/***************************************************************************/

/*                                                                         */

/*  ftlzw.c                                                                */

/*                                                                         */

/*    FreeType support for .Z compressed files.                            */

/*                                                                         */

/*  This optional component relies on NetBSD's zopen().  It should mainly  */

/*  be used to parse compressed PCF fonts, as found with many X11 server   */

/*  distributions.                                                         */

/*                                                                         */

/*  Copyright 2004, 2005, 2006, 2009, 2010 by                              */

/*  Albert Chin-A-Young.                                                   */

/*                                                                         */

/*  Based on code in src/gzip/ftgzip.c, Copyright 2004 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 FT_INTERNAL_MEMORY_H

#include FT_INTERNAL_STREAM_H

#include FT_INTERNAL_DEBUG_H

#include FT_LZW_H

#include FT_CONFIG_STANDARD_LIBRARY_H

#include FT_MODULE_ERRORS_H

#undef __FTERRORS_H__

#define FT_ERR_PREFIX  LZW_Err_

#define FT_ERR_BASE    FT_Mod_Err_LZW

#include FT_ERRORS_H

#ifdef FT_CONFIG_OPTION_USE_LZW

#ifdef FT_CONFIG_OPTION_PIC

#error "lzw code does not support PIC yet"

#endif 

#include "ftzopen.h"

/***************************************************************************/

/***************************************************************************/

/*****                                                                 *****/

/*****                  M E M O R Y   M A N A G E M E N T              *****/

/*****                                                                 *****/

/***************************************************************************/

/***************************************************************************/

/***************************************************************************/

/***************************************************************************/

/*****                                                                 *****/

/*****                   F I L E   D E S C R I P T O R                 *****/

/*****                                                                 *****/

/***************************************************************************/

/***************************************************************************/

#define FT_LZW_BUFFER_SIZE  4096

  typedef struct  FT_LZWFileRec_

  {

    FT_Stream       source;         /* parent/source stream        */

    FT_Stream       stream;         /* embedding stream            */

    FT_Memory       memory;         /* memory allocator            */

    FT_LzwStateRec  lzw;            /* lzw decompressor state      */

    FT_Byte         buffer[FT_LZW_BUFFER_SIZE]; /* output buffer      */

    FT_ULong        pos;                        /* position in output */

    FT_Byte*        cursor;

    FT_Byte*        limit;

  } FT_LZWFileRec, *FT_LZWFile;

  /* check and skip .Z header */

  static FT_Error

  ft_lzw_check_header( FT_Stream  stream )

  {

    FT_Error  error;

    FT_Byte   head[2];

    if ( FT_STREAM_SEEK( 0 )       ||

         FT_STREAM_READ( head, 2 ) )

      goto Exit;

    /* head[0] && head[1] are the magic numbers */

    if ( head[0] != 0x1f ||

         head[1] != 0x9d )

      error = LZW_Err_Invalid_File_Format;

  Exit:

    return error;

  }

  static FT_Error

  ft_lzw_file_init( FT_LZWFile  zip,

                    FT_Stream   stream,

                    FT_Stream   source )

  {

    FT_LzwState  lzw   = &zip->lzw;

    FT_Error     error = LZW_Err_Ok;

    zip->stream = stream;

    zip->source = source;

    zip->memory = stream->memory;

    zip->limit  = zip->buffer + FT_LZW_BUFFER_SIZE;

    zip->cursor = zip->limit;

    zip->pos    = 0;

    /* check and skip .Z header */

    error = ft_lzw_check_header( source );

    if ( error )

      goto Exit;

    /* initialize internal lzw variable */

    ft_lzwstate_init( lzw, source );

  Exit:

    return error;

  }

  static void

  ft_lzw_file_done( FT_LZWFile  zip )

  {

    /* clear the rest */

    ft_lzwstate_done( &zip->lzw );

    zip->memory = NULL;

    zip->source = NULL;

    zip->stream = NULL;

  }

  static FT_Error

  ft_lzw_file_reset( FT_LZWFile  zip )

  {

    FT_Stream  stream = zip->source;

    FT_Error   error;

    if ( !FT_STREAM_SEEK( 0 ) )

    {

      ft_lzwstate_reset( &zip->lzw );

      zip->limit  = zip->buffer + FT_LZW_BUFFER_SIZE;

      zip->cursor = zip->limit;

      zip->pos    = 0;

    }

    return error;

  }

  static FT_Error

  ft_lzw_file_fill_output( FT_LZWFile  zip )

  {

    FT_LzwState  lzw = &zip->lzw;

    FT_ULong     count;

    FT_Error     error = LZW_Err_Ok;

    zip->cursor = zip->buffer;

    count = ft_lzwstate_io( lzw, zip->buffer, FT_LZW_BUFFER_SIZE );

    zip->limit = zip->cursor + count;

    if ( count == 0 )

      error = LZW_Err_Invalid_Stream_Operation;

    return error;

  }

  /* fill output buffer; `count' must be <= FT_LZW_BUFFER_SIZE */

  static FT_Error

  ft_lzw_file_skip_output( FT_LZWFile  zip,

                           FT_ULong    count )

  {

    FT_Error  error = LZW_Err_Ok;

    /* first, we skip what we can from the output buffer */

    {

      FT_ULong  delta = (FT_ULong)( zip->limit - zip->cursor );

      if ( delta >= count )

        delta = count;

      zip->cursor += delta;

      zip->pos    += delta;

      count -= delta;

    }

    /* next, we skip as many bytes remaining as possible */

    while ( count > 0 )

    {

      FT_ULong  delta = FT_LZW_BUFFER_SIZE;

      FT_ULong  numread;

      if ( delta > count )

        delta = count;

      numread = ft_lzwstate_io( &zip->lzw, NULL, delta );

      if ( numread < delta )

      {

        /* not enough bytes */

        error = LZW_Err_Invalid_Stream_Operation;

        break;

      }

      zip->pos += delta;

      count    -= delta;

    }

    return error;

  }

  static FT_ULong

  ft_lzw_file_io( FT_LZWFile  zip,

                  FT_ULong    pos,

                  FT_Byte*    buffer,

                  FT_ULong    count )

  {

    FT_ULong  result = 0;

    FT_Error  error;

    /* seeking backwards. */

    if ( pos < zip->pos )

    {

      /* If the new position is within the output buffer, simply       */

      /* decrement pointers, otherwise we reset the stream completely! */

      if ( ( zip->pos - pos ) <= (FT_ULong)( zip->cursor - zip->buffer ) )

      {

        zip->cursor -= zip->pos - pos;

        zip->pos     = pos;

      }

      else

      {

        error = ft_lzw_file_reset( zip );

        if ( error )

          goto Exit;

      }

    }

    /* skip unwanted bytes */

    if ( pos > zip->pos )

    {

      error = ft_lzw_file_skip_output( zip, (FT_ULong)( pos - zip->pos ) );

      if ( error )

        goto Exit;

    }

    if ( count == 0 )

      goto Exit;

    /* now read the data */

    for (;;)

    {

      FT_ULong  delta;

      delta = (FT_ULong)( zip->limit - zip->cursor );

      if ( delta >= count )

        delta = count;

      FT_MEM_COPY( buffer + result, zip->cursor, delta );

      result      += delta;

      zip->cursor += delta;

      zip->pos    += delta;

      count -= delta;

      if ( count == 0 )

        break;

      error = ft_lzw_file_fill_output( zip );

      if ( error )

        break;

    }

  Exit:

    return result;

  }

/***************************************************************************/

/***************************************************************************/

/*****                                                                 *****/

/*****            L Z W   E M B E D D I N G   S T R E A M              *****/

/*****                                                                 *****/

/***************************************************************************/

/***************************************************************************/

  static void

  ft_lzw_stream_close( FT_Stream  stream )

  {

    FT_LZWFile  zip    = (FT_LZWFile)stream->descriptor.pointer;

    FT_Memory   memory = stream->memory;

    if ( zip )

    {

      /* finalize lzw file descriptor */

      ft_lzw_file_done( zip );

      FT_FREE( zip );

      stream->descriptor.pointer = NULL;

    }

  }

  static FT_ULong

  ft_lzw_stream_io( FT_Stream  stream,

                    FT_ULong   pos,

                    FT_Byte*   buffer,

                    FT_ULong   count )

  {

    FT_LZWFile  zip = (FT_LZWFile)stream->descriptor.pointer;

    return ft_lzw_file_io( zip, pos, buffer, count );

  }

  FT_EXPORT_DEF( FT_Error )

  FT_Stream_OpenLZW( FT_Stream  stream,

                     FT_Stream  source )

  {

    FT_Error    error;

    FT_Memory   memory = source->memory;

    FT_LZWFile  zip;

    /*

     *  Check the header right now; this prevents allocation of a huge

     *  LZWFile object (400 KByte of heap memory) if not necessary.

     *

     *  Did I mention that you should never use .Z compressed font

     *  files?

     */

    error = ft_lzw_check_header( source );

    if ( error )

      goto Exit;

    FT_ZERO( stream );

    stream->memory = memory;

    if ( !FT_NEW( zip ) )

    {

      error = ft_lzw_file_init( zip, stream, source );

      if ( error )

      {

        FT_FREE( zip );

        goto Exit;

      }

      stream->descriptor.pointer = zip;

    }

    stream->size  = 0x7FFFFFFFL;  /* don't know the real size! */

    stream->pos   = 0;

    stream->base  = 0;

    stream->read  = ft_lzw_stream_io;

    stream->close = ft_lzw_stream_close;

  Exit:

    return error;

  }

#include "ftzopen.c"

#else  /* !FT_CONFIG_OPTION_USE_LZW */

  FT_EXPORT_DEF( FT_Error )

  FT_Stream_OpenLZW( FT_Stream  stream,

                     FT_Stream  source )

  {

    FT_UNUSED( stream );

    FT_UNUSED( source );

    return LZW_Err_Unimplemented_Feature;

  }

#endif /* !FT_CONFIG_OPTION_USE_LZW */

/* END */