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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 
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   /* 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 
145 FT_END_HEADER
146 
147 #endif /* __FTVALID_H__ */
148 
149 
150 /* END */
151