Split cc1 from compiler driver

chibicc.h

@@ -9,6 +9,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <strings.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
 
 #define MAX(x, y) ((x) < (y) ? (y) : (x))
 #define MIN(x, y) ((x) < (y) ? (x) : (y))

main.c

@@ -1,5 +1,7 @@
 #include "chibicc.h"
 
+static bool opt_cc1;
+static bool opt_hash_hash_hash;
 static char *opt_o;
 
 static char *input_path;
@@ -11,6 +13,16 @@ static void usage(int status) {
 
 static void parse_args(int argc, char **argv) {
   for (int i = 1; i < argc; i++) {
+    if (!strcmp(argv[i], "-###")) {
+      opt_hash_hash_hash = true;
+      continue;
+    }
+
+    if (!strcmp(argv[i], "-cc1")) {
+      opt_cc1 = true;
+      continue;
+    }
+
     if (!strcmp(argv[i], "--help"))
       usage(0);
 
@@ -46,9 +58,37 @@ static FILE *open_file(char *path) {
   return out;
 }
 
-int main(int argc, char **argv) {
-  parse_args(argc, argv);
+static void run_subprocess(char **argv) {
+  // If -### is given, dump the subprocess's command line.
+  if (opt_hash_hash_hash) {
+    fprintf(stderr, "%s", argv[0]);
+    for (int i = 1; argv[i]; i++)
+      fprintf(stderr, " %s", argv[i]);
+    fprintf(stderr, "\n");
+  }
 
+  if (fork() == 0) {
+    // Child process. Run a new command.
+    execvp(argv[0], argv);
+    fprintf(stderr, "exec failed: %s: %s\n", argv[0], strerror(errno));
+    _exit(1);
+  }
+
+  // Wait for the child process to finish.
+  int status;
+  while (wait(&status) > 0);
+  if (status != 0)
+    exit(1);
+}
+
+static void run_cc1(int argc, char **argv) {
+  char **args = calloc(argc + 10, sizeof(char *));
+  memcpy(args, argv, argc * sizeof(char *));
+  args[argc++] = "-cc1";
+  run_subprocess(args);
+}
+
+static void cc1(void) {
   // Tokenize and parse.
   Token *tok = tokenize_file(input_path);
   Obj *prog = parse(tok);
@@ -57,5 +97,16 @@ int main(int argc, char **argv) {
   FILE *out = open_file(opt_o);
   fprintf(out, ".file 1 \"%s\"\n", input_path);
   codegen(prog, out);
+}
+
+int main(int argc, char **argv) {
+  parse_args(argc, argv);
+
+  if (opt_cc1) {
+    cc1();
+    return 0;
+  }
+
+  run_cc1(argc, argv);
   return 0;
 }

self.py

@@ -68,6 +68,16 @@ double strtod(char *nptr, char **endptr);
 static void va_end(va_list ap) {}
 long strtoul(char *nptr, char **endptr, int base);
 void exit(int code);
+char *basename(char *path);
+char *strrchr(char *s, int c);
+int unlink(char *pathname);
+int mkstemp(char *template);
+int close(int fd);
+int fork(void);
+int execvp(char *file, char **argv);
+void _exit(int code);
+int wait(int *wstatus);
+int atexit(void (*)(void));
 """)
 
 for path in sys.argv[1:]: