walletutil.cpp

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// Copyright (c) 2017 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 <wallet/walletutil.h>
 
#include <common/args.h>
#include <logging.h>
 
#include <exception>
#include <fstream>
 
fs::path GetWalletDir() {
    fs::path path;
 
    if (gArgs.IsArgSet("-walletdir")) {
        path = gArgs.GetPathArg("-walletdir");
        if (!fs::is_directory(path)) {
            // If the path specified doesn't exist, we return the deliberately
            // invalid empty string.
            path = "";
        }
    } else {
        path = gArgs.GetDataDirNet();
        // If a wallets directory exists, use that, otherwise default to
        // GetDataDir
        if (fs::is_directory(path / "wallets")) {
            path /= "wallets";
        }
    }
 
    return path;
}
 
bool IsBerkeleyBtree(const fs::path &path) {
    if (!fs::exists(path)) {
        return false;
    }
 
    // A Berkeley DB Btree file has at least 4K.
    // This check also prevents opening lock files.
    std::error_code ec;
    auto size = fs::file_size(path, ec);
    if (ec) {
        LogPrintf("%s: %s %s\n", __func__, ec.message(),
                  fs::PathToString(path));
    }
    if (size < 4096) {
        return false;
    }
 
    std::ifstream file{path, std::ios::binary};
    if (!file.is_open()) {
        return false;
    }
 
    // Magic bytes start at offset 12
    file.seekg(12, std::ios::beg);
    uint32_t data = 0;
    // Read 4 bytes of file to compare against magic
    file.read((char *)&data, sizeof(data));
 
    // Berkeley DB Btree magic bytes, from:
    //  https://github.com/file/file/blob/5824af38469ec1ca9ac3ffd251e7afe9dc11e227/magic/Magdir/database#L74-L75
    //  - big endian systems - 00 05 31 62
    //  - little endian systems - 62 31 05 00
    return data == 0x00053162 || data == 0x62310500;
}
 
std::vector<fs::path> ListWalletDir() {
    const fs::path wallet_dir = GetWalletDir();
    const size_t offset = fs::PathToString(wallet_dir).size() + 1;
    std::vector<fs::path> paths;
    std::error_code ec;
 
    for (auto it = fs::recursive_directory_iterator(wallet_dir, ec);
         it != fs::recursive_directory_iterator(); it.increment(ec)) {
        if (ec) {
            LogPrintf("%s: %s %s\n", __func__, ec.message(),
                      fs::PathToString(it->path()));
            continue;
        }
 
        try {
            // Get wallet path relative to walletdir by removing walletdir from
            // the wallet path. This can be replaced by
            // boost::filesystem::lexically_relative once boost is bumped
            // to 1.60.
            const auto path_str = it->path().native().substr(offset);
            const fs::path path{path_str.begin(), path_str.end()};
 
            if (it->status().type() == fs::file_type::directory &&
                IsBerkeleyBtree(it->path() / "wallet.dat")) {
                // Found a directory which contains wallet.dat btree file, add
                // it as a wallet.
                paths.emplace_back(path);
            } else if (it.depth() == 0 &&
                       it->symlink_status().type() == fs::file_type::regular &&
                       IsBerkeleyBtree(it->path())) {
                if (it->path().filename() == "wallet.dat") {
                    // Found top-level wallet.dat btree file, add top level
                    // directory "" as a wallet.
                    paths.emplace_back();
                } else {
                    // Found top-level btree file not called wallet.dat. Current
                    // bitcoin software will never create these files but will
                    // allow them to be opened in a shared database environment
                    // for backwards compatibility. Add it to the list of
                    // available wallets.
                    paths.emplace_back(path);
                }
            }
        } catch (const std::exception &e) {
            LogPrintf("%s: Error scanning %s: %s\n", __func__,
                      it->path().string(), e.what());
            it.disable_recursion_pending();
        }
    }
 
    return paths;
}