/* vi: set sw=4 ts=4: */
/*
 * echo implementation for busybox - used as a helper for testsuite/*
 * on systems lacking "echo -en"
 *
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Original copyright notice is retained at the end of this file.
 */

/* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */

/* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
 *
 * Because of behavioral differences, implemented configurable SUSv3
 * or 'fancy' gnu-ish behaviors.  Also, reduced size and fixed bugs.
 * 1) In handling '\c' escape, the previous version only suppressed the
 *     trailing newline.  SUSv3 specifies _no_ output after '\c'.
 * 2) SUSv3 specifies that octal escapes are of the form \0{#{#{#}}}.
 *    The previous version did not allow 4-digit octals.
 */

#include <stdio.h>
#include <string.h>
#include <limits.h>

#define WANT_HEX_ESCAPES 1

/* Usual "this only works for ascii compatible encodings" disclaimer. */
#undef _tolower
#define _tolower(X) ((X)|((char) 0x20))

static char bb_process_escape_sequence(const char **ptr)
{
        static const char charmap[] = {
                'a',  'b',  'f',  'n',  'r',  't',  'v',  '\\', 0,
                '\a', '\b', '\f', '\n', '\r', '\t', '\v', '\\', '\\' };

        const char *p;
        const char *q;
        unsigned int num_digits;
        unsigned int r;
        unsigned int n;
        unsigned int d;
        unsigned int base;

        num_digits = n = 0;
        base = 8;
        q = *ptr;

#ifdef WANT_HEX_ESCAPES
        if (*q == 'x') {
                ++q;
                base = 16;
                ++num_digits;
        }
#endif

        do {
                d = (unsigned char)(*q) - '0';
#ifdef WANT_HEX_ESCAPES
                if (d >= 10) {
                        d = (unsigned char)(_tolower(*q)) - 'a' + 10;
                }
#endif

                if (d >= base) {
#ifdef WANT_HEX_ESCAPES
                        if ((base == 16) && (!--num_digits)) {
/*                              return '\\'; */
                                --q;
                        }
#endif
                        break;
                }

                r = n * base + d;
                if (r > UCHAR_MAX) {
                        break;
                }

                n = r;
                ++q;
        } while (++num_digits < 3);

        if (num_digits == 0) {  /* mnemonic escape sequence? */
                p = charmap;
                do {
                        if (*p == *q) {
                                q++;
                                break;
                        }
                } while (*++p);
                n = *(p + (sizeof(charmap)/2));
        }

        *ptr = q;

        return (char) n;
}


int main(int argc, char **argv)
{
        const char *arg;
        const char *p;
        char nflag = 1;
        char eflag = 0;

        /* We must check that stdout is not closed. */
        if (dup2(1, 1) != 1)
                return -1;

        while (1) {
                arg = *++argv;
                if (!arg)
                        goto newline_ret;
                if (*arg != '-')
                        break;

                /* If it appears that we are handling options, then make sure
                 * that all of the options specified are actually valid.
                 * Otherwise, the string should just be echoed.
                 */
                p = arg + 1;
                if (!*p)        /* A single '-', so echo it. */
                        goto just_echo;

                do {
                        if (!strrchr("neE", *p))
                                goto just_echo;
                } while (*++p);

                /* All of the options in this arg are valid, so handle them. */
                p = arg + 1;
                do {
                        if (*p == 'n')
                                nflag = 0;
                        if (*p == 'e')
                                eflag = '\\';
                } while (*++p);
        }
 just_echo:
        while (1) {
                /* arg is already == *argv and isn't NULL */
                int c;

                if (!eflag) {
                        /* optimization for very common case */
                        fputs(arg, stdout);
                } else while ((c = *arg++)) {
                        if (c == eflag) {       /* Check for escape seq. */
                                if (*arg == 'c') {
                                        /* '\c' means cancel newline and
                                         * ignore all subsequent chars. */
                                        goto ret;
                                }
                                {
                                        /* Since SUSv3 mandates a first digit of 0, 4-digit octals
                                        * of the form \0### are accepted. */
                                        if (*arg == '0') {
                                                /* NB: don't turn "...\0" into "...\" */
                                                if (arg[1] && ((unsigned char)(arg[1]) - '0') < 8) {
                                                        arg++;
                                                }
                                        }
                                        /* bb_process_escape_sequence handles NUL correctly
                                         * ("...\" case. */
                                        c = bb_process_escape_sequence(&arg);
                                }
                        }
                        putchar(c);
                }

                arg = *++argv;
                if (!arg)
                        break;
                putchar(' ');
        }

 newline_ret:
        if (nflag) {
                putchar('\n');
        }
 ret:
        return fflush(NULL);
}

/*-
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * 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. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
 *              ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
 *
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 *      @(#)echo.c      8.1 (Berkeley) 5/31/93
 */