• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /****************************************************************************
2  *
3  * ftvalid.h
4  *
5  *   FreeType validation support (specification).
6  *
7  * Copyright 2004-2018 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 
26 FT_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     ft_jmp_buf          jump_buffer; /* used for exception handling      */
91 
92     const FT_Byte*      base;        /* address of table in memory       */
93     const FT_Byte*      limit;       /* `base' + sizeof(table) in memory */
94     FT_ValidationLevel  level;       /* validation level                 */
95     FT_Error            error;       /* error returned. 0 means success  */
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 #define FT_INVALID( _error )  FT_INVALID_( _error )
130 #define FT_INVALID_( _error ) \
131           ft_validator_error( valid, FT_THROW( _error ) )
132 
133   /* called when a broken table is detected */
134 #define FT_INVALID_TOO_SHORT \
135           FT_INVALID( Invalid_Table )
136 
137   /* called when an invalid offset is detected */
138 #define FT_INVALID_OFFSET \
139           FT_INVALID( Invalid_Offset )
140 
141   /* called when an invalid format/value is detected */
142 #define FT_INVALID_FORMAT \
143           FT_INVALID( Invalid_Table )
144 
145   /* called when an invalid glyph index is detected */
146 #define FT_INVALID_GLYPH_ID \
147           FT_INVALID( Invalid_Glyph_Index )
148 
149   /* called when an invalid field value is detected */
150 #define FT_INVALID_DATA \
151           FT_INVALID( Invalid_Table )
152 
153 
154 FT_END_HEADER
155 
156 #endif /* FTVALID_H_ */
157 
158 
159 /* END */
160