/*      $OpenBSD: echo.c,v 1.12 2026/02/25 21:57:43 jcs Exp $   */
/*      $NetBSD: echo.c,v 1.6 1995/03/21 09:04:27 cgd Exp $     */

/*
 * Copyright (c) 1989, 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 <ctype.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <err.h>

int escape(const char *);

int
main(int argc, char *argv[])
{
        int nflag = 0, eflag = 0;
        const char *p;

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

        /* This utility may NOT do getopt(3) option parsing. */
        for (++argv; argv[0] && *argv[0] == '-'; argv++) {
                for (p = *argv + 1; *p != '\0'; p++) {
                        switch (*p) {
                        case 'E':
                                eflag = 0;
                                break;
                        case 'e':
                                eflag = 1;
                                break;
                        case 'n':
                                nflag = 1;
                                break;
                        default:
                                eflag = nflag = 0;
                                goto echoargs;
                        }
                }
        }

echoargs:
        while (*argv) {
                if (eflag) {
                        if (escape(*argv) != 0)
                                /* \c encountered */
                                return 0;
                } else
                        (void)fputs(*argv, stdout);
                if (*++argv)
                        putchar(' ');
        }
        if (!nflag)
                putchar('\n');

        return 0;
}

/* return -1 on \c to suppress further output */
int
escape(const char *s)
{
        int ch, n;

        while ((ch = *s++) != '\0') {
                if (ch != '\\') {
                        putchar(ch);
                        continue;
                }

                switch ((ch = *s++)) {
                case '\0':
                        putchar('\\');
                        return 0;
                case '\\':
                        putchar('\\');
                        break;
                case 'a':
                        putchar('\a');
                        break;
                case 'b':
                        putchar('\b');
                        break;
                case 'c':
                        return -1;
                case 'e':
                        putchar('\033');
                        break;
                case 'f':
                        putchar('\f');
                        break;
                case 'n':
                        putchar('\n');
                        break;
                case 'r':
                        putchar('\r');
                        break;
                case 't':
                        putchar('\t');
                        break;
                case 'v':
                        putchar('\v');
                        break;
                case '0':
                        /* octal: \0nnn */
                        ch = 0;
                        for (n = 0; n < 3 && *s >= '0' && *s <= '7'; n++)
                                ch = ch * 8 + (*s++ - '0');
                        putchar(ch);
                        break;
                case 'x':
                        /* hexadecimal: \xhh */
                        if (isxdigit((unsigned char)*s)) {
                                ch = 0;
                                for (n = 0;
                                    n < 2 && isxdigit(*s); n++) {
                                        ch *= 16;
                                        if (*s >= '0' && *s <= '9')
                                                ch += *s - '0';
                                        else if (*s >= 'a' && *s <= 'f')
                                                ch += *s - 'a' + 10;
                                        else
                                                ch += *s - 'A' + 10;
                                        s++;
                                }
                                putchar(ch);
                        } else {
                                putchar('\\');
                                putchar('x');
                        }
                        break;
                default:
                        putchar('\\');
                        putchar(ch);
                        break;
                }
        }

        return 0;
}