Refactor process initialization to obtain name of process file in process_execute

src/userprog/process.c

@@ -34,6 +34,18 @@ struct arg_elem
     struct list_elem elem;
   };
 
+/* Holds the data required to be passed from a kernel thread to a thread
+   that executes process_start for the purpose of starting a user process. */
+struct process_start_data
+  {
+    char *cmd; /* Pointer to a copy of the command used to execute the process.
+                  Allocated a page that must be freed by process_start. */
+    char *cmd_saveptr; /*  Value pointed to by 'saveptr' argument used by
+                           successive calls to strtok_r to split 'cmd' into
+                           tokens while maintaining state. */
+    char *file_name; /* Name of the file of the process to be started. */
+  };
+
 static thread_func start_process NO_RETURN;
 static bool load (const char *cmdline, void (**eip) (void), void **esp);
 
@@ -44,66 +56,73 @@ static bool load (const char *cmdline, void (**eip) (void), void **esp);
 tid_t
 process_execute (const char *cmd) 
 {
-  char *fn_copy;
+  char *cmd_copy;
   tid_t tid;
+  struct process_start_data data;
 
-  /* Make a copy of FILE_NAME.
+  /* Make a copy of command.
      Otherwise there's a race between the caller and load(). */
-  fn_copy = palloc_get_page (0);
+  cmd_copy = palloc_get_page (0);
-  if (fn_copy == NULL)
+  if (cmd_copy == NULL)
     return TID_ERROR;
 
   /* Imposing implicit limit that the command line arguments
     including the user program name fit within a single page. */
-  strlcpy (fn_copy, cmd, PGSIZE);
+  strlcpy (cmd_copy, cmd, PGSIZE);
 
-  /* Create a new thread to execute FILE_NAME. */
+  /* Retrieve first argument of command, which is the file name
-  tid = thread_create (cmd, PRI_DEFAULT, start_process, fn_copy);
+     of the process. */
+  char *file_name = strtok_r (cmd_copy, " ", &data.cmd_saveptr);
+  if (strlen (file_name) > FNAME_MAX_LEN)
+    file_name[FNAME_MAX_LEN + 1] = '\n';
+
+  /* Create a new thread to execute the command, by initializing
+     it running the function 'start_process' with the appropriate
+     arguments. For details of arguments, see 'start_process'. */
+  data.cmd = cmd_copy;
+  data.file_name = file_name;
+  
+  tid = thread_create (file_name, PRI_DEFAULT, start_process, &data);
   if (tid == TID_ERROR)
-    palloc_free_page (fn_copy); 
+    palloc_free_page (cmd_copy); 
   return tid;
 }
 
 static bool process_init_stack (char *cmd_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
+/* Make the current thread execute 'cmd', passing in a copy of the
-   running. */
+   command string used for processing, the saveptr used by strtok_r
+   (in order to further tokenize the same command and retrieve its
+   arguments), as well as the name of the file being executed. This
+   involves loading the specified file and starting it running. */
 static void
-start_process (void *cmd)
+start_process (void *proc_start_data)
 {
   struct intr_frame if_;
   bool success;
 
-   /* Retrieve first argument of command, which is the file name
+  struct process_start_data *data = proc_start_data;
-     of the process. */
+  ASSERT (data->cmd_saveptr != NULL);
-  char *saveptr;
-  char *file_name = strtok_r (cmd, " ", &saveptr);
-  if (strlen (file_name) > FNAME_MAX_LEN)
-    file_name[FNAME_MAX_LEN + 1] = '\n';
-
-  /* TODO: Move naming of thread to process_execute, so start
-    tokenizing there. */
-  strlcpy (thread_current ()->name, file_name, FNAME_MAX_LEN + 1);
 
   /* Initialize interrupt frame and load executable. */
   memset (&if_, 0, sizeof if_);
   if_.gs = if_.fs = if_.es = if_.ds = if_.ss = SEL_UDSEG;
   if_.cs = SEL_UCSEG;
   if_.eflags = FLAG_IF | FLAG_MBS;
-  success = load (file_name, &if_.eip, &if_.esp);
+  success = load (data->file_name, &if_.eip, &if_.esp);
 
   /* If load failed, quit. */
   if (!success) 
     {
-      palloc_free_page (cmd);
+      palloc_free_page (data->cmd);
       thread_exit ();
     }
 
   /* 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);
+  success = process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
-  palloc_free_page (cmd);
+  palloc_free_page (data->cmd);
   
   /* If stack initialization failed, free resources and quit. */
   if (!success)