* cygtls.cc (_cygtls::init_exception_handler): Revert patch

        from 2005-12-02.
        * exceptions.cc (stack_info::walk): Add workaround for NT 5.2
        64 bit OSes.
        * wincap.h (wincaps::has_restricted_stack_args): New element.
        * wincap.cc: Implement above element throughout.
        (wincapc::init): Reset has_restricted_stack_args if not running
        under WOW64.

5 files changed, 58 insertions, 5 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 969dd03f6..0163a57d2 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,14 @@
+2008-02-13  Corinna Vinschen  <corinna@vinschen.de>
+
+	* cygtls.cc (_cygtls::init_exception_handler): Revert patch
+	from 2005-12-02.
+	* exceptions.cc (stack_info::walk): Add workaround for NT 5.2
+	64 bit OSes.
+	* wincap.h (wincaps::has_restricted_stack_args): New element.
+	* wincap.cc: Implement above element throughout.
+	(wincapc::init): Reset has_restricted_stack_args if not running
+	under WOW64.
+
 2008-02-11  Corinna Vinschen  <corinna@vinschen.de>
 
 	* fhandler_disk_file.cc (fhandler_disk_file::fgetxattr): Remove unused
diff --git a/winsup/cygwin/cygtls.cc b/winsup/cygwin/cygtls.cc
index 2bc7e85ba..af2723e95 100644
--- a/winsup/cygwin/cygtls.cc
+++ b/winsup/cygwin/cygtls.cc
@@ -260,7 +260,23 @@ void
 _cygtls::init_exception_handler (exception_handler *eh)
 {
   el.handler = eh;
-  el.prev = &el;
+  /* Apparently Windows stores some information about an exception and tries
+     to figure out if the SEH which returned 0 last time actually solved the
+     problem, or if the problem still persists (e.g. same exception at same
+     address).  In this case Windows seems to decide that it can't trust
+     that SEH and calls the next handler in the chain instead.
+
+     At one point this was a loop (el.prev = &el;).  This outsmarted the
+     above behaviour.  Unfortunately this trick doesn't work anymore with
+     Windows 2008, which irremediably gets into an endless loop, taking 100%
+     CPU.  That's why we reverted to a normal SEH chain.
+
+     On the bright side, Windows' behaviour is covered by POSIX:
+
+     "If and when the function returns, if the value of sig was SIGFPE,
+     SIGILL, or SIGSEGV or any other implementation-defined value
+     corresponding to a computational exception, the behavior is undefined." */
+  el.prev = _except_list;
   _except_list = &el;
 }
 
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index fc361b59b..05cc91696 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -245,9 +245,20 @@ stack_info::walk ()
   sf.AddrReturn.Offset = (DWORD) *++ebp;
 
   if (needargs)
-    /* The arguments follow the return address */
-    for (unsigned i = 0; i < NPARAMS; i++)
-      sf.Params[i] = (DWORD) *++ebp;
+    {
+      unsigned nparams = NPARAMS;
+
+      /* The arguments follow the return address */
+      sf.Params[0] = (DWORD) *++ebp;
+      /* Hack for XP/2K3 WOW64.  If the first stack param points to the
+	 application entry point, we can only fetch one additional
+	 parameter.  Accessing anything beyond this address results in
+	 a SEGV.  This is fixed in Vista/2K8 WOW64. */
+      if (wincap.has_restricted_stack_args () && sf.Params[0] == 0x401000)
+	nparams = 2;
+      for (unsigned i = 0; i < nparams; i++)
+	sf.Params[i] = (DWORD) *++ebp;
+    }
 
   return 1;
 }
diff --git a/winsup/cygwin/wincap.cc b/winsup/cygwin/wincap.cc
index e8b44c0e6..0a808e563 100644
--- a/winsup/cygwin/wincap.cc
+++ b/winsup/cygwin/wincap.cc
@@ -40,6 +40,7 @@ static NO_COPY wincaps wincap_unknown = {
   has_gaa_prefixes:false,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_nt4 = {
@@ -69,6 +70,7 @@ static NO_COPY wincaps wincap_nt4 = {
   has_gaa_prefixes:false,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_nt4sp4 = {
@@ -98,6 +100,7 @@ static NO_COPY wincaps wincap_nt4sp4 = {
   has_gaa_prefixes:false,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_2000 = {
@@ -127,6 +130,7 @@ static NO_COPY wincaps wincap_2000 = {
   has_gaa_prefixes:false,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_2000sp4 = {
@@ -156,6 +160,7 @@ static NO_COPY wincaps wincap_2000sp4 = {
   has_gaa_prefixes:false,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_xp = {
@@ -185,6 +190,7 @@ static NO_COPY wincaps wincap_xp = {
   has_gaa_prefixes:false,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_xpsp1 = {
@@ -214,6 +220,7 @@ static NO_COPY wincaps wincap_xpsp1 = {
   has_gaa_prefixes:true,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_xpsp2 = {
@@ -243,6 +250,7 @@ static NO_COPY wincaps wincap_xpsp2 = {
   has_gaa_prefixes:true,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:false,
 };
 
 static NO_COPY wincaps wincap_2003 = {
@@ -272,6 +280,7 @@ static NO_COPY wincaps wincap_2003 = {
   has_gaa_prefixes:true,
   has_gaa_on_link_prefix:false,
   supports_all_posix_ai_flags:false,
+  has_restricted_stack_args:true,
 };
 
 static NO_COPY wincaps wincap_vista = {
@@ -301,6 +310,7 @@ static NO_COPY wincaps wincap_vista = {
   has_gaa_prefixes:true,
   has_gaa_on_link_prefix:true,
   supports_all_posix_ai_flags:true,
+  has_restricted_stack_args:false,
 };
 
 wincapc wincap __attribute__((section (".cygwin_dll_common"), shared));
@@ -388,7 +398,10 @@ wincapc::init ()
   if (IsWow64Process (GetCurrentProcess (), &is_wow64_proc))
     wow64 = is_wow64_proc;
   else
-    ((wincaps *)this->caps)->needs_count_in_si_lpres2 = false;
+    {
+      ((wincaps *)this->caps)->needs_count_in_si_lpres2 = false;
+      ((wincaps *)this->caps)->has_restricted_stack_args = false;
+    }
 
   __small_sprintf (osnam, "NT-%d.%d", version.dwMajorVersion,
 		   version.dwMinorVersion);
diff --git a/winsup/cygwin/wincap.h b/winsup/cygwin/wincap.h
index 55dc19cdb..167ea5e19 100644
--- a/winsup/cygwin/wincap.h
+++ b/winsup/cygwin/wincap.h
@@ -39,6 +39,7 @@ struct wincaps
   unsigned has_gaa_prefixes				: 1;
   unsigned has_gaa_on_link_prefix			: 1;
   unsigned supports_all_posix_ai_flags			: 1;
+  unsigned has_restricted_stack_args			: 1;
 };
 
 class wincapc
@@ -84,6 +85,7 @@ public:
   bool	IMPLEMENT (has_gaa_prefixes)
   bool	IMPLEMENT (has_gaa_on_link_prefix)
   bool	IMPLEMENT (supports_all_posix_ai_flags)
+  bool	IMPLEMENT (has_restricted_stack_args)
 
 #undef IMPLEMENT
 };