/*      $NetBSD: scandir.c,v 1.30 2022/03/12 17:31:39 christos 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[] = "@(#)scandir.c   8.3 (Berkeley) 1/2/94";
#else
__RCSID("$NetBSD: scandir.c,v 1.30 2022/03/12 17:31:39 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

/*
 * Scan the directory dirname calling selectfn to make a list of selected
 * directory entries then sort using qsort and compare routine dcomp.
 * Returns the number of entries and a pointer to a list of pointers to
 * struct dirent (through namelist). Returns -1 if there were any errors.
 */

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

#include <assert.h>
#include <errno.h>
#include <dirent.h>
#include <stdlib.h>
#include <string.h>

/*
 * Compute an estimate of the number of entries in a directory based on
 * the file size. Returns the estimated number of entries or 0 on failure.
 */
static size_t
dirsize(int fd, size_t olen)
{
        struct stat stb;
        size_t nlen;

        if (fstat(fd, &stb) == -1)
                return 0;
        /*
         * Estimate the array size by taking the size of the directory file
         * and dividing it by a multiple of the minimum size entry. 
         */
        nlen = (size_t)(stb.st_size / _DIRENT_MINSIZE((struct dirent *)0));
        /*
         * If the size turns up 0, switch to an alternate strategy and use the
         * file size as the number of entries like ZFS returns. If that turns
         * out to be 0 too return a minimum of 10 entries, plus the old length.
         */
        if (nlen == 0)
                nlen = (size_t)(stb.st_size ? stb.st_size : 10);
        return olen + nlen;
}

#ifndef COMPARARG
#define COMPARARG struct dirent **
#endif

int
scandir(const char *dirname, struct dirent ***namelist,
    int (*selectfn)(const struct dirent *),
    int (*dcomp)(const COMPARARG, const COMPARARG))
{
        struct dirent *d, *p, **names;
        size_t nitems, arraysz;
        DIR *dirp;
        int serrno;

        _DIAGASSERT(dirname != NULL);
        _DIAGASSERT(namelist != NULL);

        if ((dirp = opendir(dirname)) == NULL)
                return -1;

        if ((arraysz = dirsize(dirp->dd_fd, 0)) == 0)
                goto bad;

        names = NULL;
        errno = reallocarr(&names, arraysz, sizeof(*names));
        if (errno)
                goto bad;

        nitems = 0;
        while ((d = readdir(dirp)) != NULL) {
                if (selectfn != NULL && !(*selectfn)(d))
                        continue;       /* just selected names */

                /*
                 * Check to make sure the array has space left and
                 * realloc the maximum size.
                 */
                if (nitems >= arraysz) {
                        if ((arraysz = dirsize(dirp->dd_fd, arraysz)) == 0)
                                goto bad2;
                        errno = reallocarr(&names, arraysz, sizeof(*names));
                        if (errno)
                                goto bad2;
                }

                /*
                 * Make a minimum size copy of the data
                 */
                p = malloc((size_t)_DIRENT_SIZE(d));
                if (p == NULL)
                        goto bad2;
                p->d_fileno = d->d_fileno;
                p->d_reclen = d->d_reclen;
                p->d_type = d->d_type;
                p->d_namlen = d->d_namlen;
                (void)memmove(p->d_name, d->d_name, (size_t)(p->d_namlen + 1));
                names[nitems++] = p;
        }
        (void)closedir(dirp);
        if (nitems && dcomp != NULL)
                qsort(names, nitems, sizeof(*names),
                      (int (*)(const void *, const void *))dcomp);
        *namelist = names;
        _DIAGASSERT(__type_fit(int, nitems));
        return (int)nitems;

bad2:
        serrno = errno;
        while (nitems-- > 0)
                free(names[nitems]);
        free(names);
        errno = serrno;
bad:
        serrno = errno;
        (void)closedir(dirp);
        errno = serrno;
        return -1;
}