From f4c900e56cc85273015ecc4cf562d4190a0ea087 Mon Sep 17 00:00:00 2001
From: sBubshait <s.bobshit@gmail.com>
Date: Fri, 15 Nov 2024 14:37:38 +0000
Subject: [PATCH] Refactor process.c for comments, clarity and readability

---
 src/userprog/process.c | 36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/src/userprog/process.c b/src/userprog/process.c
index afc39f4..ad0bdec 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -84,9 +84,9 @@ process_execute (const char *cmd)
 
   /* Validates that the current file to be executed can be opened/exists. */
   lock_acquire (&filesys_lock);
-  bool valid_file = filesys_open (file_name) != NULL;
+  struct file *file = filesys_open (file_name);
   lock_release (&filesys_lock);
-  if (!valid_file)
+  if (file == NULL)
     return TID_ERROR;
 
   /* Create a new thread to execute the command, by initializing
@@ -128,7 +128,6 @@ static void
 start_process (void *proc_start_data)
 {
   struct intr_frame if_;
-
   struct process_start_data *data = proc_start_data;
 
   /* Initialize interrupt frame and load executable. */
@@ -136,41 +135,46 @@ start_process (void *proc_start_data)
   if_.gs = if_.fs = if_.es = if_.ds = if_.ss = SEL_UDSEG;
   if_.cs = SEL_UCSEG;
   if_.eflags = FLAG_IF | FLAG_MBS;
-  
+
+  /* Acquire the file system lock to prevent race conditions. */
   lock_acquire (&filesys_lock);
-  
-  /* Prevent writing to the file being executed. */
+
   struct file *exec_file = filesys_open (data->file_name);
   if (exec_file == NULL)
     {
+      /* If the executable file cannot be opened, free resources and quit. */
       lock_release (&filesys_lock);
       sema_up (&data->loaded);
       thread_exit ();
     }
+
+  /* Deny write to the executable file to prevent writing to it and release the
+     file system lock. */
   file_deny_write (exec_file);
   lock_release (&filesys_lock);
+
   thread_current ()->exec_file = exec_file;
 
+  /* Load the ELF executable file, and store the success of the operation in
+     the 'success' variable in data. */
   data->success = load (data->file_name, &if_.eip, &if_.esp);
 
-  /* If load failed, quit. */
-  if (!data->success) 
+  /* If load was sucessful, initialize user process stack and free page used
+ to store the command that executed the process. */
+  if (data->success)
     {
-      sema_up (&data->loaded);
-      thread_exit ();
+      data->success =
+        process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
     }
 
-  /* Initialize user process stack and free page used to store the
-     command that executed the process. */
-  data->success = process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
+  /* Signal that the process has finished attempting to load. */
   bool success = data->success;
   sema_up (&data->loaded);
   
-  /* If stack initialization failed, free resources and quit. */
+  /* If the load was unsuccessful or if it was but the stack initialization
+     failed, exit the thread. */
   if (!success)
-    {
       thread_exit ();
-    }
 
   /* Start the user process by simulating a return from an
      interrupt, implemented by intr_exit (in