X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=cbits%2FinputReady.c;h=51f278feb15a001b2a4239050e0576a70116de3b;hb=7dbb606d7b57cdad87a0ffbdb6ea4a274ebca7c0;hp=f539110f19a8793a11c3c9d8618d5b4d54d74d44;hpb=57ea7ee5ac5f1851ce3cebf2244d48b9d475dc63;p=ghc-base.git

diff --git a/cbits/inputReady.c b/cbits/inputReady.c
index f539110..51f278f 100644
--- a/cbits/inputReady.c
+++ b/cbits/inputReady.c
@@ -56,41 +56,113 @@ fdReady(int fd, int write, int msecs, int isSock)
 	HANDLE hFile = (HANDLE)_get_osfhandle(fd);
 	DWORD avail;
 
-	// WaitForMultipleObjects() works for Console input, but it
-	// doesn't work for pipes (it always returns WAIT_OBJECT_0
-	// even when no data is available).  There doesn't seem to be
-	// an easy way to distinguish the two kinds of HANDLE, so we
-	// try to detect pipe input first, and if that fails we try
-	// WaitForMultipleObjects().
-	//
-	rc = PeekNamedPipe( hFile, NULL, 0, NULL, &avail, NULL );
-	if (rc != 0) {
-	    if (avail != 0) {
-		return 1;
-	    } else {
-		return 0;
-	    }
-	} else {
-	    rc = GetLastError();
-	    if (rc == ERROR_BROKEN_PIPE) {
-		return 1; // this is probably what we want
-	    }
-	    if (rc != ERROR_INVALID_HANDLE) {
-		return -1;
-	    }
-	}
+        switch (GetFileType(hFile)) {
 
-	rc = WaitForMultipleObjects( 1,
-				     &hFile,
-				     TRUE,   /* wait all */
-				     msecs); /*millisecs*/
-	
-	/* 1 => Input ready, 0 => not ready, -1 => error */
-	switch (rc) {
-	case WAIT_TIMEOUT: return 0;
-	case WAIT_OBJECT_0: return 1;
-	default: return -1;
-	}
+        case FILE_TYPE_CHAR:
+        {
+            INPUT_RECORD buf[1];
+            DWORD count;
+
+            // nightmare.  A Console Handle will appear to be ready
+            // (WaitForSingleObject() returned WAIT_OBJECT_0) when
+            // it has events in its input buffer, but these events might
+            // not be keyboard events, so when we read from the Handle the
+            // read() will block.  So here we try to discard non-keyboard
+            // events from a console handle's input buffer and then try
+            // the WaitForSingleObject() again.
+
+            while (1) // keep trying until we find a real key event
+            {
+                rc = WaitForSingleObject( hFile, msecs );
+                switch (rc) {
+                case WAIT_TIMEOUT: return 0;
+                case WAIT_OBJECT_0: break;
+                default: /* WAIT_FAILED */ maperrno(); return -1;
+                }
+
+                while (1) // discard non-key events
+                {
+                    rc = PeekConsoleInput(hFile, buf, 1, &count);
+                    // printf("peek, rc=%d, count=%d, type=%d\n", rc, count, buf[0].EventType);
+                    if (rc == 0) {
+                        rc = GetLastError();
+                        if (rc == ERROR_INVALID_HANDLE || rc == ERROR_INVALID_FUNCTION) {
+                            return 1;
+                        } else {
+                            maperrno();
+                            return -1;
+                        }
+                    }
+
+                    if (count == 0) break; // no more events => wait again
+
+                    // discard console events that are not "key down", because
+                    // these will also be discarded by ReadFile().
+                    if (buf[0].EventType == KEY_EVENT &&
+                        buf[0].Event.KeyEvent.bKeyDown &&
+                        buf[0].Event.KeyEvent.uChar.AsciiChar != '\0')
+                    {
+                        // it's a proper keypress:
+                        return 1;
+                    }
+                    else
+                    {
+                        // it's a non-key event, a key up event, or a
+                        // non-character key (e.g. shift).  discard it.
+                        rc = ReadConsoleInput(hFile, buf, 1, &count);
+                        if (rc == 0) {
+                            rc = GetLastError();
+                            if (rc == ERROR_INVALID_HANDLE || rc == ERROR_INVALID_FUNCTION) {
+                                return 1;
+                            } else {
+                                maperrno();
+                                return -1;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        case FILE_TYPE_DISK:
+            // assume that disk files are always ready:
+            return 1;
+
+        case FILE_TYPE_PIPE:
+            // WaitForMultipleObjects() doesn't work for pipes (it
+            // always returns WAIT_OBJECT_0 even when no data is
+            // available).  If the HANDLE is a pipe, therefore, we try
+            // PeekNamedPipe:
+            //
+            rc = PeekNamedPipe( hFile, NULL, 0, NULL, &avail, NULL );
+            if (rc != 0) {
+                if (avail != 0) {
+                    return 1;
+                } else {
+                    return 0;
+                }
+            } else {
+                rc = GetLastError();
+                if (rc == ERROR_BROKEN_PIPE) {
+                    return 1; // this is probably what we want
+                }
+                if (rc != ERROR_INVALID_HANDLE && rc != ERROR_INVALID_FUNCTION) {
+                    maperrno();
+                    return -1;
+                }
+            }
+            /* PeekNamedPipe didn't work - fall through to the general case */
+
+        default:
+            rc = WaitForSingleObject( hFile, msecs );
+
+            /* 1 => Input ready, 0 => not ready, -1 => error */
+            switch (rc) {
+            case WAIT_TIMEOUT: return 0;
+            case WAIT_OBJECT_0: return 1;
+            default: /* WAIT_FAILED */ maperrno(); return -1;
+            }
+        }
     }
 #endif
 }