Make standalone installations relocatable

This is achieved by registering a qt.conf file with a Prefix pointing
to a directory relative to the loaded PySide2 module (e.g. QtCore).
Thus Qt does not crash due to not finding platform plugins.

Because this change would affect tests, which are ran before the
PySide package is installed, a new environment variable called
PYSIDE_DISABLE_INTERNAL_QT_CONF is introduced. This variable disables
the registration of the internal qt.conf file, thus it will not point
to a not yet created location, which will allow tests to run as
before.

Change-Id: I5a96037adfafe1f08ea57535aa4a2a0d1660dfaf
Task-number: PYSIDE-558
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Christian Tismer <tismer@stackless.com>

1 files changed, 129 insertions, 1 deletions

diff --git a/sources/pyside2/libpyside/pyside.cpp b/sources/pyside2/libpyside/pyside.cpp
index 17366ce6e..b223edc6c 100644
--- a/sources/pyside2/libpyside/pyside.cpp
+++ b/sources/pyside2/libpyside/pyside.cpp
@@ -61,14 +61,20 @@
 #include <typeinfo>
 #include <cstring>
 #include <cctype>
-#include <QStack>
+#include <QByteArray>
 #include <QCoreApplication>
 #include <QDebug>
+#include <QDir>
+#include <QFileInfo>
 #include <QSharedPointer>
+#include <QStack>
 
 static QStack<PySide::CleanupFunction> cleanupFunctionList;
 static void* qobjectNextAddr;
 
+extern bool qRegisterResourceData(int, const unsigned char *, const unsigned char *,
+        const unsigned char *);
+
 namespace PySide
 {
 
@@ -387,5 +393,127 @@ void setQuickRegisterItemFunction(QuickRegisterItemFunction function)
 }
 #endif // PYSIDE_QML_SUPPORT
 
+// Inspired by Shiboken::String::toCString;
+QString pyStringToQString(PyObject *str) {
+    if (str == Py_None)
+        return QString();
+
+#ifdef IS_PY3K
+    if (PyUnicode_Check(str)) {
+        const char *unicodeBuffer = _PyUnicode_AsString(str);
+        if (unicodeBuffer)
+            return QString::fromUtf8(unicodeBuffer);
+    }
+#endif
+    if (PyBytes_Check(str)) {
+        const char *asciiBuffer = PyBytes_AS_STRING(str);
+        if (asciiBuffer)
+            return QString::fromLatin1(asciiBuffer);
+    }
+    return QString();
+}
+
+static const unsigned char qt_resource_name[] = {
+  // qt
+  0x0,0x2,
+  0x0,0x0,0x7,0x84,
+  0x0,0x71,
+  0x0,0x74,
+    // etc
+  0x0,0x3,
+  0x0,0x0,0x6c,0xa3,
+  0x0,0x65,
+  0x0,0x74,0x0,0x63,
+    // qt.conf
+  0x0,0x7,
+  0x8,0x74,0xa6,0xa6,
+  0x0,0x71,
+  0x0,0x74,0x0,0x2e,0x0,0x63,0x0,0x6f,0x0,0x6e,0x0,0x66
+};
+
+static const unsigned char qt_resource_struct[] = {
+  // :
+  0x0,0x0,0x0,0x0,0x0,0x2,0x0,0x0,0x0,0x1,0x0,0x0,0x0,0x1,
+  // :/qt
+  0x0,0x0,0x0,0x0,0x0,0x2,0x0,0x0,0x0,0x1,0x0,0x0,0x0,0x2,
+  // :/qt/etc
+  0x0,0x0,0x0,0xa,0x0,0x2,0x0,0x0,0x0,0x1,0x0,0x0,0x0,0x3,
+  // :/qt/etc/qt.conf
+  0x0,0x0,0x0,0x16,0x0,0x0,0x0,0x0,0x0,0x1,0x0,0x0,0x0,0x0
+};
+
+bool registerInternalQtConf()
+{
+    // Guard to ensure single registration.
+#ifdef PYSIDE_QT_CONF_PREFIX
+        static bool registrationAttempted = false;
+#else
+        static bool registrationAttempted = true;
+#endif
+    static bool isRegistered = false;
+    if (registrationAttempted)
+        return isRegistered;
+    registrationAttempted = true;
+
+    // Allow disabling the usage of the internal qt.conf. This is necessary for tests to work,
+    // because tests are executed before the package is installed, and thus the Prefix specified
+    // in qt.conf would point to a not yet existing location.
+    bool disableInternalQtConf =
+            qEnvironmentVariableIntValue("PYSIDE_DISABLE_INTERNAL_QT_CONF") > 0 ? true : false;
+    if (disableInternalQtConf) {
+        registrationAttempted = true;
+        return false;
+    }
+
+    PyObject *pysideModule = PyImport_ImportModule("PySide2");
+    if (!pysideModule)
+        return false;
+
+    // Querying __file__ should be done only for modules that have finished their initialization.
+    // Thus querying for the top-level PySide2 package works for us whenever any Qt-wrapped module
+    // is loaded.
+    PyObject *pysideInitFilePath = PyObject_GetAttrString(pysideModule, "__file__");
+    Py_DECREF(pysideModule);
+    if (!pysideInitFilePath)
+        return false;
+
+    QString initPath = pyStringToQString(pysideInitFilePath);
+    Py_DECREF(pysideInitFilePath);
+    if (initPath.isEmpty())
+        return false;
+
+    // pysideDir - absolute path to the directory containing the init file, which also contains
+    // the rest of the PySide2 modules.
+    // prefixPath - absolute path to the directory containing the installed Qt (prefix).
+    QDir pysideDir = QFileInfo(QDir::fromNativeSeparators(initPath)).absoluteDir();
+    QString setupPrefix;
+#ifdef PYSIDE_QT_CONF_PREFIX
+    setupPrefix = QStringLiteral(PYSIDE_QT_CONF_PREFIX);
+#endif
+    QString prefixPath = pysideDir.absoluteFilePath(setupPrefix);
+
+    // rccData needs to be static, otherwise when it goes out of scope, the Qt resource system
+    // will point to invalid memory.
+    static QByteArray rccData = QByteArray("[Paths]\nPrefix = ") + prefixPath.toLocal8Bit();
+    rccData.append('\n');
+
+    // The RCC data structure expects a 4-byte size value representing the actual data.
+    int size = rccData.size();
+
+    for (int i = 0; i < 4; ++i) {
+        rccData.prepend((size & 0xff));
+        size >>= 8;
+    }
+
+    const int version = 0x01;
+    isRegistered = qRegisterResourceData(version, qt_resource_struct, qt_resource_name,
+                                         reinterpret_cast<const unsigned char *>(
+                                             rccData.constData()));
+
+    return isRegistered;
+}
+
+
+
 } //namespace PySide