From b2a49edd4effb13a1a9c7db2812652cf00609aef Mon Sep 17 00:00:00 2001 From: Vladislav Vaintroub Date: Mon, 1 Sep 2008 17:46:37 -0400 Subject: Bug#37226 Explicit call of my_thread_init() on Windows for every new thread. Bug#33031 app linked to libmysql.lib crash if run as service in vista under localsystem There are some problems using DllMain hook functions on Windows that automatically do global and per-thread initialization for libmysqld.dll 1)per-thread initialization(DLL_THREAD_ATTACH) MySQL internally counts number of active threads that and causes a delay in in my_end() if not all threads are exited. But,there are threads that can be started either by Windows internally (often in TCP/IP scenarios) or by user himself - those threads are not necessarily using libmysql.dll functionality, but nonetheless the contribute to the count of open threads. 2)process-initialization (DLL_PROCESS_ATTACH) my_init() calls WSAStartup that itself loads DLLs and can lead to a deadlock in Windows loader. Fix is to remove dll initialization code from libmysql.dll in general case. I still leave an environment variable LIBMYSQL_DLLINIT, which if set to any value will cause the old behavior (DLL init hooks will be called). This env.variable exists only to prevent breakage of existing Windows-only applications that don't do mysql_thread_init() and work ok today. Use of LIBMYSQL_DLLINIT is discouraged and it will be removed in 6.0 --- libmysql/dll.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'libmysql') diff --git a/libmysql/dll.c b/libmysql/dll.c index b0e4b9cab3b..7bea5f880c5 100644 --- a/libmysql/dll.c +++ b/libmysql/dll.c @@ -89,9 +89,20 @@ BOOL APIENTRY LibMain(HANDLE hInst,DWORD ul_reason_being_called, UNREFERENCED_PARAMETER(lpReserved); } /* LibMain */ + +static BOOL do_libmain; int __stdcall DllMain(HANDLE hInst,DWORD ul_reason_being_called,LPVOID lpReserved) { - return LibMain(hInst,ul_reason_being_called,lpReserved); + /* + Unless environment variable LIBMYSQL_DLLINIT is set, do nothing. + The environment variable is checked once, during the first call to DllMain() + (in DLL_PROCESS_ATTACH hook). + */ + if (ul_reason_being_called == DLL_PROCESS_ATTACH) + do_libmain = (getenv("LIBMYSQL_DLLINIT") != NULL); + if (do_libmain) + return LibMain(hInst,ul_reason_being_called,lpReserved); + return TRUE; } #elif defined(WINDOWS) -- cgit v1.2.1