may work

cat/Makefile

@@ -2,6 +2,6 @@ cat: cat.c
 	$(CC) -g -o cat cat.c
 
 clean:
-	rm -f cat.c
+	rm -f cat
 
 .PHONY: clean

cat/cat.c

@@ -14,14 +14,12 @@ static char *default_argv[] = {
 	"-",
 	(char *)NULL
 };
-static char *stdout_name = "/dev/stdin";
+static char *stdin_name = "/dev/stdin";
 
 int main(int argc, char *argv[]){
-	int arguing;
+	char *argv0;
 	int c;
 	extern int errno;
-	extern int opterr;
-	extern int optind;
 	struct stat fi; /* info */
 	char *fn; /* name */
 	FILE *fo; /* object */
@@ -33,31 +31,27 @@ int main(int argc, char *argv[]){
 			default_argv[0] = argv[0];
 		argv = default_argv;
 	}
-	arguing = 1;
-	opterr = 0;
-	while(optind < argc){
-		if(arguing && (c = getopt(argc, argv, "hu")) != -1)
-			switch(c){
+
+	while((c = getopt(argc, argv, "hu")) != -1)
+		switch(c){
 			case 'u':
 				setvbuf(stdout, NULL, _IONBF, 0);
 				continue;
-			case '-':
-				arguing = 0;
-				continue;
 			case 'h': default: usage:
 				fprintf(stderr, "Usage: %s (-h) (file...)\n",
 					argv[0]);
 				return EX_USAGE;
-			}
-		if(arguing && *argv[optind] == '-'){ /* "--" */
-			arguing = 0;
-			continue;
 		}
-		if(*argv[optind] == '-' && argv[optind][1] == '\0'){ /* "-" */
+	argv0 = argv[0];
+	argc -= optind;
+	argv += optind;
+
+	while(argc --> 0){
+		if(argv[0][0] == '-' && argv[0][1] == '\0'){ /* "-" */
 			fn = stdin_name;
 			fo = stdin;
 		}else{
-			fn = argv[optind];
+			fn = argv[0];
 			if(stat(fn, &fi) == -1){
 				switch(errno){
 				case EFAULT: case ENOENT: case ENOTDIR:
@@ -105,7 +99,6 @@ int main(int argc, char *argv[]){
 
 		if(fo != stdin)
 			fclose(fo);
-		++optind;
 	}
 
 	return EX_OK;