Bitcoin Core  27.99.0
P2P Digital Currency
db.cpp
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1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2021 The Bitcoin Core developers
3 // Distributed under the MIT software license, see the accompanying
4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 
6 #include <chainparams.h>
7 #include <common/args.h>
8 #include <logging.h>
9 #include <util/fs.h>
10 #include <wallet/db.h>
11 
12 #include <exception>
13 #include <fstream>
14 #include <string>
15 #include <system_error>
16 #include <vector>
17 
18 namespace wallet {
19 bool operator<(BytePrefix a, Span<const std::byte> b) { return a.prefix < b.subspan(0, std::min(a.prefix.size(), b.size())); }
20 bool operator<(Span<const std::byte> a, BytePrefix b) { return a.subspan(0, std::min(a.size(), b.prefix.size())) < b.prefix; }
21 
22 std::vector<fs::path> ListDatabases(const fs::path& wallet_dir)
23 {
24  std::vector<fs::path> paths;
25  std::error_code ec;
26 
27  for (auto it = fs::recursive_directory_iterator(wallet_dir, ec); it != fs::recursive_directory_iterator(); it.increment(ec)) {
28  if (ec) {
29  if (fs::is_directory(*it)) {
30  it.disable_recursion_pending();
31  LogPrintf("%s: %s %s -- skipping.\n", __func__, ec.message(), fs::PathToString(it->path()));
32  } else {
33  LogPrintf("%s: %s %s\n", __func__, ec.message(), fs::PathToString(it->path()));
34  }
35  continue;
36  }
37 
38  try {
39  const fs::path path{it->path().lexically_relative(wallet_dir)};
40 
41  if (it->status().type() == fs::file_type::directory &&
42  (IsBDBFile(BDBDataFile(it->path())) || IsSQLiteFile(SQLiteDataFile(it->path())))) {
43  // Found a directory which contains wallet.dat btree file, add it as a wallet.
44  paths.emplace_back(path);
45  } else if (it.depth() == 0 && it->symlink_status().type() == fs::file_type::regular && IsBDBFile(it->path())) {
46  if (it->path().filename() == "wallet.dat") {
47  // Found top-level wallet.dat btree file, add top level directory ""
48  // as a wallet.
49  paths.emplace_back();
50  } else {
51  // Found top-level btree file not called wallet.dat. Current bitcoin
52  // software will never create these files but will allow them to be
53  // opened in a shared database environment for backwards compatibility.
54  // Add it to the list of available wallets.
55  paths.emplace_back(path);
56  }
57  }
58  } catch (const std::exception& e) {
59  LogPrintf("%s: Error scanning %s: %s\n", __func__, fs::PathToString(it->path()), e.what());
60  it.disable_recursion_pending();
61  }
62  }
63 
64  return paths;
65 }
66 
67 fs::path BDBDataFile(const fs::path& wallet_path)
68 {
69  if (fs::is_regular_file(wallet_path)) {
70  // Special case for backwards compatibility: if wallet path points to an
71  // existing file, treat it as the path to a BDB data file in a parent
72  // directory that also contains BDB log files.
73  return wallet_path;
74  } else {
75  // Normal case: Interpret wallet path as a directory path containing
76  // data and log files.
77  return wallet_path / "wallet.dat";
78  }
79 }
80 
82 {
83  return path / "wallet.dat";
84 }
85 
86 bool IsBDBFile(const fs::path& path)
87 {
88  if (!fs::exists(path)) return false;
89 
90  // A Berkeley DB Btree file has at least 4K.
91  // This check also prevents opening lock files.
92  std::error_code ec;
93  auto size = fs::file_size(path, ec);
94  if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), fs::PathToString(path));
95  if (size < 4096) return false;
96 
97  std::ifstream file{path, std::ios::binary};
98  if (!file.is_open()) return false;
99 
100  file.seekg(12, std::ios::beg); // Magic bytes start at offset 12
101  uint32_t data = 0;
102  file.read((char*) &data, sizeof(data)); // Read 4 bytes of file to compare against magic
103 
104  // Berkeley DB Btree magic bytes, from:
105  // https://github.com/file/file/blob/5824af38469ec1ca9ac3ffd251e7afe9dc11e227/magic/Magdir/database#L74-L75
106  // - big endian systems - 00 05 31 62
107  // - little endian systems - 62 31 05 00
108  return data == 0x00053162 || data == 0x62310500;
109 }
110 
111 bool IsSQLiteFile(const fs::path& path)
112 {
113  if (!fs::exists(path)) return false;
114 
115  // A SQLite Database file is at least 512 bytes.
116  std::error_code ec;
117  auto size = fs::file_size(path, ec);
118  if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), fs::PathToString(path));
119  if (size < 512) return false;
120 
121  std::ifstream file{path, std::ios::binary};
122  if (!file.is_open()) return false;
123 
124  // Magic is at beginning and is 16 bytes long
125  char magic[16];
126  file.read(magic, 16);
127 
128  // Application id is at offset 68 and 4 bytes long
129  file.seekg(68, std::ios::beg);
130  char app_id[4];
131  file.read(app_id, 4);
132 
133  file.close();
134 
135  // Check the magic, see https://sqlite.org/fileformat.html
136  std::string magic_str(magic, 16);
137  if (magic_str != std::string{"SQLite format 3\000", 16}) {
138  return false;
139  }
140 
141  // Check the application id matches our network magic
142  return memcmp(Params().MessageStart().data(), app_id, 4) == 0;
143 }
144 
146 {
147  // Override current options with args values, if any were specified
148  options.use_unsafe_sync = args.GetBoolArg("-unsafesqlitesync", options.use_unsafe_sync);
149  options.use_shared_memory = !args.GetBoolArg("-privdb", !options.use_shared_memory);
150  options.max_log_mb = args.GetIntArg("-dblogsize", options.max_log_mb);
151 }
152 
153 } // namespace wallet
ArgsManager & args
Definition: bitcoind.cpp:267
const CChainParams & Params()
Return the currently selected parameters.
int64_t GetIntArg(const std::string &strArg, int64_t nDefault) const
Return integer argument or default value.
Definition: args.cpp:480
bool GetBoolArg(const std::string &strArg, bool fDefault) const
Return boolean argument or default value.
Definition: args.cpp:505
constexpr std::size_t size() const noexcept
Definition: span.h:187
CONSTEXPR_IF_NOT_DEBUG Span< C > subspan(std::size_t offset) const noexcept
Definition: span.h:195
Path class wrapper to block calls to the fs::path(std::string) implicit constructor and the fs::path:...
Definition: fs.h:33
path(std::filesystem::path path)
Definition: fs.h:38
#define LogPrintf(...)
Definition: logging.h:244
static bool exists(const path &p)
Definition: fs.h:89
static std::string PathToString(const path &path)
Convert path object to a byte string.
Definition: fs.h:151
void ReadDatabaseArgs(const ArgsManager &args, DatabaseOptions &options)
Definition: db.cpp:145
fs::path SQLiteDataFile(const fs::path &path)
Definition: db.cpp:81
std::vector< fs::path > ListDatabases(const fs::path &wallet_dir)
Recursively list database paths in directory.
Definition: db.cpp:22
bool IsBDBFile(const fs::path &path)
Definition: db.cpp:86
fs::path BDBDataFile(const fs::path &wallet_path)
Definition: db.cpp:67
bool operator<(BytePrefix a, Span< const std::byte > b)
Definition: db.cpp:19
bool IsSQLiteFile(const fs::path &path)
Definition: db.cpp:111
Span< const std::byte > prefix
Definition: db.h:25
bool use_shared_memory
Let other processes access the database.
Definition: db.h:200
bool use_unsafe_sync
Disable file sync for faster performance.
Definition: db.h:199
int64_t max_log_mb
Max log size to allow before consolidating.
Definition: db.h:201