utxo_snapshot.cpp

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// Copyright (c) 2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <node/utxo_snapshot.h>
 
#include <common/args.h>
#include <logging.h>
#include <primitives/blockhash.h>
#include <streams.h>
#include <util/fs.h>
#include <validation.h>
 
#include <cstdio>
#include <optional>
 
namespace node {
 
bool WriteSnapshotBaseBlockhash(Chainstate &snapshot_chainstate) {
    AssertLockHeld(::cs_main);
    assert(snapshot_chainstate.m_from_snapshot_blockhash);
 
    const std::optional<fs::path> chaindir =
        snapshot_chainstate.CoinsDB().StoragePath();
    // Sanity check that chainstate isn't in-memory.
    assert(chaindir);
    const fs::path write_to = *chaindir / node::SNAPSHOT_BLOCKHASH_FILENAME;
 
    FILE *file{fsbridge::fopen(write_to, "wb")};
    AutoFile afile{file};
    if (afile.IsNull()) {
        LogPrintf(
            "[snapshot] failed to open base blockhash file for writing: %s\n",
            fs::PathToString(write_to));
        return false;
    }
    afile << *snapshot_chainstate.m_from_snapshot_blockhash;
 
    if (afile.fclose() != 0) {
        LogPrintf(
            "[snapshot] failed to close base blockhash file %s after writing\n",
            fs::PathToString(write_to));
        return false;
    }
    return true;
}
 
std::optional<BlockHash> ReadSnapshotBaseBlockhash(const fs::path &chaindir) {
    if (!fs::exists(chaindir)) {
        LogPrintf("[snapshot] cannot read base blockhash: no chainstate dir "
                  "exists at path %s\n",
                  fs::PathToString(chaindir));
        return std::nullopt;
    }
    const fs::path read_from = chaindir / node::SNAPSHOT_BLOCKHASH_FILENAME;
    const std::string read_from_str = fs::PathToString(read_from);
 
    if (!fs::exists(read_from)) {
        LogPrintf("[snapshot] snapshot chainstate dir is malformed! no base "
                  "blockhash file exists at path %s. Try deleting %s and "
                  "calling loadtxoutset again?\n",
                  fs::PathToString(chaindir), read_from_str);
        return std::nullopt;
    }
 
    BlockHash base_blockhash;
    FILE *file{fsbridge::fopen(read_from, "rb")};
    AutoFile afile{file};
    if (afile.IsNull()) {
        LogPrintf(
            "[snapshot] failed to open base blockhash file for reading: %s\n",
            read_from_str);
        return std::nullopt;
    }
    afile >> base_blockhash;
 
    if (std::fgetc(afile.Get()) != EOF) {
        LogPrintf("[snapshot] warning: unexpected trailing data in %s\n",
                  read_from_str);
    } else if (std::ferror(afile.Get())) {
        LogPrintf("[snapshot] warning: i/o error reading %s\n", read_from_str);
    }
    return base_blockhash;
}
 
std::optional<fs::path> FindSnapshotChainstateDir() {
    fs::path possible_dir =
        gArgs.GetDataDirNet() /
        fs::u8path(strprintf("chainstate%s", SNAPSHOT_CHAINSTATE_SUFFIX));
 
    if (fs::exists(possible_dir)) {
        return possible_dir;
    }
    return std::nullopt;
}
 
} // namespace node