/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1992, 1993, 1994 Henry Spencer.
 * Copyright (c) 1992, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Henry Spencer.
 *
 * 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 <stdio.h>
#include <string.h>
#include <limits.h>
#include <stdlib.h>
#include <regex.h>

#include "utils.h"

/* ========= begin header generated by ./mkh ========= */
#ifdef __cplusplus
extern "C" {
#endif

/* === regerror.c === */
static const char *regatoi(const regex_t *preg, char *localbuf);

#ifdef __cplusplus
}
#endif
/* ========= end header generated by ./mkh ========= */
/*
 = #define      REG_NOMATCH      1
 = #define      REG_BADPAT       2
 = #define      REG_ECOLLATE     3
 = #define      REG_ECTYPE       4
 = #define      REG_EESCAPE      5
 = #define      REG_ESUBREG      6
 = #define      REG_EBRACK       7
 = #define      REG_EPAREN       8
 = #define      REG_EBRACE       9
 = #define      REG_BADBR       10
 = #define      REG_ERANGE      11
 = #define      REG_ESPACE      12
 = #define      REG_BADRPT      13
 = #define      REG_EMPTY       14
 = #define      REG_ASSERT      15
 = #define      REG_INVARG      16
 = #define      REG_ILLSEQ      17
 = #define      REG_ATOI        255     // convert name to number (!)
 = #define      REG_ITOA        0400    // convert number to name (!)
 */
static struct rerr {
        int code;
        const char *name;
        const char *explain;
} rerrs[] = {
        {REG_NOMATCH,   "REG_NOMATCH",  "regexec() failed to match"},
        {REG_BADPAT,    "REG_BADPAT",   "invalid regular expression"},
        {REG_ECOLLATE,  "REG_ECOLLATE", "invalid collating element"},
        {REG_ECTYPE,    "REG_ECTYPE",   "invalid character class"},
        {REG_EESCAPE,   "REG_EESCAPE",  "trailing backslash (\\)"},
        {REG_ESUBREG,   "REG_ESUBREG",  "invalid backreference number"},
        {REG_EBRACK,    "REG_EBRACK",   "brackets ([ ]) not balanced"},
        {REG_EPAREN,    "REG_EPAREN",   "parentheses not balanced"},
        {REG_EBRACE,    "REG_EBRACE",   "braces not balanced"},
        {REG_BADBR,     "REG_BADBR",    "invalid repetition count(s)"},
        {REG_ERANGE,    "REG_ERANGE",   "invalid character range"},
        {REG_ESPACE,    "REG_ESPACE",   "out of memory"},
        {REG_BADRPT,    "REG_BADRPT",   "repetition-operator operand invalid"},
        {REG_EMPTY,     "REG_EMPTY",    "empty (sub)expression"},
        {REG_ASSERT,    "REG_ASSERT",   "\"can't happen\" -- you found a bug"},
        {REG_INVARG,    "REG_INVARG",   "invalid argument to regex routine"},
        {REG_ILLSEQ,    "REG_ILLSEQ",   "illegal byte sequence"},
        {0,             "",             "*** unknown regexp error code ***"}
};

/*
 - regerror - the interface to error numbers
 = extern size_t regerror(int, const regex_t *, char *, size_t);
 */
/* ARGSUSED */
size_t
regerror(int errcode,
         const regex_t * __restrict preg,
         char * __restrict errbuf,
         size_t errbuf_size)
{
        struct rerr *r;
        size_t len;
        int target = errcode &~ REG_ITOA;
        const char *s;
        char convbuf[50];

        if (errcode == REG_ATOI)
                s = regatoi(preg, convbuf);
        else {
                for (r = rerrs; r->code != 0; r++)
                        if (r->code == target)
                                break;

                if (errcode&REG_ITOA) {
                        if (r->code != 0)
                                (void) strcpy(convbuf, r->name);
                        else
                                sprintf(convbuf, "REG_0x%x", target);
                        assert(strlen(convbuf) < sizeof(convbuf));
                        s = convbuf;
                } else
                        s = r->explain;
        }

        len = strlen(s) + 1;
        if (errbuf_size > 0) {
                if (errbuf_size > len)
                        (void) strcpy(errbuf, s);
                else {
                        (void) strncpy(errbuf, s, errbuf_size-1);
                        errbuf[errbuf_size-1] = '\0';
                }
        }

        return(len);
}

/*
 - regatoi - internal routine to implement REG_ATOI
 == static char *regatoi(const regex_t *preg, char *localbuf);
 */
static const char *
regatoi(const regex_t *preg, char *localbuf)
{
        struct rerr *r;

        for (r = rerrs; r->code != 0; r++)
                if (strcmp(r->name, preg->re_endp) == 0)
                        break;
        if (r->code == 0)
                return("0");

        sprintf(localbuf, "%d", r->code);
        return(localbuf);
}