[#71] Separte child infos into a new structure

src/threads/thread.c

@@ -189,14 +189,23 @@ thread_create (const char *name, int priority,
 #ifdef USERPROG
   struct process *curr_proc = process_current ();
   struct process *new_proc = &t->process;
+  struct process_info *new_proc_info;
 
   /* Initialize process. */
-  new_proc->pid = t->tid;
+  new_proc->pid = (pid_t) t->tid;
   new_proc->parent = curr_proc;
-  new_proc->status = PROCESS_LOADING;
-  new_proc->exit_code = -1;
-  new_proc->is_waiting = false;
-  list_push_back (&curr_proc->child_list, &new_proc->elem);
+
+  new_proc_info = (struct process_info *) malloc (sizeof (struct process_info));
+  if (new_proc_info == NULL)
+    return TID_ERROR;
+
+  new_proc->info = new_proc_info;
+  new_proc_info->pid = (pid_t) t->tid;
+  new_proc_info->process = new_proc;
+  new_proc_info->status = PROCESS_LOADING;
+  new_proc_info->exit_code = -1;
+  new_proc_info->is_waiting = false;
+  list_push_back (&curr_proc->child_list, &new_proc_info->elem);
 #endif
 
   /* Stack frame for kernel_thread(). */

src/userprog/process.c

@@ -103,9 +103,9 @@ start_process (void *arguments)
   /* Save load result. */
   struct process *curr = process_current ();
   if (success)
-    curr->status |= PROCESS_RUNNING;
+    curr->info->status |= PROCESS_RUNNING;
   else
-    curr->status |= PROCESS_FAIL;
+    curr->info->status |= PROCESS_FAIL;
   curr->exec_file = exec_file;
   curr->fd_next = FD_MIN;
   list_init (&curr->file_list);
@@ -138,15 +138,18 @@ int
 process_wait (tid_t child_tid UNUSED) 
 {
   struct process *curr = process_current ();
-  struct process *child = process_find_child (curr, child_tid);
+  struct process_info *child = process_find_child (curr, child_tid);
 
   if (child == NULL || child->is_waiting)
     return -1;
   child->is_waiting = true;
   while (!(child->status & PROCESS_EXIT))
     thread_yield ();
 
-  return child->exit_code;
+  int exit_code = child->exit_code;
+  list_remove (&child->elem);
+  free (child);
+  return exit_code;
 }
 
 /* Frees the current process's resources. */
@@ -160,14 +163,13 @@ process_exit (void)
   for (e = list_begin (&proc->child_list); e != list_end (&proc->child_list);
        e = list_next (e))
     {
-      struct process *child = list_entry (e, struct process, elem);
+      struct process_info *child = list_entry (e, struct process_info, elem);
       if (!(child->status & PROCESS_EXIT))
-        child->parent = NULL;
+        child->process->parent = NULL;
     }
 
   /* Update the process status and free resources. */
-  proc->status |= PROCESS_EXIT;
-  list_remove (&proc->elem);
+  proc->info->status |= PROCESS_EXIT;
   file_close (proc->exec_file);
   for (e = list_begin (&proc->file_list); e != list_end (&proc->file_list);)
     {
@@ -222,14 +224,14 @@ process_current (void)
 }
 
 /* Returns the child process of the given process with the given pid value. */
-struct process *
+struct process_info *
 process_find_child (struct process *proc, pid_t pid)
 {
   struct list_elem *e;
   for (e = list_begin (&proc->child_list); e != list_end (&proc->child_list);
        e = list_next (e))
     {
-      struct process *child = list_entry (e, struct process, elem);
+      struct process_info *child = list_entry (e, struct process_info, elem);
       if (child->pid == pid)
         return child;
     }

src/userprog/process.h

@@ -21,12 +21,19 @@ struct process
     struct file *exec_file;         /* Process executable file. */
     struct list child_list;         /* List of child processes. */
     struct list file_list;          /* List of files in use. */
-    struct list_elem elem;          /* List element. */
+    struct process_info *info;      /* Process information for its parent. */
+    int fd_next;                    /* File descriptor tracker. */
+  };
 
+/* An user process information for its parent process. */
+struct process_info
+  {
+    pid_t pid;                      /* Process identifier. */
+    struct process *process;        /* Process. */
     int status;                     /* Process status. */
     int exit_code;                  /* Exit code. */
     bool is_waiting;                /* Whether parent is waiting or not. */
-    int fd_next;                    /* File descriptor tracker. */
+    struct list_elem elem;          /* List element. */
   };
 
 /* A file held by some process. */
@@ -42,7 +49,7 @@ int process_wait (tid_t);
 void process_exit (void);
 void process_activate (void);
 struct process *process_current (void);
-struct process *process_find_child (struct process *proc, pid_t pid);
+struct process_info *process_find_child (struct process *proc, pid_t pid);
 struct file *process_get_file (int fd);
 int process_set_file (struct file * file);
 

src/userprog/syscall.c

@@ -174,7 +174,7 @@ void
 syscall_exit (int status)
 {
   /* Set exit code. */
-  process_current ()->exit_code = status;
+  process_current ()->info->exit_code = status;
 
   /* Print the termination message. */
   printf ("%s: exit(%d)\n", thread_current ()->name, status);
@@ -199,18 +199,18 @@ syscall_exec (const char *cmd_line)
     return pid;
 
   /* Obtain the new process. */
-  struct process *p = process_find_child (process_current (), pid);
-  if (p == NULL)
+  struct process_info *child = process_find_child (process_current (), pid);
+  if (child == NULL)
     return PID_ERROR;
 
   /* Wait until the new process is successfully loaded. */
-  while (p->status == PROCESS_LOADING)
+  while (child->status == PROCESS_LOADING)
     thread_yield ();
 
   /* Return PID. */
-  if (p->status & PROCESS_FAIL)
+  if (child->status & PROCESS_FAIL)
     return PID_ERROR;
-  return p->pid;
+  return pid;
 }
 
 /* Waits for a child process pid and retrieves the child's exit status. */