src/wallet/db.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2016 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 #ifndef BITCOIN_WALLET_DB_H
   7 #define BITCOIN_WALLET_DB_H
   8
   9 #include "clientversion.h"
  10 #include "fs.h"
  11 #include "serialize.h"
  12 #include "streams.h"
  13 #include "sync.h"
  14 #include "version.h"
  15
  16 #include <map>
  17 #include <string>
  18 #include <vector>
  19
  20 #include <db_cxx.h>
  21
  22 static const unsigned int DEFAULT_WALLET_DBLOGSIZE = 100;
  23 static const bool DEFAULT_WALLET_PRIVDB = true;
  24
  25 class CDBEnv
  26 {
  27 private:
  28     bool fDbEnvInit;
  29     bool fMockDb;
  30     // Don't change into fs::path, as that can result in
  31     // shutdown problems/crashes caused by a static initialized internal pointer.
  32     std::string strPath;
  33
  34     void EnvShutdown();
  35
  36 public:
  37     mutable CCriticalSection cs_db;
  38     DbEnv *dbenv;
  39     std::map<std::string, int> mapFileUseCount;
  40     std::map<std::string, Db*> mapDb;
  41
  42     CDBEnv();
  43     ~CDBEnv();
  44     void Reset();
  45
  46     void MakeMock();
  47     bool IsMock() { return fMockDb; }
  48
  49     /**
  50      * Verify that database file strFile is OK. If it is not,
  51      * call the callback to try to recover.
  52      * This must be called BEFORE strFile is opened.
  53      * Returns true if strFile is OK.
  54      */
  55     enum VerifyResult { VERIFY_OK,
  56                         RECOVER_OK,
  57                         RECOVER_FAIL };
  58     VerifyResult Verify(const std::string& strFile, bool (*recoverFunc)(const std::string& strFile));
  59     /**
  60      * Salvage data from a file that Verify says is bad.
  61      * fAggressive sets the DB_AGGRESSIVE flag (see berkeley DB->verify() method documentation).
  62      * Appends binary key/value pairs to vResult, returns true if successful.
  63      * NOTE: reads the entire database into memory, so cannot be used
  64      * for huge databases.
  65      */
  66     typedef std::pair<std::vector<unsigned char>, std::vector<unsigned char> > KeyValPair;
  67     bool Salvage(const std::string& strFile, bool fAggressive, std::vector<KeyValPair>& vResult);
  68
  69     bool Open(const fs::path& path);
  70     void Close();
  71     void Flush(bool fShutdown);
  72     void CheckpointLSN(const std::string& strFile);
  73
  74     void CloseDb(const std::string& strFile);
  75
  76     DbTxn* TxnBegin(int flags = DB_TXN_WRITE_NOSYNC)
  77     {
  78         DbTxn* ptxn = NULL;
  79         int ret = dbenv->txn_begin(NULL, &ptxn, flags);
  80         if (!ptxn || ret != 0)
  81             return NULL;
  82         return ptxn;
  83     }
  84 };
  85
  86 extern CDBEnv bitdb;
  87
  88 /** An instance of this class represents one database.
  89  * For BerkeleyDB this is just a (env, strFile) tuple.
  90  **/
  91 class CWalletDBWrapper
  92 {
  93     friend class CDB;
  94 public:
  95     /** Create dummy DB handle */
  96     CWalletDBWrapper(): env(nullptr)
  97     {
  98     }
  99
 100     /** Create DB handle to real database */
 101     CWalletDBWrapper(CDBEnv *env_in, const std::string &strFile_in):
 102         env(env_in), strFile(strFile_in)
 103     {
 104     }
 105
 106     /** Rewrite the entire database on disk, with the exception of key pszSkip if non-zero
 107      */
 108     bool Rewrite(const char* pszSkip=nullptr);
 109
 110     /** Back up the entire database to a file.
 111      */
 112     bool Backup(const std::string& strDest);
 113
 114     /** Get a name for this database, for debugging etc.
 115      */
 116     std::string GetName() const { return strFile; }
 117
 118     /** Make sure all changes are flushed to disk.
 119      */
 120     void Flush(bool shutdown);
 121
 122 private:
 123     /** BerkeleyDB specific */
 124     CDBEnv *env;
 125     std::string strFile;
 126
 127     /** Return whether this database handle is a dummy for testing.
 128      * Only to be used at a low level, application should ideally not care
 129      * about this.
 130      */
 131     bool IsDummy() { return env == nullptr; }
 132 };
 133
 134
 135 /** RAII class that provides access to a Berkeley database */
 136 class CDB
 137 {
 138 protected:
 139     Db* pdb;
 140     std::string strFile;
 141     DbTxn* activeTxn;
 142     bool fReadOnly;
 143     bool fFlushOnClose;
 144     CDBEnv *env;
 145
 146 public:
 147     explicit CDB(CWalletDBWrapper& dbw, const char* pszMode = "r+", bool fFlushOnCloseIn=true);
 148     ~CDB() { Close(); }
 149
 150     void Flush();
 151     void Close();
 152     static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue));
 153
 154     /* flush the wallet passively (TRY_LOCK)
 155        ideal to be called periodically */
 156     static bool PeriodicFlush(CWalletDBWrapper& dbw);
 157     /* verifies the database environment */
 158     static bool VerifyEnvironment(const std::string& walletFile, const fs::path& dataDir, std::string& errorStr);
 159     /* verifies the database file */
 160     static bool VerifyDatabaseFile(const std::string& walletFile, const fs::path& dataDir, std::string& warningStr, std::string& errorStr, bool (*recoverFunc)(const std::string& strFile));
 161
 162 private:
 163     CDB(const CDB&);
 164     void operator=(const CDB&);
 165
 166 public:
 167     template <typename K, typename T>
 168     bool Read(const K& key, T& value)
 169     {
 170         if (!pdb)
 171             return false;
 172
 173         // Key
 174         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
 175         ssKey.reserve(1000);
 176         ssKey << key;
 177         Dbt datKey(ssKey.data(), ssKey.size());
 178
 179         // Read
 180         Dbt datValue;
 181         datValue.set_flags(DB_DBT_MALLOC);
 182         int ret = pdb->get(activeTxn, &datKey, &datValue, 0);
 183         memset(datKey.get_data(), 0, datKey.get_size());
 184         if (datValue.get_data() == NULL)
 185             return false;
 186
 187         // Unserialize value
 188         try {
 189             CDataStream ssValue((char*)datValue.get_data(), (char*)datValue.get_data() + datValue.get_size(), SER_DISK, CLIENT_VERSION);
 190             ssValue >> value;
 191         } catch (const std::exception&) {
 192             return false;
 193         }
 194
 195         // Clear and free memory
 196         memset(datValue.get_data(), 0, datValue.get_size());
 197         free(datValue.get_data());
 198         return (ret == 0);
 199     }
 200
 201     template <typename K, typename T>
 202     bool Write(const K& key, const T& value, bool fOverwrite = true)
 203     {
 204         if (!pdb)
 205             return true;
 206         if (fReadOnly)
 207             assert(!"Write called on database in read-only mode");
 208
 209         // Key
 210         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
 211         ssKey.reserve(1000);
 212         ssKey << key;
 213         Dbt datKey(ssKey.data(), ssKey.size());
 214
 215         // Value
 216         CDataStream ssValue(SER_DISK, CLIENT_VERSION);
 217         ssValue.reserve(10000);
 218         ssValue << value;
 219         Dbt datValue(ssValue.data(), ssValue.size());
 220
 221         // Write
 222         int ret = pdb->put(activeTxn, &datKey, &datValue, (fOverwrite ? 0 : DB_NOOVERWRITE));
 223
 224         // Clear memory in case it was a private key
 225         memset(datKey.get_data(), 0, datKey.get_size());
 226         memset(datValue.get_data(), 0, datValue.get_size());
 227         return (ret == 0);
 228     }
 229
 230     template <typename K>
 231     bool Erase(const K& key)
 232     {
 233         if (!pdb)
 234             return false;
 235         if (fReadOnly)
 236             assert(!"Erase called on database in read-only mode");
 237
 238         // Key
 239         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
 240         ssKey.reserve(1000);
 241         ssKey << key;
 242         Dbt datKey(ssKey.data(), ssKey.size());
 243
 244         // Erase
 245         int ret = pdb->del(activeTxn, &datKey, 0);
 246
 247         // Clear memory
 248         memset(datKey.get_data(), 0, datKey.get_size());
 249         return (ret == 0 || ret == DB_NOTFOUND);
 250     }
 251
 252     template <typename K>
 253     bool Exists(const K& key)
 254     {
 255         if (!pdb)
 256             return false;
 257
 258         // Key
 259         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
 260         ssKey.reserve(1000);
 261         ssKey << key;
 262         Dbt datKey(ssKey.data(), ssKey.size());
 263
 264         // Exists
 265         int ret = pdb->exists(activeTxn, &datKey, 0);
 266
 267         // Clear memory
 268         memset(datKey.get_data(), 0, datKey.get_size());
 269         return (ret == 0);
 270     }
 271
 272     Dbc* GetCursor()
 273     {
 274         if (!pdb)
 275             return NULL;
 276         Dbc* pcursor = NULL;
 277         int ret = pdb->cursor(NULL, &pcursor, 0);
 278         if (ret != 0)
 279             return NULL;
 280         return pcursor;
 281     }
 282
 283     int ReadAtCursor(Dbc* pcursor, CDataStream& ssKey, CDataStream& ssValue, bool setRange = false)
 284     {
 285         // Read at cursor
 286         Dbt datKey;
 287         unsigned int fFlags = DB_NEXT;
 288         if (setRange) {
 289             datKey.set_data(ssKey.data());
 290             datKey.set_size(ssKey.size());
 291             fFlags = DB_SET_RANGE;
 292         }
 293         Dbt datValue;
 294         datKey.set_flags(DB_DBT_MALLOC);
 295         datValue.set_flags(DB_DBT_MALLOC);
 296         int ret = pcursor->get(&datKey, &datValue, fFlags);
 297         if (ret != 0)
 298             return ret;
 299         else if (datKey.get_data() == NULL || datValue.get_data() == NULL)
 300             return 99999;
 301
 302         // Convert to streams
 303         ssKey.SetType(SER_DISK);
 304         ssKey.clear();
 305         ssKey.write((char*)datKey.get_data(), datKey.get_size());
 306         ssValue.SetType(SER_DISK);
 307         ssValue.clear();
 308         ssValue.write((char*)datValue.get_data(), datValue.get_size());
 309
 310         // Clear and free memory
 311         memset(datKey.get_data(), 0, datKey.get_size());
 312         memset(datValue.get_data(), 0, datValue.get_size());
 313         free(datKey.get_data());
 314         free(datValue.get_data());
 315         return 0;
 316     }
 317
 318 public:
 319     bool TxnBegin()
 320     {
 321         if (!pdb || activeTxn)
 322             return false;
 323         DbTxn* ptxn = bitdb.TxnBegin();
 324         if (!ptxn)
 325             return false;
 326         activeTxn = ptxn;
 327         return true;
 328     }
 329
 330     bool TxnCommit()
 331     {
 332         if (!pdb || !activeTxn)
 333             return false;
 334         int ret = activeTxn->commit(0);
 335         activeTxn = NULL;
 336         return (ret == 0);
 337     }
 338
 339     bool TxnAbort()
 340     {
 341         if (!pdb || !activeTxn)
 342             return false;
 343         int ret = activeTxn->abort();
 344         activeTxn = NULL;
 345         return (ret == 0);
 346     }
 347
 348     bool ReadVersion(int& nVersion)
 349     {
 350         nVersion = 0;
 351         return Read(std::string("version"), nVersion);
 352     }
 353
 354     bool WriteVersion(int nVersion)
 355     {
 356         return Write(std::string("version"), nVersion);
 357     }
 358
 359     bool static Rewrite(CWalletDBWrapper& dbw, const char* pszSkip = NULL);
 360 };
 361
 362 #endif // BITCOIN_WALLET_DB_H