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/* Cast to struct T, reference to reference */
45template<typename Type, typename TObject>
46static inline const Type& CastR(const TObject &X)
47{ return reinterpret_cast<const Type&> (X); }
48template<typename Type, typename TObject>
49static inline Type& CastR(TObject &X)
50{ return reinterpret_cast<Type&> (X); }
51
52/* Cast to struct T, pointer to pointer */
53template<typename Type, typename TObject>
54static inline const Type* CastP(const TObject *X)
55{ return reinterpret_cast<const Type*> (X); }
56template<typename Type, typename TObject>
57static inline Type* CastP(TObject *X)
58{ return reinterpret_cast<Type*> (X); }
59
60/* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory
61 * location pointed to by P plus Ofs bytes. */
62template<typename Type>
63static inline const Type& StructAtOffset(const void *P, unsigned int offset)
64{ return * reinterpret_cast<const Type*> ((const char *) P + offset); }
65template<typename Type>
66static inline Type& StructAtOffset(void *P, unsigned int offset)
67{ return * reinterpret_cast<Type*> ((char *) P + offset); }
68template<typename Type>
69static inline const Type& StructAtOffsetUnaligned(const void *P, unsigned int offset)
70{
71#pragma GCC diagnostic push
72#pragma GCC diagnostic ignored "-Wcast-align"
73 return * reinterpret_cast<Type*> ((char *) P + offset);
74#pragma GCC diagnostic pop
75}
76template<typename Type>
77static inline Type& StructAtOffsetUnaligned(void *P, unsigned int offset)
78{
79#pragma GCC diagnostic push
80#pragma GCC diagnostic ignored "-Wcast-align"
81 return * reinterpret_cast<Type*> ((char *) P + offset);
82#pragma GCC diagnostic pop
83}
84
85/* StructAfter<T>(X) returns the struct T& that is placed after X.
86 * Works with X of variable size also. X must implement get_size() */
87template<typename Type, typename TObject>
88static inline const Type& StructAfter(const TObject &X)
89{ return StructAtOffset<Type>(&X, X.get_size()); }
90template<typename Type, typename TObject>
91static inline Type& StructAfter(TObject &X)
92{ return StructAtOffset<Type>(&X, X.get_size()); }
93
94
95/*
96 * Size checking
97 */
98
99/* Check _assertion in a method environment */
100#define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \
101 void _instance_assertion_on_line_##_line () const \
102 { static_assert ((_assertion), ""); }
103# define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion)
104# define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion)
105
106/* Check that _code compiles in a method environment */
107#define _DEFINE_COMPILES_ASSERTION1(_line, _code) \
108 void _compiles_assertion_on_line_##_line () const \
109 { _code; }
110# define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code)
111# define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code)
112
113
114#define DEFINE_SIZE_STATIC(size) \
115 DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \
116 unsigned int get_size () const { return (size); } \
117 static constexpr unsigned null_size = (size); \
118 static constexpr unsigned min_size = (size); \
119 static constexpr unsigned static_size = (size)
120
121#define DEFINE_SIZE_UNION(size, _member) \
122 DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \
123 DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \
124 static constexpr unsigned null_size = (size); \
125 static constexpr unsigned min_size = (size)
126
127#define DEFINE_SIZE_MIN(size) \
128 DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
129 static constexpr unsigned null_size = (size); \
130 static constexpr unsigned min_size = (size)
131
132#define DEFINE_SIZE_UNBOUNDED(size) \
133 DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \
134 static constexpr unsigned min_size = (size)
135
136#define DEFINE_SIZE_ARRAY(size, array) \
137 DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \
138 DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + HB_VAR_ARRAY * sizeof ((array)[0])) \
139 static constexpr unsigned null_size = (size); \
140 static constexpr unsigned min_size = (size)
141
142#define DEFINE_SIZE_ARRAY_SIZED(size, array) \
143 unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \
144 DEFINE_SIZE_ARRAY(size, array)
145
146
147
148/*
149 * Lazy loaders.
150 */
151
152template <typename Data, unsigned int WheresData>
153struct hb_data_wrapper_t
154{
155 static_assert (WheresData > 0, "");
156
157 Data * get_data () const
158 { return *(((Data **) (void *) this) - WheresData); }
159
160 bool is_inert () const { return !get_data (); }
161
162 template <typename Stored, typename Subclass>
163 Stored * call_create () const { return Subclass::create (get_data ()); }
164};
165template <>
166struct hb_data_wrapper_t<void, 0>
167{
168 bool is_inert () const { return false; }
169
170 template <typename Stored, typename Funcs>
171 Stored * call_create () const { return Funcs::create (); }
172};
173
174template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; };
175template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; };
176
177template <typename Returned,
178 typename Subclass = void,
179 typename Data = void,
180 unsigned int WheresData = 0,
181 typename Stored = Returned>
182struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData>
183{
184 typedef typename hb_non_void_t<Subclass,
185 hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored>
186 >::value Funcs;
187
188 void init0 () {} /* Init, when memory is already set to 0. No-op for us. */
189 void init () { instance.set_relaxed (nullptr); }
190 void fini () { do_destroy (instance.get ()); }
191
192 void free_instance ()
193 {
194 retry:
195 Stored *p = instance.get ();
196 if (unlikely (p && !cmpexch (p, nullptr)))
197 goto retry;
198 do_destroy (p);
199 }
200
201 static void do_destroy (Stored *p)
202 {
203 if (p && p != const_cast<Stored *> (Funcs::get_null ()))
204 Funcs::destroy (p);
205 }
206
207 const Returned * operator -> () const { return get (); }
208 const Returned & operator * () const { return *get (); }
209 explicit operator bool () const
210 { return get_stored () != Funcs::get_null (); }
211 template <typename C> operator const C * () const { return get (); }
212
213 Stored * get_stored () const
214 {
215 retry:
216 Stored *p = this->instance.get ();
217 if (unlikely (!p))
218 {
219 if (unlikely (this->is_inert ()))
220 return const_cast<Stored *> (Funcs::get_null ());
221
222 p = this->template call_create<Stored, Funcs> ();
223 if (unlikely (!p))
224 p = const_cast<Stored *> (Funcs::get_null ());
225
226 if (unlikely (!cmpexch (nullptr, p)))
227 {
228 do_destroy (p);
229 goto retry;
230 }
231 }
232 return p;
233 }
234 Stored * get_stored_relaxed () const
235 {
236 return this->instance.get_relaxed ();
237 }
238
239 bool cmpexch (Stored *current, Stored *value) const
240 {
241 /* This *must* be called when there are no other threads accessing. */
242 return this->instance.cmpexch (current, value);
243 }
244
245 const Returned * get () const { return Funcs::convert (get_stored ()); }
246 const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); }
247 Returned * get_unconst () const { return const_cast<Returned *> (Funcs::convert (get_stored ())); }
248
249 /* To be possibly overloaded by subclasses. */
250 static Returned* convert (Stored *p) { return p; }
251
252 /* By default null/init/fini the object. */
253 static const Stored* get_null () { return &Null(Stored); }
254 static Stored *create (Data *data)
255 {
256 Stored *p = (Stored *) calloc (1, sizeof (Stored));
257 if (likely (p))
258 p->init (data);
259 return p;
260 }
261 static Stored *create ()
262 {
263 Stored *p = (Stored *) calloc (1, sizeof (Stored));
264 if (likely (p))
265 p->init ();
266 return p;
267 }
268 static void destroy (Stored *p)
269 {
270 p->fini ();
271 free (p);
272 }
273
274// private:
275 /* Must only have one pointer. */
276 hb_atomic_ptr_t<Stored *> instance;
277};
278
279/* Specializations. */
280
281template <typename T, unsigned int WheresFace>
282struct hb_face_lazy_loader_t : hb_lazy_loader_t<T,
283 hb_face_lazy_loader_t<T, WheresFace>,
284 hb_face_t, WheresFace> {};
285
286template <typename T, unsigned int WheresFace>
287struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
288 hb_table_lazy_loader_t<T, WheresFace>,
289 hb_face_t, WheresFace,
290 hb_blob_t>
291{
292 static hb_blob_t *create (hb_face_t *face)
293 { return hb_sanitize_context_t ().reference_table<T> (face); }
294 static void destroy (hb_blob_t *p) { hb_blob_destroy (p); }
295
296 static const hb_blob_t *get_null ()
297 { return hb_blob_get_empty (); }
298
299 static const T* convert (const hb_blob_t *blob)
300 { return blob->as<T> (); }
301
302 hb_blob_t* get_blob () const { return this->get_stored (); }
303};
304
305template <typename Subclass>
306struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<hb_font_funcs_t, Subclass>
307{
308 static void destroy (hb_font_funcs_t *p)
309 { hb_font_funcs_destroy (p); }
310 static const hb_font_funcs_t *get_null ()
311 { return hb_font_funcs_get_empty (); }
312};
313template <typename Subclass>
314struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<hb_unicode_funcs_t, Subclass>
315{
316 static void destroy (hb_unicode_funcs_t *p)
317 { hb_unicode_funcs_destroy (p); }
318 static const hb_unicode_funcs_t *get_null ()
319 { return hb_unicode_funcs_get_empty (); }
320};
321
322
323#endif /* HB_MACHINERY_HH */
324