Repository: bitcoin/bitcoin
File: src/init.cpp (C++)

Code before:
        if (args.GetBoolArg("-txindex", DEFAULT_TXINDEX))
            return InitError(_("Prune mode is incompatible with -txindex."));
        if (args.GetBoolArg("-reindex-chainstate", false)) {
            return InitError(_("Prune mode is incompatible with -reindex-chainstate. Use full -reindex instead."));
        }
    }

    // If -forcednsseed is set to true, ensure -dnsseed has not been set to false
    if (args.GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED) && !args.GetBoolArg("-dnsseed", DEFAULT_DNSSEED)){
        return InitError(_("Cannot set -forcednsseed to true when setting -dnsseed to false."));
    }

    // -bind and -whitebind can't be set when not listening
    size_t nUserBind = args.GetArgs("-bind").size() + args.GetArgs("-whitebind").size();
    if (nUserBind != 0 && !args.GetBoolArg("-listen", DEFAULT_LISTEN)) {
        return InitError(Untranslated("Cannot set -bind or -whitebind together with -listen=0"));
    }

    // if listen=0, then disallow listenonion=1
    if (!args.GetBoolArg("-listen", DEFAULT_LISTEN) && args.GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION)) {
        return InitError(Untranslated("Cannot set -listen=0 together with -listenonion=1"));
    }

    // Make sure enough file descriptors are available
    int nBind = std::max(nUserBind, size_t(1));
    nUserMaxConnections = args.GetIntArg("-maxconnections", DEFAULT_MAX_PEER_CONNECTIONS);
    nMaxConnections = std::max(nUserMaxConnections, 0);

    nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS + MAX_ADDNODE_CONNECTIONS + nBind + NUM_FDS_MESSAGE_CAPTURE);

#ifdef USE_POLL
    int fd_max = nFD;
#else
    int fd_max = FD_SETSIZE;
#endif
    // Trim requested connection counts, to fit into system limitations
    // <int> in std::min<int>(...) to work around FreeBSD compilation issue described in #2695
    nMaxConnections = std::max(std::min<int>(nMaxConnections, fd_max - nBind - MIN_CORE_FILEDESCRIPTORS - MAX_ADDNODE_CONNECTIONS - NUM_FDS_MESSAGE_CAPTURE), 0);
    if (nFD < MIN_CORE_FILEDESCRIPTORS)
        return InitError(_("Not enough file descriptors available."));
    nMaxConnections = std::min(nFD - MIN_CORE_FILEDESCRIPTORS - MAX_ADDNODE_CONNECTIONS - NUM_FDS_MESSAGE_CAPTURE, nMaxConnections);

    if (nMaxConnections < nUserMaxConnections)
        InitWarning(strprintf(_("Reducing -maxconnections from %d to %d, because of system limitations."), nUserMaxConnections, nMaxConnections));

    // ********************************************************* Step 3: parameter-to-internal-flags
    if (auto result{init::SetLoggingCategories(args)}; !result) return InitError(util::ErrorString(result));
    if (auto result{init::SetLoggingLevel(args)}; !result) return InitError(util::ErrorString(result));

    nConnectTimeout = args.GetIntArg("-timeout", DEFAULT_CONNECT_TIMEOUT);
    if (nConnectTimeout <= 0) {

Review comment (refactor):
I think now could also be the time to remove this FreeBSD workaround. It was needed because older versions of FreeBSD, used to ship with an old Clang (3.x). However we now require Clang 15+, and the effected version of FreeBSD 10.x, is long EOL.

Code after:
        if (args.GetBoolArg("-txindex", DEFAULT_TXINDEX))
            return InitError(_("Prune mode is incompatible with -txindex."));
        if (args.GetBoolArg("-reindex-chainstate", false)) {
            return InitError(_("Prune mode is incompatible with -reindex-chainstate. Use full -reindex instead."));
        }
    }

    // If -forcednsseed is set to true, ensure -dnsseed has not been set to false
    if (args.GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED) && !args.GetBoolArg("-dnsseed", DEFAULT_DNSSEED)){
        return InitError(_("Cannot set -forcednsseed to true when setting -dnsseed to false."));
    }

    // -bind and -whitebind can't be set when not listening
    size_t nUserBind = args.GetArgs("-bind").size() + args.GetArgs("-whitebind").size();
    if (nUserBind != 0 && !args.GetBoolArg("-listen", DEFAULT_LISTEN)) {
        return InitError(Untranslated("Cannot set -bind or -whitebind together with -listen=0"));
    }

    // if listen=0, then disallow listenonion=1
    if (!args.GetBoolArg("-listen", DEFAULT_LISTEN) && args.GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION)) {
        return InitError(Untranslated("Cannot set -listen=0 together with -listenonion=1"));
    }

    // Make sure enough file descriptors are available. We need to reserve enough FDs to account for the bare minimum,
    // plus all manual connections and all bound interfaces. Any remainder will be available for connection sockets

    // Number of bound interfaces (we have at least one)
    int nBind = std::max(nUserBind, size_t(1));
    // Maximum number of connections with other nodes, this accounts for all types of outbounds and inbounds except for manual
    int user_max_connection = args.GetIntArg("-maxconnections", DEFAULT_MAX_PEER_CONNECTIONS);
    if (user_max_connection < 0) {
        return InitError(Untranslated("-maxconnections must be greater or equal than zero"));
    }
    // Reserve enough FDs to account for the bare minimum, plus any manual connections, plus the bound interfaces
    int min_required_fds = MIN_CORE_FDS + MAX_ADDNODE_CONNECTIONS + nBind;

    // Try raising the FD limit to what we need (available_fds may be smaller than the requested amount if this fails)
    available_fds = RaiseFileDescriptorLimit(user_max_connection + min_required_fds);
    // If we are using select instead of poll, our actual limit may be even smaller
#ifndef USE_POLL
    available_fds = std::min(FD_SETSIZE, available_fds);
#endif
    if (available_fds < min_required_fds)
        return InitError(strprintf(_("Not enough file descriptors available. %d available, %d required."), available_fds, min_required_fds));

    // Trim requested connection counts, to fit into system limitations
    nMaxConnections = std::min(available_fds - min_required_fds, user_max_connection);

    if (nMaxConnections < user_max_connection)
        InitWarning(strprintf(_("Reducing -maxconnections from %d to %d, because of system limitations."), user_max_connection, nMaxConnections));