ttfile.c

神龙卡开发原代码

/*******************************************************************
 *
 *  ttfile.c (extended version)                                 2.1
 *
 *    File I/O Component (body).
 *
 *  Copyright 1996-1999 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.
 *
 *  NOTES:
 *
 *   This implementation relies on the ANSI libc.  You may wish to
 *   modify it to get rid of libc and go straight to the your
 *   platform's stream routines.
 *
 *   The same source code can be used for thread-safe and re-entrant
 *   builds of the library.
 *
 *  Changes between 2.0 and 2.1 :
 *
 *  - it is now possible to close a stream's file handle explicitely
 *    through the new API "TT_Flush_Stream". This will simply close
 *    a stream's file handle (useful to save system resources when
 *    dealing with lots of opened fonts). Of course, the function
 *    "TT_Use_Stream" will automatically re-open a stream's handle if
 *    necessary.
 *
 *  - added "TT_Stream_Size" to replace "TT_File_Size" which wasn't
 *    used anyway. This one returns the size of any stream, even
 *    flushed one (when the previous TT_File_Size could only return
 *    the size of the current working stream). This is used by the
 *    new "Load_TrueType_Any" function in the tables loader.
 *
 ******************************************************************/

#include "ttconfig.h"

#include <stdio.h>
#include <string.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "freetype.h"
#include "tttypes.h"
#include "ttdebug.h"
#include "ttengine.h"
#include "ttmutex.h"
#include "ttmemory.h"
#include "ttfile.h"     /* our prototypes */

/* required by the tracing mode */
#undef  TT_COMPONENT
#define TT_COMPONENT  trace_file


/* For now, we don't define additional error messages in the core library */
/* to report open-on demand errors. Define these error as standard ones   */

#define TT_Err_Could_Not_ReOpen_File  TT_Err_Could_Not_Open_File
#define TT_Err_Could_Not_ReSeek_File  TT_Err_Could_Not_Open_File

  /* This definition is mandatory for each file component! */
  EXPORT_FUNC
  const TFileFrame  TT_Null_FileFrame = { NULL, 0, 0 };

/* It has proven useful to do some bounds checks during development phase. */
/* They should probably be undefined for speed reasons in a later release. */

#if DEBUG_FILE
#define CHECK_FRAME( frame, n )                          \
  do {                                                   \
    if ( frame.cursor + n > frame.address + frame.size ) \
      Panic( "Frame boundary error!\n" );                \
  } while ( 0 )
#else
#define CHECK_FRAME( frame, n )  /* nothing */
#endif

  /* Because a stream can be flushed, i.e. its file handle can be      */
  /* closed to save system resources, we must keep the stream's file   */
  /* pathname to be able to re-open it on demand when it is flushed    */

  struct  TStream_Rec_;
  typedef struct TStream_Rec_  TStream_Rec;
  typedef TStream_Rec*         PStream_Rec;

  struct  TStream_Rec_
  {
    Bool      opened;                  /* is the stream handle opened ?    */
    TT_Text*  name;                    /* the file's pathname              */
    Long      position;                /* current position within the file */

    FILE*     file;                    /* file handle                      */
    Long      base;                    /* stream base in file              */
    Long      size;                    /* stream size in file              */
  };

  /* We support embedded TrueType files by allowing them to be       */
  /* inside any file, at any location, hence the 'base' argument.    */
  /* Note however that the current implementation does not allow you */
  /* to specify a 'base' index when opening a file.                  */
  /* (will come later)                                               */
  /* I still don't know if this will turn out useful ??   - DavidT   */

#define STREAM2REC( x )  ( (TStream_Rec*)HANDLE_Val( x ) )

  static  TT_Error  Stream_Activate  ( PStream_Rec  stream );
  static  TT_Error  Stream_Deactivate( PStream_Rec  stream );


#ifndef TT_CONFIG_OPTION_THREAD_SAFE

  /*******************************************************************/
  /*******************************************************************/
  /*******************************************************************/
  /****                                                           ****/
  /****  N O N   R E E N T R A N T   I M P L E M E N T A T I O N  ****/
  /****                                                           ****/
  /*******************************************************************/
  /*******************************************************************/
  /*******************************************************************/

  /* in non-rentrant builds, we allocate a single block where we'll  */
  /* place all the frames smaller than FRAME_CACHE_SIZE, rather than */
  /* allocating a new block on each access.  Bigger frames will be   */
  /* malloced normally in the heap.                                  */
  /*                                                                 */
  /* See TT_Access_Frame() and TT_Forget_Frame() for details.        */

#define FRAME_CACHE_SIZE  2048

  /* The TFile_Component structure holds all the data that was */
  /* previously declared static or global in this component.   */
  /*                                                           */
  /* It is accessible through the 'engine.file_component'      */
  /* variable in re-entrant builds, or directly through the    */
  /* static 'files' variable in other builds.                  */

  struct  TFile_Component_
  {
    TMutex       lock;        /* used by the thread-safe build only */
    Byte*        frame_cache; /* frame cache     */
    PStream_Rec  stream;      /* current stream  */
    TFileFrame   frame;       /* current frame   */
  };

  typedef struct TFile_Component_  TFile_Component;

  static TFile_Component  files;

#define CUR_Stream  files.stream
#define CUR_Frame   files.frame

#define STREAM_VARS  /* void */
#define STREAM_VAR   /* void */

/* The macro CUR_Stream denotes the current input stream.            */
/* Note that for the re-entrant version, the 'stream' name has been  */
/* chosen according to the macro STREAM_ARGS.                        */

/* The macro CUR_Frame denotes the current file frame.              */
/* Note that for the re-entrant version, the 'frame' name has been  */
/* chosen according to the macro FRAME_ARGS.                        */

/* The macro STREAM_VAR is used when calling public functions */
/* that need an 'optional' stream argument.                   */


/*******************************************************************
 *
 *  Function    :  TTFile_Init
 *
 *  Description :  Initializes the File component.
 *
 ******************************************************************/

  LOCAL_FUNC
  TT_Error  TTFile_Init( PEngine_Instance  engine )
  {
    TT_Error  error;


    MUTEX_Create( files.lock );
    files.stream = NULL;
    ZERO_Frame( files.frame );

    if ( ALLOC( files.frame_cache, FRAME_CACHE_SIZE ) )
      return error;

    return TT_Err_Ok;
  }


/*******************************************************************
 *
 *  Function    :  TTFile_Done
 *
 *  Description :  Finalizes the File component.
 *
 ******************************************************************/

  LOCAL_FUNC
  TT_Error  TTFile_Done( PEngine_Instance  engine )
  {
    FREE( files.frame_cache );
    MUTEX_Destroy( files.lock );

    return TT_Err_Ok;
  }


/*******************************************************************
 *
 *  Function    : TT_Use_Stream
 *
 *  Description : Copies or duplicates a given stream.
 *
 *  Input  :  org_stream   original stream
 *            stream       target stream (copy or duplicate)
 *
 *  Output :  Error code.
 *
 ******************************************************************/

  EXPORT_FUNC
  TT_Error  TT_Use_Stream( TT_Stream   org_stream,
                           TT_Stream*  stream )
  {
     MUTEX_Lock( files.lock );                /* lock file mutex    */

     *stream = org_stream;                    /* copy the stream    */
     files.stream = STREAM2REC(org_stream);   /* set current stream */

     Stream_Activate( files.stream );

     return TT_Err_Ok;
  }


/*******************************************************************
 *
 *  Function    : TT_Done_Stream
 *
 *  Description : Releases a given stream.
 *
 *  Input  :  stream  target stream
 *
 *  Output :  Error code.
 *
 ******************************************************************/

  EXPORT_FUNC
  TT_Error  TT_Done_Stream( TT_Stream*  stream )
  {
     HANDLE_Set( *stream, NULL );
     MUTEX_Release( files.lock );

     return TT_Err_Ok;
  }


/*******************************************************************
 *
 *  Function    :  TT_Access_Frame
 *
 *  Description :  Notifies the component that we're going to read
 *                 'size' bytes from the current file position.
 *                 This function should load/cache/map these bytes
 *                 so that they will be addressed by the GET_xxx
 *                 functions easily.
 *
 *  Input  :  size   number of bytes to access.
 *
 *  Output :  SUCCESS on success. FAILURE on error.
 *
 *  Notes:    The function fails if the byte range is not within the
 *            the file, or if there is not enough memory to cache
 *            the bytes properly (which usually means that `size' is
 *            too big in both cases).
 *
 ******************************************************************/

  EXPORT_FUNC
  TT_Error  TT_Access_Frame( STREAM_ARGS FRAME_ARGS Long  size )
  {
    TT_Error  error;


    if ( CUR_Frame.address != NULL )
      return TT_Err_Nested_Frame_Access;

    if ( size <= FRAME_CACHE_SIZE )
    {
      /* use the cache */
      CUR_Frame.address = files.frame_cache;
      CUR_Frame.size    = FRAME_CACHE_SIZE;
    }
    else
    {
      if ( ALLOC( CUR_Frame.address, size ) )
        return error;
      CUR_Frame.size    = size;
    }

    error = TT_Read_File( STREAM_VARS (void*)CUR_Frame.address, size );
    if (error)
    {
      if ( size > FRAME_CACHE_SIZE )
        FREE( CUR_Frame.address );
      CUR_Frame.address = NULL;
      CUR_Frame.size    = 0;
    }

    CUR_Frame.cursor = CUR_Frame.address;
    return error;
  }


/*******************************************************************
 *
 *  Function    :  TT_Check_And_Access_Frame
 *
 *  Description :  Notifies the component that we're going to read
 *                 `size' bytes from the current file position.
 *                 This function should load/cache/map these bytes
 *                 so that they will be addressed by the GET_xxx
 *                 functions easily.
 *
 *  Input  :  size   number of bytes to access.
 *
 *  Output :  SUCCESS on success. FAILURE on error.
 *
 *  Notes:    The function truncates `size' if the byte range is not
 *            within the file.
 *
 *            It will fail if there is not enough memory to cache
 *            the bytes properly (which usually means that `size' is
 *            too big).
 *
 *            It will fail if you make two consecutive calls
 *            to TT_Access_Frame(), without a TT_Forget_Frame() between
 *            them.
 *
 *            The only difference with TT_Access_Frame() is that we
 *            check that the frame is within the current file.  We
 *            otherwise truncate it.
 *
 ******************************************************************/

  EXPORT_FUNC
  TT_Error  TT_Check_And_Access_Frame( STREAM_ARGS FRAME_ARGS Long  size )
  {
    TT_Error  error;
    Long      readBytes, requested;


    if ( CUR_Frame.address != NULL )
      return TT_Err_Nested_Frame_Access;

    if ( size <= FRAME_CACHE_SIZE )
    {
      /* use the cache */
      CUR_Frame.address = files.frame_cache;
      CUR_Frame.size    = FRAME_CACHE_SIZE;
    }
    else
    {
      if ( ALLOC( CUR_Frame.address, size ) )
        return error;
      CUR_Frame.size    = size;
    }

    requested = size;
    readBytes = CUR_Stream->size - TT_File_Pos( STREAM_VAR );
    if ( size > readBytes )
      size = readBytes;

    error = TT_Read_File( STREAM_VARS (void*)CUR_Frame.address, size );
    if (error)
    {
      if ( requested > FRAME_CACHE_SIZE )
        FREE( CUR_Frame.address );
      CUR_Frame.address = NULL;
      CUR_Frame.size    = 0;