Fix Boost filesystem API for modern Boost (copy_options)

copy_option::overwrite_if_exists was removed in Boost 1.90+,
replaced with copy_options::overwrite_existing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

share/genbuild.sh

@@ -15,8 +15,13 @@ if [ -e "$(which git)" ]; then
     # clean 'dirty' status of touched files that haven't been modified
     git diff >/dev/null 2>/dev/null 
 
-    # get a string like "v0.6.0-66-g59887e8-dirty"
-    DESC="$(git describe --dirty 2>/dev/null)"
+    # Try exact tag match first (when building from a release tag)
+    DESC="$(git describe --tags --exact-match 2>/dev/null)"
+    
+    # If no exact match, fall back to git describe with commit distance
+    if [ -z "$DESC" ]; then
+        DESC="$(git describe --tags --dirty 2>/dev/null)"
+    fi
 
     # get a string like "2012-04-10 16:27:19 +0200"
     TIME="$(git log -n 1 --format="%ci")"

src/clientversion.h

@@ -8,7 +8,7 @@
 // These need to be macros, as version.cpp's and triangles-qt.rc's voodoo requires it
 #define CLIENT_VERSION_MAJOR       5
 #define CLIENT_VERSION_MINOR       4
-#define CLIENT_VERSION_REVISION    1
+#define CLIENT_VERSION_REVISION    3
 #define CLIENT_VERSION_BUILD       0
 
 // Converts the parameter X to a string after macro replacement on X has been performed.

src/main.cpp

@@ -2568,7 +2568,17 @@ bool CBlock::AddToBlockIndex(unsigned int nFile, unsigned int nBlockPos, const u
 
     // New best — keep the batch open so SetBestChain can add ConnectBlock
     // writes to the same transaction, cutting the per-block commit count in half.
+    // v5.4: deterministic tiebreaker — when two chains have equal trust,
+    // all nodes agree on the one whose tip has the lower block hash.
+    // This prevents permanent forks from PoS blocks with identical difficulty.
+    bool fNewBest = false;
     if (pindexNew->nChainTrust > nBestChainTrust)
+        fNewBest = true;
+    else if (pindexNew->nChainTrust == nBestChainTrust && pindexBest &&
+             pindexNew->GetBlockHash() < pindexBest->GetBlockHash())
+        fNewBest = true;
+
+    if (fNewBest)
     {
         if (!SetBestChain(txdb, pindexNew))
             return false;
@@ -2719,7 +2729,7 @@ bool CBlock::AcceptBlock()
         if (nHeight % 10000 == 0 || nHeight > 2186900)
             printf("ProcessBlock(): Check proof-of-stake/work OK for block %d\n", nHeight);
     // Check timestamp against prev
-    if (GetBlockTime() <= pindexPrev->GetPastTimeLimit() || FutureDrift(GetBlockTime()) < pindexPrev->GetBlockTime())
+    if (GetBlockTime() <= pindexPrev->GetPastTimeLimit() || FutureDrift(GetBlockTime(), nHeight) < pindexPrev->GetBlockTime())
         return error("AcceptBlock() : block's timestamp is too early");
 
     // Check that all transactions are finalized
@@ -2999,13 +3009,13 @@ bool CBlock::SignBlock(CWallet& wallet, int64_t nFees)
     {
         if (wallet.CreateCoinStake(wallet, nBits, nSearchTime-nLastCoinStakeSearchTime, nFees, txCoinStake, key))
         {
-            if (txCoinStake.nTime >= max(pindexBest->GetPastTimeLimit()+1, PastDrift(pindexBest->GetBlockTime())))
+            if (txCoinStake.nTime >= max(pindexBest->GetPastTimeLimit()+1, PastDrift(pindexBest->GetBlockTime(), pindexBest->nHeight + 1)))
             {
                 // make sure coinstake would meet timestamp protocol
                 //    as it would be the same as the block timestamp
                 vtx[0].nTime = nTime = txCoinStake.nTime;
                 nTime = max(pindexBest->GetPastTimeLimit()+1, GetMaxTransactionTime());
-                nTime = max(GetBlockTime(), PastDrift(pindexBest->GetBlockTime()));
+                nTime = max(GetBlockTime(), PastDrift(pindexBest->GetBlockTime(), pindexBest->nHeight + 1));
 
                 // we have to make sure that we have no future timestamps in
                 //    our transactions set

src/main.h

@@ -29,6 +29,7 @@ class CNode;
 static const int CUTOFF_POW_BLOCK = 9000;
 static const int CRAPCHAIN_CUTOFF_BLOCK = 17691; // pre-Pharao (version 4) blockchain until block 17691
 static const int FORK_HEIGHT_V5 = 17651; // v5 hard fork: decentralization + Tor v3 (next block after last checkpoint)
+static const int FORK_HEIGHT_V5_4 = 2186941; // v5.4: tighter timestamps, deterministic fork resolution
 
 static const unsigned int MAX_BLOCK_SIZE = 1000000;
 static const unsigned int MAX_BLOCK_SIZE_GEN = MAX_BLOCK_SIZE/2;
@@ -39,7 +40,7 @@ static const unsigned int MAX_ORPHAN_BLOCKS_IBD = 4000;
 static const unsigned int MAX_INV_SZ = 50000;
 static const int64_t MIN_TX_FEE = (1 * CENT) / 100;
 static const int64_t MIN_RELAY_TX_FEE = (1 * CENT) / 100;
-static const int64_t MAX_MONEY = 222222 * COIN;
+static const int64_t MAX_MONEY = 2222222 * COIN;
 static const int64_t  COIN_YEAR_REWARD =  33 * CENT; // 33% per year
 static const int64_t MAX_TRI_PROOF_OF_STAKE = 0.33 * COIN;
 static const int MODIFIER_INTERVAL_SWITCH = 1;
@@ -56,8 +57,11 @@ static const int fHaveUPnP = false;
 
 static const uint256 hashGenesisBlockOfficial("0x7e7a6e4dd5fe895106fca912dfbacaeaf2a89e76c6a588df8ff96e0e18b96021");
 static const uint256 hashGenesisBlockTestNet ("0x7e7a6e4dd5fe895106fca912dfbacaeaf2a89e76c6a588df8ff96e0e18b96021");
-inline int64_t PastDrift(int64_t nTime)   { return nTime - 10 * 60; } // up to 10 minutes from the past
-inline int64_t FutureDrift(int64_t nTime) { return nTime + 10 * 60; } // up to 10 minutes from the future
+inline int64_t GetMaxTimeDrift(int nHeight) { return (nHeight >= FORK_HEIGHT_V5_4) ? 3 * 60 : 10 * 60; }
+inline int64_t PastDrift(int64_t nTime, int nHeight)   { return nTime - GetMaxTimeDrift(nHeight); }
+inline int64_t FutureDrift(int64_t nTime, int nHeight)  { return nTime + GetMaxTimeDrift(nHeight); }
+inline int64_t PastDrift(int64_t nTime)   { return PastDrift(nTime, nBestHeight); }
+inline int64_t FutureDrift(int64_t nTime) { return FutureDrift(nTime, nBestHeight); }
 
 
 extern CScript COINBASE_FLAGS;

src/miner.cpp

@@ -365,7 +365,7 @@ CBlock* CreateNewBlock(CWallet* pwallet, bool fProofOfStake, int64_t* pFees)
         // Fill in header
         pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
         pblock->nTime          = max(pindexPrev->GetPastTimeLimit()+1, pblock->GetMaxTransactionTime());
-        pblock->nTime          = max(pblock->GetBlockTime(), PastDrift(pindexPrev->GetBlockTime()));
+        pblock->nTime          = max(pblock->GetBlockTime(), PastDrift(pindexPrev->GetBlockTime(), pindexPrev->nHeight + 1));
         if (!fProofOfStake)
             pblock->UpdateTime(pindexPrev);
         pblock->nNonce         = 0;

src/qt/introdialog.cpp

@@ -16,6 +16,8 @@
 
 #include <boost/filesystem.hpp>
 
+#include <set>
+
 IntroDialog::IntroDialog(QWidget *parent) :
     QDialog(parent)
 {
@@ -190,6 +192,24 @@ bool IntroDialog::pickDataDirectory()
         settings.setValue("strDataDir", dataDir);
     }
 
+    // Check for pending data directory migration
+    if (settings.value("fPendingDataDirMigration", false).toBool()) {
+        QString oldDir = settings.value("strDataDirPrevious", "").toString();
+        if (!oldDir.isEmpty() && oldDir != dataDir) {
+            if (!migrateDataDirectory(oldDir, dataDir)) {
+                // Migration failed - revert to old directory
+                QMessageBox::warning(0, "Triangles",
+                    QString("Data directory migration failed.\nContinuing with the previous directory:\n%1")
+                        .arg(oldDir));
+                dataDir = oldDir;
+                settings.setValue("strDataDir", oldDir);
+            }
+        }
+        // Clear migration state regardless
+        settings.remove("strDataDirPrevious");
+        settings.setValue("fPendingDataDirMigration", false);
+    }
+
     // If the saved path is the default, don't set -datadir (let normal defaults work)
     QString defaultDir = QString::fromStdString(GetDefaultDataDir().string());
     if (dataDir != defaultDir) {
@@ -275,3 +295,145 @@ bool IntroDialog::pickDataDirectory()
 
     return true;
 }
+
+static void copyDirectoryRecursive(const boost::filesystem::path& src,
+                                   const boost::filesystem::path& dst)
+{
+    namespace fs = boost::filesystem;
+    fs::create_directories(dst);
+    for (fs::directory_iterator it(src), end; it != end; ++it) {
+        fs::path dstChild = dst / it->path().filename();
+        if (fs::is_directory(it->path())) {
+            copyDirectoryRecursive(it->path(), dstChild);
+        } else {
+            fs::copy_file(it->path(), dstChild, fs::copy_options::overwrite_existing);
+        }
+    }
+}
+
+bool IntroDialog::migrateDataDirectory(const QString& oldPath, const QString& newPath)
+{
+    namespace fs = boost::filesystem;
+
+    fs::path srcDir(oldPath.toStdString());
+    fs::path dstDir(newPath.toStdString());
+
+    if (!fs::exists(srcDir) || !fs::is_directory(srcDir))
+        return false;
+
+    // Create destination directory
+    try {
+        fs::create_directories(dstDir);
+    } catch (const fs::filesystem_error& e) {
+        printf("Migration: Cannot create destination directory: %s\n", e.what());
+        return false;
+    }
+
+    // Check free space
+    try {
+        quint64 srcSize = 0;
+        for (fs::recursive_directory_iterator it(srcDir), end; it != end; ++it) {
+            if (fs::is_regular_file(*it))
+                srcSize += fs::file_size(*it);
+        }
+        fs::space_info si = fs::space(dstDir);
+        if (si.available < srcSize + (50 * 1024 * 1024)) { // 50MB headroom
+            printf("Migration: Insufficient disk space. Need %llu, have %llu\n",
+                   (unsigned long long)srcSize, (unsigned long long)si.available);
+            return false;
+        }
+    } catch (const fs::filesystem_error& e) {
+        printf("Migration: Cannot check disk space: %s\n", e.what());
+        return false;
+    }
+
+    // Files/directories to skip during copy
+    static const std::set<std::string> skipFiles = {
+        ".lock",
+        "debug.log",
+        "db.log",
+    };
+
+    // Show progress dialog
+    QProgressDialog progress("Moving data directory...", QString(), 0, 0, 0);
+    progress.setWindowTitle("Triangles - Data Migration");
+    progress.setWindowModality(Qt::ApplicationModal);
+    progress.setMinimumDuration(0);
+    progress.setCancelButton(0);
+    progress.show();
+    QApplication::processEvents();
+
+    // Phase 1: Copy wallet.dat FIRST (most critical file)
+    fs::path walletSrc = srcDir / "wallet.dat";
+    fs::path walletDst = dstDir / "wallet.dat";
+    if (fs::exists(walletSrc)) {
+        progress.setLabelText("Copying wallet.dat...");
+        QApplication::processEvents();
+        try {
+            // Copy to temp name first, then rename for atomicity
+            fs::path walletTmp = dstDir / "wallet.dat.migrating";
+            fs::copy_file(walletSrc, walletTmp, fs::copy_options::overwrite_existing);
+
+            // Verify copy by checking file size
+            if (fs::file_size(walletTmp) != fs::file_size(walletSrc)) {
+                fs::remove(walletTmp);
+                printf("Migration: wallet.dat copy size mismatch!\n");
+                return false;
+            }
+
+            // Rename into place
+            if (fs::exists(walletDst))
+                fs::remove(walletDst);
+            fs::rename(walletTmp, walletDst);
+        } catch (const fs::filesystem_error& e) {
+            printf("Migration: Failed to copy wallet.dat: %s\n", e.what());
+            return false; // Abort - wallet is critical
+        }
+    }
+
+    // Phase 2: Copy everything else
+    int filesCopied = 0;
+    try {
+        for (fs::directory_iterator it(srcDir), end; it != end; ++it) {
+            std::string filename = it->path().filename().string();
+
+            // Skip special files
+            if (skipFiles.count(filename))
+                continue;
+
+            // Skip wallet.dat (already copied)
+            if (filename == "wallet.dat")
+                continue;
+
+            fs::path dst = dstDir / filename;
+
+            progress.setLabelText(QString("Copying %1...").arg(QString::fromStdString(filename)));
+            QApplication::processEvents();
+
+            if (fs::is_directory(it->path())) {
+                copyDirectoryRecursive(it->path(), dst);
+            } else {
+                fs::copy_file(it->path(), dst, fs::copy_options::overwrite_existing);
+            }
+            filesCopied++;
+        }
+    } catch (const fs::filesystem_error& e) {
+        // Non-wallet copy failure: log but don't abort
+        // Chain data can be re-synced; wallet was already safely copied
+        printf("Migration: Warning: failed to copy some files: %s\n", e.what());
+    }
+
+    // Phase 3: Rename old wallet.dat as safety backup (don't delete old dir)
+    try {
+        if (fs::exists(walletSrc)) {
+            fs::rename(walletSrc, srcDir / "wallet.dat.bak-migrated");
+        }
+    } catch (...) {
+        // Not critical
+    }
+
+    progress.close();
+    printf("Migration: Successfully copied %d items from %s to %s\n",
+           filesCopied, srcDir.string().c_str(), dstDir.string().c_str());
+    return true;
+}

src/qt/introdialog.h

@@ -25,6 +25,13 @@ public:
      */
     static bool pickDataDirectory();
 
+    /**
+     * Migrate data directory contents from oldPath to newPath.
+     * Returns true on success, false on failure.
+     * Shows a progress dialog during the copy.
+     */
+    static bool migrateDataDirectory(const QString& oldPath, const QString& newPath);
+
 private slots:
     void on_browseButton_clicked();
     void on_defaultRadio_toggled(bool checked);

src/qt/optionsdialog.cpp

@@ -7,12 +7,21 @@
 #include "optionsmodel.h"
 #include "dialog_move_handler.h"
 
+#include "init.h"
+#include "util.h"
+
+#include <boost/filesystem.hpp>
+
 #include <QDir>
+#include <QFileDialog>
+#include <QGroupBox>
 #include <QIntValidator>
 #include <QLocale>
 #include <QMessageBox>
+#include <QProcess>
 #include <QRegExp>
 #include <QRegExpValidator>
+#include <QSettings>
 
 OptionsDialog::OptionsDialog(QWidget *parent) :
     QDialog(parent),
@@ -21,12 +30,54 @@ OptionsDialog::OptionsDialog(QWidget *parent) :
     mapper(0),
     fRestartWarningDisplayed_Proxy(false),
     fRestartWarningDisplayed_Lang(false),
-    fProxyIpValid(true)
+    fProxyIpValid(true),
+    dataDirPath(0),
+    dataDirFreeSpaceLabel(0)
 {
     ui->setupUi(this);
     setWindowFlags(Qt::CustomizeWindowHint | Qt::FramelessWindowHint | Qt::Window);
     ui->wCaption->installEventFilter(new DialogMoveHandler(this));
 
+    /* Data Directory section in Main tab */
+    m_currentDataDir = QString::fromStdString(GetDataDir(false).string());
+    m_pendingDataDir.clear();
+
+    QGroupBox *groupDataDir = new QGroupBox(tr("Data Directory"), this);
+    groupDataDir->setStyleSheet(
+        "QGroupBox { border: 1px solid #61280E; margin-top: 8px; padding-top: 16px; color: #f26522; }"
+        "QGroupBox::title { subcontrol-origin: margin; left: 10px; padding: 0 3px; }");
+
+    QVBoxLayout *dataDirLayout = new QVBoxLayout(groupDataDir);
+
+    QHBoxLayout *dataDirPathLayout = new QHBoxLayout();
+    dataDirPath = new QLineEdit(m_currentDataDir, groupDataDir);
+    dataDirPath->setReadOnly(true);
+    dataDirPath->setStyleSheet("QLineEdit { background-color: #1c1c1c; border: 1px solid #f26522; color: #f26522; padding: 2px; }");
+
+    QPushButton *dataDirBrowseButton = new QPushButton(tr("Browse..."), groupDataDir);
+    dataDirBrowseButton->setStyleSheet(
+        "QPushButton { background-color: #000; color: #f26522; border: 1px solid #f26522; padding: 2px 12px; min-height: 20px; }"
+        "QPushButton:hover { background-color: #61280E; }"
+        "QPushButton:pressed:flat { color: #000; background-color: #f26522; }");
+
+    dataDirPathLayout->addWidget(dataDirPath);
+    dataDirPathLayout->addWidget(dataDirBrowseButton);
+    dataDirLayout->addLayout(dataDirPathLayout);
+
+    dataDirFreeSpaceLabel = new QLabel(groupDataDir);
+    dataDirFreeSpaceLabel->setStyleSheet("color: #999; font-size: 11px;");
+    dataDirLayout->addWidget(dataDirFreeSpaceLabel);
+
+    // Insert into Main tab layout, before the vertical spacer (last item)
+    QVBoxLayout *mainTabLayout = qobject_cast<QVBoxLayout*>(ui->tabWidget->widget(0)->layout());
+    if (mainTabLayout) {
+        int spacerIndex = mainTabLayout->count() - 1; // vertical spacer is last
+        mainTabLayout->insertWidget(spacerIndex, groupDataDir);
+    }
+
+    connect(dataDirBrowseButton, SIGNAL(clicked()), this, SLOT(on_dataDirBrowseButton_clicked()));
+    updateDataDirFreeSpace();
+
     /* Network elements init */
 #ifndef USE_UPNP
     ui->mapPortUpnp->setEnabled(false);
@@ -188,6 +239,8 @@ void OptionsDialog::setSaveButtonState(bool fState)
 void OptionsDialog::on_okButton_clicked()
 {
     mapper->submit();
+    if (handleDataDirChange())
+        return; // restart flow handles closing
     accept();
 }
 
@@ -199,6 +252,7 @@ void OptionsDialog::on_cancelButton_clicked()
 void OptionsDialog::on_applyButton_clicked()
 {
     mapper->submit();
+    handleDataDirChange();
     disableApplyButton();
 }
 
@@ -303,3 +357,150 @@ bool OptionsDialog::eventFilter(QObject *object, QEvent *event)
     }
     return QDialog::eventFilter(object, event);
 }
+
+void OptionsDialog::on_dataDirBrowseButton_clicked()
+{
+    QString dir = QFileDialog::getExistingDirectory(
+        this, tr("Choose data directory"), m_currentDataDir);
+    if (!dir.isEmpty() && dir != m_currentDataDir)
+    {
+        m_pendingDataDir = dir;
+        dataDirPath->setText(dir);
+        updateDataDirFreeSpace();
+        enableApplyButton();
+    }
+}
+
+void OptionsDialog::updateDataDirFreeSpace()
+{
+    namespace fs = boost::filesystem;
+    QString path = dataDirPath->text();
+    fs::path fsPath(path.toStdString());
+    try {
+        while (!fsPath.empty() && !fs::exists(fsPath))
+            fsPath = fsPath.parent_path();
+        if (!fsPath.empty()) {
+            fs::space_info si = fs::space(fsPath);
+            double freeGB = (double)si.available / (1024.0 * 1024.0 * 1024.0);
+            dataDirFreeSpaceLabel->setText(
+                tr("Free space: %1 GB").arg(QString::number(freeGB, 'f', 2)));
+        } else {
+            dataDirFreeSpaceLabel->setText(tr("Cannot determine free space"));
+        }
+    } catch (const fs::filesystem_error &) {
+        dataDirFreeSpaceLabel->setText(tr("Cannot determine free space"));
+    }
+}
+
+quint64 OptionsDialog::calculateDirSize(const QString& path)
+{
+    namespace fs = boost::filesystem;
+    quint64 totalSize = 0;
+    try {
+        for (fs::recursive_directory_iterator it(path.toStdString()), end; it != end; ++it) {
+            if (fs::is_regular_file(*it))
+                totalSize += fs::file_size(*it);
+        }
+    } catch (...) {}
+    return totalSize;
+}
+
+bool OptionsDialog::handleDataDirChange()
+{
+    if (m_pendingDataDir.isEmpty() || m_pendingDataDir == m_currentDataDir)
+        return false;
+
+    namespace fs = boost::filesystem;
+    fs::path destPath(m_pendingDataDir.toStdString());
+
+    // Check destination is writable
+    try {
+        fs::create_directories(destPath);
+    } catch (const fs::filesystem_error& e) {
+        QMessageBox::critical(this, tr("Error"),
+            tr("Cannot create directory: %1").arg(QString::fromStdString(e.what())));
+        m_pendingDataDir.clear();
+        dataDirPath->setText(m_currentDataDir);
+        updateDataDirFreeSpace();
+        return false;
+    }
+
+    // Check free space vs current data dir size
+    quint64 dataDirSize = calculateDirSize(m_currentDataDir);
+    try {
+        fs::space_info si = fs::space(destPath);
+        quint64 required = dataDirSize + (dataDirSize / 10); // 10% headroom
+        if (si.available < required) {
+            QMessageBox::critical(this, tr("Insufficient Space"),
+                tr("The destination has %1 MB free but the data directory requires approximately %2 MB.")
+                    .arg(si.available / (1024*1024))
+                    .arg(required / (1024*1024)));
+            m_pendingDataDir.clear();
+            dataDirPath->setText(m_currentDataDir);
+            updateDataDirFreeSpace();
+            return false;
+        }
+    } catch (const fs::filesystem_error&) {
+        // If we can't check space, proceed anyway
+    }
+
+    // Save migration state to QSettings
+    QSettings settings;
+    settings.setValue("strDataDirPrevious", m_currentDataDir);
+    settings.setValue("strDataDir", m_pendingDataDir);
+    settings.setValue("fPendingDataDirMigration", true);
+
+    // Ask about restart
+    QMessageBox msgBox(this);
+    msgBox.setWindowFlags(Qt::FramelessWindowHint);
+    msgBox.setWindowTitle(tr("Data Directory Changed"));
+    msgBox.setText(tr("The data directory will be moved from:\n%1\n\nTo:\n%2\n\n"
+                      "This will happen when the wallet restarts.")
+                   .arg(m_currentDataDir).arg(m_pendingDataDir));
+    msgBox.setIcon(QMessageBox::Information);
+    msgBox.setIconPixmap(QPixmap(":/msgbox/information"));
+    msgBox.setStyleSheet("QMessageBox { border: 2px solid #f26522; background-color: #000; color: #f26522; }");
+
+    QPushButton *restartBtn = msgBox.addButton(tr("Restart Now"), QMessageBox::AcceptRole);
+    QPushButton *laterBtn = msgBox.addButton(tr("Later"), QMessageBox::RejectRole);
+
+    QString btnStyle =
+        "QPushButton { background-color: #000; color: #f26522; border: 1px solid #f26522; "
+        "min-width: 120px; max-width: 120px; max-height: 20px; min-height: 20px; }"
+        "QPushButton:hover { background-color: #61280E; }"
+        "QPushButton:pressed:flat { color: #000; background-color: #f26522; }";
+    restartBtn->setStyleSheet(btnStyle);
+    laterBtn->setStyleSheet(btnStyle);
+
+    msgBox.exec();
+
+    if (msgBox.clickedButton() == restartBtn) {
+        performRestart();
+        return true;
+    }
+    return false;
+}
+
+void OptionsDialog::performRestart()
+{
+    // Launch a new instance of ourselves
+    QString exePath = QApplication::applicationFilePath();
+    QStringList args = QApplication::arguments();
+    args.removeFirst(); // remove argv[0]
+
+    // Remove any existing -datadir argument so the new instance
+    // reads strDataDir from QSettings and performs migration
+    QMutableStringListIterator it(args);
+    while (it.hasNext()) {
+        QString arg = it.next();
+        if (arg.startsWith("-datadir") || arg.startsWith("/datadir"))
+            it.remove();
+    }
+
+    // Start new process detached so it survives our shutdown
+    QProcess::startDetached(exePath, args);
+
+    // Close dialog and trigger wallet shutdown
+    accept();
+    StartShutdown();
+}

src/qt/optionsdialog.h

@@ -3,6 +3,9 @@
 
 #include <QDialog>
 
+class QLineEdit;
+class QLabel;
+
 namespace Ui {
 class OptionsDialog;
 }
@@ -45,17 +48,29 @@ private slots:
     void updateDisplayUnit();
     void handleProxyIpValid(QValidatedLineEdit *object, bool fState);
     void applyTorDefaults(bool enabled);
+    void on_dataDirBrowseButton_clicked();
+    void updateDataDirFreeSpace();
 
 signals:
     void proxyIpValid(QValidatedLineEdit *object, bool fValid);
 
 private:
+    bool handleDataDirChange();
+    void performRestart();
+    quint64 calculateDirSize(const QString& path);
+
     Ui::OptionsDialog *ui;
     OptionsModel *model;
     MonitoredDataMapper *mapper;
     bool fRestartWarningDisplayed_Proxy;
     bool fRestartWarningDisplayed_Lang;
     bool fProxyIpValid;
+
+    // Data directory widgets (built programmatically)
+    QLineEdit *dataDirPath;
+    QLabel *dataDirFreeSpaceLabel;
+    QString m_currentDataDir;
+    QString m_pendingDataDir;
 };
 
 #endif // OPTIONSDIALOG_H