/* Copyright (C) 2011-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <assert.h>

#include <dlfcn.h>

#include <errno.h>

#include <gconv.h>

#include <uchar.h>

#include <wcsmbsload.h>

#include <sysdep.h>

#ifndef EILSEQ

# define EILSEQ EINVAL

#endif

/* This is the private state used if PS is NULL.  */

static mbstate_t state;

size_t

mbrtoc16 (char16_t *pc16, const char *s, size_t n, mbstate_t *ps)

{

  if (ps == NULL)

    ps = &stat;;

  /* The standard text does not say that S being NULL means the state

     is reset even if the second half of a surrogate still have to be

     returned.  In fact, the error code description indicates

     otherwise.  Therefore always first try to return a second

     half.  */

  if (ps->__count & 0x80000000)

    {

      /* We have to return the second word for a surrogate.  */

      ps->__count &= 0x7fffffff;

      *pc16 = ps->__value.__wch;

      ps->__value.__wch = L'\0';

      return (size_t) -3;

    }

  wchar_t wc;

  struct __gconv_step_data data;

  int status;

  size_t result;

  size_t dummy;

  const unsigned char *inbuf, *endbuf;

  unsigned char *outbuf = (unsigned char *) &wc;

  const struct gconv_fcts *fcts;

  /* Set information for this step.  */

  data.__invocation_counter = 0;

  data.__internal_use = 1;

  data.__flags = __GCONV_IS_LAST;

  data.__statep = ps;

  /* A first special case is if S is NULL.  This means put PS in the

     initial state.  */

  if (s == NULL)

    {

      pc16 = NULL;

      s = "";

      n = 1;

    }

  if (n == 0)

    return (size_t) -2;

  /* Tell where we want the result.  */

  data.__outbuf = outbuf;

  data.__outbufend = outbuf + sizeof (wchar_t);

  /* Get the conversion functions.  */

  fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));

  /* Do a normal conversion.  */

  inbuf = (const unsigned char *) s;

  endbuf = inbuf + n;

  if (__glibc_unlikely (endbuf < inbuf))

    {

      endbuf = (const unsigned char *) ~(uintptr_t) 0;

      if (endbuf == inbuf)

	goto ilseq;

    }

  __gconv_fct fct = fcts->towc->__fct;

#ifdef PTR_DEMANGLE

  if (fcts->towc->__shlib_handle != NULL)

    PTR_DEMANGLE (fct);

#endif

  status = DL_CALL_FCT (fct, (fcts->towc, &data, &inbuf, endbuf,

			      NULL, &dummy, 0, 1));

  /* There must not be any problems with the conversion but illegal input

     characters.  The output buffer must be large enough, otherwise the

     definition of MB_CUR_MAX is not correct.  All the other possible

     errors also must not happen.  */

  assert (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT

	  || status == __GCONV_ILLEGAL_INPUT

	  || status == __GCONV_INCOMPLETE_INPUT

	  || status == __GCONV_FULL_OUTPUT);

  if (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT

      || status == __GCONV_FULL_OUTPUT)

    {

      result = inbuf - (const unsigned char *) s;

      if (wc < 0x10000)

	{

	  if (pc16 != NULL)

	    *pc16 = wc;

	  if (data.__outbuf != outbuf && wc == L'\0')

	    {

	      /* The converted character is the NUL character.  */

	      assert (__mbsinit (data.__statep));

	      result = 0;

	    }

	}

      else

	{

	  /* This is a surrogate.  */

	  if (pc16 != NULL)

	    *pc16 = 0xd7c0 + (wc >> 10);

	  ps->__count |= 0x80000000;

	  ps->__value.__wch = 0xdc00 + (wc & 0x3ff);

	}

    }

  else if (status == __GCONV_INCOMPLETE_INPUT)

    result = (size_t) -2;

  else

    {

    ilseq:

      result = (size_t) -1;

      __set_errno (EILSEQ);

    }

  return result;

}