[libredwg] crash on testSVG sample.dwg

[Thien-Thi Nguyen]

Currently, "testSVG sample.dwg" segfaults:

|./testSVG sample.dwg
|<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|<svg
|   xmlns:svg="http://www.w3.org/2000/svg";
|   xmlns="http://www.w3.org/2000/svg";
|   xmlns:xlink="http://www.w3.org/1999/xlink";
|   version="1.1"
|   width="270.030212"
|   height="280.023651"
|>
|       <defs>
|       <g id="symbol-85" >
|               <!-- *Paper_Space -->
|       </g>
|
|Compilation segmentation fault at Tue Feb 23 13:20:02

With the patch below, there is no segfault:

|$ ./testSVG sample.dwg
|<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|<svg
|   xmlns:svg="http://www.w3.org/2000/svg";
|   xmlns="http://www.w3.org/2000/svg";
|   xmlns:xlink="http://www.w3.org/1999/xlink";
|   version="1.1"
|   width="270.030212"
|   height="280.023651"
|>
|       <defs>
|       <g id="symbol-85" >
|               <!-- *Paper_Space -->
|       </g>
|Found null ref->obj->tio.object
|       </defs>
|       <g id="symbol-31" >
|               <!-- *Model_Space -->
|       <circle id="dwg-object-44" cx="250.002307" cy="170.006558" 
r="20.000000" fill="none" stroke="blue" stroke-width="0.1px" />
|       <text id="dwg-object-45" x="0.002307" y="60.006558" 
font-family="Verdana" font-size="5.000000" fill="blue">Jen teksto simpla, cxu 
ne?</text>
|       <path id="dwg-object-47" d="M 150.002307,100.006558 
250.002307,100.006558" style="fill:none;stroke:blue;stroke-width:0.1px" />
|       <path id="dwg-object-48" d="M 250.002307,0.006558 
250.002307,100.006558" style="fill:none;stroke:blue;stroke-width:0.1px" />
|       <path id="dwg-object-49" d="M 150.002307,100.006558 
250.002307,0.006558" style="fill:none;stroke:blue;stroke-width:0.1px" />
|       </g>
|       <g id="symbol-80" >
|               <!-- *Paper_Space -->
|       </g>
|</svg>

Is this patch correct?

thi

____________________________________________________________________
 examples/testSVG.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/examples/testSVG.c b/examples/testSVG.c
index 999a951..377fae6 100644
--- a/examples/testSVG.c
+++ b/examples/testSVG.c
@@ -200,6 +200,12 @@ void output_BLOCK_HEADER(Dwg_Object_Ref* ref)
       return;
     }
 
+  if (!ref->obj->tio.object)
+    {
+      fprintf(stderr, "Found null ref->obj->tio.object\n");
+      return;
+    }
+
   hdr = ref->obj->tio.object->tio.BLOCK_HEADER;
   printf(
       "\t<g id=\"symbol-%lu\" >\n\t\t<!-- %s -->\n", ref->absolute_ref, 
hdr->entry_name);