From b80d766ab943d68794e96f67c7c2e2138f65241c Mon Sep 17 00:00:00 2001
From: gka <gka@opencascade.com>
Date: Mon, 29 May 2017 18:42:55 +0300
Subject: [PATCH] 0028797: Exceptrion is raised during reading attached STEP
 file.

Protection for null handle was added in the method RWStepVisual_RWPresentationStyleAssignment::ReadStep
---
 ...StepVisual_RWPresentationStyleAssignment.cxx |  7 +++++--
 tests/bugs/step/bug28797                        | 17 +++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 tests/bugs/step/bug28797

diff --git a/src/RWStepVisual/RWStepVisual_RWPresentationStyleAssignment.cxx b/src/RWStepVisual/RWStepVisual_RWPresentationStyleAssignment.cxx
index 76a200f056..714957ce76 100644
--- a/src/RWStepVisual/RWStepVisual_RWPresentationStyleAssignment.cxx
+++ b/src/RWStepVisual/RWStepVisual_RWPresentationStyleAssignment.cxx
@@ -53,9 +53,12 @@ void RWStepVisual_RWPresentationStyleAssignment::ReadStep
       else {
         Handle(StepData_SelectMember) aMember;
         data->ReadMember(nsub1, i1, "null_style", ach, aMember);
-        Standard_CString anEnumText = aMember->EnumText();
         Handle(StepVisual_NullStyleMember) aNullStyle = new StepVisual_NullStyleMember();
-        aNullStyle->SetEnumText(0, anEnumText);
+        if(!aMember.IsNull())
+        {
+          Standard_CString anEnumText = aMember->EnumText();
+          aNullStyle->SetEnumText(0, anEnumText);
+        }
         aStylesItem.SetValue(aNullStyle);
       }
       aStyles->SetValue(i1,aStylesItem);
diff --git a/tests/bugs/step/bug28797 b/tests/bugs/step/bug28797
new file mode 100644
index 0000000000..a227a71198
--- /dev/null
+++ b/tests/bugs/step/bug28797
@@ -0,0 +1,17 @@
+puts "========"
+puts "OCC28797"
+puts "========"
+puts ""
+#########################################################################
+# Data Exchange - Exception is raised during reading attached STEP file
+#########################################################################
+
+set aFile [locate_data_file bug28797_36x60.step]
+
+if {[catch {stepread $aFile a *}]} {
+  puts "ERROR: OCC28797 is reproduced. Exception was raised during reading initial file."
+} else {
+  tpcompound result
+}
+
+checkview -display result -2d -path ${imagedir}/${test_image}.png