/* procfs -- a translator for providing GNU/Linux compatible 
             proc pseudo-filesystem

   procfs_dir.c -- This file contains definitions to perform
                   directory operations such as creating,
                   removing and refreshing directories.
               
   Copyright (C) 2008, FSF.
   Written as a Summer of Code Project
   

   procfs is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   procfs is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA. 
   
   A portion of the code in this file is based on ftpfs code
   present in the hurd repositories copyrighted to FSF. The
   Copyright notice from that file is given below.
   
   Copyright (C) 1997,98,2002 Free Software Foundation, Inc.
   Written by Miles Bader <miles@gnu.org>
   This file is part of the GNU Hurd.
*/


#include <stdio.h>
#include <unistd.h>
#include <hurd/netfs.h>
#include <hurd/ihash.h>
#include <sys/stat.h>

#include "procfs.h"

/* Initial HASHTABLE length for the new directories to be created. */
#define INIT_HTABLE_LEN 5

struct procfs_dir_entry **cur_entry;

/* Return in DIR a new procfs directory, in the filesystem FS,
   with node NODE and path PATH. */
error_t procfs_dir_create (struct procfs *fs, struct node *node,
			  const char *path, struct procfs_dir **dir)
{
  struct procfs_dir *new = malloc (sizeof (struct procfs_dir));
  if (!new) 
    return ENOMEM;
  struct procfs_dir_entry **htable = calloc (INIT_HTABLE_LEN,
                            sizeof (struct procfs_dir_entry *));
  if (!htable)
    return ENOMEM;

  /* Hold a reference to the new dir's node.  */
  spin_lock (&netfs_node_refcnt_lock);
  node->references++;
  spin_unlock (&netfs_node_refcnt_lock);

  new->num_entries = 0;
  new->num_live_entries = 0;
  new->htable_len = INIT_HTABLE_LEN;
  new->htable = htable;
  new->ordered = NULL;
  new->fs_path = path;
  new->fs = fs;
  new->node = node;
  new->stat_timestamp = 0;
  new->name_timestamp = 0;

  *dir = new;

  if (fs->root != 0)
    node->nn->dir = new;

  return 0;
}

/* Put the directory entry DIR_ENTRY into the hash table HTABLE. */
static void
insert (struct procfs_dir_entry *dir_entry,
	struct procfs_dir_entry **htable, size_t htable_len)
{
  struct procfs_dir_entry **new_htable = &htable[dir_entry->hv % htable_len];
  if (*new_htable)
    (*new_htable)->self_p = &dir_entry->next;
  dir_entry->next = *new_htable;
  dir_entry->self_p = new_htable;
  *new_htable = dir_entry;
}

/* Calculate NAME's hash value.  */
static size_t
hash (const char *name)
{
  size_t hash_value = 0;
  while (*name)
    hash_value = ((hash_value << 5) + *name++) & 0xFFFFFF;
  return hash_value;
}

/* Extend the existing hashtable for DIR to accomodate values for new length
   NEW_LEN. We retain all the previous entries. */
static error_t
rehash (struct procfs_dir *dir, size_t new_len)
{
  int count;
  size_t old_len = dir->htable_len;
  struct procfs_dir_entry **old_htable = dir->htable;
  struct procfs_dir_entry **new_htable = (struct procfs_dir_entry **)
    malloc (new_len * sizeof (struct procfs_dir_entry *));

  if (! new_htable)
    return ENOMEM;

  bzero (new_htable, new_len * sizeof (struct procfs_dir_entry *));

  for (count = 0; count < old_len; count++)
    while (old_htable[count])
      {
	struct procfs_dir_entry *dir_entry = old_htable[count];

	/* Remove DIR_ENTRY from the old table */
	old_htable[count] = dir_entry->next;

	insert (dir_entry, new_htable, new_len);
      }

  free (old_htable);

  dir->htable = new_htable;
  dir->htable_len = new_len;

  return 0;
}

/* Lookup NAME in DIR and return its entry.  If there is no such entry, and
   DNEW, the decision variable, is true, then a new entry is allocated and
   returned, otherwise 0 is returned (if DNEW is true then 0 can be returned
   if a memory allocation error occurs).  */
struct procfs_dir_entry *
lookup_entry (struct procfs_dir *dir, const char *name, int dnew)
{
  size_t hv = hash (name);
  struct procfs_dir_entry *dir_entry = dir->htable[hv % dir->htable_len];

  while (dir_entry && strcmp (name, dir_entry->name) != 0)
    dir_entry = dir_entry->next;

  if (!dir_entry && dnew)
    {
      if (dir->num_entries > dir->htable_len)
	/* Grow the hash table.  */
	if (rehash (dir, (dir->htable_len + 1) * 2 - 1) != 0)
	  return 0;

      dir_entry = 
      (struct procfs_dir_entry *) malloc (sizeof (struct procfs_dir_entry));

      if (dir_entry)
	{
	  dir_entry->hv = hv;
	  dir_entry->name = strdup (name);
	  dir_entry->node = 0;
	  dir_entry->dir = dir;
	  dir_entry->stat_timestamp = 0;
	  bzero (&dir_entry->stat, sizeof dir_entry->stat);
	  dir_entry->symlink_target = 0;
	  dir_entry->noent = 0;
	  dir_entry->valid = 0;
	  dir_entry->name_timestamp = 0;
	  dir_entry->ordered_next = 0;
	  dir_entry->ordered_self_p = 0;
	  dir_entry->next = 0;
	  dir_entry->self_p = 0;
	  insert (dir_entry, dir->htable, dir->htable_len);
	  dir->num_entries++;
	}
    }

  return dir_entry;
}


/* Lookup NAME in DIR, returning its entry, or an error. 
   *NODE will contain the result node, locked, and with
   an additional reference, or 0 if an error occurs.  */
error_t procfs_dir_lookup (struct procfs_dir *dir, const char *name,
			  struct node **node)
{
  struct procfs_dir_entry *dir_entry = 0;
  error_t err = 0;
  char *fs_path = dir->fs_path;
  
  struct timeval tv;
  maptime_read (procfs_maptime, &tv); 
  
  time_t timestamp = tv.tv_sec;
 
  if (*name == '\0' || strcmp (name, ".") == 0)
    /* Current directory -- just add an additional reference to DIR's node
       and return it.  */
    {
      netfs_nref (dir->node);
      *node = dir->node;
      return 0;
    }
  else if (strcmp (name, "..") == 0)
    /* Parent directory.  */
    {
      if (dir->node->nn->dir_entry)
	{
	  *node = dir->node->nn->dir_entry->dir->node;
	  mutex_lock (&(*node)->lock);
	  netfs_nref (*node);
	}
      else
	{
	  err = ENOENT;		/* No .. */
	  *node = 0;
	}

      mutex_unlock (&dir->node->lock);

      return err;
    }

  err =  procfs_dir_refresh (dir, dir->node == dir->fs->root);
  if (!err && !dir_entry)
    dir_entry = lookup_entry (dir, name, 0);
   
  if (! err)
    {
      if (dir_entry && !dir_entry->noent)
	/* We've got a dir entry, get a node for it.  */
	{
	  /* If there's already a node, add a ref so that it doesn't go
             away.  */
	  spin_lock (&netfs_node_refcnt_lock);
	  if (dir_entry->node)
	    dir_entry->node->references++;
	  spin_unlock (&netfs_node_refcnt_lock);

	  if (! dir_entry->node)
	    /* No node; make one and install it into E.  */
	    {
	      if (! fs_path)
                err = EROFS;

	      if (! err)
		{
		  err = procfs_create_node (dir_entry, fs_path, &dir_entry->node);

		  if (!err && dir->num_live_entries++ == 0)
		    /* Keep a reference to dir's node corresponding to
		       children.  */
		    {
		      spin_lock (&netfs_node_refcnt_lock);
		      dir->node->references++;
		      spin_unlock (&netfs_node_refcnt_lock);
		    }
		}
	    }

	  if (! err)
	    {
	      *node = dir_entry->node;
	      /* We have to unlock DIR's node before locking the child node
		 because the locking order is always child-parent.  We know
		 the child node won't go away because we already hold the
		 additional reference to it.  */
	      mutex_unlock (&dir->node->lock);
	      mutex_lock (&dir_entry->node->lock);
	    }
	}
      else
	err = ENOENT;
    }

  if (err)
    {
      *node = 0;
      mutex_unlock (&dir->node->lock);
    }

#if 0
  if (fs_path)
    free (fs_path);
#endif

  return err;
}

/* Lookup the null name in DIR, and return a node for it in NODE.  Unlike
   procfs_dir_lookup, this won't attempt to validate the existance of the
   entry (to avoid opening a new connection if possible) -- that will happen
   the first time the entry is refreshed.  Also unlink ftpfs_dir_lookup, this
   function doesn't expect DIR to be locked, and won't return *NODE locked.
   This function is only used for bootstrapping the root node.  */
error_t
procfs_dir_null_lookup (struct procfs_dir *dir, struct node **node)
{
  struct procfs_dir_entry *dir_entry;
  error_t err = 0;

  dir_entry = lookup_entry (dir, "", 1);
  if (! dir_entry)
    return ENOMEM;

  if (! dir_entry->noent)
    /* We've got a dir entry, get a node for it.  */
    {
      /* If there's already a node, add a ref so that it doesn't go away.  */
      spin_lock (&netfs_node_refcnt_lock);
      if (dir_entry->node)
	dir_entry->node->references++;
      spin_unlock (&netfs_node_refcnt_lock);

      if (! dir_entry->node)
	/* No node; make one and install it into DIR_ENTRY.  */
	{
	  err = procfs_create_node (dir_entry, dir->fs_path, &dir_entry->node);

	  if (!err && dir->num_live_entries++ == 0)
	    /* Keep a reference to dir's node corresponding to children.  */
	    {
	      spin_lock (&netfs_node_refcnt_lock);
	      dir->node->references++;
	      spin_unlock (&netfs_node_refcnt_lock);
	    }
	}

      if (! err)
	*node = dir_entry->node;
    }
  else
    err = ENOENT;

  return err;
}

/* Free the directory entry DIR_ENTRY and all resources it consumes.  */
void
free_entry (struct procfs_dir_entry *dir_entry)
{

  assert (! dir_entry->self_p);	      /* We should only free deleted nodes.  */
  free (dir_entry->name);
  if (dir_entry->symlink_target)
    free (dir_entry->symlink_target);
  free (dir_entry->node->nn->dir);
  free (dir_entry->node->nn);
  free (dir_entry->node);
  free (dir_entry); 
}

/* Remove DIR_ENTRY from its position in the ordered_next chain.  */
static void
ordered_unlink (struct procfs_dir_entry *dir_entry)
{
  if (dir_entry->ordered_self_p)
    *dir_entry->ordered_self_p = dir_entry->ordered_next;
  if (dir_entry->ordered_next)
    dir_entry->ordered_next->self_p = dir_entry->ordered_self_p;
}

/* Delete DIR_ENTRY from its directory, freeing any resources it holds.  */
static void
delete (struct procfs_dir_entry *dir_entry, struct procfs_dir *dir)
{
  dir->num_entries--;
  
  /* Take out of the hash chain.  */
  if (dir_entry->self_p)
    *dir_entry->self_p = dir_entry->next;
  if (dir_entry->next)
    dir_entry->next->self_p = dir_entry->self_p;

  /* Take out of the directory ordered list.  */
  ordered_unlink (dir_entry); 

  /* If there's a node attached, we'll delete the entry whenever it goes
     away, otherwise, just delete it now.  */
  if (! dir_entry->node)
    free_entry (dir_entry);    
}

/* Make all the directory entries invalid  */
static void
make_dir_invalid (struct procfs_dir *dir)
{
  int count;
  size_t len = dir->htable_len;
  struct procfs_dir_entry **htable = dir->htable;
  struct procfs_dir_entry *dir_entry;

  for (count = 0; count < len; count++)
    {
      dir_entry = htable[count];
      while (dir_entry)
        {
          dir_entry->valid = 0;
          dir_entry = dir_entry->next;
        }
    }  
}

/* Delete any entries in DIR which don't have their valid bit set.  */
static void
sweep (struct procfs_dir *dir)
{
  size_t len = dir->htable_len, i;
  struct procfs_dir_entry **htable = dir->htable, *dir_entry;

  for (i = 0; i < len; i++)
    {
      dir_entry = htable[i];
      while (dir_entry)
        {
          if (!dir_entry->valid && !dir_entry->noent && dir->num_entries)
            delete (dir_entry, dir);	
          dir_entry = dir_entry->next;
        }
      if (htable[i])
        {
          free (htable[i]);
          htable[i] = 0;
        }

    }      

}

/* Remove the specified DIR and free all its allocated
   storage. */
void procfs_dir_entries_remove (struct procfs_dir *dir)
{
  /* Free all entries.  */
  make_dir_invalid (dir);
  sweep (dir);  
}

/* Checks if the DIR name is in list of 
   Active pids. */
int is_in_pid_list (struct procfs_dir *dir)
{
  int dir_name;
  int count;
  pid_t *pids = NULL;
  int pidslen = 0;
  error_t err;

  if (dir->node->nn)
    {
      dir_name = atoi (dir->node->nn->dir_entry->name);
      err = proc_getallpids (getproc (), &pids, &pidslen);

      for (count = 0; count < pidslen; ++count)
        if (pids[count] == dir_name)
          return 1;
    }

  return 0;

}

/* Checks if DIR is a directory that
   represents a pid. */
int check_parent (struct procfs_dir *dir)
{
  if (dir == dir->fs->root)
    return 0;
  else
    if (is_in_pid_list (dir))
      return 1;
    else
      return 0;

}

/* Refresh DIR.  */
error_t procfs_dir_refresh (struct procfs_dir *dir, int isroot)
{
  error_t err;
  int is_parent_pid;
  struct node *node;
  
  struct timeval tv;
  maptime_read (procfs_maptime, &tv); 
  
  time_t timestamp = tv.tv_sec;
  cur_entry = &dir->ordered;
  if (isroot)
    err = procfs_fill_root_dir(dir, timestamp);
  else
    {
      err = update_dir_entries (dir, timestamp);
      is_parent_pid = check_parent (dir);
      if (is_parent_pid)
          err = procfs_create_files (dir, &node, timestamp);    
    }

  return err;
}

/* Update the directory entry for NAME to reflect STAT and SYMLINK_TARGET. 
   This also creates a valid linked list of entries imposing ordering on
   them. */
struct procfs_dir_entry*
update_entries_list (struct procfs_dir *dir, const char *name,
                             const struct stat *stat, time_t timestamp,
                             const char *symlink_target)
{
  ino_t ino;
  struct procfs_dir_entry *dir_entry = lookup_entry (dir, name, 1);
  struct procfs *fs = dir->fs;
  
  if (! dir_entry)
    return ENOMEM;

  if (dir_entry->stat.st_ino)
    ino = dir_entry->stat.st_ino;
  else
    ino = fs->next_inode++;

  dir_entry->name_timestamp = timestamp;

  if (stat)
    /* The ST and SYMLINK_TARGET parameters are only valid if ST isn't 0.  */
    {
      dir_entry->stat = *stat;
      dir_entry->stat_timestamp = timestamp;

      if (!dir_entry->symlink_target || !symlink_target
	  || strcmp (dir_entry->symlink_target, symlink_target) != 0)
	{
	  if (dir_entry->symlink_target)
	    free (dir_entry->symlink_target);
	  dir_entry->symlink_target = symlink_target ? strdup (symlink_target) : 0;
	}
    }

  /* The st_ino field is always valid.  */
  dir_entry->stat.st_ino = ino;
  dir_entry->stat.st_fsid = fs->fsid;
  dir_entry->stat.st_fstype = PROCFILESYSTEM;
 
  dir_entry->valid = 1;

  if (! dir_entry->ordered_self_p)
    /* Position DIR_ENTRY in the ordered chain following the previously seen entry.  */
    {
      /* The PREV_ENTRY_NEXT_P field holds a pointer to the NEXT-field of the
	 previous entry, or a pointer to the ORDERED field in the directory. */
      dir_entry->ordered_self_p = cur_entry;

      if (*dir_entry->ordered_self_p)
	/* Update the self_p pointer of the previous successor.  */
	(*dir_entry->ordered_self_p)->ordered_self_p = &dir_entry->ordered_next;

      /* DIR_ENTRY comes before the previous successor.  */
      dir_entry->ordered_next = *dir_entry->ordered_self_p;

      *dir_entry->ordered_self_p = dir_entry;	/* Put DIR_ENTRY there.  */
    }

  /* Put the next entry after this one. */
  cur_entry = &dir_entry->ordered_next;

  return dir_entry;
}

/* Fills DIR, the root directory with all the pids of 
   processes running in the system as directories. */
error_t 
procfs_fill_root_dir(struct procfs_dir *dir, time_t timestamp)
{
  error_t err;
  char *data;
  pid_t *pids;
  int pidslen;
  struct stat stat;
  stat.st_mode = S_IFDIR | S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | 
                  S_IROTH | S_IXOTH;
  stat.st_nlink = 1;
  stat.st_size = 0;

  int count;
  char *dir_name_pid;
  struct node *node;
  struct procfs_dir *new_dir;
  struct procfs_dir_entry *dir_entry;
  struct proc_stat *ps;
    
  pids = NULL;
  pidslen = 0;
  err = proc_getallpids (getproc (), &pids, &pidslen);

  if (!err)
    {
      for (count = 0; count < pidslen; count++)
	{
          if (asprintf (&dir_name_pid, "%d", pids[count]) == -1)
	    return errno;

#if 0
          node = (struct node *) malloc (sizeof (struct node));
          new_dir = (struct procfs_dir *) malloc (sizeof (struct procfs_dir ));

          if (! node || ! new_dir )
           return ENOMEM;
#endif
          err = _proc_stat_create (pids[count], ps_context, &ps);
          if (! err)
            {
              err = set_field_value (ps, PSTAT_PROC_INFO);
              if (! err)
                {
                  stat.st_uid = proc_stat_proc_info (ps)->owner;
                  stat.st_gid = proc_stat_proc_info (ps)->pgrp;

                  dir_entry = update_entries_list (dir, dir_name_pid,
                                 &stat, timestamp, NULL);
                  err = procfs_create_node (dir_entry, dir_name_pid, &node);

                  procfs_dir_create (dir->fs, node, 
                                      dir_name_pid, &new_dir);
                  free(dir_name_pid);
                  _proc_stat_free (ps);
                }
            }
	}
    }

  if ((err = procfs_create_uptime (dir, &node, timestamp)) != 0)
    return err;

  if ((err = procfs_create_stat (dir, &node, timestamp)) != 0)
    return err;
  
  if ((err = procfs_create_version (dir, &node, timestamp)) != 0)
    return err;

  if ((err = procfs_create_meminfo (dir, &node, timestamp)) != 0)
    return err;

  if ((err = procfs_create_loadavg (dir, &node, timestamp)) != 0)
    return err;

  return 0;
}

error_t update_dir_entries (struct procfs_dir *dir)
{
  /* STUB */
  return 0;
}