/modules/freetype2/include/freetype/internal/ftvalid.h

  1/***************************************************************************/
  2/*                                                                         */
  3/*  ftvalid.h                                                              */
  4/*                                                                         */
  5/*    FreeType validation support (specification).                         */
  6/*                                                                         */
  7/*  Copyright 2004 by                                                      */
  8/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
  9/*                                                                         */
 10/*  This file is part of the FreeType project, and may only be used,       */
 11/*  modified, and distributed under the terms of the FreeType project      */
 12/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
 13/*  this file you indicate that you have read the license and              */
 14/*  understand and accept it fully.                                        */
 15/*                                                                         */
 16/***************************************************************************/
 17
 18
 19#ifndef __FTVALID_H__
 20#define __FTVALID_H__
 21
 22#include <ft2build.h>
 23#include FT_CONFIG_STANDARD_LIBRARY_H   /* for ft_setjmp and ft_longjmp */
 24
 25
 26FT_BEGIN_HEADER
 27
 28
 29  /*************************************************************************/
 30  /*************************************************************************/
 31  /*************************************************************************/
 32  /****                                                                 ****/
 33  /****                                                                 ****/
 34  /****                    V A L I D A T I O N                          ****/
 35  /****                                                                 ****/
 36  /****                                                                 ****/
 37  /*************************************************************************/
 38  /*************************************************************************/
 39  /*************************************************************************/
 40
 41  /* handle to a validation object */
 42  typedef struct FT_ValidatorRec_ volatile*  FT_Validator;
 43
 44
 45  /*************************************************************************/
 46  /*                                                                       */
 47  /* There are three distinct validation levels defined here:              */
 48  /*                                                                       */
 49  /* FT_VALIDATE_DEFAULT ::                                                */
 50  /*   A table that passes this validation level can be used reliably by   */
 51  /*   FreeType.  It generally means that all offsets have been checked to */
 52  /*   prevent out-of-bound reads, that array counts are correct, etc.     */
 53  /*                                                                       */
 54  /* FT_VALIDATE_TIGHT ::                                                  */
 55  /*   A table that passes this validation level can be used reliably and  */
 56  /*   doesn't contain invalid data.  For example, a charmap table that    */
 57  /*   returns invalid glyph indices will not pass, even though it can     */
 58  /*   be used with FreeType in default mode (the library will simply      */
 59  /*   return an error later when trying to load the glyph).               */
 60  /*                                                                       */
 61  /*   It also checks that fields which must be a multiple of 2, 4, or 8,  */
 62  /*   don't have incorrect values, etc.                                   */
 63  /*                                                                       */
 64  /* FT_VALIDATE_PARANOID ::                                               */
 65  /*   Only for font debugging.  Checks that a table follows the           */
 66  /*   specification by 100%.  Very few fonts will be able to pass this    */
 67  /*   level anyway but it can be useful for certain tools like font       */
 68  /*   editors/converters.                                                 */
 69  /*                                                                       */
 70  typedef enum  FT_ValidationLevel_
 71  {
 72    FT_VALIDATE_DEFAULT = 0,
 73    FT_VALIDATE_TIGHT,
 74    FT_VALIDATE_PARANOID
 75
 76  } FT_ValidationLevel;
 77
 78
 79  /* validator structure */
 80  typedef struct  FT_ValidatorRec_
 81  {
 82    const FT_Byte*      base;        /* address of table in memory       */
 83    const FT_Byte*      limit;       /* `base' + sizeof(table) in memory */
 84    FT_ValidationLevel  level;       /* validation level                 */
 85    FT_Error            error;       /* error returned. 0 means success  */
 86
 87    ft_jmp_buf          jump_buffer; /* used for exception handling      */
 88
 89  } FT_ValidatorRec;
 90
 91
 92#define FT_VALIDATOR( x )  ((FT_Validator)( x ))
 93
 94
 95  FT_BASE( void )
 96  ft_validator_init( FT_Validator        valid,
 97                     const FT_Byte*      base,
 98                     const FT_Byte*      limit,
 99                     FT_ValidationLevel  level );
100
101  /* Do not use this. It's broken and will cause your validator to crash */
102  /* if you run it on an invalid font.                                   */
103  FT_BASE( FT_Int )
104  ft_validator_run( FT_Validator  valid );
105
106  /* Sets the error field in a validator, then calls `longjmp' to return */
107  /* to high-level caller.  Using `setjmp/longjmp' avoids many stupid    */
108  /* error checks within the validation routines.                        */
109  /*                                                                     */
110  FT_BASE( void )
111  ft_validator_error( FT_Validator  valid,
112                      FT_Error      error );
113
114
115  /* Calls ft_validate_error.  Assumes that the `valid' local variable */
116  /* holds a pointer to the current validator object.                  */
117  /*                                                                   */
118  /* Use preprocessor prescan to pass FT_ERR_PREFIX.                   */
119  /*                                                                   */
120#define FT_INVALID( _prefix, _error )  FT_INVALID_( _prefix, _error )
121#define FT_INVALID_( _prefix, _error ) \
122          ft_validator_error( valid, _prefix ## _error )
123
124  /* called when a broken table is detected */
125#define FT_INVALID_TOO_SHORT \
126          FT_INVALID( FT_ERR_PREFIX, Invalid_Table )
127
128  /* called when an invalid offset is detected */
129#define FT_INVALID_OFFSET \
130          FT_INVALID( FT_ERR_PREFIX, Invalid_Offset )
131
132  /* called when an invalid format/value is detected */
133#define FT_INVALID_FORMAT \
134          FT_INVALID( FT_ERR_PREFIX, Invalid_Table )
135
136  /* called when an invalid glyph index is detected */
137#define FT_INVALID_GLYPH_ID \
138          FT_INVALID( FT_ERR_PREFIX, Invalid_Glyph_Index )
139
140  /* called when an invalid field value is detected */
141#define FT_INVALID_DATA \
142          FT_INVALID( FT_ERR_PREFIX, Invalid_Table )
143
144
145FT_END_HEADER
146
147#endif /* __FTVALID_H__ */
148
149
150/* END */