lib: rework uc_index() implementation

 - Fix segfault on passing string haystack with non-string needle argument
 - Perform strict equality tests against array haystacks
 - Make string searches binary safe
 - Improve left index string search performance
 - Improve right index array search performance
 - Add missing test coverage for index() and rindex()

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/custom/04_bugs/38_index_segfault b/tests/custom/04_bugs/38_index_segfault
new file mode 100644
index 0000000..e29b99f
--- /dev/null
+++ b/tests/custom/04_bugs/38_index_segfault
@@ -0,0 +1,28 @@
+When index() or rindex() was invoked with a string haystack and a non-
+string needle argument, a segmentation fault occurred due to an internal
+strlen() invocation on a NULL pointer.
+
+-- Testcase --
+print(index("abc", []), "\n")
+-- End --
+
+-- Args --
+-R
+-- End --
+
+-- Expect stdout --
+-1
+-- End --
+
+
+-- Testcase --
+print(rindex("abc", []), "\n")
+-- End --
+
+-- Args --
+-R
+-- End --
+
+-- Expect stdout --
+-1
+-- End --