From 882185145944e90e5a637c2c4023850208e80a8a Mon Sep 17 00:00:00 2001
From: Themis Demetriades <td1223@ic.ac.uk>
Date: Thu, 14 Nov 2024 14:42:26 +0000
Subject: [PATCH] Refactor process_execute to remove use of 'goto'

---
 src/userprog/process.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/src/userprog/process.c b/src/userprog/process.c
index ddd1997..9f404c7 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -67,9 +67,6 @@ process_execute (const char *cmd)
   
   struct process_start_data data;
 
-  sema_init (&data.loaded, 0);
-  data.success = false;
-
   /* Make a copy of command.
      Otherwise there's a race between the caller and load(). */
   cmd_copy = palloc_get_page (0);
@@ -99,6 +96,8 @@ process_execute (const char *cmd)
      arguments. For details of arguments, see 'start_process'. */
   data.cmd = cmd_copy;
   strlcpy (data.file_name, file_name, FNAME_MAX_LEN + 1);
+  sema_init (&data.loaded, 0);
+  data.success = false;
 
   tid = thread_create (file_name, PRI_DEFAULT, start_process, &data);
   if (tid == TID_ERROR)
@@ -126,7 +125,6 @@ static void
 start_process (void *proc_start_data)
 {
   struct intr_frame if_;
-  bool success;
 
   struct process_start_data *data = proc_start_data;
 
@@ -143,34 +141,36 @@ start_process (void *proc_start_data)
   if (exec_file == NULL)
     {
       lock_release (&filesys_lock);
-      goto fail;
+      sema_up (&data->loaded);
+      thread_exit ();
     }
   thread_current ()->exec_file = exec_file;
   file_deny_write (exec_file);
   lock_release (&filesys_lock);
 
-  success = load (data->file_name, &if_.eip, &if_.esp);
+  data->success = load (data->file_name, &if_.eip, &if_.esp);
 
   /* If load failed, quit. */
-  if (!success) 
+  if (!data->success) 
     {
       palloc_free_page (data->cmd);
-      goto fail;
+      sema_up (&data->loaded);
+      thread_exit ();
     }
 
   /* Initialize user process stack and free page used to store the
      command that executed the process. */
-  success = process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
+  data->success = process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
+  bool success = data->success;
   palloc_free_page (data->cmd);
+  sema_up (&data->loaded);
   
   /* If stack initialization failed, free resources and quit. */
   if (!success)
     {
-      goto fail;
+      thread_exit ();
     }
 
-  data->success = true;
-  sema_up (&data->loaded);
   /* 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
@@ -179,12 +179,6 @@ start_process (void *proc_start_data)
      and jump to it. */
   asm volatile ("movl %0, %%esp; jmp intr_exit" : : "g" (&if_) : "memory");
   NOT_REACHED ();
-
-  /* If starting the process failed, exit. */
-fail:
-  data->success = false;
-  sema_up (&data->loaded);
-  thread_exit ();
 }
 
 /* Helper function that initializes the stack of a newly created