Re: MinGW setjmp SEGV

[Andrew STUBBS <andrew.stubbs@st.com>]

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On Fri, 05 Aug 2005 15:00:53 +0100, Dave Korn <dave.korn@artimi.com> wrote:

>> The attached patch (code copied from sourceforge) is sufficient to fix  
>> the
>> issue. Note that I have included the diff of the whole file and it
>> includes one of the minor changes mentioned above.
>
>   That'll be the deleted _INSIDE_CYGWIN_ then?
>
>>
>> Hopefully this patch will help others who have hit the same problem.
>
>
>     Hi Andrew,
>
>   I was looking through this area just the other day
> (http://sourceware.org/ml/insight/2005-q3/msg00021.html), and ISTM that  
> the
> substance of this patch is already in CVS HEAD.  The changes appear to  
> have
> been added in rev1.9
> (http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/tcl/win/tclWin32Dll.c?cvsr
> oot=src#rev1.9) when tcl 8.4.1 was merged from upstream.  Just FYI.
>
>
>     cheers,
>       DaveK

Many apologies. I have got the diff backwards! It is tcl 8.4.1 that is  
broken and AFAIKT CVS HEAD is little altered.

Please find a correct one attached.

Andrew Stubbs

[-- Attachment #2: insight-win.patch --]
[-- Type: application/octet-stream, Size: 5413 bytes --]

--- /view/stubbsa-import/vob/insight.cmp/src/tcl/win/tclWin32Dll.c@@/main/INSIGHT-6.1	2005-07-29 16:22:32.000000000 +0100
+++ /view/stubbsa-import/vob/insight.cmp/src/tcl/win/tclWin32Dll.c	2005-08-05 14:21:03.000000000 +0100
@@ -12,6 +12,10 @@
  * RCS: @(#) $Id: tclWin32Dll.c,v 1.16 2002/06/13 09:40:01 vincentdarley Exp $
  */
 
+/* The following is a workaround for a w32api problem.
+   See http://sources.redhat.com/ml/insight/2004-q4/msg00039.html */
+#define __INSIDE_CYGWIN__
+
 #include "tclWinInt.h"
 
 /*
@@ -38,6 +42,23 @@
 static int platformId;		/* Running under NT, or 95/98? */
 
 #ifdef HAVE_NO_SEH
+/*
+ * Unlike Borland and Microsoft, we don't register exception handlers by
+ * pushing registration records onto the runtime stack. Instead, we register
+ * them by creating an EXCEPTION_REGISTRATION within the activation record.
+ */
+
+typedef struct EXCEPTION_REGISTRATION {
+    struct EXCEPTION_REGISTRATION *link;
+    EXCEPTION_DISPOSITION (*handler)(
+	    struct _EXCEPTION_RECORD*, void*, struct _CONTEXT*, void*);
+    void *ebp;
+    void *esp;
+    int status;
+} EXCEPTION_REGISTRATION;
+#endif
+
+#ifdef HAVE_NO_SEH
 static void *ESP;
 static void *EBP;
 #endif /* HAVE_NO_SEH */
@@ -347,65 +368,111 @@
 int
 TclpCheckStackSpace()
 {
+
+#ifdef HAVE_NO_SEH
+    EXCEPTION_REGISTRATION registration;
+#endif
     int retval = 0;
 
     /*
-     * We can recurse only if there is at least TCL_WIN_STACK_THRESHOLD
-     * bytes of stack space left.  alloca() is cheap on windows; basically
-     * it just subtracts from the stack pointer causing the OS to throw an
-     * exception if the stack pointer is set below the bottom of the stack.
+     * We can recurse only if there is at least TCL_WIN_STACK_THRESHOLD bytes
+     * of stack space left. alloca() is cheap on windows; basically it just
+     * subtracts from the stack pointer causing the OS to throw an exception
+     * if the stack pointer is set below the bottom of the stack.
      */
 
 #ifdef HAVE_NO_SEH
     __asm__ __volatile__ (
-            "movl  %esp, _ESP" "\n\t"
-            "movl  %ebp, _EBP");
 
-    __asm__ __volatile__ (
-            "pushl $__except_checkstackspace_handler" "\n\t"
-            "pushl %fs:0" "\n\t"
-            "mov   %esp, %fs:0");
-#else
+	/*
+	 * Construct an EXCEPTION_REGISTRATION to protect the call to __alloca
+	 */
+
+	"leal	%[registration], %%edx"		"\n\t"
+	"movl	%%fs:0,		%%eax"		"\n\t"
+	"movl	%%eax,		0x0(%%edx)"	"\n\t" /* link */
+	"leal	1f,		%%eax"		"\n\t"
+	"movl	%%eax,		0x4(%%edx)"	"\n\t" /* handler */
+	"movl	%%ebp,		0x8(%%edx)"	"\n\t" /* ebp */
+	"movl	%%esp,		0xc(%%edx)"	"\n\t" /* esp */
+	"movl	%[error],	0x10(%%edx)"	"\n\t" /* status */
+	
+	/*
+	 * Link the EXCEPTION_REGISTRATION on the chain
+	 */
+
+	"movl	%%edx,		%%fs:0"		"\n\t"
+
+	/*
+	 * Attempt a call to __alloca, to determine whether there's sufficient
+	 * memory to be had.
+	 */
+
+	"movl	%[size],	%%eax"		"\n\t"
+	"pushl	%%eax"				"\n\t"
+	"call	__alloca"			"\n\t"
+
+	/*
+	 * Come here on a normal exit. Recover the EXCEPTION_REGISTRATION and
+	 * store a TCL_OK status
+	 */
+
+	"movl	%%fs:0,		%%edx"		"\n\t"
+	"movl	%[ok],		%%eax"		"\n\t"
+	"movl	%%eax,		0x10(%%edx)"	"\n\t"
+	"jmp	2f"				"\n"
+
+	/*
+	 * Come here on an exception. Get the EXCEPTION_REGISTRATION that we
+	 * previously put on the chain.
+	 */
+
+	"1:"					"\t"
+	"movl	%%fs:0,		%%edx"		"\n\t"
+	"movl	0x8(%%edx),	%%edx"		"\n\t"
+	
+	/* 
+	 * Come here however we exited. Restore context from the
+	 * EXCEPTION_REGISTRATION in case the stack is unbalanced.
+	 */
+	
+	"2:"					"\t"
+	"movl	0xc(%%edx),	%%esp"		"\n\t"
+	"movl	0x8(%%edx),	%%ebp"		"\n\t"
+	"movl	0x0(%%edx),	%%eax"		"\n\t"
+	"movl	%%eax,		%%fs:0"		"\n\t"
+	
+	:
+	/* No outputs */
+	:
+	[registration]	"m"	(registration),
+	[ok]		"i"	(TCL_OK),
+	[error]		"i"	(TCL_ERROR),
+	[size]		"i"	(TCL_WIN_STACK_THRESHOLD)
+	:
+	"%eax", "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"
+	);
+    retval = (registration.status == TCL_OK);
+
+#else /* !HAVE_NO_SEH */
     __try {
-#endif /* HAVE_NO_SEH */
+#ifdef HAVE_ALLOCA_GCC_INLINE
+	__asm__ __volatile__ (
+	    "movl  %0, %%eax" "\n\t"
+	    "call  __alloca" "\n\t"
+	    :
+	    : "i"(TCL_WIN_STACK_THRESHOLD)
+	    : "%eax");
+#else
 	alloca(TCL_WIN_STACK_THRESHOLD);
+#endif /* HAVE_ALLOCA_GCC_INLINE */
 	retval = 1;
-#ifdef HAVE_NO_SEH
-    __asm__ __volatile__ (
-            "jmp   checkstackspace_pop" "\n"
-            "checkstackspace_reentry:" "\n\t"
-            "movl  _ESP, %esp" "\n\t"
-            "movl  _EBP, %ebp");
-
-    __asm__ __volatile__ (
-            "checkstackspace_pop:" "\n\t"
-            "mov   (%esp), %eax" "\n\t"
-            "mov   %eax, %fs:0" "\n\t"
-            "add   $8, %esp");
-#else
     } __except (EXCEPTION_EXECUTE_HANDLER) {}
 #endif /* HAVE_NO_SEH */
-
-    /*
-     * Avoid using control flow statements in the SEH guarded block!
-     */
+    
     return retval;
 }
-#ifdef HAVE_NO_SEH
-static
-__attribute__ ((cdecl))
-EXCEPTION_DISPOSITION
-_except_checkstackspace_handler(
-    struct _EXCEPTION_RECORD *ExceptionRecord,
-    void *EstablisherFrame,
-    struct _CONTEXT *ContextRecord,
-    void *DispatcherContext)
-{
-    __asm__ __volatile__ (
-            "jmp checkstackspace_reentry");
-    return 0; /* Function does not return */
-}
-#endif /* HAVE_NO_SEH */
+
 \f
 /*
  *----------------------------------------------------------------------