From 2ab03f3ab4838fc013b995cc303118fd6e3079ee Mon Sep 17 00:00:00 2001
From: Daniel Lehman <dlehman@esri.com>
Date: Fri, 19 May 2017 11:21:52 -0700
Subject: [PATCH 3/7] msvcrt: Unwind the catch block frame.

this ties into the previous commit in support of nested c++ exceptions

normally, unwinding past a frame calls the destructors
for all objects from the ControlPc to the lowest state

but there seems to be a special case for catch blocks.
they are unwound separately, stopping where the handler is NULL

the program below produces this on Windows:
...                     <- throw new obj inside of a's catch block
klass::~klass: a catch  <- unwinding past a's catch block
klass::~klass: a obj    <- destroying a's exception object
klass::~klass: a        <- finish unwinding the rest of a
main catch              <- how we handle the new exception
klass::~klass: new obj

when combined with the previous commit, this commit produces the same
output as Windows when unwinding to the exception handler:
a
_CxxThrowException  <- call '~klass: a'         (cxx_frame_handler -> cxx_local_unwind)
...
call_consolidate
call_catch_block    <- call '~klass: a obj'     (cxx_catch_cleanup)
catch$0             <- call '~klass: a catch'   (cxx_frame_handler -> cxx_catch_unwind)

===============================
// cl /Od /MD /EHs  standalone.cpp
include <stdio.h>
include <windows.h>

struct klass
{
    klass(const char *msg) : str(msg) {}
   ~klass() { printf("%s: %s\n", __FUNCTION__, str); }
    const char *str;
};

void a(void)
{
    klass foo("a");
    try { throw klass("a obj"); }
    catch (klass &k) { klass foo("a catch"); throw klass("new obj"); }
}

int main(int argc, char **argv)
{
    try { a(); }
    catch (klass &k) {printf("main catch\n");}
    return 0;
}

Signed-off-by: Daniel Lehman <dlehman@esri.com>
---
 dlls/msvcrt/except_x86_64.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/dlls/msvcrt/except_x86_64.c b/dlls/msvcrt/except_x86_64.c
index ec18746..68ea33a 100644
--- a/dlls/msvcrt/except_x86_64.c
+++ b/dlls/msvcrt/except_x86_64.c
@@ -473,6 +473,44 @@ static inline void find_catch_block(EXCEPTION_RECORD *rec, ULONG64 frame,
     TRACE("no matching catch block found\n");
 }
 
+static void cxx_catch_unwind(ULONG64 frame, DISPATCHER_CONTEXT *dispatch,
+                             const cxx_function_descr *descr)
+{
+    const unwind_info *unwind_table = rva_to_ptr(descr->unwind_table, dispatch->ImageBase);
+    void (__cdecl *handler)(ULONG64 unk, ULONG64 rbp);
+    int *unwind_help = rva_to_ptr(descr->unwind_help, frame);
+    int trylevel;
+
+    if (unwind_help[0] == -2)
+    {
+        trylevel = ip_to_state(rva_to_ptr(descr->ipmap, dispatch->ImageBase),
+                descr->ipmap_count, dispatch->ControlPc-dispatch->ImageBase);
+    }
+    else
+    {
+        trylevel = unwind_help[0];
+    }
+
+    TRACE("current level: %d\n", trylevel);
+    while (trylevel != -1)
+    {
+        if (trylevel<0 || trylevel>=descr->unwind_count)
+        {
+            ERR("invalid trylevel %d\n", trylevel);
+            MSVCRT_terminate();
+        }
+        handler = rva_to_ptr(unwind_table[trylevel].handler, dispatch->ImageBase);
+        if (!handler) break;
+
+        TRACE("handler: %p\n", handler);
+        handler(0, frame);
+
+        trylevel = unwind_table[trylevel].prev;
+    }
+    unwind_help[0] = trylevel;
+    unwind_help[1] = trylevel;
+}
+
 extern void __wine_rtl_unwind( EXCEPTION_REGISTRATION_RECORD* frame, EXCEPTION_RECORD *record,
                                void (*target)(void) );
 extern void CDECL __DestructExceptionObject(EXCEPTION_RECORD *rec);
@@ -572,11 +610,15 @@ static DWORD cxx_frame_handler(EXCEPTION_RECORD *rec, ULONG64 frame,
             }
             else if(frame == orig_frame)
                 cxx_local_unwind(frame, dispatch, descr, -1);
+            else
+                cxx_catch_unwind(orig_frame, dispatch, descr);
             return ExceptionContinueSearch;
         }
 
         if (frame == orig_frame)
             cxx_local_unwind(frame, dispatch, descr, rec->ExceptionFlags & EH_TARGET_UNWIND ? trylevel : -1);
+        else
+            cxx_catch_unwind(orig_frame, dispatch, descr);
         return ExceptionContinueSearch;
     }
     if (!descr->tryblock_count) return ExceptionContinueSearch;
-- 
1.9.5