From ef67c6ad9ff46574076efd2e6cda52e20874e4aa Mon Sep 17 00:00:00 2001
From: Claudio Maggioni <maggicl@usi.ch>
Date: Mon, 25 May 2020 21:18:53 +0200
Subject: [PATCH] I am fed up with this

---
 pintos-env/pintos/userprog/syscall.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/pintos-env/pintos/userprog/syscall.c b/pintos-env/pintos/userprog/syscall.c
index 2d12b76..64c5dc4 100755
--- a/pintos-env/pintos/userprog/syscall.c
+++ b/pintos-env/pintos/userprog/syscall.c
@@ -125,7 +125,6 @@ int sys_open(const char* file) {
   fd->fd = next_fd++;
   //printf("Hash put: %x %d\n", file_opened, fd->fd);
   hash_insert(&fd_table, &fd->elem);
-
   lock_release (&filesys_lock);
   return fd->fd;
 }
@@ -134,7 +133,9 @@ int sys_filesize(int fd) {
   lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
-  struct fd_item* file_d = hash_entry(hash_find(&fd_table, &i.elem), struct fd_item, elem);
+  struct hash_elem* h = hash_find(&fd_table, &i.elem);
+  if (h == NULL) sys_exit(-1);
+  struct fd_item* file_d = hash_entry(h, struct fd_item, elem);
 
   if(file_d == NULL) {
     lock_release (&filesys_lock);
@@ -150,7 +151,9 @@ void sys_seek(int fd, unsigned position) {
   lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
-  struct fd_item* file_d = hash_entry(hash_find(&fd_table, &i.elem), struct fd_item, elem);
+  struct hash_elem* h = hash_find(&fd_table, &i.elem);
+  if (h == NULL) sys_exit(-1);
+  struct fd_item* file_d = hash_entry(h, struct fd_item, elem);
 
   if(file_d && file_d->file) {
     file_seek(file_d->file, position);
@@ -165,7 +168,9 @@ unsigned sys_tell(int fd) {
   lock_acquire (&filesys_lock);
   struct fd_item i;
   i.fd = fd;
-  struct fd_item* file_d = hash_entry(hash_find(&fd_table, &i.elem), struct fd_item, elem);
+  struct hash_elem* h = hash_find(&fd_table, &i.elem);
+  if (h == NULL) sys_exit(-1);
+  struct fd_item* file_d = hash_entry(h, struct fd_item, elem);
 
   unsigned ret;
   if(file_d && file_d->file) {