Handles special errors from FlushFileBuffers() for Windows.

cmdline/mingw.c

@@ -810,8 +810,30 @@ int windows_fsync(int fd)
 	}
 
 	if (!FlushFileBuffers(h)) {
-		windows_errno(GetLastError());
-		return -1;
+		DWORD error = GetLastError();
+
+		switch (error) {
+		case ERROR_INVALID_HANDLE :
+			/*
+			 * FlushFileBuffers returns this error if the handle
+			 * doesn't support buffering, like the console output.
+			 *
+			 * We had report also for ATA-over-Ethernet reporting this
+			 * error.
+			 */
+			return 0;
+
+		case ERROR_ACCESS_DENIED
+			/*
+			 * FlushFileBuffers returns this error for read-only
+			 * data, that cannot have to be flushed.
+			 */
+			return 0;
+
+		default:
+			windows_errno(error);
+			return -1;
+		}
 	}
 
 	return 0;