Add -o and --help options

Makefile

@@ -9,6 +9,7 @@ $(OBJS): chibicc.h
 
 test: chibicc
 	./test.sh
+	./test-driver.sh
 
 clean:
 	rm -f chibicc *.o *~ tmp*

chibicc.h

@@ -186,4 +186,4 @@ void add_type(Node *node);
 // codegen.c
 //
 
-void codegen(Obj *prog);
+void codegen(Obj *prog, FILE *out);

codegen.c

@@ -1,5 +1,6 @@
 #include "chibicc.h"
 
+static FILE *output_file;
 static int depth;
 static char *argreg8[] = {"%dil", "%sil", "%dl", "%cl", "%r8b", "%r9b"};
 static char *argreg64[] = {"%rdi", "%rsi", "%rdx", "%rcx", "%r8", "%r9"};
@@ -11,9 +12,9 @@ static void gen_stmt(Node *node);
 static void println(char *fmt, ...) {
   va_list ap;
   va_start(ap, fmt);
-  vprintf(fmt, ap);
+  vfprintf(output_file, fmt, ap);
   va_end(ap);
-  printf("\n");
+  fprintf(output_file, "\n");
 }
 
 static int count(void) {
@@ -292,7 +293,9 @@ static void emit_text(Obj *prog) {
   }
 }
 
-void codegen(Obj *prog) {
+void codegen(Obj *prog, FILE *out) {
+  output_file = out;
+
   assign_lvar_offsets(prog);
   emit_data(prog);
   emit_text(prog);

main.c

@@ -1,15 +1,60 @@
 #include "chibicc.h"
 
+static char *opt_o;
+
+static char *input_path;
+
+static void usage(int status) {
+  fprintf(stderr, "chibicc [ -o <path> ] <file>\n");
+  exit(status);
+}
+
+static void parse_args(int argc, char **argv) {
+  for (int i = 1; i < argc; i++) {
+    if (!strcmp(argv[i], "--help"))
+      usage(0);
+
+    if (!strcmp(argv[i], "-o")) {
+      if (!argv[++i])
+        usage(1);
+      opt_o = argv[i];
+      continue;
+    }
+
+    if (!strncmp(argv[i], "-o", 2)) {
+      opt_o = argv[i] + 2;
+      continue;
+    }
+
+    if (argv[i][0] == '-' && argv[i][1] != '\0')
+      error("unknown argument: %s", argv[i]);
+
+    input_path = argv[i];
+  }
+
+  if (!input_path)
+    error("no input files");
+}
+
+static FILE *open_file(char *path) {
+  if (!path || strcmp(path, "-") == 0)
+    return stdout;
+
+  FILE *out = fopen(path, "w");
+  if (!out)
+    error("cannot open output file: %s: %s", path, strerror(errno));
+  return out;
+}
+
 int main(int argc, char **argv) {
-  if (argc != 2)
-    error("%s: invalid number of arguments", argv[0]);
+  parse_args(argc, argv);
 
   // Tokenize and parse.
-  Token *tok = tokenize_file(argv[1]);
+  Token *tok = tokenize_file(input_path);
   Obj *prog = parse(tok);
 
   // Traverse the AST to emit assembly.
-  codegen(prog);
-
+  FILE *out = open_file(opt_o);
+  codegen(prog, out);
   return 0;
 }

test-driver.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+tmp=`mktemp -d /tmp/chibicc-test-XXXXXX`
+trap 'rm -rf $tmp' INT TERM HUP EXIT
+echo > $tmp/empty.c
+
+check() {
+    if [ $? -eq 0 ]; then
+        echo "testing $1 ... passed"
+    else
+        echo "testing $1 ... failed"
+        exit 1
+    fi
+}
+
+# -o
+rm -f $tmp/out
+./chibicc -o $tmp/out $tmp/empty.c
+[ -f $tmp/out ]
+check -o
+
+# --help
+./chibicc --help 2>&1 | grep -q chibicc
+check --help
+
+echo OK

test.sh

@@ -14,7 +14,7 @@ assert() {
   expected="$1"
   input="$2"
 
-  echo "$input" | ./chibicc - > tmp.s || exit
+  echo "$input" | ./chibicc -o tmp.s - || exit
   gcc -static -o tmp tmp.s tmp2.o
   ./tmp
   actual="$?"