actively try to obtain PID of non-pthread inferiors with gdb < 7 on linux

Reviewed-by: hjk

src/plugins/debugger/gdb/gdbengine.cpp

@@ -1152,14 +1152,21 @@ void GdbEngine::handleStopResponse(const GdbMi &data)
     setState(InferiorStopped);
 
 #ifdef Q_OS_LINUX
-    // For some reason, attaching to a stopped process causes *two* stops
-    // when trying to continue (kernel i386 2.6.24-23-ubuntu, gdb 6.8).
-    // Interestingly enough, on MacOSX no signal is delivered at all.
     if (!m_entryPoint.isEmpty()) {
-        if (reason == "signal-received"
-            && data.findChild("signal-name").data() == "SIGSTOP") {
-            GdbMi frameData = data.findChild("frame");
-            if (frameData.findChild("addr").data() == m_entryPoint) {
+        GdbMi frameData = data.findChild("frame");
+        if (frameData.findChild("addr").data() == m_entryPoint) {
+            if (reason == "signal-received"
+                && data.findChild("signal-name").data() == "SIGSTOP") {
+                // For some reason, attaching to a stopped process causes *two* stops
+                // when trying to continue (kernel i386 2.6.24-23-ubuntu, gdb 6.8).
+                // Interestingly enough, on MacOSX no signal is delivered at all.
+                continueInferiorInternal();
+                return;
+            }
+            if (reason.isEmpty()) { // tbreak does that
+                // For programs without -pthread under gdb <= 6.8.
+                if (!inferiorPid())
+                    postCommand(_("info proc"), CB(handleInfoProc));
                 continueInferiorInternal();
                 return;
             }
@@ -1325,6 +1332,18 @@ void GdbEngine::handleStop1(const GdbMi &data)
     manager()->reloadRegisters();
 }
 
+#ifdef Q_OS_LINUX
+void GdbEngine::handleInfoProc(const GdbResponse &response)
+{
+    if (response.resultClass == GdbResultDone) {
+        static QRegExp re(_("\\bprocess ([0-9]+)\n"));
+        QTC_ASSERT(re.isValid(), return);
+        if (re.indexIn(_(response.data.findChild("consolestreamoutput").data())) != -1)
+            maybeHandleInferiorPidChanged(re.cap(1));
+    }
+}
+#endif
+
 void GdbEngine::handleShowVersion(const GdbResponse &response)
 {
     //qDebug () << "VERSION 2:" << response.data.findChild("consolestreamoutput").data();

src/plugins/debugger/gdb/gdbengine.h

@@ -302,6 +302,8 @@ private: ////////// Inferior Management //////////
     void maybeHandleInferiorPidChanged(const QString &pid);
 
 #ifdef Q_OS_LINUX
+    void handleInfoProc(const GdbResponse &response);
+
     QByteArray m_entryPoint;
 #endif
 

src/plugins/debugger/gdb/plaingdbadapter.cpp

@@ -110,6 +110,13 @@ void PlainGdbAdapter::handleFileExecAndSymbols(const GdbResponse &response)
 {
     QTC_ASSERT(state() == InferiorStarting, qDebug() << state());
     if (response.resultClass == GdbResultDone) {
+#ifdef Q_OS_LINUX
+        // Old gdbs do not announce the PID for programs without pthreads.
+        // Note that successfully preloading the debugging helpers will
+        // automatically load pthreads, so this will be unnecessary.
+        if (m_engine->m_gdbVersion < 70000)
+            m_engine->postCommand(_("info target"), CB(handleInfoTarget));
+#endif
         emit inferiorPrepared();
     } else {
         QString msg = tr("Starting executable failed:\n") +
@@ -118,6 +125,29 @@ void PlainGdbAdapter::handleFileExecAndSymbols(const GdbResponse &response)
     }
 }
 
+#ifdef Q_OS_LINUX
+void PlainGdbAdapter::handleInfoTarget(const GdbResponse &response)
+{
+    if (response.resultClass == GdbResultDone) {
+        // [some leading stdout here]
+        // >&"        Entry point: 0x80831f0  0x08048134 - 0x08048147 is .interp\n"
+        // [some trailing stdout here]
+        QString msg = _(response.data.findChild("consolestreamoutput").data());
+        QRegExp needle(_("\\bEntry point: 0x([0-9a-f]+)\\b"));
+        if (needle.indexIn(msg) != -1) {
+            m_engine->m_entryPoint =
+                    "0x" + needle.cap(1).toLatin1().rightJustified(sizeof(void *) * 2, '0');
+            m_engine->postCommand(_("tbreak *0x") + needle.cap(1));
+            // Do nothing here - inferiorPrepared handles the sequencing.
+        } else {
+            emit inferiorStartFailed(_("Parsing start address failed"));
+        }
+    } else if (response.resultClass == GdbResultError) {
+        emit inferiorStartFailed(_("Fetching start address failed"));
+    }
+}
+#endif
+
 void PlainGdbAdapter::startInferiorPhase2()
 {
     setState(InferiorRunningRequested);

src/plugins/debugger/gdb/plaingdbadapter.h

@@ -62,6 +62,9 @@ public:
 private:
     void handleFileExecAndSymbols(const GdbResponse &response);
     void handleExecRun(const GdbResponse &response);
+#ifdef Q_OS_LINUX
+    void handleInfoTarget(const GdbResponse &response);
+#endif
 
     OutputCollector m_outputCollector;
 };