/*-
 * Copyright (c) 2000-2001 Boris Popov
 * 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.
 *
 * $FreeBSD: head/sys/libkern/iconv.c 267291 2014-06-09 19:27:47Z jhb $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/iconv.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/syslog.h>

#include "iconv_converter_if.h"

SYSCTL_DECL(_kern_iconv);

SYSCTL_NODE(_kern, OID_AUTO, iconv, CTLFLAG_RW, NULL, "kernel iconv interface");

MALLOC_DEFINE(M_ICONV, "iconv", "ICONV structures");
static MALLOC_DEFINE(M_ICONVDATA, "iconv_data", "ICONV data");

MODULE_VERSION(libiconv, 2);

static struct lock iconv_lock;

#ifdef notnow
/*
 * iconv converter instance
 */
struct iconv_converter {
        KOBJ_FIELDS;
        void *                  c_data;
};
#endif

struct sysctl_oid *iconv_oid_hook = &sysctl___kern_iconv;

/*
 * List of loaded converters
 */
static TAILQ_HEAD(iconv_converter_list, iconv_converter_class)
    iconv_converters = TAILQ_HEAD_INITIALIZER(iconv_converters);

/*
 * List of supported/loaded charsets pairs
 */
static TAILQ_HEAD(, iconv_cspair)
    iconv_cslist = TAILQ_HEAD_INITIALIZER(iconv_cslist);
static int iconv_csid = 1;

static char iconv_unicode_string[] = "unicode"; /* save eight bytes when possible */

static void iconv_unregister_cspair(struct iconv_cspair *csp);

static int
iconv_mod_unload(void)
{
        struct iconv_cspair *csp;

        lockmgr(&iconv_lock, LK_EXCLUSIVE);
        TAILQ_FOREACH(csp, &iconv_cslist, cp_link) {
                if (csp->cp_refcount) {
                        lockmgr(&iconv_lock, LK_RELEASE);
                        return EBUSY;
                }
        }

        while ((csp = TAILQ_FIRST(&iconv_cslist)) != NULL)
                iconv_unregister_cspair(csp);
        lockmgr(&iconv_lock, LK_RELEASE);
        lockuninit(&iconv_lock);
        return 0;
}

static int
iconv_mod_handler(module_t mod, int type, void *data)
{
        int error;

        switch (type) {
            case MOD_LOAD:
                error = 0;
                lockinit(&iconv_lock, "iconv", 0, LK_CANRECURSE);
                break;
            case MOD_UNLOAD:
                error = iconv_mod_unload();
                break;
            default:
                error = EINVAL;
        }
        return error;
}

static moduledata_t iconv_mod = {
        "iconv", iconv_mod_handler, NULL
};

DECLARE_MODULE(iconv, iconv_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);

static int
iconv_register_converter(struct iconv_converter_class *dcp)
{
        kobj_class_instantiate((kobj_class_t)dcp);
        TAILQ_INSERT_TAIL(&iconv_converters, dcp, cc_link);
        return 0;
}

static int
iconv_unregister_converter(struct iconv_converter_class *dcp)
{
        if (dcp->refs != 1) {
                ICDEBUG("converter has %d references left\n", dcp->refs);
                return EBUSY;
        }
        TAILQ_REMOVE(&iconv_converters, dcp, cc_link);
        kobj_class_uninstantiate((kobj_class_t)dcp);
        return 0;
}

static int
iconv_lookupconv(const char *name, struct iconv_converter_class **dcpp)
{
        struct iconv_converter_class *dcp;

        TAILQ_FOREACH(dcp, &iconv_converters, cc_link) {
                if (name == NULL)
                        continue;
                if (strcmp(name, ICONV_CONVERTER_NAME(dcp)) == 0) {
                        if (dcpp)
                                *dcpp = dcp;
                        return 0;
                }
        }
        return ENOENT;
}

static int
iconv_lookupcs(const char *to, const char *from, struct iconv_cspair **cspp)
{
        struct iconv_cspair *csp;

        TAILQ_FOREACH(csp, &iconv_cslist, cp_link) {
                if (strcasecmp(csp->cp_to, to) == 0 &&
                    strcasecmp(csp->cp_from, from) == 0) {
                        if (cspp)
                                *cspp = csp;
                        return 0;
                }
        }
        return ENOENT;
}

static int
iconv_register_cspair(const char *to, const char *from,
        struct iconv_converter_class *dcp, void *data,
        struct iconv_cspair **cspp)
{
        struct iconv_cspair *csp;
        char *cp;
        int csize, ucsto, ucsfrom;

        if (iconv_lookupcs(to, from, NULL) == 0)
                return EEXIST;
        csize = sizeof(*csp);
        ucsto = strcmp(to, iconv_unicode_string) == 0;
        if (!ucsto)
                csize += strlen(to) + 1;
        ucsfrom = strcmp(from, iconv_unicode_string) == 0;
        if (!ucsfrom)
                csize += strlen(from) + 1;
        csp = kmalloc(csize, M_ICONV, M_WAITOK | M_ZERO);
        csp->cp_id = iconv_csid++;
        csp->cp_dcp = dcp;
        cp = (char*)(csp + 1);
        if (!ucsto) {
                strcpy(cp, to);
                csp->cp_to = cp;
                cp += strlen(cp) + 1;
        } else
                csp->cp_to = iconv_unicode_string;
        if (!ucsfrom) {
                strcpy(cp, from);
                csp->cp_from = cp;
        } else
                csp->cp_from = iconv_unicode_string;
        csp->cp_data = data;

        TAILQ_INSERT_TAIL(&iconv_cslist, csp, cp_link);
        *cspp = csp;
        return 0;
}

static void
iconv_unregister_cspair(struct iconv_cspair *csp)
{
        TAILQ_REMOVE(&iconv_cslist, csp, cp_link);
        if (csp->cp_data)
                kfree(csp->cp_data, M_ICONVDATA);
        kfree(csp, M_ICONV);
}

/*
 * Lookup and create an instance of converter.
 * Currently this layer didn't have associated 'instance' structure
 * to avoid unnesessary memory allocation.
 */
int
iconv_open(const char *to, const char *from, void **handle)
{
        struct iconv_cspair *csp, *cspfrom, *cspto;
        struct iconv_converter_class *dcp;
        const char *cnvname;
        int error;

        /*
         * First, lookup fully qualified cspairs
         */
        error = iconv_lookupcs(to, from, &csp);
        if (error == 0)
                return ICONV_CONVERTER_OPEN(csp->cp_dcp, csp, NULL, handle);

        /*
         * Well, nothing found. Now try to construct a composite conversion
         * ToDo: add a 'capability' field to converter
         */
        TAILQ_FOREACH(dcp, &iconv_converters, cc_link) {
                cnvname = ICONV_CONVERTER_NAME(dcp);
                if (cnvname == NULL)
                        continue;
                error = iconv_lookupcs(cnvname, from, &cspfrom);
                if (error)
                        continue;
                error = iconv_lookupcs(to, cnvname, &cspto);
                if (error)
                        continue;
                /*
                 * Fine, we're found a pair which can be combined together
                 */
                return ICONV_CONVERTER_OPEN(dcp, cspto, cspfrom, handle);
        }
        return ENOENT;
}

int
iconv_close(void *handle)
{
        return ICONV_CONVERTER_CLOSE(handle);
}

int
iconv_conv(void *handle, const char **inbuf,
        size_t *inbytesleft, char **outbuf, size_t *outbytesleft)
{
        return ICONV_CONVERTER_CONV(handle, inbuf, inbytesleft, outbuf, outbytesleft, 0, 0);
}

int
iconv_conv_case(void *handle, const char **inbuf,
        size_t *inbytesleft, char **outbuf, size_t *outbytesleft, int casetype)
{
        return ICONV_CONVERTER_CONV(handle, inbuf, inbytesleft, outbuf, outbytesleft, 0, casetype);
}

int
iconv_convchr(void *handle, const char **inbuf,
        size_t *inbytesleft, char **outbuf, size_t *outbytesleft)
{
        return ICONV_CONVERTER_CONV(handle, inbuf, inbytesleft, outbuf, outbytesleft, 1, 0);
}

int
iconv_convchr_case(void *handle, const char **inbuf,
        size_t *inbytesleft, char **outbuf, size_t *outbytesleft, int casetype)
{
        return ICONV_CONVERTER_CONV(handle, inbuf, inbytesleft, outbuf, outbytesleft, 1, casetype);
}

int
towlower(int c, void *handle)
{
        return ICONV_CONVERTER_TOLOWER(handle, c);
}

int
towupper(int c, void *handle)
{
        return ICONV_CONVERTER_TOUPPER(handle, c);
}

/*
 * Give a list of loaded converters. Each name terminated with 0.
 * An empty string terminates the list.
 */
static int
iconv_sysctl_drvlist(SYSCTL_HANDLER_ARGS)
{
        struct iconv_converter_class *dcp;
        const char *name;
        char spc;
        int error;

        error = 0;

        lockmgr(&iconv_lock, LK_SHARED);
        TAILQ_FOREACH(dcp, &iconv_converters, cc_link) {
                name = ICONV_CONVERTER_NAME(dcp);
                if (name == NULL)
                        continue;
                error = SYSCTL_OUT(req, name, strlen(name) + 1);
                if (error)
                        break;
        }
        lockmgr(&iconv_lock, LK_RELEASE);
        if (error)
                return error;
        spc = 0;
        error = SYSCTL_OUT(req, &spc, sizeof(spc));
        return error;
}

SYSCTL_PROC(_kern_iconv, OID_AUTO, drvlist, CTLFLAG_RD | CTLTYPE_OPAQUE,
            NULL, 0, iconv_sysctl_drvlist, "S,xlat", "registered converters");

/*
 * List all available charset pairs.
 */
static int
iconv_sysctl_cslist(SYSCTL_HANDLER_ARGS)
{
        struct iconv_cspair *csp;
        struct iconv_cspair_info csi;
        int error;

        error = 0;
        bzero(&csi, sizeof(csi));
        csi.cs_version = ICONV_CSPAIR_INFO_VER;

        lockmgr(&iconv_lock, LK_SHARED);
        TAILQ_FOREACH(csp, &iconv_cslist, cp_link) {
                csi.cs_id = csp->cp_id;
                csi.cs_refcount = csp->cp_refcount;
                csi.cs_base = csp->cp_base ? csp->cp_base->cp_id : 0;
                strcpy(csi.cs_to, csp->cp_to);
                strcpy(csi.cs_from, csp->cp_from);
                error = SYSCTL_OUT(req, &csi, sizeof(csi));
                if (error)
                        break;
        }
        lockmgr(&iconv_lock, LK_RELEASE);
        return error;
}

SYSCTL_PROC(_kern_iconv, OID_AUTO, cslist, CTLFLAG_RD | CTLTYPE_OPAQUE,
            NULL, 0, iconv_sysctl_cslist, "S,xlat", "registered charset pairs");

int
iconv_add(const char *converter, const char *to, const char *from)
{
        struct iconv_converter_class *dcp;
        struct iconv_cspair *csp;

        if (iconv_lookupconv(converter, &dcp) != 0)
                return EINVAL;

        return iconv_register_cspair(to, from, dcp, NULL, &csp);
}

/*
 * Add new charset pair
 */
static int
iconv_sysctl_add(SYSCTL_HANDLER_ARGS)
{
        struct iconv_converter_class *dcp;
        struct iconv_cspair *csp;
        struct iconv_add_in din;
        struct iconv_add_out dout;
        int error;

        error = SYSCTL_IN(req, &din, sizeof(din));
        if (error)
                return error;
        if (din.ia_version != ICONV_ADD_VER)
                return EINVAL;
        if (din.ia_datalen > ICONV_CSMAXDATALEN)
                return EINVAL;
        if (strlen(din.ia_from) >= ICONV_CSNMAXLEN)
                return EINVAL;
        if (strlen(din.ia_to) >= ICONV_CSNMAXLEN)
                return EINVAL;
        if (strlen(din.ia_converter) >= ICONV_CNVNMAXLEN)
                return EINVAL;
        if (iconv_lookupconv(din.ia_converter, &dcp) != 0)
                return EINVAL;
        lockmgr(&iconv_lock, LK_EXCLUSIVE);
        error = iconv_register_cspair(din.ia_to, din.ia_from, dcp, NULL, &csp);
        if (error) {
                lockmgr(&iconv_lock, LK_RELEASE);
                return error;
        }
        if (din.ia_datalen) {
                csp->cp_data = kmalloc(din.ia_datalen, M_ICONVDATA, M_WAITOK);
                error = copyin(din.ia_data, csp->cp_data, din.ia_datalen);
                if (error)
                        goto bad;
        }
        dout.ia_csid = csp->cp_id;
        error = SYSCTL_OUT(req, &dout, sizeof(dout));
        if (error)
                goto bad;
        lockmgr(&iconv_lock, LK_RELEASE);
        ICDEBUG("%s => %s, %d bytes\n",din.ia_from, din.ia_to, din.ia_datalen);
        return 0;
bad:
        iconv_unregister_cspair(csp);
        lockmgr(&iconv_lock, LK_RELEASE);
        return error;
}

SYSCTL_PROC(_kern_iconv, OID_AUTO, add, CTLFLAG_RW | CTLTYPE_OPAQUE,
            NULL, 0, iconv_sysctl_add, "S,xlat", "register charset pair");

/*
 * Default stubs for converters
 */
int
iconv_converter_initstub(struct iconv_converter_class *dp)
{
        return 0;
}

int
iconv_converter_donestub(struct iconv_converter_class *dp)
{
        return 0;
}

int
iconv_converter_tolowerstub(int c, void *handle)
{
        return (c);
}

int
iconv_converter_handler(module_t mod, int type, void *data)
{
        struct iconv_converter_class *dcp = data;
        int error;

        switch (type) {
            case MOD_LOAD:
                lockmgr(&iconv_lock, LK_EXCLUSIVE);
                error = iconv_register_converter(dcp);
                if (error) {
                        lockmgr(&iconv_lock, LK_RELEASE);
                        break;
                }
                error = ICONV_CONVERTER_INIT(dcp);
                if (error)
                        iconv_unregister_converter(dcp);
                lockmgr(&iconv_lock, LK_RELEASE);
                break;
            case MOD_UNLOAD:
                lockmgr(&iconv_lock, LK_EXCLUSIVE);
                ICONV_CONVERTER_DONE(dcp);
                error = iconv_unregister_converter(dcp);
                lockmgr(&iconv_lock, LK_RELEASE);
                break;
            default:
                error = EINVAL;
        }
        return error;
}

/*
 * Common used functions (don't use with unicode)
 */
char *
iconv_convstr(void *handle, char *dst, const char *src)
{
        char *p = dst;
        size_t inlen, outlen;
        int error;

        if (handle == NULL) {
                strcpy(dst, src);
                return dst;
        }
        inlen = outlen = strlen(src);
        error = iconv_conv(handle, NULL, NULL, &p, &outlen);
        if (error)
                return NULL;
        error = iconv_conv(handle, &src, &inlen, &p, &outlen);
        if (error)
                return NULL;
        *p = 0;
        return dst;
}

void *
iconv_convmem(void *handle, void *dst, const void *src, int size)
{
        const char *s = src;
        char *d = dst;
        size_t inlen, outlen;
        int error;

        if (size == 0)
                return dst;
        if (handle == NULL) {
                memcpy(dst, src, size);
                return dst;
        }
        inlen = outlen = size;
        error = iconv_conv(handle, NULL, NULL, &d, &outlen);
        if (error)
                return NULL;
        error = iconv_conv(handle, &s, &inlen, &d, &outlen);
        if (error)
                return NULL;
        return dst;
}

int
iconv_lookupcp(char **cpp, const char *s)
{
        if (cpp == NULL) {
                ICDEBUG("warning a NULL list passed\n", "");
                return ENOENT;
        }
        for (; *cpp; cpp++)
                if (strcmp(*cpp, s) == 0)
                        return 0;
        return ENOENT;
}

/*
 * Return if fsname is in use of not
 */
int
iconv_vfs_refcount(const char *fsname)
{
        struct vfsconf *vfsp;

        vfsp = vfsconf_find_by_name(fsname);
        if (vfsp != NULL && vfsp->vfc_refcount > 0)
                return (EBUSY);
        return (0);
}