Tidy up a69b9c808e

Add validation to check for missing files in exec() args

See merge request lab2425_autumn/pintos_22!36

src/threads/synch.c

@@ -212,6 +212,7 @@ donate_priority (struct thread *donee) {
   ASSERT (intr_get_level () == INTR_OFF);
 
   struct thread *donor = thread_current ();
+  list_remove (&donor->donor_elem);
   list_push_back (&donee->donors_list, &donor->donor_elem);
   
   while (donee != NULL)
@@ -260,6 +261,7 @@ lock_acquire (struct lock *lock)
   ASSERT (!lock_held_by_current_thread (lock));
 
   struct thread *t = thread_current ();
+  ASSERT (t->waiting_lock == NULL);
 
   enum intr_level old_level = intr_disable ();
   if (lock->holder != NULL)
@@ -341,7 +343,6 @@ lock_release (struct lock *lock)
      released, transfer the remaining orphaned donors to its donor list. */
   if (max_donor != NULL)
     {
-      list_remove (&max_donor->donor_elem);
       while (!list_empty (&orphan_list))
         list_push_back (&max_donor->donors_list, list_pop_front (&orphan_list));
     }

src/threads/thread.c

@@ -373,7 +373,9 @@ thread_exit (void)
      and schedule another process.  That process will destroy us
      when it calls thread_schedule_tail(). */
   intr_disable ();
-  list_remove (&thread_current()->allelem);
+  struct thread *t = thread_current ();
+  list_remove (&t->allelem);
+  list_remove (&t->donor_elem);
   thread_current ()->status = THREAD_DYING;
   schedule ();
   NOT_REACHED ();
@@ -679,6 +681,7 @@ init_thread (struct thread *t, const char *name, int nice, int priority,
   t->base_priority
       = thread_mlfqs ? calculate_bsd_priority (recent_cpu, nice) : priority;
   list_init (&t->donors_list);
+  list_push_back (&t->donors_list, &t->donor_elem);
   t->waiting_lock = NULL;
 
   t->nice = nice;

src/userprog/process.c

@@ -8,6 +8,7 @@
 #include <string.h>
 #include "userprog/gdt.h"
 #include "userprog/pagedir.h"
+#include "userprog/syscall.h"
 #include "userprog/tss.h"
 #include "filesys/directory.h"
 #include "filesys/file.h"
@@ -81,6 +82,16 @@ process_execute (const char *cmd)
      of the process. */
   char *file_name = strtok_r (cmd_copy, " ", &data->cmd_saveptr);
 
+  /* NOTE: Currently, the file being executed is closed in load () and then
+          reopened here. Because load is an exported public function, this
+          might be necessary. */
+  lock_acquire (&filesys_lock);
+  /* Validates that the current file to be executed is a valid file */
+  bool valid_file = filesys_open (file_name) != NULL;
+  lock_release (&filesys_lock);
+  if (!valid_file)
+    return TID_ERROR;
+
   /* 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'. */
@@ -116,6 +127,15 @@ 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;
+  
+  lock_acquire (&filesys_lock);
+  
+  /* Prevent writing to the file being executed. */
+  struct file *exec_file = filesys_open (data->file_name);
+  thread_current ()->exec_file = exec_file;
+  file_deny_write (exec_file);
+  lock_release (&filesys_lock);
+
   success = load (data->file_name, &if_.eip, &if_.esp);
 
   /* If load failed, quit. */
@@ -137,13 +157,6 @@ start_process (void *proc_start_data)
       goto fail;
     }
 
-  /* NOTE: Currently, the file being executed is closed in load () and then 
-           reopened here. Because load is an exported public function, this
-           might be necessary. */
-  struct file *exec_file = filesys_open (data->file_name);
-  thread_current ()->exec_file = exec_file;
-  file_deny_write (exec_file);
-
   /* 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
@@ -312,7 +325,13 @@ process_exit (void)
   uint32_t *pd;
 
   printf ("%s: exit(%d)\n", cur->name, cur->exit_status);
-  file_close (cur->exec_file);
+  if (cur->exec_file != NULL)
+    {
+      lock_acquire (&filesys_lock);
+      file_allow_write (cur->exec_file);
+      file_close (cur->exec_file);
+      lock_release (&filesys_lock);
+    }
 
   /* Update process result. */
   if (cur->result != NULL)
@@ -472,6 +491,7 @@ load (const char *file_name, void (**eip) (void), void **esp)
   off_t file_ofs;
   bool success = false;
   int i;
+  lock_acquire (&filesys_lock);
 
   /* Allocate and activate page directory. */
   t->pagedir = pagedir_create ();
@@ -571,6 +591,7 @@ load (const char *file_name, void (**eip) (void), void **esp)
  done:
   /* We arrive here whether the load is successful or not. */
   file_close (file);
+  lock_release (&filesys_lock);
   return success;
 }
 

src/userprog/syscall.c

@@ -13,7 +13,6 @@
 #include <stdio.h>
 #include <syscall-nr.h>
 
-static struct lock filesys_lock;
 static unsigned fd_counter = MIN_USER_FD;
 
 struct open_file
@@ -143,9 +142,7 @@ syscall_exec (const char *cmd_line)
 {
   validate_user_pointer (cmd_line, 1);
 
-  lock_acquire (&filesys_lock);
   pid_t pid = process_execute(cmd_line);
-  lock_release (&filesys_lock);
 
   return pid;
 }

src/userprog/syscall.h

@@ -2,11 +2,14 @@
 #define USERPROG_SYSCALL_H
 
 #include <hash.h>
+#include "threads/synch.h"
 
 #define MIN_USER_FD 2
 
 typedef int pid_t;
 
+struct lock filesys_lock;
+
 void syscall_init (void);
 
 unsigned fd_hash (const struct hash_elem *element, void *aux);