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);
-  if (res == ERROR_SUCCESS) {
-    max_subkey_len++; //For null character
-    LPTSTR key_name = new TCHAR[max_subkey_len];
 
-    for (uint i=0; i<subkeys_count; i++) {
+    DWORD cSubKeys = 0;
-      res = ::RegEnumKeyEx(handle, 0, key_name, &max_subkey_len, NULL, NULL, NULL, NULL);
+    DWORD cMaxSubKeyLen = 0;
+    LONG res = ::RegQueryInfoKeyW(handle, NULL, NULL, NULL, &cSubKeys, &cMaxSubKeyLen, NULL, NULL, NULL, NULL, NULL, NULL);
+
+    if (res == ERROR_SUCCESS) {
+        cMaxSubKeyLen++; // For null character
+        LPWSTR lpName = new WCHAR[cMaxSubKeyLen];
+        DWORD cName;
+
+        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 getRegValue(HKEY handle, const QString &name = QString())
-  QString end_result;
+{
-  DWORD type = 0;
+    QString result;
-  DWORD size = 0;
-  DWORD array_size = 0;
 
-  LPTSTR value_name = NULL;
+    DWORD type = 0;
+    DWORD cbData = 0;
+    LPWSTR lpValueName = NULL;
     if (!name.isEmpty()) {
-    value_name = new TCHAR[name.size()+1];
+        lpValueName = new WCHAR[name.size() + 1];
-    name.toWCharArray(value_name);
+        name.toWCharArray(lpValueName);
-    value_name[name.size()] = '\0';
+        lpValueName[name.size()] = 0;
     }
 
     // Discover the size of the value
-  ::RegQueryValueEx(handle, value_name, NULL, &type, NULL, &size);
+    ::RegQueryValueExW(handle, lpValueName, NULL, &type, NULL, &cbData);
-  array_size = size / sizeof(TCHAR);
+    DWORD cBuffer = (cbData / sizeof(WCHAR)) + 1;
-  if (size % sizeof(TCHAR))
+    LPWSTR lpData = new WCHAR[cBuffer];
-    array_size++;
+    LONG res = ::RegQueryValueExW(handle, lpValueName, NULL, &type, (LPBYTE)lpData, &cbData);
-  array_size++; //For null character
+    if (lpValueName)
-  LPTSTR value = new TCHAR[array_size];
+        delete[] lpValueName;
-
-  long res = ::RegQueryValueEx(handle, value_name, NULL, &type, (LPBYTE)value, &size);
-  if (res == ERROR_SUCCESS) {
-    value[array_size] = '\0';
-    end_result = QString::fromWCharArray(value);
-  }
-
-  if (value_name)
-    delete[] value_name;
-  if (value)
-    delete[] value;
-
-  return end_result;
-}
-
-QString pythonSearchReg(const REG_SEARCH_TYPE type) {
-  HKEY key_handle1;
-  long res = 0;
-
-  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;
-  }
 
     if (res == ERROR_SUCCESS) {
-    QStringList versions = getRegSubkeys(key_handle1);
+        lpData[cBuffer] = 0;
+        result = QString::fromWCharArray(lpData);
+    }
+    delete[] lpData;
+
+    return result;
+}
+
+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;
+
+    QString path;
+    LONG res = 0;
+    HKEY hkPythonCore;
+    res = ::RegOpenKeyExW(hkRoot, L"SOFTWARE\\Python\\PythonCore", 0, samDesired, &hkPythonCore);
+
+    if (res == ERROR_SUCCESS) {
+        QStringList versions = getRegSubkeys(hkPythonCore);
         qDebug("Python versions nb: %d", versions.size());
         versions.sort();
 
-    while(!versions.empty()) {
+        bool found = false;
+        while(!found && !versions.empty()) {
             const QString version = versions.takeLast() + "\\InstallPath";
-      HKEY key_handle2;
+            LPWSTR lpSubkey = new WCHAR[version.size() + 1];
-      LPTSTR subkey = new TCHAR[version.size()+1];
+            version.toWCharArray(lpSubkey);
-      version.toWCharArray(subkey);
+            lpSubkey[version.size()] = 0;
-      subkey[version.size()] = '\0';
 
-      switch (type) {
+            HKEY hkInstallPath;
-      case USER:
+            res = ::RegOpenKeyExW(hkPythonCore, lpSubkey, 0, samDesired, &hkInstallPath);
-        res = ::RegOpenKeyEx(key_handle1, subkey, 0, KEY_READ, &key_handle2);
+            delete[] lpSubkey;
-        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;
-      }
 
-      delete[] subkey;
             if (res == ERROR_SUCCESS) {
                 qDebug("Detected possible Python v%s location", qPrintable(version));
-        QString path = getRegValue(key_handle2);
+                path = getRegValue(hkInstallPath);
-        ::RegCloseKey(key_handle2);
+                ::RegCloseKey(hkInstallPath);
+
                 if (!path.isEmpty() && QDir(path).exists("python.exe")) {
                     qDebug("Found python.exe at %s", qPrintable(path));
-          ::RegCloseKey(key_handle1);
+                    found = true;
+                }
+            }
+        }
+
+        if (!found)
+            path = QString();
+
+        ::RegCloseKey(hkPythonCore);
+    }
+
     return path;
 }
-      }
-      else
-        ::RegCloseKey(key_handle2);
-    }
-  }
-  ::RegCloseKey(key_handle1);
-  return QString::null;
-}
 
 }
 
-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;
 
@@ -1477,7 +1481,8 @@ QString Preferences::getPythonPath() {
         if (QFile::exists("C:/Python" + v + "/python.exe"))
             return "C:/Python" + v;
     }
-  return QString::null;
+
+    return QString();
 }
 
 bool Preferences::neverCheckFileAssoc() const {