[PATCH] ntdll: Properly return errors when failing to unwind

[Martin Storsjo]

If libunwind is unavailable, make libunwind_virtual_unwind return an
error. Likewise if there was no PE exception info and we didn't try
unwinding using libunwind, we need to return an error when realizing
we were unable to unwind, instead of just warning and returning
success.

This fixes hangs/infinite loops on crashes when unwinding fails.

Signed-off-by: Martin Storsjo 
---
 dlls/ntdll/signal_arm64.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/dlls/ntdll/signal_arm64.c b/dlls/ntdll/signal_arm64.c
index 3ed2953c33..c37e80df85 100644
--- a/dlls/ntdll/signal_arm64.c
+++ b/dlls/ntdll/signal_arm64.c
@@ -599,8 +599,10 @@ static NTSTATUS libunwind_virtual_unwind( ULONG_PTR ip, ULONG_PTR *frame, CONTEX
           context->u.s.X24, context->u.s.X25, context->u.s.X26, context->u.s.X27 );
     TRACE(" x28=%016lx  fp=%016lx  lr=%016lx  sp=%016lx\n",
           context->u.s.X28, context->u.s.Fp, context->u.s.Lr, context->Sp );
-#endif
     return STATUS_SUCCESS;
+#else
+    return STATUS_INVALID_DISPOSITION;
+#endif
 }

@@ -647,7 +649,11 @@ static NTSTATUS virtual_unwind( ULONG type, DISPATCHER_CONTEXT *dispatch, CONTEX
             return STATUS_SUCCESS;
         }
     }
-    else WARN( "exception data not found in %s\n", debugstr_w(module->BaseDllName.Buffer) );
+    else
+    {
+        WARN( "exception data not found in %s\n", debugstr_w(module->BaseDllName.Buffer) );
+        return STATUS_INVALID_DISPOSITION;
+    }

dispatch->EstablisherFrame = context->u.s.Fp;
     dispatch->LanguageHandler = NULL;