From be72339b2de9fd3f2cd12b2f1b559b2a32f595ad Mon Sep 17 00:00:00 2001
From: Anna Schumaker <Anna@OcarinaProject.net>
Date: Tue, 12 Aug 2014 09:59:00 -0400
Subject: [PATCH] filter: Check for empty results when filtering

The user could search for a term that isn't stored in the filter index.
This is represented through a NULL pointer returned from the
Index.find() function.  Let's check this pointer before attempting to
dereference it ...

Signed-off-by: Anna Schumaker <Anna@OcarinaProject.net>
---
 core/filter.cpp       | 15 +++++++++++----
 tests/core/filter.cpp |  3 +++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/core/filter.cpp b/core/filter.cpp
index 941c797f..a998c759 100644
--- a/core/filter.cpp
+++ b/core/filter.cpp
@@ -90,14 +90,21 @@ std::string filter :: add(const std::string &text, unsigned int track_id)
 	return reassemble_text(parsed);
 }
 
+static void do_set_intersection(std::set<unsigned int> &a,
+				std::set<unsigned int> &b,
+				std::set<unsigned int> &res)
+{
+	set_intersection(a.begin(), a.end(), b.begin(), b.end(),
+			 std::inserter<std::set<unsigned int> >(res, res.begin()));
+}
+
 static void find_intersection(std::string &text, std::set<unsigned int> &res)
 {
-	IndexEntry *it = filter_index.find(text);
 	std::set<unsigned int> tmp;
+	IndexEntry *it = filter_index.find(text);
 
-	set_intersection(it->values.begin(), it->values.end(),
-		res.begin(), res.end(),
-		std::inserter<std::set<unsigned int> >(tmp, tmp.begin()));
+	if (it)
+		do_set_intersection(res, it->values, tmp);
 	res.swap(tmp);
 }
 
diff --git a/tests/core/filter.cpp b/tests/core/filter.cpp
index 75b27767..7e5781c0 100644
--- a/tests/core/filter.cpp
+++ b/tests/core/filter.cpp
@@ -96,6 +96,9 @@ static void test_search()
 
 	unsigned int res5[] = {};
 	do_test_search("unknown terms", 0, res5);
+
+	unsigned int res6[] = {};
+	do_test_search("the chestZ", 0, res6);
 }
 
 int main(int argc, char **argv)