/*
 * Copyright (c) 2002 Marcel Moolenaar
 * Copyright (c) 2022 Tobias C. Berner
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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/param.h>
#include <sys/capsicum.h>
#include <sys/uuid.h>

#include <capsicum_helpers.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <uuid.h>

static void
usage(void)
{
        (void)fprintf(stderr,
            "usage: uuidgen [-1] [-r] [-n count] [-o filename]\n");
        exit(1);
}

static void
uuid_to_compact_string(const uuid_t *u, char **s, uint32_t *status)
{
        uuid_t nil;

        if (status != NULL)
                *status = uuid_s_ok;

        if (s == NULL)
                return;

        if (u == NULL) {
                u = &nil;
                uuid_create_nil(&nil, NULL);
        }

        asprintf(s, "%08x%04x%04x%02x%02x%02x%02x%02x%02x%02x%02x",
            u->time_low, u->time_mid, u->time_hi_and_version,
            u->clock_seq_hi_and_reserved, u->clock_seq_low, u->node[0],
            u->node[1], u->node[2], u->node[3], u->node[4], u->node[5]);

        if (*s == NULL && status != NULL)
                *status = uuid_s_no_memory;
}

static int
uuidgen_v4(struct uuid *store, int count)
{
        int size;
        struct uuid *item;

        if (count < 1) {
                errno = EINVAL;
                return (-1);
        }
        size = sizeof(struct uuid) * count;
        arc4random_buf(store, size);
        item = store;
        for (int i = 0; i < count; ++i) {
                /*
                 * Set the two most significant bits (bits 6 and 7) of the
                 * clock_seq_hi_and_reserved to zero and one, respectively.
                 */
                item->clock_seq_hi_and_reserved &= ~(3 << 6);
                item->clock_seq_hi_and_reserved |= (2 << 6);
                /*
                 * Set the four most significant bits (bits 12 through 15) of
                 * the time_hi_and_version field to the 4-bit version number
                 * from  Section 4.1.3.
                 */
                item->time_hi_and_version &= ~(15 << 12);
                item->time_hi_and_version |= (4 << 12);
                item++;
        };
        return (0);
}

int
main(int argc, char *argv[])
{
        FILE *fp;
        uuid_t *store, *uuid;
        char *p;
        int ch, count, i, iterate, status, version;
        void (*tostring)(const uuid_t *, char **, uint32_t *) = uuid_to_string;

        count = -1;  /* no count yet */
        fp = stdout; /* default output file */
        iterate = 0; /* not one at a time */
        version = 1; /* create uuid v1 by default */
        while ((ch = getopt(argc, argv, "1crn:o:")) != -1)
                switch (ch) {
                case '1':
                        iterate = 1;
                        break;
                case 'c':
                        tostring = uuid_to_compact_string;
                        break;
                case 'r':
                        version = 4;
                        break;
                case 'n':
                        if (count > 0)
                                usage();
                        count = strtol(optarg, &p, 10);
                        if (*p != 0 || count < 1)
                                usage();
                        break;
                case 'o':
                        if (fp != stdout)
                                errx(1, "multiple output files not allowed");
                        fp = fopen(optarg, "w");
                        if (fp == NULL)
                                err(1, "fopen");
                        break;
                default:
                        usage();
                }
        argv += optind;
        argc -= optind;

        if (argc)
                usage();

        caph_cache_catpages();
        if (caph_limit_stdio() < 0)
                err(1, "Unable to limit stdio");
        if (caph_enter() < 0)
                err(1, "Unable to enter capability mode");

        if (count == -1)
                count = 1;

    store = calloc(MIN(count, UUIDGEN_BATCH_MAX), sizeof(uuid_t));
    if (store == NULL)
        err(1, "calloc()");

    while (count > 0) {
        int batch = (count > UUIDGEN_BATCH_MAX) ? UUIDGEN_BATCH_MAX : count;

        if (!iterate) {
            if (version == 1) {
                if (uuidgen(store, batch) != 0)
                    err(1, "uuidgen()");
            } else if (version == 4) {
                if (uuidgen_v4(store, batch) != 0)
                    err(1, "uuidgen_v4()");
            } else {
                err(1, "unsupported version");
            }
        } else {
            uuid = store;
            for (i = 0; i < batch; i++) {
                if (version == 1) {
                    if (uuidgen(uuid++, 1) != 0)
                        err(1, "uuidgen()");
                } else if (version == 4) {
                    if (uuidgen_v4(uuid++, 1) != 0)
                        err(1, "uuidgen_v4()");
                } else {
                    err(1, "unsupported version");
                }
            }
        }

        uuid = store;
        for (i = 0; i < batch; i++) {
            tostring(uuid++, &p, &status);
            if (status != uuid_s_ok)
                err(1, "cannot stringify a UUID");
            fprintf(fp, "%s\n", p);
            free(p);
        }

        count -= batch;
    }
    free(store);

        if (fp != stdout)
                fclose(fp);
        return (0);
}