Improve Windows Registry searching for Python.

Simplify logic of related functions.
Make sure that all open handles are closed.
Explicitly use Unicode versions of Windows API functions.
Prevent max subkey length overwrite.
Use Windows API style of variable names.

src/preferences/preferences.cpp

@@ -1339,134 +1339,138 @@ void Preferences::disableRecursiveDownload(bool disable) {
 
 #ifdef Q_OS_WIN
 namespace {
-enum REG_SEARCH_TYPE {USER, SYSTEM_32BIT, SYSTEM_64BIT};
+enum REG_SEARCH_TYPE
+{
+    USER,
+    SYSTEM_32BIT,
+    SYSTEM_64BIT
+};
 
-QStringList getRegSubkeys(const HKEY &handle) {
+QStringList getRegSubkeys(HKEY handle)
+{
     QStringList keys;
-  DWORD subkeys_count = 0;
-  DWORD max_subkey_len = 0;
-  long res = ::RegQueryInfoKey(handle, NULL, NULL, NULL, &subkeys_count, &max_subkey_len, NULL, NULL, NULL, NULL, NULL, NULL);
+
+    DWORD cSubKeys = 0;
+    DWORD cMaxSubKeyLen = 0;
+    LONG res = ::RegQueryInfoKeyW(handle, NULL, NULL, NULL, &cSubKeys, &cMaxSubKeyLen, NULL, NULL, NULL, NULL, NULL, NULL);
+
     if (res == ERROR_SUCCESS) {
-    max_subkey_len++; //For null character
-    LPTSTR key_name = new TCHAR[max_subkey_len];
+        cMaxSubKeyLen++; // For null character
+        LPWSTR lpName = new WCHAR[cMaxSubKeyLen];
+        DWORD cName;
 
-    for (uint i=0; i<subkeys_count; i++) {
-      res = ::RegEnumKeyEx(handle, 0, key_name, &max_subkey_len, NULL, NULL, NULL, NULL);
+        for (DWORD i = 0; i < cSubKeys; ++i) {
+            cName = cMaxSubKeyLen;
+            res = ::RegEnumKeyExW(handle, 0, lpName, &cName, NULL, NULL, NULL, NULL);
             if (res == ERROR_SUCCESS)
-        keys.push_back(QString::fromWCharArray(key_name));
+                keys.push_back(QString::fromWCharArray(lpName));
         }
-    delete[] key_name;
+
+        delete[] lpName;
     }
 
     return keys;
 }
 
-QString getRegValue(const HKEY &handle, const QString &name = QString()) {
-  QString end_result;
-  DWORD type = 0;
-  DWORD size = 0;
-  DWORD array_size = 0;
+QString getRegValue(HKEY handle, const QString &name = QString())
+{
+    QString result;
 
-  LPTSTR value_name = NULL;
+    DWORD type = 0;
+    DWORD cbData = 0;
+    LPWSTR lpValueName = NULL;
     if (!name.isEmpty()) {
-    value_name = new TCHAR[name.size()+1];
-    name.toWCharArray(value_name);
-    value_name[name.size()] = '\0';
+        lpValueName = new WCHAR[name.size() + 1];
+        name.toWCharArray(lpValueName);
+        lpValueName[name.size()] = 0;
     }
 
     // Discover the size of the value
-  ::RegQueryValueEx(handle, value_name, NULL, &type, NULL, &size);
-  array_size = size / sizeof(TCHAR);
-  if (size % sizeof(TCHAR))
-    array_size++;
-  array_size++; //For null character
-  LPTSTR value = new TCHAR[array_size];
-
-  long res = ::RegQueryValueEx(handle, value_name, NULL, &type, (LPBYTE)value, &size);
+    ::RegQueryValueExW(handle, lpValueName, NULL, &type, NULL, &cbData);
+    DWORD cBuffer = (cbData / sizeof(WCHAR)) + 1;
+    LPWSTR lpData = new WCHAR[cBuffer];
+    LONG res = ::RegQueryValueExW(handle, lpValueName, NULL, &type, (LPBYTE)lpData, &cbData);
+    if (lpValueName)
+        delete[] lpValueName;
+
     if (res == ERROR_SUCCESS) {
-    value[array_size] = '\0';
-    end_result = QString::fromWCharArray(value);
+        lpData[cBuffer] = 0;
+        result = QString::fromWCharArray(lpData);
     }
+    delete[] lpData;
 
-  if (value_name)
-    delete[] value_name;
-  if (value)
-    delete[] value;
-
-  return end_result;
+    return result;
 }
 
-QString pythonSearchReg(const REG_SEARCH_TYPE type) {
-  HKEY key_handle1;
-  long res = 0;
+QString pythonSearchReg(const REG_SEARCH_TYPE type)
+{
+    HKEY hkRoot;
+    if (type == USER)
+        hkRoot = HKEY_CURRENT_USER;
+    else
+        hkRoot = HKEY_LOCAL_MACHINE;
+
+    REGSAM samDesired = KEY_READ;
+    if (type == SYSTEM_32BIT)
+        samDesired |= KEY_WOW64_32KEY;
+    else if (type == SYSTEM_64BIT)
+        samDesired |= KEY_WOW64_64KEY;
 
-  switch (type) {
-  case USER:
-    res = ::RegOpenKeyEx(HKEY_CURRENT_USER, TEXT("SOFTWARE\\Python\\PythonCore"), 0, KEY_READ, &key_handle1);
-    break;
-  case SYSTEM_32BIT:
-    res = ::RegOpenKeyEx(HKEY_LOCAL_MACHINE, TEXT("SOFTWARE\\Python\\PythonCore"), 0, KEY_READ|KEY_WOW64_32KEY, &key_handle1);
-    break;
-  case SYSTEM_64BIT:
-    res = ::RegOpenKeyEx(HKEY_LOCAL_MACHINE, TEXT("SOFTWARE\\Python\\PythonCore"), 0, KEY_READ|KEY_WOW64_64KEY, &key_handle1);
-    break;
-  }
+    QString path;
+    LONG res = 0;
+    HKEY hkPythonCore;
+    res = ::RegOpenKeyExW(hkRoot, L"SOFTWARE\\Python\\PythonCore", 0, samDesired, &hkPythonCore);
 
     if (res == ERROR_SUCCESS) {
-    QStringList versions = getRegSubkeys(key_handle1);
+        QStringList versions = getRegSubkeys(hkPythonCore);
         qDebug("Python versions nb: %d", versions.size());
         versions.sort();
 
-    while(!versions.empty()) {
-      const QString version = versions.takeLast()+"\\InstallPath";
-      HKEY key_handle2;
-      LPTSTR subkey = new TCHAR[version.size()+1];
-      version.toWCharArray(subkey);
-      subkey[version.size()] = '\0';
-
-      switch (type) {
-      case USER:
-        res = ::RegOpenKeyEx(key_handle1, subkey, 0, KEY_READ, &key_handle2);
-        break;
-      case SYSTEM_32BIT:
-        res = ::RegOpenKeyEx(key_handle1, subkey, 0, KEY_READ|KEY_WOW64_32KEY, &key_handle2);
-        break;
-      case SYSTEM_64BIT:
-        res = ::RegOpenKeyEx(key_handle1, subkey, 0, KEY_READ|KEY_WOW64_64KEY, &key_handle2);
-        break;
-      }
+        bool found = false;
+        while(!found && !versions.empty()) {
+            const QString version = versions.takeLast() + "\\InstallPath";
+            LPWSTR lpSubkey = new WCHAR[version.size() + 1];
+            version.toWCharArray(lpSubkey);
+            lpSubkey[version.size()] = 0;
+
+            HKEY hkInstallPath;
+            res = ::RegOpenKeyExW(hkPythonCore, lpSubkey, 0, samDesired, &hkInstallPath);
+            delete[] lpSubkey;
 
-      delete[] subkey;
             if (res == ERROR_SUCCESS) {
                 qDebug("Detected possible Python v%s location", qPrintable(version));
-        QString path = getRegValue(key_handle2);
-        ::RegCloseKey(key_handle2);
+                path = getRegValue(hkInstallPath);
+                ::RegCloseKey(hkInstallPath);
+
                 if (!path.isEmpty() && QDir(path).exists("python.exe")) {
                     qDebug("Found python.exe at %s", qPrintable(path));
-          ::RegCloseKey(key_handle1);
-          return path;
+                    found = true;
                 }
             }
-      else
-        ::RegCloseKey(key_handle2);
         }
+
+        if (!found)
+            path = QString();
+
+        ::RegCloseKey(hkPythonCore);
     }
-  ::RegCloseKey(key_handle1);
-  return QString::null;
+
+    return path;
 }
 
 }
 
-QString Preferences::getPythonPath() {
+QString Preferences::getPythonPath()
+{
     QString path = pythonSearchReg(USER);
-  if (path.isEmpty())
+    if (!path.isEmpty())
+        return path;
+
     path = pythonSearchReg(SYSTEM_32BIT);
-  else return path;
+    if (!path.isEmpty())
+        return path;
 
-  if (path.isEmpty())
     path = pythonSearchReg(SYSTEM_64BIT);
-  else return path;
-
     if (!path.isEmpty())
         return path;
 
@@ -1474,10 +1478,11 @@ QString Preferences::getPythonPath() {
     QStringList supported_versions;
     supported_versions << "32" << "31" << "30" << "27" << "26" << "25";
     foreach (const QString &v, supported_versions) {
-    if (QFile::exists("C:/Python"+v+"/python.exe"))
-      return "C:/Python"+v;
+        if (QFile::exists("C:/Python" + v + "/python.exe"))
+            return "C:/Python" + v;
     }
-  return QString::null;
+
+    return QString();
 }
 
 bool Preferences::neverCheckFileAssoc() const {