1 /**************************************************************************** 2 * 3 * ftvalid.h 4 * 5 * FreeType validation support (specification). 6 * 7 * Copyright (C) 2004-2020 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 be 58 * used with FreeType in default mode (the library will simply return an 59 * 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 level 67 * 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