/*      $OpenBSD: rev.c,v 1.16 2022/02/08 17:44:18 cheloha Exp $        */
/*      $NetBSD: rev.c,v 1.5 1995/09/28 08:49:40 tls Exp $      */

/*-
 * Copyright (c) 1987, 1992, 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/types.h>

#include <err.h>
#include <errno.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int multibyte;

int isu8cont(unsigned char);
int rev_file(const char *);
void usage(void);

int
main(int argc, char *argv[])
{
        int ch, rval;

        setlocale(LC_CTYPE, "");
        multibyte = MB_CUR_MAX > 1;

        if (pledge("stdio rpath", NULL) == -1)
                err(1, "pledge");

        while ((ch = getopt(argc, argv, "")) != -1)
                switch(ch) {
                default:
                        usage();
                }

        argc -= optind;
        argv += optind;

        rval = 0;
        if (argc == 0) {
                if (pledge("stdio", NULL) == -1)
                        err(1, "pledge");

                rval = rev_file(NULL);
        } else {
                for (; *argv != NULL; argv++)
                        rval |= rev_file(*argv);
        }
        return rval;
}

int
isu8cont(unsigned char c)
{
        return (c & (0x80 | 0x40)) == 0x80;
}

int
rev_file(const char *path)
{
        char *p = NULL, *t, *te, *u;
        const char *filename;
        FILE *fp;
        size_t ps = 0;
        ssize_t len;
        int rval = 0;

        if (path != NULL) {
                fp = fopen(path, "r");
                if (fp == NULL) {
                        warn("%s", path);
                        return 1;
                }
                filename = path;
        } else {
                fp = stdin;
                filename = "stdin";
        }

        while ((len = getline(&p, &ps, fp)) != -1) {
                if (p[len - 1] == '\n')
                        --len;
                for (t = p + len - 1; t >= p; --t) {
                        te = t;
                        if (multibyte)
                                while (t > p && isu8cont(*t))
                                        --t;
                        for (u = t; u <= te; ++u)
                                if (putchar(*u) == EOF)
                                        err(1, "stdout");
                }
                if (putchar('\n') == EOF)
                        err(1, "stdout");
        }
        free(p);
        if (ferror(fp)) {
                warn("%s", filename);
                rval = 1;
        }

        (void)fclose(fp);

        return rval;
}

void
usage(void)
{
        extern char *__progname;

        (void)fprintf(stderr, "usage: %s [file ...]\n", __progname);
        exit(1);
}