos{0};  //!< how many bytes have been read from source
     uint64_t m_read_pos{0}; //!< how many bytes have been read from this
     uint64_t nReadLimit;  //!< up to which position we're allowed to read
@@ -598,9 +596,9 @@ private:
             readNow = nAvail;
         if (readNow == 0)
             return false;
-        size_t nBytes = fread((void*)&vchBuf[pos], 1, readNow, src);
+        size_t nBytes{m_src.detail_fread(Span{vchBuf}.subspan(pos, readNow))};
         if (nBytes == 0) {
-            throw std::ios_base::failure(feof(src) ? "BufferedFile::Fill: end of file" : "BufferedFile::Fill: fread failed");
+            throw std::ios_base::failure{m_src.feof() ? "BufferedFile::Fill: end of file" : "BufferedFile::Fill: fread failed"};
         }
         nSrcPos += nBytes;
         return true;
@@ -629,36 +627,18 @@ private:
     }
 
 public:
-    BufferedFile(FILE* fileIn, uint64_t nBufSize, uint64_t nRewindIn, int nVersionIn)
-        : nVersion{nVersionIn}, nReadLimit{std::numeric_limits<uint64_t>::max()}, nRewind{nRewindIn}, vchBuf(nBufSize, std::byte{0})
+    BufferedFile(CAutoFile& file, uint64_t nBufSize, uint64_t nRewindIn)
+        : m_src{file}, nReadLimit{std::numeric_limits<uint64_t>::max()}, nRewind{nRewindIn}, vchBuf(nBufSize, std::byte{0})
     {
         if (nRewindIn >= nBufSize)
             throw std::ios_base::failure("Rewind limit must be less than buffer size");
-        src = fileIn;
-    }
-
-    ~BufferedFile()
-    {
-        fclose();
     }
 
-    // Disallow copies
-    BufferedFile(const BufferedFile&) = delete;
-    BufferedFile& operator=(const BufferedFile&) = delete;
-
-    int GetVersion() const { return nVersion; }
-
-    void fclose()
-    {
-        if (src) {
-            ::fclose(src);
-            src = nullptr;
-        }
-    }
+    int GetVersion() const { return m_src.GetVersion(); }
 
     //! check whether we're at the end of the source file
     bool eof() const {
-        return m_read_pos == nSrcPos && feof(src);
+        return m_read_pos == nSrcPos && m_src.feof();
     }
 
     //! read a number of bytes
diff --git a/src/test/blockmanager_tests.cpp b/src/test/blockmanager_tests.cpp
index 636f5b9388..c6800c498b 100644
--- a/src/test/blockmanager_tests.cpp
+++ b/src/test/blockmanager_tests.cpp
@@ -74,13 +74,13 @@ BOOST_FIXTURE_TEST_CASE(blockmanager_scan_unlink_already_pruned_files, TestChain
     // Check that the file is not unlinked after ScanAndUnlinkAlreadyPrunedFiles
     // if m_have_pruned is not yet set
     WITH_LOCK(chainman->GetMutex(), blockman.ScanAndUnlinkAlreadyPrunedFiles());
-    BOOST_CHECK(!AutoFile(blockman.OpenBlockFile(pos, true)).IsNull());
+    BOOST_CHECK(!blockman.OpenBlockFile(pos, true).IsNull());
 
     // Check that the file is unlinked after ScanAndUnlinkAlreadyPrunedFiles
     // once m_have_pruned is set
     blockman.m_have_pruned = true;
     WITH_LOCK(chainman->GetMutex(), blockman.ScanAndUnlinkAlreadyPrunedFiles());
-    BOOST_CHECK(AutoFile(blockman.OpenBlockFile(pos, true)).IsNull());
+    BOOST_CHECK(blockman.OpenBlockFile(pos, true).IsNull());
 
     // Check that calling with already pruned files doesn't cause an error
     WITH_LOCK(chainman->GetMutex(), blockman.ScanAndUnlinkAlreadyPrunedFiles());
@@ -90,7 +90,7 @@ BOOST_FIXTURE_TEST_CASE(blockmanager_scan_unlink_already_pruned_files, TestChain
     BOOST_CHECK_NE(old_tip, new_tip);
     const int new_file_number{WITH_LOCK(chainman->GetMutex(), return new_tip->GetBlockPos().nFile)};
     const FlatFilePos new_pos(new_file_number, 0);
-    BOOST_CHECK(!AutoFile(blockman.OpenBlockFile(new_pos, true)).IsNull());
+    BOOST_CHECK(!blockman.OpenBlockFile(new_pos, true).IsNull());
 }
 
 BOOST_FIXTURE_TEST_CASE(blockmanager_block_data_availability, TestChain100Setup)
diff --git a/src/test/fuzz/buffered_file.cpp b/src/test/fuzz/buffered_file.cpp
index 1116274e3d..636f11b381 100644
--- a/src/test/fuzz/buffered_file.cpp
+++ b/src/test/fuzz/buffered_file.cpp
@@ -19,15 +19,12 @@ FUZZ_TARGET(buffered_file)
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
     FuzzedFileProvider fuzzed_file_provider = ConsumeFile(fuzzed_data_provider);
     std::optional<BufferedFile> opt_buffered_file;
-    FILE* fuzzed_file = fuzzed_file_provider.open();
+    CAutoFile fuzzed_file{fuzzed_file_provider.open(), 0};
     try {
-        opt_buffered_file.emplace(fuzzed_file, fuzzed_data_provider.ConsumeIntegralInRange<uint64_t>(0, 4096), fuzzed_data_provider.ConsumeIntegralInRange<uint64_t>(0, 4096), fuzzed_data_provider.ConsumeIntegral<int>());
+        opt_buffered_file.emplace(fuzzed_file, fuzzed_data_provider.ConsumeIntegralInRange<uint64_t>(0, 4096), fuzzed_data_provider.ConsumeIntegralInRange<uint64_t>(0, 4096));
     } catch (const std::ios_base::failure&) {
-        if (fuzzed_file != nullptr) {
-            fclose(fuzzed_file);
-        }
     }
-    if (opt_buffered_file && fuzzed_file != nullptr) {
+    if (opt_buffered_file && !fuzzed_file.IsNull()) {
         bool setpos_fail = false;
         LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000) {
             CallOneOf(
diff --git a/src/test/fuzz/load_external_block_file.cpp b/src/test/fuzz/load_external_block_file.cpp
index bdaa4ad1b8..fc903e5ec2 100644
--- a/src/test/fuzz/load_external_block_file.cpp
+++ b/src/test/fuzz/load_external_block_file.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chainparams.h>
+#include <clientversion.h>
 #include <flatfile.h>
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
@@ -27,8 +28,8 @@ FUZZ_TARGET(load_external_block_file, .init = initialize_load_external_block_fil
 {
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
     FuzzedFileProvider fuzzed_file_provider = ConsumeFile(fuzzed_data_provider);
-    FILE* fuzzed_block_file = fuzzed_file_provider.open();
-    if (fuzzed_block_file == nullptr) {
+    CAutoFile fuzzed_block_file{fuzzed_file_provider.open(), CLIENT_VERSION};
+    if (fuzzed_block_file.IsNull()) {
         return;
     }
     if (fuzzed_data_provider.ConsumeBool()) {
diff --git a/src/test/streams_tests.cpp b/src/test/streams_tests.cpp
index 99740ee779..8ff65b5377 100644
--- a/src/test/streams_tests.cpp
+++ b/src/test/streams_tests.cpp
@@ -249,18 +249,18 @@ BOOST_AUTO_TEST_CASE(streams_serializedata_xor)
 BOOST_AUTO_TEST_CASE(streams_buffered_file)
 {
     fs::path streams_test_filename = m_args.GetDataDirBase() / "streams_test_tmp";
-    FILE* file = fsbridge::fopen(streams_test_filename, "w+b");
+    CAutoFile file{fsbridge::fopen(streams_test_filename, "w+b"), 333};
 
     // The value at each offset is the offset.
     for (uint8_t j = 0; j < 40; ++j) {
-        fwrite(&j, 1, 1, file);
+        file << j;
     }
-    rewind(file);
+    std::rewind(file.Get());
 
     // The buffer size (second arg) must be greater than the rewind
     // amount (third arg).
     try {
-        BufferedFile bfbad{file, 25, 25, 333};
+        BufferedFile bfbad{file, 25, 25};
         BOOST_CHECK(false);
     } catch (const std::exception& e) {
         BOOST_CHECK(strstr(e.what(),
@@ -268,7 +268,7 @@ BOOST_AUTO_TEST_CASE(streams_buffered_file)
     }
 
     // The buffer is 25 bytes, allow rewinding 10 bytes.
-    BufferedFile bf{file, 25, 10, 333};
+    BufferedFile bf{file, 25, 10};
     BOOST_CHECK(!bf.eof());
 
     // This member has no functional effect.
@@ -375,7 +375,7 @@ BOOST_AUTO_TEST_CASE(streams_buffered_file)
     BOOST_CHECK(bf.GetPos() <= 30U);
 
     // We can explicitly close the file, or the destructor will do it.
-    bf.fclose();
+    file.fclose();
 
     fs::remove(streams_test_filename);
 }
@@ -383,15 +383,15 @@ BOOST_AUTO_TEST_CASE(streams_buffered_file)
 BOOST_AUTO_TEST_CASE(streams_buffered_file_skip)
 {
     fs::path streams_test_filename = m_args.GetDataDirBase() / "streams_test_tmp";
-    FILE* file = fsbridge::fopen(streams_test_filename, "w+b");
+    CAutoFile file{fsbridge::fopen(streams_test_filename, "w+b"), 333};
     // The value at each offset is the byte offset (e.g. byte 1 in the file has the value 0x01).
     for (uint8_t j = 0; j < 40; ++j) {
-        fwrite(&j, 1, 1, file);
+        file << j;
     }
-    rewind(file);
+    std::rewind(file.Get());
 
     // The buffer is 25 bytes, allow rewinding 10 bytes.
-    BufferedFile bf{file, 25, 10, 333};
+    BufferedFile bf{file, 25, 10};
 
     uint8_t i;
     // This is like bf >> (7-byte-variable), in that it will cause data
@@ -425,7 +425,7 @@ BOOST_AUTO_TEST_CASE(streams_buffered_file_skip)
     bf.SkipTo(13);
     BOOST_CHECK_EQUAL(bf.GetPos(), 13U);
 
-    bf.fclose();
+    file.fclose();
     fs::remove(streams_test_filename);
 }
 
@@ -436,16 +436,16 @@ BOOST_AUTO_TEST_CASE(streams_buffered_file_rand)
 
     fs::path streams_test_filename = m_args.GetDataDirBase() / "streams_test_tmp";
     for (int rep = 0; rep < 50; ++rep) {
-        FILE* file = fsbridge::fopen(streams_test_filename, "w+b");
+        CAutoFile file{fsbridge::fopen(streams_test_filename, "w+b"), 333};
         size_t fileSize = InsecureRandRange(256);
         for (uint8_t i = 0; i < fileSize; ++i) {
-            fwrite(&i, 1, 1, file);
+            file << i;
         }
-        rewind(file);
+        std::rewind(file.Get());
 
         size_t bufSize = InsecureRandRange(300) + 1;
         size_t rewindSize = InsecureRandRange(bufSize);
-        BufferedFile bf{file, bufSize, rewindSize, 333};
+        BufferedFile bf{file, bufSize, rewindSize};
         size_t currentPos = 0;
         size_t maxPos = 0;
         for (int step = 0; step < 100; ++step) {
diff --git a/src/validation.cpp b/src/validation.cpp
index 0ce2902195..4acd5c7cb0 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -4577,7 +4577,7 @@ bool Chainstate::LoadGenesisBlock()
 }
 
 void ChainstateManager::LoadExternalBlockFile(
-    FILE* fileIn,
+    CAutoFile& file_in,
     FlatFilePos* dbp,
     std::multimap<uint256, FlatFilePos>* blocks_with_unknown_parent)
 {
@@ -4589,8 +4589,7 @@ void ChainstateManager::LoadExternalBlockFile(
 
     int nLoaded = 0;
     try {
-        // This takes over fileIn and calls fclose() on it in the BufferedFile destructor
-        BufferedFile blkdat{fileIn, 2 * MAX_BLOCK_SERIALIZED_SIZE, MAX_BLOCK_SERIALIZED_SIZE + 8, CLIENT_VERSION};
+        BufferedFile blkdat{file_in, 2 * MAX_BLOCK_SERIALIZED_SIZE, MAX_BLOCK_SERIALIZED_SIZE + 8};
         // nRewind indicates where to resume scanning in case something goes wrong,
         // such as a block fails to deserialize.
         uint64_t nRewind = blkdat.GetPos();
diff --git a/src/validation.h b/src/validation.h
index 6640bb5b50..3f0a2312b5 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -607,7 +607,6 @@ public:
     bool ResizeCoinsCaches(size_t coinstip_size, size_t coinsdb_size)
         EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
-
     /**
      * Update the on-disk chain state.
      * The caches and indexes are flushed depending on the mode we're called with
@@ -1087,14 +1086,14 @@ public:
      * -loadblock= option. There's no unknown-parent tracking, so the last two arguments are omitted.
      *
      *
-     * @param[in]     fileIn                        FILE handle to file containing blocks to read
+     * @param[in]     file_in                       File containing blocks to read
      * @param[in]     dbp                           (optional) Disk block position (only for reindex)
      * @param[in,out] blocks_with_unknown_parent    (optional) Map of disk positions for blocks with
      *                                              unknown parent, key is parent block hash
      *                                              (only used for reindex)
      * */
     void LoadExternalBlockFile(
-        FILE* fileIn,
+        CAutoFile& file_in,
         FlatFilePos* dbp = nullptr,
         std::multimap<uint256, FlatFilePos>* blocks_with_unknown_parent = nullptr);