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 */