cffparse.c

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/***************************************************************************/
/*                                                                         */
/*  cffparse.c                                                             */
/*                                                                         */
/*    CFF token stream parser (body)                                       */
/*                                                                         */
/*  Copyright 1996-2001, 2002, 2003, 2004, 2007, 2008 by                   */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/


#include <ft2build.h>
#include "cffparse.h"
#include FT_INTERNAL_STREAM_H
#include FT_INTERNAL_DEBUG_H

#include "cfferrs.h"


  /*************************************************************************/
  /*                                                                       */
  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  /* messages during execution.                                            */
  /*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_cffparse


  enum
  {
    cff_kind_none = 0,
    cff_kind_num,
    cff_kind_fixed,
    cff_kind_fixed_thousand,
    cff_kind_string,
    cff_kind_bool,
    cff_kind_delta,
    cff_kind_callback,

    cff_kind_max  /* do not remove */
  };


  /* now generate handlers for the most simple fields */
  typedef FT_Error  (*CFF_Field_Reader)( CFF_Parser  parser );

  typedef struct  CFF_Field_Handler_
  {
    int               kind;
    int               code;
    FT_UInt           offset;
    FT_Byte           size;
    CFF_Field_Reader  reader;
    FT_UInt           array_max;
    FT_UInt           count_offset;

  } CFF_Field_Handler;


  FT_LOCAL_DEF( void )
  cff_parser_init( CFF_Parser  parser,
                   FT_UInt     code,
                   void*       object )
  {
    FT_MEM_ZERO( parser, sizeof ( *parser ) );

    parser->top         = parser->stack;
    parser->object_code = code;
    parser->object      = object;
  }


  /* read an integer */
  static FT_Long
  cff_parse_integer( FT_Byte*  start,
                     FT_Byte*  limit )
  {
    FT_Byte*  p   = start;
    FT_Int    v   = *p++;
    FT_Long   val = 0;


    if ( v == 28 )
    {
      if ( p + 2 > limit )
        goto Bad;

      val = (FT_Short)( ( (FT_Int)p[0] << 8 ) | p[1] );
      p  += 2;
    }
    else if ( v == 29 )
    {
      if ( p + 4 > limit )
        goto Bad;

      val = ( (FT_Long)p[0] << 24 ) |
            ( (FT_Long)p[1] << 16 ) |
            ( (FT_Long)p[2] <<  8 ) |
                       p[3];
      p += 4;
    }
    else if ( v < 247 )
    {
      val = v - 139;
    }
    else if ( v < 251 )
    {
      if ( p + 1 > limit )
        goto Bad;

      val = ( v - 247 ) * 256 + p[0] + 108;
      p++;
    }
    else
    {
      if ( p + 1 > limit )
        goto Bad;

      val = -( v - 251 ) * 256 - p[0] - 108;
      p++;
    }

  Exit:
    return val;

  Bad:
    val = 0;
    goto Exit;
  }


  static const FT_Long power_tens[] =
  {
    1L,
    10L,
    100L,
    1000L,
    10000L,
    100000L,
    1000000L,
    10000000L,
    100000000L,
    1000000000L
  };


  /* read a real */
  static FT_Fixed
  cff_parse_real( FT_Byte*  start,
                  FT_Byte*  limit,
                  FT_Int    power_ten,
                  FT_Int*   scaling )
  {
    FT_Byte*  p = start;
    FT_UInt   nib;
    FT_UInt   phase;

    FT_Long   result, number, rest, exponent;
    FT_Int    sign = 0, exponent_sign = 0;
    FT_Int    exponent_add, integer_length, fraction_length;


    if ( scaling )
      *scaling  = 0;

    result = 0;

    number   = 0;
    rest     = 0;
    exponent = 0;

    exponent_add    = 0;
    integer_length  = 0;
    fraction_length = 0;

    /* First of all, read the integer part. */
    phase = 4;

    for (;;)
    {
      /* If we entered this iteration with phase == 4, we need to */
      /* read a new byte.  This also skips past the initial 0x1E. */
      if ( phase )
      {
        p++;

        /* Make sure we don't read past the end. */
        if ( p >= limit )
          goto Exit;
      }

      /* Get the nibble. */
      nib   = ( p[0] >> phase ) & 0xF;
      phase = 4 - phase;

      if ( nib == 0xE )
        sign = 1;
      else if ( nib > 9 )
        break;
      else
      {
        /* Increase exponent if we can't add the digit. */
        if ( number >= 0xCCCCCCCL )
          exponent_add++;
        /* Skip leading zeros. */
        else if ( nib || number )
        {
          integer_length++;
          number = number * 10 + nib;
        }
      }
    }

    /* Read fraction part, if any. */
    if ( nib == 0xa )
      for (;;)
      {
        /* If we entered this iteration with phase == 4, we need */
        /* to read a new byte.                                   */
        if ( phase )
        {
          p++;

          /* Make sure we don't read past the end. */
          if ( p >= limit )
            goto Exit;
        }

        /* Get the nibble. */
        nib   = ( p[0] >> phase ) & 0xF;
        phase = 4 - phase;
        if ( nib >= 10 )
          break;

        /* Skip leading zeros if possible. */
        if ( !nib && !number )
          exponent_add--;
        /* Only add digit if we don't overflow. */
        else if ( number < 0xCCCCCCCL )
        {
          fraction_length++;
          number = number * 10 + nib;
        }
      }

    /* Read exponent, if any. */
    if ( nib == 12 )
    {
      exponent_sign = 1;
      nib           = 11;
    }

    if ( nib == 11 )
    {
      for (;;)
      {
        /* If we entered this iteration with phase == 4, */
        /* we need to read a new byte.                   */
        if ( phase )
        {
          p++;

          /* Make sure we don't read past the end. */
          if ( p >= limit )
            goto Exit;
        }

        /* Get the nibble. */
        nib   = ( p[0] >> phase ) & 0xF;
        phase = 4 - phase;
        if ( nib >= 10 )
          break;

        exponent = exponent * 10 + nib;

        /* Arbitrarily limit exponent. */
        if ( exponent > 1000 )
          goto Exit;
      }

      if ( exponent_sign )
        exponent = -exponent;
    }

    /* We don't check `power_ten' and `exponent_add'. */
    exponent += power_ten + exponent_add;

    if ( scaling )
    {
      /* Only use `fraction_length'. */
      fraction_length += integer_length;
      exponent        += integer_length;

      if ( fraction_length <= 5 )
      {
        if ( number > 0x7FFFL )
        {
          result   = FT_DivFix( number, 10 );
          *scaling = exponent - fraction_length + 1;
        }
        else
        {
          if ( exponent > 0 )
          {
            FT_Int  new_fraction_length, shift;


            /* Make `scaling' as small as possible. */
            new_fraction_length = FT_MIN( exponent, 5 );
            exponent           -= new_fraction_length;
            shift               = new_fraction_length - fraction_length;

            number *= power_tens[shift];
            if ( number > 0x7FFFL )
            {
              number   /= 10;
              exponent += 1;
            }
          }
          else
            exponent -= fraction_length;

          result   = number << 16;
          *scaling = exponent;
        }
      }
      else
      {
        if ( ( number / power_tens[fraction_length - 5] ) > 0x7FFFL )
        {
          result   = FT_DivFix( number, power_tens[fraction_length - 4] );
          *scaling = exponent - 4;
        }
        else
        {
          result   = FT_DivFix( number, power_tens[fraction_length - 5] );
          *scaling = exponent - 5;
        }
      }
    }
    else
    {
      integer_length  += exponent;
      fraction_length -= exponent;

      /* Check for overflow and underflow. */
      if ( FT_ABS( integer_length ) > 5 )
        goto Exit;

      /* Convert into 16.16 format. */
      if ( fraction_length > 0 )
      {
        if ( ( number / power_tens[fraction_length] ) > 0x7FFFL )
          goto Exit;

        result = FT_DivFix( number, power_tens[fraction_length] );
      }
      else
      {
        number *= power_tens[-fraction_length];

        if ( number > 0x7FFFL )
          goto Exit;

        result = number << 16;
      }
    }

    if ( sign )
      result = -result;

  Exit:
    return result;
  }


  /* read a number, either integer or real */
  static FT_Long
  cff_parse_num( FT_Byte**  d )
  {
    return **d == 30 ? ( cff_parse_real( d[0], d[1], 0, NULL ) >> 16 )
                     :   cff_parse_integer( d[0], d[1] );
  }


  /* read a floating point number, either integer or real */
  static FT_Fixed
  cff_parse_fixed( FT_Byte**  d )
  {
    return **d == 30 ? cff_parse_real( d[0], d[1], 0, NULL )
                     : cff_parse_integer( d[0], d[1] ) << 16;
  }


  /* read a floating point number, either integer or real, */
  /* but return `10^scaling' times the number read in      */
  static FT_Fixed
  cff_parse_fixed_scaled( FT_Byte**  d,
                          FT_Int     scaling )
  {
    return **d ==
      30 ? cff_parse_real( d[0], d[1], scaling, NULL )
         : (FT_Fixed)FT_MulFix( cff_parse_integer( d[0], d[1] ) << 16,
                                                   power_tens[scaling] );
  }


  /* read a floating point number, either integer or real,     */
  /* and return it as precise as possible -- `scaling' returns */
  /* the scaling factor (as a power of 10)                     */
  static FT_Fixed
  cff_parse_fixed_dynamic( FT_Byte**  d,
                           FT_Int*    scaling )
  {