/*      $NetBSD: gettext_iconv.c,v 1.9 2019/10/24 18:18:00 kamil Exp $  */

/*-
 * Copyright (c) 2004 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.
 *
 * $Citrus$
 */


#include <sys/types.h>
#include <sys/param.h>

#include <errno.h>
#include <iconv.h>
#include <libintl.h>
#include <langinfo.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>

#include "libintl_local.h"

struct cache {
        const char *c_origmsg;
        const char *c_resultmsg;
};

static const struct cache *cache_find(const char *, struct domainbinding *);
static int cache_enter(const char *, const char *);
static int cache_cmp(const void *, const void *);

static void *cacheroot;

/* ARGSUSED1 */
static const struct cache *
cache_find(const char *msg, struct domainbinding *db)
{
        struct cache key;
        struct cache **c;

        key.c_origmsg = msg;
        c = tfind(&key, &cacheroot, cache_cmp);

        return c ? *c : NULL;
}

static int
cache_enter(const char *origmsg, const char *resultmsg)
{
        struct cache *c;

        c = malloc(sizeof(*c));
        if (c == NULL)
                return -1;

        c->c_origmsg = origmsg;
        c->c_resultmsg = resultmsg;

        if (tsearch(c, &cacheroot, cache_cmp) == NULL) {
                free(c);
                return -1;
        }

        return 0;
}

static int
cache_cmp(const void *va, const void *vb)
{
        const struct cache *a = va;
        const struct cache *b = vb;
        int result;

        if (a->c_origmsg > b->c_origmsg) {
                result = 1;
        } else if (a->c_origmsg < b->c_origmsg) {
                result = -1;
        } else {
                result = 0;
        }

        return result;
}

#define GETTEXT_ICONV_MALLOC_CHUNK      (16 * 1024)

const char *
__gettext_iconv(const char *origmsg, struct domainbinding *db)
{
        const char *tocode;
        const char *fromcode = db->mohandle.mo.mo_charset;
        const struct cache *cache;
        const char *result;
        iconv_t cd;
        const char *src;
        char *dst;
        size_t origlen;
        size_t srclen;
        size_t dstlen;
        size_t nvalid;
        int savederrno = errno;

        /*
         * static buffer for converted texts.
         *
         * note:
         * we never free buffers once returned to callers.
         * because of interface design of gettext, we can't know
         * the lifetime of them.
         */
        static char *buffer;
        static size_t bufferlen;

        /*
         * don't convert message if *.mo doesn't specify codeset.
         */
        if (fromcode == NULL)
                return origmsg;

        tocode = db->codeset;
        if (tocode == NULL) {
                /*
                 * codeset isn't specified explicitly by
                 * bind_textdomain_codeset().
                 * use current locale(LC_CTYPE)'s codeset.
                 *
                 * XXX maybe wrong; it can mismatch with
                 * environment variable setting.
                 */
                tocode = nl_langinfo(CODESET);
        }

        /*
         * shortcut if possible.
         * XXX should handle aliases
         */
        if (!strcasecmp(tocode, fromcode))
                return origmsg;

        /* XXX LOCK */

        /* XXX should detect change of tocode and purge caches? */

        /*
         * see if we have already converted this message.
         */
        cache = cache_find(origmsg, db);
        if (cache) {
                result = cache->c_resultmsg;
                goto out;
        }

        origlen = strlen(origmsg) + 1;
again:
        cd = iconv_open(tocode, fromcode);
        if (cd == (iconv_t)-1) {
                result = origmsg;
                goto out;
        }

        src = origmsg;
        srclen = origlen;
        dst = buffer;
        dstlen = bufferlen;
        nvalid = iconv(cd, __UNCONST(&src), &srclen, &dst, &dstlen);
        iconv_close(cd);

        if (nvalid == (size_t)-1) {
                /*
                 * try to allocate a new buffer.
                 *
                 * just give up if GETTEXT_ICONV_MALLOC_CHUNK was not enough.
                 */
                if (errno == E2BIG &&
                    bufferlen != GETTEXT_ICONV_MALLOC_CHUNK) {
                        buffer = malloc(GETTEXT_ICONV_MALLOC_CHUNK);
                        if (buffer) {
                                bufferlen = GETTEXT_ICONV_MALLOC_CHUNK;
                                goto again;
                        }
                }

                result = origmsg;
        } else if (cache_enter(origmsg, buffer)) {
                /*
                 * failed to enter cache.  give up.
                 */
                result = origmsg;
        } else {
                size_t resultlen = dst - buffer;

                result = buffer;
                bufferlen -= resultlen;
                buffer += resultlen;
        }

out:
        /* XXX UNLOCK */
        errno = savederrno;

        return result;
}