Update syscall.c to use syscall_exit on failure instead of calling thread_exit directly

src/userprog/syscall.c

@@ -81,7 +81,6 @@ static const syscall_arguments syscall_lookup[] =
 static const int LOOKUP_SIZE
   = sizeof (syscall_lookup) / sizeof (syscall_arguments);
 
-
 /* Initialises the syscall handling system, as well as a global lock to
    synchronise all file access between processes. */
 void
@@ -103,13 +102,14 @@ syscall_handler (struct intr_frame *f)
 
   /* Ensures the number corresponds to a system call that can be handled. */
   if (syscall_number >= LOOKUP_SIZE)
-    thread_exit ();
+    syscall_exit (EXIT_FAILURE);
 
   syscall_arguments syscall = syscall_lookup[syscall_number];
 
   /* Next, read and copy the arguments from the stack pointer. */
   validate_user_pointer (f->esp + sizeof (uintptr_t),
                          syscall.arity * sizeof (uintptr_t));
+
   uintptr_t args[MAX_SYSCALL_ARGS] = {0};
   for (int i = 0; i < syscall.arity && i < MAX_SYSCALL_ARGS; i++)
     args[i] = *(uintptr_t *) (f->esp + sizeof (uintptr_t) * (i + 1));
@@ -427,13 +427,13 @@ validate_user_pointer (const void *start, size_t size)
   const void *end = start + size - 1;
 
   if (start == NULL || !is_user_vaddr (start) || !is_user_vaddr (end))
-    thread_exit ();
+    syscall_exit (EXIT_FAILURE);
 
   /* We now need to check if the entire memory block is mapped to physical
      memory by the page table. */
   for (const void *ptr = start; ptr <= end; ptr += PGSIZE)
     if (pagedir_get_page (thread_current ()->pagedir, ptr) == NULL)
-      thread_exit ();
+      syscall_exit (EXIT_FAILURE);
 }
 
 /* Validates if a string is fully contained within user virtual memory. Kills
@@ -443,7 +443,7 @@ static void
 validate_user_string (const char *str)
 {
   if (str == NULL || !is_user_vaddr (str))
-    thread_exit ();
+    syscall_exit (EXIT_FAILURE);
 
   size_t length = 0;
   size_t offset = (uintptr_t) str % PGSIZE;
@@ -455,7 +455,7 @@ validate_user_string (const char *str)
 
     if (!is_user_vaddr(page) ||
         pagedir_get_page (thread_current ()->pagedir, page) == NULL)
-      thread_exit ();
+      syscall_exit (EXIT_FAILURE);
 
     while (offset < PGSIZE)
       {