[project @ 2004-11-17 19:07:38 by sof]

[ghc-hetmet.git] / ghc / rts / win32 / IOManager.c

diff --git a/ghc/rts/win32/IOManager.c b/ghc/rts/win32/IOManager.c
index c08c4e3..96e5794 100644 (file)
--- a/ghc/rts/win32/IOManager.c
+++ b/ghc/rts/win32/IOManager.c
@@ -42,7 +42,7 @@ IOWorkerProc(PVOID param)
     WorkQueue* pq = iom->workQueue;
     WorkItem*  work;
     int        len = 0, fd = 0;
-    DWORD      errCode;
+    DWORD      errCode = 0;
     void*      complData;
 
     hWaits[0] = (HANDLE)iom->hExitEvent;
@@ -96,9 +96,40 @@ IOWorkerProc(PVOID param)
                            errCode = WSAGetLastError();
                        }
                    } else {
+                       DWORD dw;
+
+                       /* Do the read(), with extra-special handling for Ctrl+C */
                        len = read(work->workData.ioData.fd,
                                   work->workData.ioData.buf,
                                   work->workData.ioData.len);
+                       if ( len == 0 && work->workData.ioData.len != 0 ) {
+                           /* Given the following scenario:
+                            *     - a console handler has been registered that handles Ctrl+C
+                            *       events.
+                            *     - we've not tweaked the 'console mode' settings to turn on
+                            *       ENABLE_PROCESSED_INPUT.
+                            *     - we're blocked waiting on input from standard input.
+                            *     - the user hits Ctrl+C.
+                            *
+                            * The OS will invoke the console handler (in a separate OS thread),
+                            * and the above read() (i.e., under the hood, a ReadFile() op) returns
+                            * 0, with the error set to ERROR_OPERATION_ABORTED. We don't
+                            * want to percolate this non-EOF condition too far back up, but ignore
+                            * it. However, we do want to give the RTS an opportunity to deliver the
+                            * console event.
+                            * 
+                            * Hence, we set 'errorCode' to (-2), which we then look out for in
+                            * GHC.Conc.asyncRead.
+                            */
+                           dw = GetLastError();
+                           if ( dw == ERROR_OPERATION_ABORTED ) {
+                               /* Only do the retry when dealing with the standard input handle. */
+                               HANDLE h  = (HANDLE)GetStdHandle(STD_INPUT_HANDLE);
+                               if ( _get_osfhandle(work->workData.ioData.fd) == (long)h ) {
+                                   errCode = (DWORD)-2;
+                               }
+                           }
+                       }
                        if (len == -1) { errCode = errno; }
                    }
                    complData = work->workData.ioData.buf;