diff options
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | win/tclWinSock.c | 48 |
2 files changed, 54 insertions, 1 deletions
@@ -1,3 +1,10 @@ +2010-09-24 Andreas Kupries <andreask@activestate.com> + + * tclWinsock.c: [Bug 3056775]: Fixed race condition between thread + and internal co-thread access of a socket's structure because of + the thread not using the socketListLock in TcpAccept(). Added + documentation on how the module works to the top. + 2010-09-23 Jan Nijtmans <nijtmans@users.sf.net> * generic/tclDecls.h: Make Tcl_SetPanicProc and Tcl_GetStringResult diff --git a/win/tclWinSock.c b/win/tclWinSock.c index b4ef80b..f3127d5 100644 --- a/win/tclWinSock.c +++ b/win/tclWinSock.c @@ -8,7 +8,43 @@ * See the file "license.terms" for information on usage and redistribution of * this file, and for a DISCLAIMER OF ALL WARRANTIES. * - * RCS: @(#) $Id: tclWinSock.c,v 1.74 2010/09/13 14:20:39 nijtmans Exp $ + * RCS: @(#) $Id: tclWinSock.c,v 1.75 2010/09/24 17:53:39 andreas_kupries Exp $ + * + * ----------------------------------------------------------------------- + * + * General information on how this module works. + * + * - Each Tcl-thread with its sockets maintains an internal window to receive + * socket messages from the OS. + * + * - To ensure that message reception is always running this window is + * actually owned and handled by an internal thread. This we call the + * co-thread of Tcl's thread. + * + * - The whole structure is set up by InitSockets() which is called for each + * Tcl thread. The implementation of the co-thread is in SocketThread(), + * and the messages are handled by SocketProc(). The connection between + * both is not directly visible, it is done through a Win32 window class. + * This class is initialized by InitSockets() as well, and used in the + * creation of the message receiver windows. + * + * - An important thing to note is that *both* thread and co-thread have + * access to the list of sockets maintained in the private TSD data of the + * thread. The co-thread was given access to it upon creation through the + * new thread's client-data. + * + * Because of this dual access the TSD data contains an OS mutex, the + * "socketListLock", to mediate exclusion between thread and co-thread. + * + * The co-thread's access is all in SocketProc(). The thread's access is + * through SocketEventProc() (1) and the functions called by it. + * + * (Ad 1) This is the handler function for all queued socket events, which + * all the OS messages are translated to through the EventSource (2) + * driven by the OS messages. + * + * (Ad 2) The main functions for this are SocketSetupProc() and + * SocketCheckProc(). */ #include "tclWinInt.h" @@ -1463,6 +1499,12 @@ TcpAccept( &len); /* + * Protect access to sockets (acceptEventCount, readyEvents) in socketList + * by the lock. Fix for SF Tcl Bug 3056775. + */ + WaitForSingleObject(tsdPtr->socketListLock, INFINITE); + + /* * Clear the ready mask so we can detect the next connection request. Note * that connection requests are level triggered, so if there is a request * already pending, a new event will be generated. @@ -1471,6 +1513,8 @@ TcpAccept( if (newSocket == INVALID_SOCKET) { infoPtr->acceptEventCount = 0; infoPtr->readyEvents &= ~(FD_ACCEPT); + + SetEvent(tsdPtr->socketListLock); return; } @@ -1486,6 +1530,8 @@ TcpAccept( infoPtr->readyEvents &= ~(FD_ACCEPT); } + SetEvent(tsdPtr->socketListLock); + /* * Win-NT has a misfeature that sockets are inherited in child processes * by default. Turn off the inherit bit. |