From 5538b3e4ae6dee32c47db9dfc85b07bbe7b90f6c Mon Sep 17 00:00:00 2001 From: Adam Jackson Date: Fri, 24 Mar 2017 11:07:36 -0400 Subject: [PATCH 2/2] _XDefaultIOError: Do better at detecting explicit shutdown Currently, when the X server crashes or a client is disconnected with XKillClient, you get a somewhat confusing error message from libX11 along the lines of: XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":0" after 98 requests (40 known processed) with 0 events remaining. What's happening here is the previous recvmsg has thrown EAGAIN, since the socket is non-blocking. In this case, check whether the socket has any more data to read, and if not treat it like EPIPE. Signed-off-by: Adam Jackson --- src/XlibInt.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/src/XlibInt.c b/src/XlibInt.c index 903e47f3..dd39445b 100644 --- a/src/XlibInt.c +++ b/src/XlibInt.c @@ -50,6 +50,8 @@ from The Open Group. #ifdef XTHREADS #include "locking.h" +#include + /* these pointers get initialized by XInitThreads */ LockInfoPtr _Xglobal_lock = NULL; void (*_XCreateMutex_fn)(LockInfoPtr) = NULL; @@ -1234,6 +1236,21 @@ _XWireToEvent( return(True); } +static int +SocketBytesReadable(Display *dpy) +{ + int bytes = 0, last_error; +#ifdef WIN32 + last_error = WSAGetLastError(); + ioctlsocket(ConnectionNumber(dpy), FIONREAD, &bytes); + WSASetLastError(last_error); +#else + last_error = errno; + ioctl(ConnectionNumber(dpy), FIONREAD, &bytes); + errno = last_error; +#endif + return bytes; +} /* * _XDefaultIOError - Default fatal system error reporting routine. Called @@ -1242,7 +1259,17 @@ _XWireToEvent( _X_NORETURN int _XDefaultIOError( Display *dpy) { - if (ECHECK(EPIPE)) { + int killed = ECHECK(EPIPE); + + /* + * If the socket was closed on the far end, the final recvmsg in + * xcb will have thrown EAGAIN because we're non-blocking. Detect + * this to get the more informative error message. + */ + if (ECHECK(EAGAIN) && SocketBytesReadable(dpy) <= 0) + killed = True; + + if (killed) { fprintf (stderr, "X connection to %s broken (explicit kill or server shutdown).\r\n", DisplayString (dpy)); -- 2.21.0