/*      $NetBSD: readdir.c,v 1.28 2026/04/03 08:53:43 mlelstv 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>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)readdir.c   8.3 (Berkeley) 9/29/94";
#else
__RCSID("$NetBSD: readdir.c,v 1.28 2026/04/03 08:53:43 mlelstv Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.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)
{
        const int saved_errno = errno;
        struct dirent *dp;

        for (;;) {
                if (dirp->dd_loc >= dirp->dd_size) {
                        if (dirp->dd_flags & __DTF_READALL)
                                break;
                        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) /* end of directory */
                                break;
                        if (dirp->dd_size == -1) /* getdents sets errno */
                                return NULL;
                        if (dirp->dd_size < 0) { /* paranoia */
                                errno = EIO;
                                return NULL;
                        }
                }
                dp = (struct dirent *)
                    (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
                /* bogus pointer check */
                if ((intptr_t)dp & _DIRENT_ALIGN(dp)) {
                        errno = EIO;
                        return NULL;
                }
                /* d_reclen is unsigned; no need to compare it <= 0 */
                if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc) {
                        errno = EIO;
                        return NULL;
                }
                dirp->dd_loc += dp->d_reclen;
                if (dp->d_ino == 0 && skipdeleted)
                        continue;
                if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
                        continue;
                return dp;
        }

        errno = saved_errno;
        return NULL;
}

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;

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

        return (0);
}