Update process_init_stack to return success, refactoring error handling to occur inside start_process

src/userprog/process.c

@@ -60,8 +60,7 @@ process_execute (const char *file_name)
   return tid;
 }
 
-static void process_init_stack (void *file_name_, char *saveptr, void **esp,
-                                char *file_name);
+static bool process_init_stack (char *saveptr, void **esp, char *file_name);
 static void *push_to_stack (void **esp, void *data, size_t data_size);
 
 /* A thread function that loads a user process and starts it
@@ -97,9 +96,18 @@ start_process (void *file_name_)
       thread_exit ();
     }
 
-  process_init_stack (file_name_, saveptr, &if_.esp, file_name);
+  /* Initialize user process stack and free page used to store the
+     command that executed the process. */
+  success = process_init_stack (saveptr, &if_.esp, file_name);
   palloc_free_page (file_name_);
   
+  /* If stack initialization failed, free resources and quit. */
+  if (!success)
+    {
+      process_exit ();
+      thread_exit ();
+    }
+
   /* Start the user process by simulating a return from an
      interrupt, implemented by intr_exit (in
      threads/intr-stubs.S).  Because intr_exit takes all of its
@@ -111,10 +119,9 @@ start_process (void *file_name_)
 }
 
 /* Helper function that initializes the stack of a newly created 
-   user process. */
-static void
-process_init_stack (void *file_name_, char *saveptr, void **esp,
-                    char *file_name)
+   user process. Returns true if successful, false otherwise. */
+static bool
+process_init_stack (char *saveptr, void **esp, char *file_name)
   {
     /* Load command line argument *data* to user process stack.
        This can't cause overflow due to enforcing that the size of
@@ -134,9 +141,7 @@ process_init_stack (void *file_name_, char *saveptr, void **esp,
           {
             printf("ERROR: Couldn't allocate argument pointer memory for %s!\n",
                    thread_current ()->name);
-            palloc_free_page (file_name_);
-            process_exit ();
-            thread_exit ();
+            return false;
           }
 
         arg_elem->arg = *esp;
@@ -196,11 +201,12 @@ process_init_stack (void *file_name_, char *saveptr, void **esp,
     /* Push fake return address (null pointer). */
     *esp -= sizeof (char *);
     *(char *) *esp = 0;
+
+    return true;
  }
 
 /* Helper function that pushes the first 'data_size' bytes stored in the
-   address '*data' into the stack given a pointer to the stack pointer
-   '**esp'. */
+   address '*data' into the stack given a pointer to the stack pointer '**esp'. */
 static void *
 push_to_stack (void **esp, void *data, size_t data_size)
 {