Add -I<dir> option

Makefile

@@ -14,7 +14,7 @@ chibicc: $(OBJS)
 $(OBJS): chibicc.h
 
 test/%.exe: chibicc test/%.c
-	./chibicc -c -o test/$*.o test/$*.c
+	./chibicc -Itest -c -o test/$*.o test/$*.c
 	$(CC) -o $@ test/$*.o -xc test/common
 
 test: $(TESTS)
@@ -35,7 +35,7 @@ stage2/%.o: chibicc self.py %.c
 
 stage2/test/%.exe: stage2/chibicc test/%.c
 	mkdir -p stage2/test
-	./stage2/chibicc -c -o stage2/test/$*.o test/$*.c
+	./stage2/chibicc -Itest -c -o stage2/test/$*.o test/$*.c
 	$(CC) -o $@ stage2/test/$*.o -xc test/common
 
 test-stage2: $(TESTS:test/%=stage2/test/%)

chibicc.h

@@ -348,4 +348,5 @@ int align_to(int n, int align);
 
 bool file_exists(char *path);
 
+extern StringArray include_paths;
 extern char *base_file;

main.c

@@ -1,5 +1,7 @@
 #include "chibicc.h"
 
+StringArray include_paths;
+
 static bool opt_E;
 static bool opt_S;
 static bool opt_c;
@@ -19,7 +21,12 @@ static void usage(int status) {
 }
 
 static bool take_arg(char *arg) {
-  return !strcmp(arg, "-o");
+  char *x[] = {"-o", "-I"};
+
+  for (int i = 0; i < sizeof(x) / sizeof(*x); i++)
+    if (!strcmp(arg, x[i]))
+      return true;
+  return false;
 }
 
 static void parse_args(int argc, char **argv) {
@@ -69,6 +76,11 @@ static void parse_args(int argc, char **argv) {
       continue;
     }
 
+    if (!strncmp(argv[i], "-I", 2)) {
+      strarray_push(&include_paths, argv[i] + 2);
+      continue;
+    }
+
     if (!strcmp(argv[i], "-cc1-input")) {
       base_file = argv[++i];
       continue;

preprocess.c

@@ -596,6 +596,19 @@ static bool expand_macro(Token **rest, Token *tok) {
   return true;
 }
 
+static char *search_include_paths(char *filename) {
+  if (filename[0] == '/')
+    return filename;
+
+  // Search a file from the include paths.
+  for (int i = 0; i < include_paths.len; i++) {
+    char *path = format("%s/%s", include_paths.data[i], filename);
+    if (file_exists(path))
+      return path;
+  }
+  return NULL;
+}
+
 // Read an #include argument.
 static char *read_include_filename(Token **rest, Token *tok, bool *is_dquote) {
   // Pattern 1: #include "foo.h"
@@ -669,16 +682,16 @@ static Token *preprocess2(Token *tok) {
       bool is_dquote;
       char *filename = read_include_filename(&tok, tok->next, &is_dquote);
 
-      if (filename[0] != '/') {
+      if (filename[0] != '/' && is_dquote) {
         char *path = format("%s/%s", dirname(strdup(start->file->name)), filename);
         if (file_exists(path)) {
           tok = include_file(tok, path, start->next->next);
           continue;
         }
       }
 
-      // TODO: Search a file from the include paths.
-      tok = include_file(tok, filename, start->next->next);
+      char *path = search_include_paths(filename);
+      tok = include_file(tok, path ? path : filename, start->next->next);
       continue;
     }
 

self.py

@@ -95,6 +95,8 @@
 char *dirname(char *path);
 char *strncpy(char *dest, char *src, long n);
 int stat(char *pathname, struct stat *statbuf);
+int stat(char *pathname, struct stat *statbuf);
+char *dirname(char *path);
 """)
 
 for path in sys.argv[1:]:

test/driver.sh

@@ -85,4 +85,10 @@ echo "#include \"$tmp/out1\"" | $chibicc -E -o $tmp/out2 -
 cat $tmp/out2 | grep -q foo
 check '-E and -o'
 
+# -I
+mkdir $tmp/dir
+echo foo > $tmp/dir/i-option-test
+echo "#include \"i-option-test\"" | $chibicc -I$tmp/dir -E - | grep -q foo
+check -I
+
 echo OK