ultrajsondec.c

/*
Developed by ESN, an Electronic Arts Inc. studio.
Copyright (c) 2014, Electronic Arts Inc.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* 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.
* Neither the name of ESN, Electronic Arts Inc. 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 COPYRIGHT HOLDERS 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 ELECTRONIC ARTS INC. 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.


Portions of code from MODP_ASCII - Ascii transformations (upper/lower, etc)
https://github.com/client9/stringencoders
Copyright (c) 2007  Nick Galbreath -- nickg [at] modp [dot] com. All rights reserved.

Numeric decoder derived from from TCL library
https://opensource.apple.com/source/tcl/tcl-14/tcl/license.terms
* Copyright (c) 1988-1993 The Regents of the University of California.
* Copyright (c) 1994 Sun Microsystems, Inc.
*/

#include "ultrajson.h"
#include <math.h>
#include <assert.h>
#include <string.h>
#include <limits.h>
#include <wchar.h>
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>

#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif
#ifndef NULL
#define NULL 0
#endif

struct DecoderState
{
  char *start;
  char *end;
  wchar_t *escStart;
  wchar_t *escEnd;
  int escHeap;
  int lastType;
  JSUINT32 objDepth;
  void *prv;
  JSONObjectDecoder *dec;
};

static JSOBJ FASTCALL_MSVC decode_any( struct DecoderState *ds) FASTCALL_ATTR;
typedef JSOBJ (*PFN_DECODER)( struct DecoderState *ds);

static JSOBJ SetError( struct DecoderState *ds, int offset, const char *message)
{
  ds->dec->errorOffset = ds->start + offset;
  ds->dec->errorStr = (char *) message;
  return NULL;
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decodeDouble(struct DecoderState *ds)
{
  int processed_characters_count;
  int len = (int)(ds->end - ds->start);
  double value = dconv_s2d(ds->dec->s2d, ds->start, len, &processed_characters_count);
  ds->lastType = JT_DOUBLE;
  ds->start += processed_characters_count;
  return ds->dec->newDouble(ds->prv, value);
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_numeric (struct DecoderState *ds)
{
  int intNeg = 1;
  int hasError = 0;
  JSUINT64 intValue;
  JSUINT64 addIntValue;
  int chr;
  char *offset = ds->start;

  JSUINT64 maxIntValue = ULLONG_MAX;
  JSUINT64 overflowLimit = maxIntValue / 10LLU;

  if (*(offset) == 'I')
  {
    goto DECODE_INF;
  }
  else if (*(offset) == 'N')
  {
    goto DECODE_NAN;
  }
  else if (*(offset) == '-')
  {
    offset++;
    intNeg = -1;
    if (*(offset) == 'I')
    {
      goto DECODE_INF;
    }
    maxIntValue = -(JSUINT64) LLONG_MIN;
    overflowLimit = maxIntValue / 10LL;
  }

  // Scan integer part
  intValue = 0;

  while (1)
  {
    chr = (int) (unsigned char) *(offset);

    switch (chr)
    {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
      {
        // check whether multiplication would be out of bounds
        if (intValue > overflowLimit)
        {
          hasError = 1;
        }
        intValue *= 10ULL;
        addIntValue = (JSUINT64) (chr - 48);

        // check whether addition would be out of bounds
        if (maxIntValue - intValue < addIntValue)
        {
          hasError = 1;
        }

        intValue += addIntValue;
        offset ++;
        break;
      }
      case '.':
      {
        offset ++;
        return decodeDouble(ds);
      }
      case 'e':
      case 'E':
      {
        offset ++;
        return decodeDouble(ds);
      }

      default:
      {
        if (hasError)
        {
          return SetError(ds, -1, intNeg == 1 ? "Value is too big" : "Value is too small");
        }
        goto BREAK_INT_LOOP;
        break;
      }
    }
  }

BREAK_INT_LOOP:

  ds->lastType = JT_INT;
  ds->start = offset;

  if (intNeg == 1 && (intValue & 0x8000000000000000ULL) != 0)
  {
    return ds->dec->newUnsignedLong(ds->prv, intValue);
  }
  else if ((intValue >> 31))
  {
    return ds->dec->newLong(ds->prv, (JSINT64) (intValue * (JSINT64) intNeg));
  }
  else
  {
    return ds->dec->newInt(ds->prv, (JSINT32) (intValue * intNeg));
  }

DECODE_NAN:
    offset++;
    if (*(offset++) != 'a') goto SET_NAN_ERROR;
    if (*(offset++) != 'N') goto SET_NAN_ERROR;

    ds->lastType = JT_NAN;
    ds->start = offset;
    return ds->dec->newNaN(ds->prv);

SET_NAN_ERROR:
    return SetError(ds, -1, "Unexpected character found when decoding 'NaN'");

DECODE_INF:
    offset++;
    if (*(offset++) != 'n') goto SET_INF_ERROR;
    if (*(offset++) != 'f') goto SET_INF_ERROR;
    if (*(offset++) != 'i') goto SET_INF_ERROR;
    if (*(offset++) != 'n') goto SET_INF_ERROR;
    if (*(offset++) != 'i') goto SET_INF_ERROR;
    if (*(offset++) != 't') goto SET_INF_ERROR;
    if (*(offset++) != 'y') goto SET_INF_ERROR;

    ds->start = offset;

    if (intNeg == 1) {
      ds->lastType = JT_POS_INF;
      return ds->dec->newPosInf(ds->prv);
    } else {
      ds->lastType = JT_NEG_INF;
      return ds->dec->newNegInf(ds->prv);
    }

SET_INF_ERROR:
    if (intNeg == 1) {
      const char *msg = "Unexpected character found when decoding 'Infinity'";
      return SetError(ds, -1, msg);
    } else {
      const char *msg = "Unexpected character found when decoding '-Infinity'";
      return SetError(ds, -1, msg);
    }

}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_true ( struct DecoderState *ds)
{
  char *offset = ds->start;
  offset ++;

  if (*(offset++) != 'r')
    goto SETERROR;
  if (*(offset++) != 'u')
    goto SETERROR;
  if (*(offset++) != 'e')
    goto SETERROR;

  ds->lastType = JT_TRUE;
  ds->start = offset;
  return ds->dec->newTrue(ds->prv);

SETERROR:
  return SetError(ds, -1, "Unexpected character found when decoding 'true'");
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_false ( struct DecoderState *ds)
{
  char *offset = ds->start;
  offset ++;

  if (*(offset++) != 'a')
    goto SETERROR;
  if (*(offset++) != 'l')
    goto SETERROR;
  if (*(offset++) != 's')
    goto SETERROR;
  if (*(offset++) != 'e')
    goto SETERROR;

  ds->lastType = JT_FALSE;
  ds->start = offset;
  return ds->dec->newFalse(ds->prv);

SETERROR:
  return SetError(ds, -1, "Unexpected character found when decoding 'false'");
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_null ( struct DecoderState *ds)
{
  char *offset = ds->start;
  offset ++;

  if (*(offset++) != 'u')
    goto SETERROR;
  if (*(offset++) != 'l')
    goto SETERROR;
  if (*(offset++) != 'l')
    goto SETERROR;

  ds->lastType = JT_NULL;
  ds->start = offset;
  return ds->dec->newNull(ds->prv);

SETERROR:
  return SetError(ds, -1, "Unexpected character found when decoding 'null'");
}

static FASTCALL_ATTR void FASTCALL_MSVC SkipWhitespace(struct DecoderState *ds)
{
  char *offset = ds->start;

  for (;;)
  {
    switch (*offset)
    {
      case ' ':
      case '\t':
      case '\r':
      case '\n':
        offset ++;
        break;

      default:
        ds->start = offset;
        return;
    }
  }
}

enum DECODESTRINGSTATE
{
  DS_ISNULL = 0x32,
  DS_ISQUOTE,
  DS_ISESCAPE,
  DS_UTFLENERROR,

};

static const JSUINT8 g_decoderLookup[256] =
{
  /* 0x00 */ DS_ISNULL, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x10 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x20 */ 1, 1, DS_ISQUOTE, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x30 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x40 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x50 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, DS_ISESCAPE, 1, 1, 1,
  /* 0x60 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x70 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x80 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0x90 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0xa0 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0xb0 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  /* 0xc0 */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  /* 0xd0 */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  /* 0xe0 */ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
  /* 0xf0 */ 4, 4, 4, 4, 4, 4, 4, 4, DS_UTFLENERROR, DS_UTFLENERROR, DS_UTFLENERROR, DS_UTFLENERROR, DS_UTFLENERROR, DS_UTFLENERROR, DS_UTFLENERROR, DS_UTFLENERROR,
};

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_string ( struct DecoderState *ds)
{
  int index;
  wchar_t *escOffset;
  wchar_t *escStart;
  size_t escLen = (ds->escEnd - ds->escStart);
  JSUINT8 *inputOffset;
  JSUTF16 ch = 0;
#if WCHAR_MAX >= 0x10FFFF
  JSUINT8 *lastHighSurrogate = NULL;
#endif
  JSUINT8 oct;
  JSUTF32 ucs;
  ds->lastType = JT_INVALID;
  ds->start ++;

  if ( (size_t) (ds->end - ds->start) > escLen)
  {
    size_t newSize = (ds->end - ds->start);

    if (ds->escHeap)
    {
      if (newSize > (SIZE_MAX / sizeof(wchar_t)))
      {
        return SetError(ds, -1, "Could not reserve memory block");
      }
      escStart = (wchar_t *)ds->dec->realloc(ds->escStart, newSize * sizeof(wchar_t));
      if (!escStart)
      {
        ds->dec->free(ds->escStart);
        return SetError(ds, -1, "Could not reserve memory block");
      }
      ds->escStart = escStart;
    }
    else
    {
      wchar_t *oldStart = ds->escStart;
      if (newSize > (SIZE_MAX / sizeof(wchar_t)))
      {
        return SetError(ds, -1, "Could not reserve memory block");
      }
      ds->escStart = (wchar_t *) ds->dec->malloc(newSize * sizeof(wchar_t));
      if (!ds->escStart)
      {
        return SetError(ds, -1, "Could not reserve memory block");
      }
      ds->escHeap = 1;
      memcpy(ds->escStart, oldStart, escLen * sizeof(wchar_t));
    }

    ds->escEnd = ds->escStart + newSize;
  }

  escOffset = ds->escStart;
  inputOffset = (JSUINT8 *) ds->start;

  for (;;)
  {
    switch (g_decoderLookup[(JSUINT8)(*inputOffset)])
    {
      case DS_ISNULL:
      {
        return SetError(ds, -1, "Unmatched '\"' when decoding 'string'");
      }
      case DS_ISQUOTE:
      {
        ds->lastType = JT_UTF8;
        inputOffset ++;
        ds->start += ( (char *) inputOffset - (ds->start));
        return ds->dec->newString(ds->prv, ds->escStart, escOffset);
      }
      case DS_UTFLENERROR:
      {
        return SetError (ds, -1, "Invalid UTF-8 sequence length when decoding 'string'");
      }
      case DS_ISESCAPE:
      {
        inputOffset ++;
        switch (*inputOffset)
        {
          case '\\': *(escOffset++) = L'\\'; inputOffset++; continue;
          case '\"': *(escOffset++) = L'\"'; inputOffset++; continue;
          case '/':  *(escOffset++) = L'/';  inputOffset++; continue;
          case 'b':  *(escOffset++) = L'\b'; inputOffset++; continue;
          case 'f':  *(escOffset++) = L'\f'; inputOffset++; continue;
          case 'n':  *(escOffset++) = L'\n'; inputOffset++; continue;
          case 'r':  *(escOffset++) = L'\r'; inputOffset++; continue;
          case 't':  *(escOffset++) = L'\t'; inputOffset++; continue;

          case 'u':
          {
            int index;
            inputOffset ++;

            for (index = 0; index < 4; index ++)
            {
              switch (*inputOffset)
              {
                case '\0': return SetError (ds, -1, "Unterminated unicode escape sequence when decoding 'string'");
                default: return SetError (ds, -1, "Unexpected character in unicode escape sequence when decoding 'string'");

                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                  ch = (ch << 4) + (JSUTF16) (*inputOffset - '0');
                  break;

                case 'a':
                case 'b':
                case 'c':
                case 'd':
                case 'e':
                case 'f':
                  ch = (ch << 4) + 10 + (JSUTF16) (*inputOffset - 'a');
                  break;

                case 'A':
                case 'B':
                case 'C':
                case 'D':
                case 'E':
                case 'F':
                  ch = (ch << 4) + 10 + (JSUTF16) (*inputOffset - 'A');
                  break;
              }

              inputOffset ++;
            }

#if WCHAR_MAX >= 0x10FFFF
            if ((ch & 0xfc00) == 0xdc00 && lastHighSurrogate == inputOffset - 6 * sizeof(*inputOffset))
            {
              // Low surrogate immediately following a high surrogate
              // Overwrite existing high surrogate with combined character
              *(escOffset-1) = (((*(escOffset-1) - 0xd800) <<10) | (ch - 0xdc00)) + 0x10000;
            }
            else
#endif
            {
              *(escOffset++) = (wchar_t) ch;
            }
#if WCHAR_MAX >= 0x10FFFF
            if ((ch & 0xfc00) == 0xd800)
            {
              lastHighSurrogate = inputOffset;
            }
#endif
            break;
          }

          case '\0': return SetError(ds, -1, "Unterminated escape sequence when decoding 'string'");
          default: return SetError(ds, -1, "Unrecognized escape sequence when decoding 'string'");
        }
        break;
      }

      case 1:
      {
        *(escOffset++) = (wchar_t) (*inputOffset++);
        break;
      }

      case 2:
      {
        ucs = (*inputOffset++) & 0x1f;
        ucs <<= 6;
        if (((*inputOffset) & 0x80) != 0x80)
        {
          return SetError(ds, -1, "Invalid octet in UTF-8 sequence when decoding 'string'");
        }
        ucs |= (*inputOffset++) & 0x3f;
        if (ucs < 0x80) return SetError (ds, -1, "Overlong 2 byte UTF-8 sequence detected when decoding 'string'");
        *(escOffset++) = (wchar_t) ucs;
        break;
      }

      case 3:
      {
        JSUTF32 ucs = 0;
        ucs |= (*inputOffset++) & 0x0f;

        for (index = 0; index < 2; index ++)
        {
          ucs <<= 6;
          oct = (*inputOffset++);

          if ((oct & 0x80) != 0x80)
          {
            return SetError(ds, -1, "Invalid octet in UTF-8 sequence when decoding 'string'");
          }

          ucs |= oct & 0x3f;
        }

        if (ucs < 0x800) return SetError (ds, -1, "Overlong 3 byte UTF-8 sequence detected when encoding string");
        *(escOffset++) = (wchar_t) ucs;
        break;
      }

      case 4:
      {
        JSUTF32 ucs = 0;
        ucs |= (*inputOffset++) & 0x07;

        for (index = 0; index < 3; index ++)
        {
          ucs <<= 6;
          oct = (*inputOffset++);

          if ((oct & 0x80) != 0x80)
          {
            return SetError(ds, -1, "Invalid octet in UTF-8 sequence when decoding 'string'");
          }

          ucs |= oct & 0x3f;
        }

        if (ucs < 0x10000) return SetError (ds, -1, "Overlong 4 byte UTF-8 sequence detected when decoding 'string'");

#if WCHAR_MAX == 0xffff
        if (ucs >= 0x10000)
        {
          ucs -= 0x10000;
          *(escOffset++) = (wchar_t) (ucs >> 10) + 0xd800;
          *(escOffset++) = (wchar_t) (ucs & 0x3ff) + 0xdc00;
        }
        else
        {
          *(escOffset++) = (wchar_t) ucs;
        }
#else
        *(escOffset++) = (wchar_t) ucs;
#endif
        break;
      }
    }
  }
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_array(struct DecoderState *ds)
{
  JSOBJ itemValue;
  JSOBJ newObj;
  int len;
  ds->objDepth++;
  if (ds->objDepth > JSON_MAX_OBJECT_DEPTH) {
    return SetError(ds, -1, "Reached object decoding depth limit");
  }

  newObj = ds->dec->newArray(ds->prv);
  len = 0;

  ds->lastType = JT_INVALID;
  ds->start ++;

  for (;;)
  {
    SkipWhitespace(ds);

    if ((*ds->start) == ']')
    {
      ds->objDepth--;
      if (len == 0)
      {
        ds->start ++;
        return newObj;
      }

      ds->dec->releaseObject(ds->prv, newObj);
      return SetError(ds, -1, "Unexpected character found when decoding array value (1)");
    }

    itemValue = decode_any(ds);

    if (itemValue == NULL)
    {
      ds->dec->releaseObject(ds->prv, newObj);
      return NULL;
    }

    ds->dec->arrayAddItem (ds->prv, newObj, itemValue);

    SkipWhitespace(ds);

    switch (*(ds->start++))
    {
    case ']':
    {
      ds->objDepth--;
      return newObj;
    }
    case ',':
      break;

    default:
      ds->dec->releaseObject(ds->prv, newObj);
      return SetError(ds, -1, "Unexpected character found when decoding array value (2)");
    }

    len++;
  }
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_object( struct DecoderState *ds)
{
  JSOBJ itemName;
  JSOBJ itemValue;
  JSOBJ newObj;
  int len;

  ds->objDepth++;
  if (ds->objDepth > JSON_MAX_OBJECT_DEPTH)
  {
    return SetError(ds, -1, "Reached object decoding depth limit");
  }

  newObj = ds->dec->newObject(ds->prv);
  len = 0;

  ds->start ++;

  for (;;)
  {
    SkipWhitespace(ds);

    if ((*ds->start) == '}')
    {
      ds->objDepth--;
      if (len == 0)
      {
        ds->start ++;
        return newObj;
      }

      ds->dec->releaseObject(ds->prv, newObj);
      return SetError(ds, -1, "Unexpected character in found when decoding object value");
    }

    ds->lastType = JT_INVALID;
    itemName = decode_any(ds);

    if (itemName == NULL)
    {
      ds->dec->releaseObject(ds->prv, newObj);
      return NULL;
    }

    if (ds->lastType != JT_UTF8)
    {
      ds->dec->releaseObject(ds->prv, newObj);
      ds->dec->releaseObject(ds->prv, itemName);
      return SetError(ds, -1, "Key name of object must be 'string' when decoding 'object'");
    }

    SkipWhitespace(ds);

    if (*(ds->start++) != ':')
    {
      ds->dec->releaseObject(ds->prv, newObj);
      ds->dec->releaseObject(ds->prv, itemName);
      return SetError(ds, -1, "No ':' found when decoding object value");
    }

    SkipWhitespace(ds);

    itemValue = decode_any(ds);

    if (itemValue == NULL)
    {
      ds->dec->releaseObject(ds->prv, newObj);
      ds->dec->releaseObject(ds->prv, itemName);
      return NULL;
    }

    ds->dec->objectAddKey (ds->prv, newObj, itemName, itemValue);

    SkipWhitespace(ds);

    switch (*(ds->start++))
    {
      case '}':
      {
        ds->objDepth--;
        return newObj;
      }
      case ',':
        break;

      default:
        ds->dec->releaseObject(ds->prv, newObj);
        return SetError(ds, -1, "Unexpected character in found when decoding object value");
    }

    len++;
  }
}

static FASTCALL_ATTR JSOBJ FASTCALL_MSVC decode_any(struct DecoderState *ds)
{
  for (;;)
  {
    switch (*ds->start)
    {
      case '\"':
        return decode_string (ds);
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
      case 'I':
      case 'N':
      case '-':
        return decode_numeric (ds);

      case '[': return decode_array (ds);
      case '{': return decode_object (ds);
      case 't': return decode_true (ds);
      case 'f': return decode_false (ds);
      case 'n': return decode_null (ds);

      case ' ':
      case '\t':
      case '\r':
      case '\n':
        // White space
        ds->start ++;
        break;

      default:
        return SetError(ds, -1, "Expected object or value");
    }
  }
}

JSOBJ JSON_DecodeObject(JSONObjectDecoder *dec, const char *buffer, size_t cbBuffer)
{
  /*
  FIXME: Base the size of escBuffer of that of cbBuffer so that the unicode escaping doesn't run into the wall each time */
  struct DecoderState ds;
  wchar_t escBuffer[(JSON_MAX_STACK_BUFFER_SIZE / sizeof(wchar_t))];
  JSOBJ ret;

  ds.start = (char *) buffer;
  ds.end = ds.start + cbBuffer;

  ds.escStart = escBuffer;
  ds.escEnd = ds.escStart + (JSON_MAX_STACK_BUFFER_SIZE / sizeof(wchar_t));
  ds.escHeap = 0;
  ds.prv = dec->prv;
  ds.dec = dec;
  ds.dec->errorStr = NULL;
  ds.dec->errorOffset = NULL;
  ds.objDepth = 0;

  ds.dec = dec;

  ret = decode_any (&ds);

  if (ds.escHeap)
  {
    dec->free(ds.escStart);
  }

  if (!(dec->errorStr))
  {
    if ((ds.end - ds.start) > 0)
    {
      SkipWhitespace(&ds);
    }

    if (ds.start != ds.end && ret)
    {
      dec->releaseObject(ds.prv, ret);
      return SetError(&ds, -1, "Trailing data");
    }
  }

  return ret;
}