Add test of strnlen().

targettest/strnlen.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+const char * str = "0123456789";
+
+void
+check (size_t result, size_t expected)
+{
+    if (result != expected) {
+        printf ("Expected strnlen() to return %d, got %d.\n",
+                expected, result);
+        exit (EXIT_FAILURE);
+    }
+}
+
+int
+main (void)
+{
+    size_t  maxlen = strlen (str);
+    size_t  result;
+    size_t  expected;
+
+    for (expected = 0; expected < maxlen; expected++)
+        check (strnlen (str, expected), expected);
+
+    check (strnlen (str, maxlen << 1), maxlen);
+
+    printf ("strnlen() OK.\n");
+
+    return EXIT_SUCCESS;
+}