1// Copyright (c) 2022-present The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5#include <node/utxo_snapshot.h>
6
7#include <streams.h>
8#include <sync.h>
9#include <tinyformat.h>
10#include <uint256.h>
11#include <util/fs.h>
12#include <util/log.h>
13#include <validation.h>
14
15#include <cassert>
16#include <cstdio>
17#include <optional>
18#include <string>
19
20namespace node {
21
22bool WriteSnapshotBaseBlockhash(Chainstate& snapshot_chainstate)
23{
24    AssertLockHeld(::cs_main);
25    assert(snapshot_chainstate.m_from_snapshot_blockhash);
26
27    const std::optional<fs::path> chaindir = snapshot_chainstate.StoragePath();
28    assert(chaindir); // Sanity check that chainstate isn't in-memory.
29    const fs::path write_to = *chaindir / node::SNAPSHOT_BLOCKHASH_FILENAME;
30
31    FILE* file{fsbridge::fopen(write_to, "wb")};
32    AutoFile afile{file};
33    if (afile.IsNull()) {
34        LogError("[snapshot] failed to open base blockhash file for writing: %s",
35                  fs::PathToString(write_to));
36        return false;
37    }
38    afile << *snapshot_chainstate.m_from_snapshot_blockhash;
39
40    if (afile.fclose() != 0) {
41        LogError("[snapshot] failed to close base blockhash file %s after writing",
42                  fs::PathToString(write_to));
43        return false;
44    }
45    return true;
46}
47
48std::optional<uint256> ReadSnapshotBaseBlockhash(fs::path chaindir)
49{
50    if (!fs::exists(chaindir)) {
51        LogWarning("[snapshot] cannot read base blockhash: no chainstate dir "
52            "exists at path %s", fs::PathToString(chaindir));
53        return std::nullopt;
54    }
55    const fs::path read_from = chaindir / node::SNAPSHOT_BLOCKHASH_FILENAME;
56    const std::string read_from_str = fs::PathToString(read_from);
57
58    if (!fs::exists(read_from)) {
59        LogWarning("[snapshot] snapshot chainstate dir is malformed! no base blockhash file "
60            "exists at path %s. Try deleting %s and calling loadtxoutset again?",
61            fs::PathToString(chaindir), read_from_str);
62        return std::nullopt;
63    }
64
65    uint256 base_blockhash;
66    FILE* file{fsbridge::fopen(read_from, "rb")};
67    AutoFile afile{file};
68    if (afile.IsNull()) {
69        LogWarning("[snapshot] failed to open base blockhash file for reading: %s",
70            read_from_str);
71        return std::nullopt;
72    }
73    afile >> base_blockhash;
74
75    int64_t position = afile.tell();
76    afile.seek(0, SEEK_END);
77    if (position != afile.tell()) {
78        LogWarning("[snapshot] unexpected trailing data in %s", read_from_str);
79    }
80    return base_blockhash;
81}
82
83std::optional<fs::path> FindAssumeutxoChainstateDir(const fs::path& data_dir)
84{
85    fs::path possible_dir =
86        data_dir / fs::u8path(strprintf("chainstate%s", SNAPSHOT_CHAINSTATE_SUFFIX));
87
88    if (fs::exists(possible_dir)) {
89        return possible_dir;
90    }
91    return std::nullopt;
92}
93
94} // namespace node
95