some fixes

src/file.c

@@ -1,10 +1,14 @@
 #include "file.h"
 
+#include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 char *read_file(const char *path) {
+  create_file_if_not_exists(path);
   FILE *fp = fopen(path, "rb");
   if (fp == NULL) {
     perror("Error opening file");
@@ -36,6 +40,7 @@ char *read_file(const char *path) {
 }
 
 char *write_file(const char *path, const char *data) {
+  create_file_if_not_exists(path);
   FILE *fp = fopen(path, "w");
   if (fp == NULL) {
     printf("%s\n", path);
@@ -50,3 +55,23 @@ char *write_file(const char *path, const char *data) {
   char *ret = strdup(data);
   return ret;
 }
+
+int create_file_if_not_exists(const char *filename) {
+  if (!check_file_exists(filename)) {
+    return 0;
+  }
+  FILE *file = fopen(filename, "w");
+  if (file == nullptr) {
+    perror("Error creating file");
+    return -1;
+  }
+  fclose(file);
+  return 0;
+}
+
+int check_file_exists(const char *filename) {
+  if (access(filename, F_OK) == 0) {
+    return 0;
+  }
+  return -1;
+}