/*	$NetBSD: readdir.c,v 1.26 2012/06/25 22:32:43 abs Exp $	*/

/*
 * Copyright (c) 1983, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>

#include "reentrant.h"
#include "extern.h"

#include <sys/param.h>

#include <dirent.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

#include "dirent_private.h"

/*
 * get next entry in a directory.
 */
struct dirent *_readdir_unlocked(DIR *dirp, int skipdeleted) {
  struct dirent *dp;
  int saved_errno = errno;

  for (;;) {
    if (dirp->dd_loc >= dirp->dd_size) {
      if (dirp->dd_flags & __DTF_READALL)
        return (NULL);
      dirp->dd_loc = 0;
    }
    if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
      dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
      dirp->dd_size = getdents(dirp->dd_fd, dirp->dd_buf, (size_t)dirp->dd_len);
      if (dirp->dd_size < 0)
        return (NULL);
      if (dirp->dd_size == 0) {
        errno = saved_errno;
        return (NULL);
      }
    }
    dp = (struct dirent *)(void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
    if ((intptr_t)dp & _DIRENT_ALIGN(dp)) /* bogus pointer check */
      return (NULL);
    /* d_reclen is unsigned; no need to compare it <= 0 */
    if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
      return (NULL);
    dirp->dd_loc += dp->d_reclen;
    if (dp->d_fileno == 0 && skipdeleted)
      continue;
    if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
      continue;
    return (dp);
  }
}

struct dirent *readdir(DIR *dirp) {
  struct dirent *dp;

#ifdef _REENTRANT
  if (__isthreaded) {
    mutex_lock((mutex_t *)dirp->dd_lock);
    dp = _readdir_unlocked(dirp, 1);
    mutex_unlock((mutex_t *)dirp->dd_lock);
  } else
#endif
    dp = _readdir_unlocked(dirp, 1);
  return (dp);
}

int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result) {
  struct dirent *dp;
  int saved_errno;

  saved_errno = errno;
  errno = 0;
#ifdef _REENTRANT
  if (__isthreaded) {
    mutex_lock((mutex_t *)dirp->dd_lock);
    if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
      memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
    mutex_unlock((mutex_t *)dirp->dd_lock);
  } else
#endif
    if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
    memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));

  if (errno != 0) {
    if (dp == NULL)
      return (errno);
  } else
    errno = saved_errno;

  if (dp != NULL)
    *result = entry;
  else
    *result = NULL;

  return (0);
}
