text: /***************************************************************************/
  /*                                                                         */
  /*  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 2004-2015 by                                                 */
  /*  Albert Chin-A-Young.                                                   */
  /*                                                                         */
  /*  based on code in `src/gzip/ftgzip.c'                                   */
  /*                                                                         */
  /*  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__
  
  #undef  FT_ERR_PREFIX
  #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 = FT_THROW( 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;
  
  
      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 = FT_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 = FT_THROW( 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 = FT_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 = FT_THROW( 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 unsigned long
    ft_lzw_stream_io( FT_Stream       stream,
                      unsigned long   offset,
                      unsigned char*  buffer,
                      unsigned long   count )
    {
      FT_LZWFile  zip = (FT_LZWFile)stream->descriptor.pointer;
  
  
      return ft_lzw_file_io( zip, offset, buffer, count );
    }
  
  
    FT_EXPORT_DEF( FT_Error )
    FT_Stream_OpenLZW( FT_Stream  stream,
                       FT_Stream  source )
    {
      FT_Error    error;
      FT_Memory   memory;
      FT_LZWFile  zip = NULL;
  
  
      if ( !stream || !source )
      {
        error = FT_THROW( Invalid_Stream_Handle );
        goto Exit;
      }
  
      memory = source->memory;
  
      /*
       *  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 FT_THROW( Unimplemented_Feature );
    }
  
  
  #endif /* !FT_CONFIG_OPTION_USE_LZW */
  
  
  /* END */
  