dbghelp: Stop unwinding on potential 64bit frame for i386 cpu.

Transform potential error on 32 => 64 bit transition with end of stack (needed in new wow64 for dbghelp's stackwalk tests). Signed-off-by: Eric Pouech <eric.pouech@gmail.com>

dbghelp: Stop unwinding on potential 64bit frame for i386 cpu.
7de1284b · Eric Pouech · Alexandre Julliard · 00205754 · 7de1284b
Commit 7de1284b authored Feb 01, 2023 by Eric Pouech Committed by Alexandre Julliard Feb 06, 2023
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cpu_i386.c dlls/dbghelp/cpu_i386.c +8 -1

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--- a/dlls/dbghelp/cpu_i386.c
+++ b/dlls/dbghelp/cpu_i386.c
@@ -473,7 +473,14 @@ static BOOL i386_stack_walk(struct cpu_stack_walk *csw, STACKFRAME64 *frame,
        union ctx newctx = *context;

        if (!fetch_next_frame32(csw, &newctx, frame->AddrPC.Offset - deltapc))
-            goto done_err;
+        {
+            /* When running on wow64 setup, frame below can a 64 bit frame.
+             * As we don't expose 64bit frames for now, pretend it's the first frame.
+             */
+            if (frame->AddrPC.Offset == 0)
+                goto done_err;
+            newctx.x86.Eip = 0;
+        }
        frame->AddrReturn.Mode = AddrModeFlat;
        frame->AddrReturn.Offset = newctx.x86.Eip;