/*      $NetBSD: iconv.c,v 1.21 2025/11/21 15:20:54 christos Exp $ */

/*-
 * Copyright (c)2003 Citrus Project,
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: iconv.c,v 1.21 2025/11/21 15:20:54 christos Exp $");
#endif /* LIBC_SCCS and not lint */

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

static void usage(void) __dead;
static int scmp(const void *, const void *);
static void show_codesets(void);
static void do_conv(const char *, const char *, FILE *, FILE *,
    const char *, const char *, int, int);

static void
usage(void)
{
        (void)fprintf(stderr,
            "Usage:\t%1$s [-cs] [-o <outfile>] -f <from_code> -t <to_code> [file ...]\n"
            "\t%1$s [-cs] [-o <outfile>] -f <from_code> [-t <to_code>]  [file ...]\n"
            "\t%1$s [-cs] [-o <outfile>] -t <to_code> [-f <from_code>]  [file ...]\n"
            "\t%1$s -l\n", getprogname());
        exit(EXIT_FAILURE);
}

/*
 * qsort() helper function
 */
static int
scmp(const void *v1, const void *v2)
{
        const char * const *s1 = v1;
        const char * const *s2 = v2;

        return strcasecmp(*s1, *s2);
}

static void
show_codesets(void)
{
        char **list;
        size_t sz, i;

        if (__iconv_get_list(&list, &sz))
                err(EXIT_FAILURE, "__iconv_get_list()");

        qsort(list, sz, sizeof(char *), scmp);

        for (i = 0; i < sz; i++)
                (void)printf("%s\n", list[i]);

        __iconv_free_list(list, sz);
}

#define INBUFSIZE 1024
#define OUTBUFSIZE (INBUFSIZE * 2)
/*ARGSUSED*/
static void
do_conv(const char *fni, const char *fno, FILE *fi, FILE *fo,
    const char *from, const char *to, int silent, int hide_invalid)
{
        char inbuf[INBUFSIZE], outbuf[OUTBUFSIZE], *out;
        const char *in;
        size_t inbytes, outbytes, ret, invalids;
        iconv_t cd;
        uint32_t flags = 0;
        int serrno;

        if (hide_invalid)
                flags |= __ICONV_F_HIDE_INVALID;
        cd = iconv_open(to, from);
        if (cd == (iconv_t)-1)
                err(EXIT_FAILURE, "iconv_open(%s, %s)", to, from);

        invalids = 0;
        while ((inbytes = fread(inbuf, 1, INBUFSIZE, fi)) > 0) {
                in = inbuf;
                while (inbytes > 0) {
                        size_t inval;

                        out = outbuf;
                        outbytes = OUTBUFSIZE;
                        ret = __iconv(cd, __UNCONST(&in), &inbytes, &out,
                            &outbytes, flags, &inval);
                        serrno = errno;
                        invalids += inval;
                        if (outbytes < OUTBUFSIZE) {
                                if (fwrite(outbuf, 1, OUTBUFSIZE - outbytes, fo)
                                    != OUTBUFSIZE - outbytes)
                                        err(EXIT_FAILURE,
                                            "failed writing to `%s'", fno);
                        }
                        errno = serrno;
                        if (ret == (size_t)-1 && errno != E2BIG) {
                                /*
                                 * XXX: iconv(3) is bad interface.
                                 *   invalid character count is lost here.
                                 *   instead, we just provide __iconv function.
                                 */
                                if (errno != EINVAL || in == inbuf)
                                        err(EXIT_FAILURE, "iconv()");

                                /* incomplete input character */
                                (void)memmove(inbuf, in, inbytes);
                                ret = fread(inbuf + inbytes, 1,
                                    INBUFSIZE - inbytes, fi);
                                if (ret == 0) {
                                        fflush(fo);
                                        if (feof(fi))
                                                errx(EXIT_FAILURE,
                                                     "unexpected end of file; "
                                                     "the last character is "
                                                     "incomplete.");
                                        else
                                                err(EXIT_FAILURE, "fread()");
                                }
                                in = inbuf;
                                inbytes += ret;
                        }
                }
        }
        /* reset the shift state of the output buffer */
        outbytes = OUTBUFSIZE;
        out = outbuf;
        ret = iconv(cd, NULL, NULL, &out, &outbytes);
        if (ret == (size_t)-1)
                err(EXIT_FAILURE, "iconv()");
        if (outbytes < OUTBUFSIZE) {
                if (fwrite(outbuf, 1, OUTBUFSIZE - outbytes, fo)
                    != OUTBUFSIZE - outbytes)
                        err(EXIT_FAILURE, "failed writing to `%s'", fno);
        }

        if (invalids > 0 && !silent)
                warnx("warning: invalid characters: %lu",
                    (unsigned long)invalids);

        iconv_close(cd);
}

int
main(int argc, char **argv)
{
        int ch, i;
        int opt_l = 0, opt_s = 0, opt_c = 0;
        const char *opt_f = NULL, *opt_t = NULL, *opt_o = NULL;
        FILE *fi, *fo;

        setlocale(LC_ALL, "");
        setprogname(argv[0]);

        while ((ch = getopt(argc, argv, "cslf:o:t:")) != EOF) {
                switch (ch) {
                case 'c':
                        opt_c = 1;
                        break;
                case 's':
                        opt_s = 1;
                        break;
                case 'l':
                        /* list */
                        opt_l = 1;
                        break;
                case 'f':
                        /* from */
                        opt_f = estrdup(optarg);
                        break;
                case 't':
                        /* to */
                        opt_t = estrdup(optarg);
                        break;
                case 'o':
                        /* outfile */
                        opt_o = estrdup(optarg);
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;
        if (opt_l) {
                if (argc > 0 || opt_s || opt_f != NULL || opt_t != NULL) {
                        warnx("-l is not allowed with other flags.");
                        usage();
                }
                show_codesets();
        } else {
                if (opt_f == NULL) {
                        if (opt_t == NULL)
                                usage();
                        opt_f = nl_langinfo(CODESET);
                } else if (opt_t == NULL)
                        opt_t = nl_langinfo(CODESET);

                if (opt_o == NULL) {
                        fo = stdout;
                        opt_o = "<stdout>";
                } else {
                        fo = fopen(opt_o, "w");
                        if (fo == NULL)
                                err(EXIT_FAILURE, "Cannot open `%s'", opt_o);
                }

                if (argc == 0)
                        do_conv("<stdin>", opt_o, stdin, fo, opt_f, opt_t,
                            opt_s, opt_c);
                else {
                        for (i = 0; i < argc; i++) {
                                fi = fopen(argv[i], "r");
                                if (fi == NULL)
                                        err(EXIT_FAILURE, "Cannot open `%s'",
                                            argv[i]);
                                do_conv(argv[i], opt_o, fi, fo, opt_f, opt_t,
                                    opt_s, opt_c);
                                (void)fclose(fi);
                        }
                }
                if (fo != stdout)
                        (void)fclose(fo);
        }
        return EXIT_SUCCESS;
}