1 /*
2 * Copyright © 2007,2008,2009,2010 Red Hat, Inc.
3 * Copyright © 2012,2018 Google, Inc.
4 *
5 * This is part of HarfBuzz, a text shaping library.
6 *
7 * Permission is hereby granted, without written agreement and without
8 * license or royalty fees, to use, copy, modify, and distribute this
9 * software and its documentation for any purpose, provided that the
10 * above copyright notice and the following two paragraphs appear in
11 * all copies of this software.
12 *
13 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
14 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
15 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
16 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
17 * DAMAGE.
18 *
19 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
20 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
22 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
23 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
24 *
25 * Red Hat Author(s): Behdad Esfahbod
26 * Google Author(s): Behdad Esfahbod
27 */
28
29 #ifndef HB_MACHINERY_HH
30 #define HB_MACHINERY_HH
31
32 #include "hb.hh"
33 #include "hb-blob.hh"
34
35 #include "hb-dispatch.hh"
36 #include "hb-sanitize.hh"
37 #include "hb-serialize.hh"
38
39
40 /*
41 * Casts
42 */
43
44 /* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory
45 * location pointed to by P plus Ofs bytes. */
46 template<typename Type>
StructAtOffset(const void * P,unsigned int offset)47 static inline const Type& StructAtOffset(const void *P, unsigned int offset)
48 { return * reinterpret_cast<const Type*> ((const char *) P + offset); }
49 template<typename Type>
StructAtOffset(void * P,unsigned int offset)50 static inline Type& StructAtOffset(void *P, unsigned int offset)
51 { return * reinterpret_cast<Type*> ((char *) P + offset); }
52 template<typename Type>
StructAtOffsetUnaligned(const void * P,unsigned int offset)53 static inline const Type& StructAtOffsetUnaligned(const void *P, unsigned int offset)
54 {
55 #pragma GCC diagnostic push
56 #pragma GCC diagnostic ignored "-Wcast-align"
57 return * reinterpret_cast<const Type*> ((const char *) P + offset);
58 #pragma GCC diagnostic pop
59 }
60 template<typename Type>
StructAtOffsetUnaligned(void * P,unsigned int offset)61 static inline Type& StructAtOffsetUnaligned(void *P, unsigned int offset)
62 {
63 #pragma GCC diagnostic push
64 #pragma GCC diagnostic ignored "-Wcast-align"
65 return * reinterpret_cast<Type*> ((char *) P + offset);
66 #pragma GCC diagnostic pop
67 }
68
69 /* StructAfter<T>(X) returns the struct T& that is placed after X.
70 * Works with X of variable size also. X must implement get_size() */
71 template<typename Type, typename TObject>
StructAfter(const TObject & X)72 static inline const Type& StructAfter(const TObject &X)
73 { return StructAtOffset<Type>(&X, X.get_size()); }
74 template<typename Type, typename TObject>
StructAfter(TObject & X)75 static inline Type& StructAfter(TObject &X)
76 { return StructAtOffset<Type>(&X, X.get_size()); }
77
78
79 /*
80 * Size checking
81 */
82
83 /* Size signifying variable-sized array */
84 #ifndef HB_VAR_ARRAY
85 #define HB_VAR_ARRAY 1
86 #endif
87
88 /* Check _assertion in a method environment */
89 #define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \
90 void _instance_assertion_on_line_##_line () const \
91 { static_assert ((_assertion), ""); }
92 # define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion)
93 # define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion)
94
95 /* Check that _code compiles in a method environment */
96 #define _DEFINE_COMPILES_ASSERTION1(_line, _code) \
97 void _compiles_assertion_on_line_##_line () const \
98 { _code; }
99 # define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code)
100 # define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code)
101
102
103 #define DEFINE_SIZE_STATIC(size) \
104 DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \
105 unsigned int get_size () const { return (size); } \
106 static constexpr unsigned null_size = (size); \
107 static constexpr unsigned min_size = (size); \
108 static constexpr unsigned static_size = (size)
109
110 #define DEFINE_SIZE_UNION(size, _member) \
111 DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \
112 DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \
113 static constexpr unsigned null_size = (size); \
114 static constexpr unsigned min_size = (size)
115
116 #define DEFINE_SIZE_MIN(size) \
117 DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
118 static constexpr unsigned null_size = (size); \
119 static constexpr unsigned min_size = (size)
120
121 #define DEFINE_SIZE_UNBOUNDED(size) \
122 DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
123 static constexpr unsigned min_size = (size)
124
125 #define DEFINE_SIZE_ARRAY(size, array) \
126 DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \
127 DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + (HB_VAR_ARRAY+0) * sizeof ((array)[0])) \
128 static constexpr unsigned null_size = (size); \
129 static constexpr unsigned min_size = (size)
130
131 #define DEFINE_SIZE_ARRAY_SIZED(size, array) \
132 unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \
133 DEFINE_SIZE_ARRAY(size, array)
134
135
136
137 /*
138 * Lazy loaders.
139 */
140
141 template <typename Data, unsigned int WheresData>
142 struct hb_data_wrapper_t
143 {
144 static_assert (WheresData > 0, "");
145
get_datahb_data_wrapper_t146 Data * get_data () const
147 { return *(((Data **) (void *) this) - WheresData); }
148
is_inerthb_data_wrapper_t149 bool is_inert () const { return !get_data (); }
150
151 template <typename Stored, typename Subclass>
152 Stored * call_create () const { return Subclass::create (get_data ()); }
153 };
154 template <>
155 struct hb_data_wrapper_t<void, 0>
156 {
is_inerthb_data_wrapper_t157 bool is_inert () const { return false; }
158
159 template <typename Stored, typename Funcs>
160 Stored * call_create () const { return Funcs::create (); }
161 };
162
163 template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; };
164 template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; };
165
166 template <typename Returned,
167 typename Subclass = void,
168 typename Data = void,
169 unsigned int WheresData = 0,
170 typename Stored = Returned>
171 struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData>
172 {
173 typedef typename hb_non_void_t<Subclass,
174 hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored>
175 >::value Funcs;
176
init0hb_lazy_loader_t177 void init0 () {} /* Init, when memory is already set to 0. No-op for us. */
inithb_lazy_loader_t178 void init () { instance.set_relaxed (nullptr); }
finihb_lazy_loader_t179 void fini () { do_destroy (instance.get ()); }
180
free_instancehb_lazy_loader_t181 void free_instance ()
182 {
183 retry:
184 Stored *p = instance.get ();
185 if (unlikely (p && !cmpexch (p, nullptr)))
186 goto retry;
187 do_destroy (p);
188 }
189
do_destroyhb_lazy_loader_t190 static void do_destroy (Stored *p)
191 {
192 if (p && p != const_cast<Stored *> (Funcs::get_null ()))
193 Funcs::destroy (p);
194 }
195
operator ->hb_lazy_loader_t196 const Returned * operator -> () const { return get (); }
operator *hb_lazy_loader_t197 const Returned & operator * () const { return *get (); }
operator boolhb_lazy_loader_t198 explicit operator bool () const
199 { return get_stored () != Funcs::get_null (); }
operator const C*hb_lazy_loader_t200 template <typename C> operator const C * () const { return get (); }
201
get_storedhb_lazy_loader_t202 Stored * get_stored () const
203 {
204 retry:
205 Stored *p = this->instance.get ();
206 if (unlikely (!p))
207 {
208 if (unlikely (this->is_inert ()))
209 return const_cast<Stored *> (Funcs::get_null ());
210
211 p = this->template call_create<Stored, Funcs> ();
212 if (unlikely (!p))
213 p = const_cast<Stored *> (Funcs::get_null ());
214
215 if (unlikely (!cmpexch (nullptr, p)))
216 {
217 do_destroy (p);
218 goto retry;
219 }
220 }
221 return p;
222 }
get_stored_relaxedhb_lazy_loader_t223 Stored * get_stored_relaxed () const
224 {
225 return this->instance.get_relaxed ();
226 }
227
cmpexchhb_lazy_loader_t228 bool cmpexch (Stored *current, Stored *value) const
229 {
230 /* This *must* be called when there are no other threads accessing. */
231 return this->instance.cmpexch (current, value);
232 }
233
gethb_lazy_loader_t234 const Returned * get () const { return Funcs::convert (get_stored ()); }
get_relaxedhb_lazy_loader_t235 const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); }
get_unconsthb_lazy_loader_t236 Returned * get_unconst () const { return const_cast<Returned *> (Funcs::convert (get_stored ())); }
237
238 /* To be possibly overloaded by subclasses. */
converthb_lazy_loader_t239 static Returned* convert (Stored *p) { return p; }
240
241 /* By default null/init/fini the object. */
get_nullhb_lazy_loader_t242 static const Stored* get_null () { return &Null (Stored); }
createhb_lazy_loader_t243 static Stored *create (Data *data)
244 {
245 Stored *p = (Stored *) calloc (1, sizeof (Stored));
246 if (likely (p))
247 p->init (data);
248 return p;
249 }
createhb_lazy_loader_t250 static Stored *create ()
251 {
252 Stored *p = (Stored *) calloc (1, sizeof (Stored));
253 if (likely (p))
254 p->init ();
255 return p;
256 }
destroyhb_lazy_loader_t257 static void destroy (Stored *p)
258 {
259 p->fini ();
260 free (p);
261 }
262
263 // private:
264 /* Must only have one pointer. */
265 hb_atomic_ptr_t<Stored *> instance;
266 };
267
268 /* Specializations. */
269
270 template <typename T, unsigned int WheresFace>
271 struct hb_face_lazy_loader_t : hb_lazy_loader_t<T,
272 hb_face_lazy_loader_t<T, WheresFace>,
273 hb_face_t, WheresFace> {};
274
275 template <typename T, unsigned int WheresFace>
276 struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
277 hb_table_lazy_loader_t<T, WheresFace>,
278 hb_face_t, WheresFace,
279 hb_blob_t>
280 {
createhb_table_lazy_loader_t281 static hb_blob_t *create (hb_face_t *face)
282 { return hb_sanitize_context_t ().reference_table<T> (face); }
destroyhb_table_lazy_loader_t283 static void destroy (hb_blob_t *p) { hb_blob_destroy (p); }
284
get_nullhb_table_lazy_loader_t285 static const hb_blob_t *get_null ()
286 { return hb_blob_get_empty (); }
287
converthb_table_lazy_loader_t288 static const T* convert (const hb_blob_t *blob)
289 { return blob->as<T> (); }
290
get_blobhb_table_lazy_loader_t291 hb_blob_t* get_blob () const { return this->get_stored (); }
292 };
293
294 template <typename Subclass>
295 struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<hb_font_funcs_t, Subclass>
296 {
destroyhb_font_funcs_lazy_loader_t297 static void destroy (hb_font_funcs_t *p)
298 { hb_font_funcs_destroy (p); }
get_nullhb_font_funcs_lazy_loader_t299 static const hb_font_funcs_t *get_null ()
300 { return hb_font_funcs_get_empty (); }
301 };
302 template <typename Subclass>
303 struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<hb_unicode_funcs_t, Subclass>
304 {
destroyhb_unicode_funcs_lazy_loader_t305 static void destroy (hb_unicode_funcs_t *p)
306 { hb_unicode_funcs_destroy (p); }
get_nullhb_unicode_funcs_lazy_loader_t307 static const hb_unicode_funcs_t *get_null ()
308 { return hb_unicode_funcs_get_empty (); }
309 };
310
311
312 #endif /* HB_MACHINERY_HH */
313