Fix a hang on OSX while executing -exec-run.

Now we wait for input to become available before blocking in fgets.
More details on problem can be found in 
http://lists.cs.uiuc.edu/pipermail/lldb-commits/Week-of-Mon-20141201/014290.html

Patch from dawn@burble.org.

llvm-svn: 223222

lldb/tools/lldb-mi/MICmnStreamStdin.cpp

@@ -434,3 +434,16 @@ CMICmnStreamStdin::SetOSStdinHandler(IOSStdinHandler &vrHandler)
 
     return MIstatus::success;
 }
+
+//++ ------------------------------------------------------------------------------------
+// Details: Do some actions before exiting.
+// Type:    Method.
+// Args:    None.
+// Return:  None.
+// Throws:  None.
+//--
+void
+CMICmnStreamStdin::OnExitHandler(void)
+{
+    m_pStdinReadHandler->InterruptReadLine();
+}

lldb/tools/lldb-mi/MICmnStreamStdin.h

@@ -66,6 +66,7 @@ class CMICmnStreamStdin : public CMICmnBase, public CMIUtilThreadActiveObjBase,
       public:
         virtual bool InputAvailable(bool &vwbAvail) = 0;
         virtual const MIchar *ReadLine(CMIUtilString &vwErrMsg) = 0;
+        virtual void InterruptReadLine(void){};
 
         /* dtor */ virtual ~IOSStdinHandler(void){};
     };
@@ -82,6 +83,7 @@ class CMICmnStreamStdin : public CMICmnBase, public CMIUtilThreadActiveObjBase,
     void SetCtrlCHit(void);
     bool SetVisitor(IStreamStdin &vrVisitor);
     bool SetOSStdinHandler(IOSStdinHandler &vrHandler);
+    void OnExitHandler(void);
 
     // Overridden:
   public:

lldb/tools/lldb-mi/MICmnStreamStdinLinux.cpp

@@ -22,7 +22,9 @@
 // Third Party Headers:
 #if !defined(_MSC_VER)
 #include <sys/select.h>
+#include <unistd.h>
 #include <termios.h>
+#include <sys/ioctl.h>
 #endif              // !defined( _MSC_VER )
 #include <string.h> // For std::strerror()
 
@@ -153,30 +155,29 @@ CMICmnStreamStdinLinux::Shutdown(void)
 bool
 CMICmnStreamStdinLinux::InputAvailable(bool &vwbAvail)
 {
-    /* AD: Not used ATM but could come in handy just in case we need to do
-           this, poll for input
+#if !defined(_WIN32)
+    // The code below is needed on OSX where lldb-mi hangs when doing -exec-run.
+    // The hang seems to come from calling fgets and fileno from different thread.
+    // Although this problem was not observed on Linux.
+    // A solution based on 'select' was also proposed but it seems to slow things down
+    // a lot.
+    static bool bInitialized = false;
 
-            static const int STDIN = 0;
-        static bool bInitialized = false;
-
-        if( !bInitialized )
-            {
-            // Use termios to turn off line buffering
-            ::termios term;
-            ::tcgetattr( STDIN, &term );
-            ::term.c_lflag &= ~ICANON;
-            ::tcsetattr( STDIN, TCSANOW, &term );
-            ::setbuf( stdin, NULL );
-            bInitialized = true;
-        }
-
-        int nBytesWaiting;
-        ::ioctl( STDIN, FIONREAD, &nBytesWaiting );
-        vwbAvail = (nBytesWaiting > 0);
-
-            return MIstatus::success;
-    */
+    if (!bInitialized)
+    {
+        // Use termios to turn off line buffering
+        ::termios term;
+        ::tcgetattr(STDIN_FILENO, &term);
+        term.c_lflag &= ~ICANON;
+        ::tcsetattr(STDIN_FILENO, TCSANOW, &term);
+        ::setbuf(stdin, NULL);
+        bInitialized = true;
+    }
 
+    int nBytesWaiting;
+    ::ioctl(STDIN_FILENO, FIONREAD, &nBytesWaiting);
+    vwbAvail = (nBytesWaiting > 0);
+#endif
     return MIstatus::success;
 }
 
@@ -213,3 +214,16 @@ CMICmnStreamStdinLinux::ReadLine(CMIUtilString &vwErrMsg)
 
     return pText;
 }
+
+//++ ------------------------------------------------------------------------------------
+// Details: Interrupt current and prevent new ReadLine operations.
+// Type:    Method.
+// Args:    None.
+// Return:  None.
+// Throws:  None.
+//--
+void
+CMICmnStreamStdinLinux::InterruptReadLine(void)
+{
+    fclose(stdin);
+}

lldb/tools/lldb-mi/MICmnStreamStdinLinux.h

@@ -51,6 +51,7 @@ class CMICmnStreamStdinLinux : public CMICmnBase, public CMICmnStreamStdin::IOSS
     // From CMICmnStreamStdin::IOSpecificReadStreamStdin
     virtual bool InputAvailable(bool &vwbAvail);
     virtual const MIchar *ReadLine(CMIUtilString &vwErrMsg);
+    virtual void InterruptReadLine(void);
 
     // Methods:
   private:

lldb/tools/lldb-mi/MIDriver.cpp

@@ -1075,6 +1075,7 @@ CMIDriver::SetExitApplicationFlag(const bool vbForceExit)
     {
         CMIUtilThreadLock lock(m_threadMutex);
         m_bExitApp = true;
+        m_rStdin.OnExitHandler();
         return;
     }
 
@@ -1089,6 +1090,7 @@ CMIDriver::SetExitApplicationFlag(const bool vbForceExit)
     }
 
     m_bExitApp = true;
+    m_rStdin.OnExitHandler();
 }
 
 //++ ------------------------------------------------------------------------------------