From 2cdf4d07e53202f69d06d9c388f89198b0f16f5f Mon Sep 17 00:00:00 2001
From: davygrvy <davygrvy@pobox.com>
Date: Thu, 6 May 2004 01:04:32 +0000
Subject: * win/tclWin32Dll.c: Structured Exception Handling added around
 Tcl_Finalize called from DllMain's DLL_PROCESS_DETACH.  We can't be 100%
 assured that Tcl is being unloaded by the OS in a stable condition and we
 need to protect the exit handlers should the stack be in a hosed state.  AT&T
 style assembly for SEH under MinGW included, too.  [Patch 858493]

Also added DisableThreadLibraryCalls() for the DLL_PROCESS_ATTACH
case.  We're not interested in knowing about DLL_THREAD_ATTACH, so
disable the notices.
---
 win/tclWin32Dll.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 82 insertions(+), 3 deletions(-)

diff --git a/win/tclWin32Dll.c b/win/tclWin32Dll.c
index 2e341bc..2e3368c 100644
--- a/win/tclWin32Dll.c
+++ b/win/tclWin32Dll.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclWin32Dll.c,v 1.24.2.1 2003/04/14 15:45:59 vincentdarley Exp $
+ * RCS: @(#) $Id: tclWin32Dll.c,v 1.24.2.2 2004/05/06 01:04:32 davygrvy Exp $
  */
 
 #include "tclWinInt.h"
@@ -239,19 +239,98 @@ DllMain(hInst, reason, reserved)
 {
     switch (reason) {
     case DLL_PROCESS_ATTACH:
+	DisableThreadLibraryCalls(hInst);
 	TclWinInit(hInst);
 	return TRUE;
 
     case DLL_PROCESS_DETACH:
-	if (hInst == hInstance) {
-	    Tcl_Finalize();
+	/*
+	 * Protect the call to Tcl_Finalize.  The OS could be unloading
+	 * us from an exception handler and the state of the stack might
+	 * be unstable.
+	 */
+#ifdef HAVE_NO_SEH
+# ifdef TCL_MEM_DEBUG
+    __asm__ __volatile__ (
+            "movl %%esp,  %0" "\n\t"
+            "movl %%ebp,  %1" "\n\t"
+            "movl %%fs:0, %2" "\n\t"
+            : "=m"(INITIAL_ESP),
+              "=m"(INITIAL_EBP),
+              "=r"(INITIAL_HANDLER) );
+# endif /* TCL_MEM_DEBUG */
+
+    __asm__ __volatile__ (
+            "pushl %ebp" "\n\t"
+            "pushl $__except_dllmain_detach_handler" "\n\t"
+            "pushl %fs:0" "\n\t"
+            "movl  %esp, %fs:0");
+#else
+	__try {
+#endif /* HAVE_NO_SEH */
+
+  	    Tcl_Finalize();
+
+#ifdef HAVE_NO_SEH
+    __asm__ __volatile__ (
+            "jmp  dllmain_detach_pop" "\n"
+        "dllmain_detach_reentry:" "\n\t"
+            "movl %%fs:0, %%eax" "\n\t"
+            "movl 0x8(%%eax), %%esp" "\n\t"
+            "movl 0x8(%%esp), %%ebp" "\n"
+        "dllmain_detach_pop:" "\n\t"
+            "movl (%%esp), %%eax" "\n\t"
+            "movl %%eax, %%fs:0" "\n\t"
+            "add  $12, %%esp" "\n\t"
+            :
+            :
+            : "%eax");
+
+# ifdef TCL_MEM_DEBUG
+    __asm__ __volatile__ (
+            "movl  %%esp,  %0" "\n\t"
+            "movl  %%ebp,  %1" "\n\t"
+            "movl  %%fs:0, %2" "\n\t"
+            : "=m"(RESTORED_ESP),
+              "=m"(RESTORED_EBP),
+              "=r"(RESTORED_HANDLER) );
+
+    if (INITIAL_ESP != RESTORED_ESP)
+        Tcl_Panic("ESP restored incorrectly");
+    if (INITIAL_EBP != RESTORED_EBP)
+        Tcl_Panic("EBP restored incorrectly");
+    if (INITIAL_HANDLER != RESTORED_HANDLER)
+        Tcl_Panic("HANDLER restored incorrectly");
+# endif /* TCL_MEM_DEBUG */
+#else
+	} __except (EXCEPTION_EXECUTE_HANDLER) {
+	    /* empty handler body. */
 	}
+#endif /* HAVE_NO_SEH */
 	break;
     }
 
     return TRUE; 
 }
 
+#ifdef HAVE_NO_SEH
+static
+__attribute__ ((cdecl))
+EXCEPTION_DISPOSITION
+_except_dllmain_detach_handler(
+    struct _EXCEPTION_RECORD *ExceptionRecord,
+    void *EstablisherFrame,
+    struct _CONTEXT *ContextRecord,
+    void *DispatcherContext)
+{
+    __asm__ __volatile__ (
+            "jmp dllmain_detach_reentry");
+    /* Nuke compiler warning about unused static function */
+    _except_dllmain_detach_handler(NULL, NULL, NULL, NULL);
+    return 0; /* Function does not return */
+}
+#endif /* HAVE_NO_SEH */
+
 #endif /* !STATIC_BUILD */
 #endif /* __WIN32__ */
 
-- 
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