[Lldb-commits] [lldb] r202311 - A better long term fix for stopping the process when it is running by writing to the pipe that was used for cancel.

[Greg Clayton]

Author: gclayton
Date: Wed Feb 26 16:47:33 2014
New Revision: 202311

URL: http://llvm.org/viewvc/llvm-project?rev=202311&view=rev
Log:
A better long term fix for stopping the process when it is running by writing to the pipe that was used for cancel. 

We now write a 'q' to indicate to exit the IOHandlerProcessSTDIO::Run(), and a 'i' to interrupt the process. This should make this code safer to use in a signal handler function.


Modified:
    lldb/trunk/source/Target/Process.cpp

Modified: lldb/trunk/source/Target/Process.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/Process.cpp?rev=202311&r1=202310&r2=202311&view=diff
==============================================================================
--- lldb/trunk/source/Target/Process.cpp (original)
+++ lldb/trunk/source/Target/Process.cpp Wed Feb 26 16:47:33 2014
@@ -4793,7 +4793,16 @@ public:
                             // Consume the interrupt byte
                             n = 1;
                             m_pipe_read.Read (&ch, n);
-                            SetIsDone(true);
+                            switch (ch)
+                            {
+                                case 'q':
+                                    SetIsDone(true);
+                                    break;
+                                case 'i':
+                                    if (StateIsRunningState(m_process->GetState()))
+                                        m_process->Halt();
+                                    break;
+                            }
                         }
                     }
                 }
@@ -4829,15 +4838,28 @@ public:
     Cancel ()
     {
         size_t n = 1;
-        char ch = 'q';
+        char ch = 'q';  // Send 'q' for quit
         m_pipe_write.Write (&ch, n);
     }
 
     virtual void
     Interrupt ()
     {
+#ifdef _MSC_VER
+        // Windows doesn't support pipes, so we will send an async interrupt
+        // event to stop the process
         if (StateIsRunningState(m_process->GetState()))
             m_process->SendAsyncInterrupt();
+#else
+        // Do only things that are safe to do in an interrupt context (like in
+        // a SIGINT handler), like write 1 byte to a file descriptor. This will
+        // interrupt the IOHandlerProcessSTDIO::Run() and we can look at the byte
+        // that was written to the pipe and then call m_process->Halt() from a
+        // much safer location in code.
+        size_t n = 1;
+        char ch = 'i'; // Send 'i' for interrupt
+        m_pipe_write.Write (&ch, n);
+#endif
     }
     
     virtual void