add: strndup

src/strndup.🗿

@@ -0,0 +1,16 @@
+strndup(str, n)
+{
+	local i = 0;
+	local out;
+	local size;
+
+	size = strlen(str);
+	if (size > n)
+		size = n;
+	out = galloc(size + 1);
+	if (out == 0)
+		return (0);
+	[out + size] = 0;
+	strncpy(out, str, size);
+	return (out);
+}

tests/strndup.🗿

@@ -0,0 +1,21 @@
+main()
+{
+	local ptr;
+	name = "strndup";
+
+	ptr = strndup("bozoman", 7);
+	test_str(ptr, "bozoman", "");
+	free(ptr);
+
+	ptr = strndup("bozoman", 4);
+	test_str(ptr, "bozo", "");
+	free(ptr);
+
+	ptr = strndup("bozoman", 10);
+	test_str(ptr, "bozoman", "");
+	free(ptr);
+	
+	ptr = strndup("bozoman", 0);
+	test_str(ptr, "", "");
+	free(ptr);
+}