/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 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 <ctype.h>
#include <err.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <wctype.h>

#include "extern.h"

static int      backslash(STR *, int *);
static int      bracket(STR *);
static void     genclass(STR *);
static void     genequiv(STR *);
static int      genrange(STR *, int);
static void     genseq(STR *);

wint_t
next(STR *s)
{
        int is_octal;
        wint_t ch;
        wchar_t wch;
        size_t clen;

        switch (s->state) {
        case EOS:
                return (0);
        case INFINITE:
                return (1);
        case NORMAL:
                switch (*s->str) {
                case '\0':
                        s->state = EOS;
                        return (0);
                case '\\':
                        s->lastch = backslash(s, &is_octal);
                        break;
                case '[':
                        if (bracket(s))
                                return (next(s));
                        /* FALLTHROUGH */
                default:
                        clen = mbrtowc(&wch, s->str, MB_LEN_MAX, NULL);
                        if (clen == (size_t)-1 || clen == (size_t)-2 ||
                            clen == 0)
                                errc(1, EILSEQ, NULL);
                        is_octal = 0;
                        s->lastch = wch;
                        s->str += clen;
                        break;
                }

                /* We can start a range at any time. */
                if (s->str[0] == '-' && genrange(s, is_octal))
                        return (next(s));
                return (1);
        case RANGE:
                if (s->cnt-- == 0) {
                        s->state = NORMAL;
                        return (next(s));
                }
                ++s->lastch;
                return (1);
        case SEQUENCE:
                if (s->cnt-- == 0) {
                        s->state = NORMAL;
                        return (next(s));
                }
                return (1);
        case CCLASS:
        case CCLASS_UPPER:
        case CCLASS_LOWER:
                s->cnt++;
                ch = nextwctype(s->lastch, s->cclass);
                if (ch == -1) {
                        s->state = NORMAL;
                        return (next(s));
                }
                s->lastch = ch;
                return (1);
        case SET:
                if ((ch = s->set[s->cnt++]) == OOBCH) {
                        s->state = NORMAL;
                        return (next(s));
                }
                s->lastch = ch;
                return (1);
        default:
                return (0);
        }
        /* NOTREACHED */
}

static int
bracket(STR *s)
{
        char *p;

        switch (s->str[1]) {
        case ':':                               /* "[:class:]" */
                if ((p = strchr(s->str + 2, ']')) == NULL)
                        return (0);
                if (*(p - 1) != ':' || p - s->str < 4)
                        goto repeat;
                *(p - 1) = '\0';
                s->str += 2;
                genclass(s);
                s->str = p + 1;
                return (1);
        case '=':                               /* "[=equiv=]" */
                if (s->str[2] == '\0' || (p = strchr(s->str + 3, ']')) == NULL)
                        return (0);
                if (*(p - 1) != '=' || p - s->str < 4)
                        goto repeat;
                s->str += 2;
                genequiv(s);
                return (1);
        default:                                /* "[\###*n]" or "[#*n]" */
        repeat:
                if ((p = strpbrk(s->str + 2, "*]")) == NULL)
                        return (0);
                if (p[0] != '*' || strchr(p, ']') == NULL)
                        return (0);
                s->str += 1;
                genseq(s);
                return (1);
        }
        /* NOTREACHED */
}

static void
genclass(STR *s)
{

        if ((s->cclass = wctype(s->str)) == 0)
                errx(1, "unknown class %s", s->str);
        s->cnt = 0;
        s->lastch = -1;         /* incremented before check in next() */
        if (strcmp(s->str, "upper") == 0)
                s->state = CCLASS_UPPER;
        else if (strcmp(s->str, "lower") == 0)
                s->state = CCLASS_LOWER;
        else
                s->state = CCLASS;
}

static void
genequiv(STR *s)
{
        int i, p, pri;
        char src[2], dst[3];
        size_t clen;
        wchar_t wc;

        if (*s->str == '\\') {
                s->equiv[0] = backslash(s, NULL);
                if (*s->str != '=')
                        errx(1, "misplaced equivalence equals sign");
                s->str += 2;
        } else {
                clen = mbrtowc(&wc, s->str, MB_LEN_MAX, NULL);
                if (clen == (size_t)-1 || clen == (size_t)-2 || clen == 0)
                        errc(1, EILSEQ, NULL);
                s->equiv[0] = wc;
                if (s->str[clen] != '=')
                        errx(1, "misplaced equivalence equals sign");
                s->str += clen + 2;
        }

        /*
         * Calculate the set of all characters in the same equivalence class
         * as the specified character (they will have the same primary
         * collation weights).
         * XXX Knows too much about how strxfrm() is implemented. Assumes
         * it fills the string with primary collation weight bytes. Only one-
         * to-one mappings are supported.
         * XXX Equivalence classes not supported in multibyte locales.
         */
        src[0] = (char)s->equiv[0];
        src[1] = '\0';
        if (MB_CUR_MAX == 1 && strxfrm(dst, src, sizeof(dst)) == 1) {
                pri = (unsigned char)*dst;
                for (p = 1, i = 1; i < NCHARS_SB; i++) {
                        *src = i;
                        if (strxfrm(dst, src, sizeof(dst)) == 1 && pri &&
                            pri == (unsigned char)*dst)
                                s->equiv[p++] = i;
                }
                s->equiv[p] = OOBCH;
        }

        s->cnt = 0;
        s->state = SET;
        s->set = s->equiv;
}

static int
genrange(STR *s, int was_octal)
{
        int stopval, octal;
        char *savestart;
        int n, cnt, *p;
        size_t clen;
        wchar_t wc;

        octal = 0;
        savestart = s->str;
        if (*++s->str == '\\')
                stopval = backslash(s, &octal);
        else {
                clen = mbrtowc(&wc, s->str, MB_LEN_MAX, NULL);
                if (clen == (size_t)-1 || clen == (size_t)-2)
                        errc(1, EILSEQ, NULL);
                stopval = wc;
                s->str += clen;
        }
        /*
         * XXX Characters are not ordered according to collating sequence in
         * multibyte locales.
         */
        if (octal || was_octal || MB_CUR_MAX > 1) {
                if (stopval < s->lastch) {
                        s->str = savestart;
                        return (0);
                }
                s->cnt = stopval - s->lastch + 1;
                s->state = RANGE;
                --s->lastch;
                return (1);
        }
        if (charcoll((const void *)&stopval, (const void *)&(s->lastch)) < 0) {
                s->str = savestart;
                return (0);
        }
        if ((s->set = p = malloc((NCHARS_SB + 1) * sizeof(int))) == NULL)
                err(1, "genrange() malloc");
        for (cnt = 0; cnt < NCHARS_SB; cnt++)
                if (charcoll((const void *)&cnt, (const void *)&(s->lastch)) >= 0 &&
                    charcoll((const void *)&cnt, (const void *)&stopval) <= 0)
                        *p++ = cnt;
        *p = OOBCH;
        n = p - s->set;

        s->cnt = 0;
        s->state = SET;
        if (n > 1)
                mergesort(s->set, n, sizeof(*(s->set)), charcoll);
        return (1);
}

static void
genseq(STR *s)
{
        char *ep;
        wchar_t wc;
        size_t clen;

        if (s->which == STRING1)
                errx(1, "sequences only valid in string2");

        if (*s->str == '\\')
                s->lastch = backslash(s, NULL);
        else {
                clen = mbrtowc(&wc, s->str, MB_LEN_MAX, NULL);
                if (clen == (size_t)-1 || clen == (size_t)-2)
                        errc(1, EILSEQ, NULL);
                s->lastch = wc;
                s->str += clen;
        }
        if (*s->str != '*')
                errx(1, "misplaced sequence asterisk");

        switch (*++s->str) {
        case '\\':
                s->cnt = backslash(s, NULL);
                break;
        case ']':
                s->cnt = 0;
                ++s->str;
                break;
        default:
                if (isdigit((u_char)*s->str)) {
                        s->cnt = strtol(s->str, &ep, 0);
                        if (*ep == ']') {
                                s->str = ep + 1;
                                break;
                        }
                }
                errx(1, "illegal sequence count");
                /* NOTREACHED */
        }

        s->state = s->cnt ? SEQUENCE : INFINITE;
}

/*
 * Translate \??? into a character.  Up to 3 octal digits, if no digits either
 * an escape code or a literal character.
 */
static int
backslash(STR *s, int *is_octal)
{
        int ch, cnt, val;

        if (is_octal != NULL)
                *is_octal = 0;
        for (cnt = val = 0;;) {
                ch = (u_char)*++s->str;
                if (!isdigit(ch) || ch > '7')
                        break;
                val = val * 8 + ch - '0';
                if (++cnt == 3) {
                        ++s->str;
                        break;
                }
        }
        if (cnt) {
                if (is_octal != NULL)
                        *is_octal = 1;
                return (val);
        }
        if (ch != '\0')
                ++s->str;
        switch (ch) {
                case 'a':                       /* escape characters */
                        return ('\7');
                case 'b':
                        return ('\b');
                case 'f':
                        return ('\f');
                case 'n':
                        return ('\n');
                case 'r':
                        return ('\r');
                case 't':
                        return ('\t');
                case 'v':
                        return ('\13');
                case '\0':                      /*  \" -> \ */
                        s->state = EOS;
                        return ('\\');
                default:                        /* \x" -> x */
                        return (ch);
        }
}