Added usage message, added usage-then-exit function for error and non-error cases

Fortune for naka's current commit: Curse − 凶

src/main.c

@@ -10,18 +10,46 @@
 
 #include <tests.h>
 
+// TODO: Have Makefile define these, or import them from Makefile defines.
+#define PROG_NAME "naka"
+#define PROG_DESCRIPTION "find a file within other file(s)"
+#define PROG_AUTHOUR "Avril <flanchan@cumallover.me>"
+#define PROG_LICENSE "GPL3+"
+#define PROG_VERSION VERSION(0,0,0,0)
+
+void prog_info(FILE* out)
+{
+	fprintf(out, PROG_NAME " v%s - " PROG_DESCRIPTION 
+		"\n written by %s with <3\n  license %s.\n", 
+			v_ctoss(v_rawtoc(PROG_VERSION)),
+			PROG_AUTHOUR,
+			PROG_LICENSE);
+}
 
-int main(int argc, char** argv)
+void usage(FILE* out, int argc, char** argv)
 {
 	IGNORE(argc);
-	IGNORE(argv);
 
-	INFO("main start");
+	prog_info(out);
+	fprintf(out, "\nUsage: %s <needle> <haystack(s)...>\n", argv[0] ?: PROG_NAME);
+}
+
+// err: 0 for normal exit and print to stdout.
+// err: nonzero for abnormal exit and print to stderr.
+noreturn void usage_then_exit(int err, int argc, char** argv)
+{
+	usage( err ? stderr : stdout, argc, argv);
+	exit(err);
+}
 
-	//INFO("Hello world %lu %lu %lu!", i, bswap(i), bswap(bswap(i)));
+int main(int argc, char** argv)
-	//INFO("Version: 0x%x (0x%x)", vers, bswap(vers)); // Check which version endian was preferrable, we'll stick with the default system endian (little, for this one.)
+{
+	INFO("main start");
+	
+	usage_then_exit(0, argc, argv);
 
 	INFO("main end");
+
 	return 0;
 }