/*      $OpenBSD: scandir.c,v 1.23 2024/04/15 15:47:58 florian 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.
 */

/*
 * Scan the directory dirname calling select 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 <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "telldir.h"

#define MAXIMUM(a, b)   (((a) > (b)) ? (a) : (b))

/*
 * The DIRSIZ macro is the minimum record length which will hold the directory
 * entry.  This requires the amount of space in struct dirent without the
 * d_name field, plus enough space for the name and a terminating nul byte
 * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
 */
#undef DIRSIZ
#define DIRSIZ(dp)                                                      \
        ((sizeof(struct dirent) - sizeof(dp)->d_name) +                 \
            (((dp)->d_namlen + 1 + 3) &~ 3))

static int
scandir_dirp(DIR *dirp, struct dirent ***namelist,
    int (*select)(const struct dirent *),
    int (*dcomp)(const struct dirent **, const struct dirent **))
{
        struct dirent *d, *p, **names = NULL;
        size_t nitems = 0;
        struct stat stb;
        long arraysz;

        if (fstat(dirp->dd_fd, &stb) == -1)
                goto fail;

        /*
         * estimate the array size by taking the size of the directory file
         * and dividing it by a multiple of the minimum size entry.
         */
        arraysz = MAXIMUM(stb.st_size / 24, 16);
        if (arraysz > SIZE_MAX / sizeof(struct dirent *)) {
                errno = ENOMEM;
                goto fail;
        }
        names = calloc(arraysz, sizeof(struct dirent *));
        if (names == NULL)
                goto fail;

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

                /*
                 * Check to make sure the array has space left and
                 * realloc the maximum size.
                 */
                if (nitems >= arraysz) {
                        struct dirent **nnames;

                        if (fstat(dirp->dd_fd, &stb) == -1)
                                goto fail;

                        arraysz *= 2;
                        if (SIZE_MAX / sizeof(struct dirent *) < arraysz)
                                goto fail;
                        nnames = reallocarray(names,
                            arraysz, sizeof(struct dirent *));
                        if (nnames == NULL)
                                goto fail;

                        names = nnames;
                }

                /*
                 * Make a minimum size copy of the data
                 */
                p = malloc(DIRSIZ(d));
                if (p == NULL)
                        goto fail;

                p->d_ino = d->d_ino;
                p->d_type = d->d_type;
                p->d_reclen = d->d_reclen;
                p->d_namlen = d->d_namlen;
                bcopy(d->d_name, p->d_name, p->d_namlen + 1);
                names[nitems++] = p;
        }
        closedir(dirp);
        if (nitems && dcomp != NULL)
                qsort(names, nitems, sizeof(struct dirent *),
                    (int(*)(const void *, const void *))dcomp);
        *namelist = names;
        return (nitems);

fail:
        while (nitems > 0)
                free(names[--nitems]);
        free(names);
        closedir(dirp);
        return (-1);
}

int
scandir(const char *dirname, struct dirent ***namelist,
    int (*select)(const struct dirent *),
    int (*dcomp)(const struct dirent **, const struct dirent **))
{
        DIR *dirp;

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

        return (scandir_dirp(dirp, namelist, select, dcomp));
}

int
scandirat(int dirfd, const char *dirname, struct dirent ***namelist,
    int (*select)(const struct dirent *),
    int (*dcomp)(const struct dirent **, const struct dirent **))
{
        DIR *dirp;
        int fd;

        fd = HIDDEN(openat)(dirfd, dirname, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
        if (fd == -1)
                return (-1);
        dirp = __fdopendir(fd);
        if (dirp == NULL) {
                HIDDEN(close)(fd);
                return (-1);
        }
        return (scandir_dirp(dirp, namelist, select, dcomp));
}

/*
 * Alphabetic order comparison routine for those who want it.
 */
int
alphasort(const struct dirent **d1, const struct dirent **d2)
{
        return(strcmp((*d1)->d_name, (*d2)->d_name));
}