ftvalid.h revision ec0bab5697bb31ba980810145f62e3799946ec60 
1/***************************************************************************/
2/*                                                                         */
3/*  ftvalid.h                                                              */
4/*                                                                         */
5/*    FreeType validation support (specification).                         */
6/*                                                                         */
7/*  Copyright 2004, 2013 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#if defined( _MSC_VER )      /* Visual C++ (and Intel C++) */
80  /* We disable the warning `structure was padded due to   */
81  /* __declspec(align())' in order to compile cleanly with */
82  /* the maximum level of warnings.                        */
83#pragma warning( push )
84#pragma warning( disable : 4324 )
85#endif /* _MSC_VER */
86
87  /* validator structure */
88  typedef struct  FT_ValidatorRec_
89  {
90    const FT_Byte*      base;        /* address of table in memory       */
91    const FT_Byte*      limit;       /* `base' + sizeof(table) in memory */
92    FT_ValidationLevel  level;       /* validation level                 */
93    FT_Error            error;       /* error returned. 0 means success  */
94
95    ft_jmp_buf          jump_buffer; /* used for exception handling      */
96
97  } FT_ValidatorRec;
98
99#if defined( _MSC_VER )
100#pragma warning( pop )
101#endif
102
103#define FT_VALIDATOR( x )  ( (FT_Validator)( x ) )
104
105
106  FT_BASE( void )
107  ft_validator_init( FT_Validator        valid,
108                     const FT_Byte*      base,
109                     const FT_Byte*      limit,
110                     FT_ValidationLevel  level );
111
112  /* Do not use this. It's broken and will cause your validator to crash */
113  /* if you run it on an invalid font.                                   */
114  FT_BASE( FT_Int )
115  ft_validator_run( FT_Validator  valid );
116
117  /* Sets the error field in a validator, then calls `longjmp' to return */
118  /* to high-level caller.  Using `setjmp/longjmp' avoids many stupid    */
119  /* error checks within the validation routines.                        */
120  /*                                                                     */
121  FT_BASE( void )
122  ft_validator_error( FT_Validator  valid,
123                      FT_Error      error );
124
125
126  /* Calls ft_validate_error.  Assumes that the `valid' local variable */
127  /* holds a pointer to the current validator object.                  */
128  /*                                                                   */
129  /* Use preprocessor prescan to pass FT_ERR_PREFIX.                   */
130  /*                                                                   */
131#define FT_INVALID( _prefix, _error )  FT_INVALID_( _prefix, _error )
132#define FT_INVALID_( _prefix, _error ) \
133          ft_validator_error( valid, _prefix ## _error )
134
135  /* called when a broken table is detected */
136#define FT_INVALID_TOO_SHORT \
137          FT_INVALID( FT_ERR_PREFIX, Invalid_Table )
138
139  /* called when an invalid offset is detected */
140#define FT_INVALID_OFFSET \
141          FT_INVALID( FT_ERR_PREFIX, Invalid_Offset )
142
143  /* called when an invalid format/value is detected */
144#define FT_INVALID_FORMAT \
145          FT_INVALID( FT_ERR_PREFIX, Invalid_Table )
146
147  /* called when an invalid glyph index is detected */
148#define FT_INVALID_GLYPH_ID \
149          FT_INVALID( FT_ERR_PREFIX, Invalid_Glyph_Index )
150
151  /* called when an invalid field value is detected */
152#define FT_INVALID_DATA \
153          FT_INVALID( FT_ERR_PREFIX, Invalid_Table )
154
155
156FT_END_HEADER
157
158#endif /* __FTVALID_H__ */
159
160
161/* END */
162