Ticket #10732: DeviceReadBuffer.cpp-patch

--- DeviceReadBuffer.cpp.orig   2012-10-03 19:40:49.000000000 -0400
+++ DeviceReadBuffer.cpp        2012-10-03 19:37:28.000000000 -0400
@@ -421,7 +421,7 @@
         "mingw DeviceReadBuffer::Poll is not implemented");
     return false;
 #else
-    bool retval = true;
+    bool retval;
     MythTimer timer;
     timer.start();
 
@@ -441,6 +441,7 @@
         polls[1].revents = 0;
     }
 
+    retval = true;
     while (true)
     {
         polls[0].revents = 0;
@@ -455,65 +456,75 @@
 
         int ret = poll(polls, poll_cnt, timeout);
 
-        if (polls[0].revents & (POLLHUP | POLLNVAL))
-        {
-            LOG(VB_GENERAL, LOG_ERR, LOC + "poll error");
-            error = true;
-            return true;
-        }
-
         if (!dorun || !IsOpen() || IsPauseRequested())
         {
-            retval = false;
-            break; // are we supposed to pause, stop, etc.
+            return false; // are we supposed to pause, stop, etc.
         }
-
-        if (polls[0].revents & POLLPRI)
+    
+        if (ret < 0) // error
         {
-            readerCB->PriorityEvent(polls[0].fd);
-        }
+           if ((EOVERFLOW == errno))
+           // TODO shouldn't this lock and then set error=true?
+               break; // we have an error to handle
+
+            if ((EAGAIN == errno) || (EINTR  == errno))
+                continue; // errors that tell you to try again
 
-        if (polls[0].revents & POLLIN)
+            usleep(2500 /*2.5 ms*/);
+        }
+        else if (ret == 0) // timeout
         {
-            if (ret > 0)
-                break; // we have data to read :)
-            else if (ret < 0)
-            {
-                if ((EOVERFLOW == errno))
-                    break; // we have an error to handle
-
-                if ((EAGAIN == errno) || (EINTR  == errno))
-                    continue; // errors that tell you to try again
-
-                usleep(2500 /*2.5 ms*/);
-            }
-            else //  ret == 0
-            {
-                if (poll_timeout_is_error &&
-                    (timer.elapsed() >= (int)max_poll_wait))
-                {
-                    LOG(VB_GENERAL, LOG_ERR, LOC + "Poll giving up 1");
-                    QMutexLocker locker(&lock);
-                    error = true;
-                    return true;
-                }
+            if (poll_timeout_is_error &&
+                (timer.elapsed() >= (int)max_poll_wait))
+            {
+                LOG(VB_GENERAL, LOG_ERR, LOC + "Poll giving up 1");
+                QMutexLocker locker(&lock);
+                error = true;
+                return true;
             }
         }
-
-        // Clear out any pending pipe reads
-        if ((poll_cnt > 1) && (polls[1].revents & POLLIN))
+        else // normal return - some event available
         {
-            char dummy[128];
-            int cnt = (wake_pipe_flags[0] & O_NONBLOCK) ? 128 : 1;
-            cnt = ::read(wake_pipe[0], dummy, cnt);
-        }
+            if (polls[0].revents & POLLHUP)
+            {
+                LOG(VB_GENERAL, LOG_ERR, LOC + "poll eof (POLLHUP)");
+                break;
+            }
+            else if (polls[0].revents & POLLNVAL)
+            {
+                LOG(VB_GENERAL, LOG_ERR, LOC + "poll error (POLLINVAL)");
+                QMutexLocker locker(&lock);
+                error = true;
+                return true;
+            } 
 
-        if (poll_timeout_is_error && (timer.elapsed() >= (int)max_poll_wait))
-        {
-            LOG(VB_GENERAL, LOG_ERR, LOC + "Poll giving up 2");
-            QMutexLocker locker(&lock);
-            error = true;
-            return true;
+            if (polls[0].revents & POLLPRI)
+            {
+                readerCB->PriorityEvent(polls[0].fd);
+            }
+        
+            // Clear out any pending pipe reads
+            if (polls[1].revents & POLLIN)
+            {
+                char dummy[128];
+                int cnt = (wake_pipe_flags[0] & O_NONBLOCK) ? 128 : 1;
+                cnt = ::read(wake_pipe[0], dummy, cnt);
+            }
+        
+            // we have data to read :)
+            if (polls[0].revents & POLLIN)
+            {
+                break;
+            }
+        
+            if (poll_timeout_is_error && 
+            (timer.elapsed() >= (int)max_poll_wait))
+            {
+                LOG(VB_GENERAL, LOG_ERR, LOC + "Poll giving up 2");
+                QMutexLocker locker(&lock);
+                error = true;
+                return true;
+            }
         }
     }