From edd5c230afdc7341e5a5564d9c8ee714688705fe Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Tue, 13 Apr 2021 21:33:13 -0400
Subject: [PATCH] Fix crash when input has no holes.

When the search tree has no elements, it seems the CNearTreeObjects
function does not give a CVector with zero elements but rather a
null pointer.  This results in a null dereference when that is
passed to CVectorSize, instead of 0 as expected.

Add an explicit check for this case to avoid crashing.
---
 src/slotifier.c |  4 ++++
 tests/simple.at | 25 +++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/slotifier.c b/src/slotifier.c
index b74a9ec..03485f5 100644
--- a/src/slotifier.c
+++ b/src/slotifier.c
@@ -333,6 +333,9 @@ static int slotify(gerbv_image_t *drill)
 	}
 
 	CNearTreeObjects(t, &holes);
+	if (!holes)
+		goto out;
+
 	for (i = 0; i < CVectorSize(holes); i++) {
 		gerbv_net_t *hole;
 
@@ -358,6 +361,7 @@ static int slotify(gerbv_image_t *drill)
 			gerbv_image_delete_net(hole);
 	}
 
+out:
 	CNearTreeFree(&t);
 	return ret;
 }
diff --git a/tests/simple.at b/tests/simple.at
index 8e28f6b..11c59b7 100644
--- a/tests/simple.at
+++ b/tests/simple.at
@@ -85,3 +85,28 @@ M30
 ]])
 
 AT_CLEANUP
+
+AT_SETUP([no holes])
+
+AT_DATA([test.cnc],
+[[M48
+INCH,TZ
+T10C0.091
+%
+T10
+X010512Y002362G85X010512Y002047
+M30
+]])
+
+AT_CHECK([slotifier test.cnc], [0],
+[[M48
+INCH,TZ
+T10C0.091
+%
+T10
+X010512Y002362G85X010512Y002047
+M30
+
+]])
+
+AT_CLEANUP
-- 
2.43.0