random_wallpaper.c

/*
 * Copyright (c) 2004 - 2016 Han Boetes <hboetes@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "fbsetbg.h"


/* This module finds the number of images in a directory and then picks a random
 * one. It saves the name of the directory if remember is set. */
int
random_wallpaper(char *wall_path, int remember)
{

#ifndef HAVE_ARC4RANDOM
        struct timeval  tv[2];
#endif
        uint            random;
        char           *path2wallpaper;
        uint            i = 0;
        int             ret;
        int             found = FALSE;

        DIR            *dirp;
        struct dirent  *dp;

        path2wallpaper = malloc(MAXPATHLEN);
        if (path2wallpaper == NULL)
                err(1, "out of memory");

        cleanpath(wall_path);

        /* Open the directory */
        if ((dirp = opendir(wall_path)) == NULL)
                err(1, "%s", wall_path);

        /* Count the number of image-files */
        while ((dp = readdir(dirp)) != NULL)
        {
                /* step over . and .. */
                if (dp->d_name[0] == '.')
                {
                        if (dp->d_name[1] == '\0' ||
                            (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
                                continue;
                }
                /* check the extension of the file */
                if (checkextension(dp->d_name) == 0)
                        i++;
        }

        /* Verify at least one file has been found. */
        if (i < 1)
                errx(1, "directory %s does not contain any wallpapers",
                    wall_path);

        /* Use gettimeofday to get a quick and dirty random number. It's not
         * very random so try to get your hands on arc4random */
#ifdef HAVE_ARC4RANDOM
        random = (uint)arc4random();
#else
        gettimeofday(&tv[0], NULL);
        random = (uint)tv[0].tv_usec;
#endif
        random %= i;
        i = 0;

        /* Reset to first file in directory structure */
        rewinddir(dirp);
        while ((dp = readdir(dirp)) != NULL)
        {
                /* step over . and .. */
                if (dp->d_name[0] == '.')
                {
                        if (dp->d_name[1] == '\0' ||
                            (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
                                continue;
                }

                /* if it's a picture and i equals the generated random number */
                if (checkextension(dp->d_name) == 0 && i++ == random)
                {
                        ret = snprintf(path2wallpaper, MAXPATHLEN,
                            "%s/%s", wall_path, dp->d_name);
                        if (ret < 0 || ret >= MAXPATHLEN)
                                errx(1, "arguments out of bounds for pathname");
                        if (remember == REMEMBER)
                                write_lastwallpaper("random", wall_path);
                        /* TODO support other options? */
                        found = TRUE;
                        set_wallpaper(DEFAULTARG, path2wallpaper);
                        break;
                }
        }
        /* No wallpaper was found. */
        free(path2wallpaper);
        closedir(dirp);
        if (found == TRUE)
                return(TRUE);
        else
                errx(1, "no wallpaper was found in %s", wall_path);
}