CDB extension: Add qmlstack command and helpers.

Add a command that dumps the QML stack. It tries to find
the address of the JS execution context in a complete stack
trace and calls the exported function in QML to create the
trace from it.

Task-number: QTCREATORBUG-11144

Change-Id: I8fef5df2b33b95748e78d837aba703945eaeead9
Reviewed-by: David Schulz <david.schulz@digia.com>

src/libs/qtcreatorcdbext/extensioncontext.cpp

@@ -29,6 +29,7 @@
 
 #include "extensioncontext.h"
 #include "symbolgroup.h"
+#include "symbolgroupvalue.h"
 #include "eventcallback.h"
 #include "outputcallback.h"
 #include "stringutils.h"
@@ -189,6 +190,80 @@ ULONG ExtensionContext::executionStatus() const
     return (m_control && SUCCEEDED(m_control->GetExecutionStatus(&ex))) ? ex : ULONG(0);
 }
 
+// Helpers for finding the address of the JS execution context in
+// case of a QML crash: Find module
+static std::string findModule(CIDebugSymbols *syms,
+                              const std::string &name,
+                              std::string *errorMessage)
+{
+    const Modules mods = getModules(syms, errorMessage);
+    const size_t count = mods.size();
+    for (size_t m = 0; m < count; ++m)
+        if (!mods.at(m).name.compare(0, name.size(), name))
+            return mods.at(m).name;
+    return std::string();
+}
+
+// Try to find a JS execution context passed as parameter in a complete stack dump (kp)
+static ULONG64 jsExecutionContextFromStackTrace(const std::wstring &stack)
+{
+    // Search for "QV4::ExecutionContext * - varying variable names - 0x...[,)]"
+    const wchar_t needle[] = L"struct QV4::ExecutionContext * "; // .. varying variable names .. 0x...
+    const std::string::size_type varPos = stack.find(needle);
+    if (varPos == std::string::npos)
+        return 0;
+    const std::string::size_type varEnd = varPos + sizeof(needle) / sizeof(wchar_t) - 1;
+    std::string::size_type numPos = stack.find(L"0x", varEnd);
+    if (numPos == std::string::npos || numPos > (varEnd + 20))
+        return 0;
+    numPos += 2;
+    const std::string::size_type endPos = stack.find_first_of(L",)", numPos);
+    if (endPos == std::string::npos)
+        return 0;
+    // Fix hex values: (0x)000000f5`cecae5b0 -> (0x)000000f5cecae5b0
+    std::wstring address = stack.substr(numPos, endPos - numPos);
+    if (address.size() > 8 && address.at(8) == L'`')
+        address.erase(8, 1);
+    std::wistringstream str(address);
+    ULONG64 result;
+    str >> std::hex >> result;
+    return str.fail() ? 0 : result;
+}
+
+// Try to find address of jsExecutionContext by looking at the
+// stack trace in case QML is loaded.
+ULONG64 ExtensionContext::jsExecutionContext(ExtensionCommandContext &exc,
+                                             std::string *errorMessage)
+{
+
+    const QtInfo &qtInfo = QtInfo::get(SymbolGroupValueContext(exc.dataSpaces(), exc.symbols()));
+    static const std::string qmlModule =
+        findModule(exc.symbols(), qtInfo.moduleName(QtInfo::Qml), errorMessage);
+    if (qmlModule.empty()) {
+        if (errorMessage->empty())
+            *errorMessage = "QML not loaded";
+        return 0;
+    }
+    // Retrieve full stack (costly) and try to find a JS execution context passed as parameter
+    startRecordingOutput();
+    StateNotificationBlocker blocker(this);
+    const HRESULT hr = m_control->Execute(DEBUG_OUTCTL_ALL_CLIENTS, "kp", DEBUG_EXECUTE_ECHO);
+    if (FAILED(hr)) {
+        stopRecordingOutput();
+        *errorMessage = msgDebugEngineComFailed("Execute", hr);
+        return 0;
+    }
+    const std::wstring fullStackTrace = stopRecordingOutput();
+    if (fullStackTrace.empty()) {
+        *errorMessage = "Unable to obtain stack (output redirection in place?)";
+        return 0;
+    }
+    const ULONG64 result = jsExecutionContextFromStackTrace(fullStackTrace);
+    if (!result)
+        *errorMessage = "JS ExecutionContext address not found in stack";
+    return result;
+}
+
 // Complete stop parameters with common parameters and report
 static inline ExtensionContext::StopReasonMap
     completeStopReasons(CIDebugClient *client, ExtensionContext::StopReasonMap stopReasons, ULONG ex)