/*
 * 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.
 *
 * $FreeBSD: src/lib/libc/gen/opendir.c,v 1.10.2.1 2001/06/04 20:59:48 joerg Exp $
 *
 * @(#)opendir.c        8.8 (Berkeley) 5/1/95
 */

#include "namespace.h"
#include <sys/param.h>
#include <sys/stat.h>

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"

#include "gen_private.h"

#define DEFAULT_FLAGS (DTF_HIDEW | DTF_NODUP)

/*
 * Open a directory given its path.
 */
DIR *
opendir(const char *name)
{
        return (__opendir2(name, DEFAULT_FLAGS));
}

/*
 * Open a directory given a descriptor representing it.
 */
DIR *
fdopendir(int fd)
{
        return (__fdopendir2(fd, DEFAULT_FLAGS));
}

DIR *
__opendir2(const char *name, int flags)
{
        int fd;
        struct stat statb;
        DIR *dirp;
        int saved_errno;

        /*
         * stat() before _open() because opening of special files may be
         * harmful.
         */
        if (stat(name, &statb) != 0)
                return (NULL);

        fd = _open(name, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC);
        if (fd == -1)
                return (NULL);
        dirp = __fdopendir2(fd, flags);
        if (dirp == NULL) {
                saved_errno = errno;
                _close(fd);
                errno = saved_errno;
        }

        return (dirp);
}

DIR *
__fdopendir2(int fd, int flags)
{
        DIR *dirp;
        int incr;
        int saved_errno;
        struct stat statb;
        int fdflags;

        dirp = NULL;

        if (_fstat(fd, &statb) != 0)
                goto fail;
        if (!S_ISDIR(statb.st_mode)) {
                errno = ENOTDIR;
                goto fail;
        }
        fdflags = _fcntl(fd, F_GETFD, 0);
        if (fdflags == -1 || ((fdflags & FD_CLOEXEC) == 0 &&
            _fcntl(fd, F_SETFD, fdflags | FD_CLOEXEC) == -1) ||
            (dirp = malloc(sizeof(DIR))) == NULL)
                goto fail;

        /*
         * Use a multiple of DIRBLKSIZ.  Make sure the buffer size is
         * decent (at least 16K) to avoid unnecessary excess system calls.
         */
        incr = DIRBLKSIZ * 16;
        if (incr < 16384)
                incr = 16384;
        if ((incr % DIRBLKSIZ) != 0) 
                incr = DIRBLKSIZ;

        dirp->dd_len = incr;
        dirp->dd_buf = malloc(dirp->dd_len);
        if (dirp->dd_buf == NULL)
                goto fail;
        flags &= ~DTF_REWIND;

        dirp->dd_loc = 0;
        dirp->dd_fd = fd;
        dirp->dd_flags = flags;
        dirp->dd_lock = NULL;

        /*
         * Set up seek point for rewinddir.
         */
        dirp->dd_seek = 0;
        dirp->dd_rewind = telldir(dirp);

        /*
         * The file offset of the fd passed to fdopendir() determines the
         * initial entry returned by readdir().  Save this offset so that
         * telldir() right after fdopendir() returns a value pointing to this
         * initial entry.  
         * We don't have to worry about misaligned file offsets.  The kernel
         * deals with these.
         */
        if ((dirp->dd_seek = lseek(fd, 0, SEEK_CUR)) < 0)
                goto fail;

        return (dirp);

fail:
        saved_errno = errno;
        if (dirp != NULL) {
                _reclaim_telldir(dirp);
                free(dirp->dd_buf);
        }
        free(dirp);
        errno = saved_errno;
        return (NULL);
}