1 /*
2 * Copyright © 2008 Kristian Høgsberg
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the
13 * next paragraph) shall be included in all copies or substantial
14 * portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
20 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
21 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 */
25
26 /** \file wayland-util.h
27 *
28 * \brief Utility classes, functions, and macros.
29 */
30
31 #ifndef WAYLAND_UTIL_H
32 #define WAYLAND_UTIL_H
33
34 #include <math.h>
35 #include <stddef.h>
36 #include <inttypes.h>
37 #include <stdarg.h>
38
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
42
43 /** Visibility attribute */
44 #if defined(__GNUC__) && __GNUC__ >= 4
45 #define WL_EXPORT __attribute__ ((visibility("default")))
46 #else
47 #define WL_EXPORT
48 #endif
49
50 /** Deprecated attribute */
51 #if defined(__GNUC__) && __GNUC__ >= 4
52 #define WL_DEPRECATED __attribute__ ((deprecated))
53 #else
54 #define WL_DEPRECATED
55 #endif
56
57 /**
58 * Printf-style argument attribute
59 *
60 * \param x Ordinality of the format string argument
61 * \param y Ordinality of the argument to check against the format string
62 *
63 * \sa https://gcc.gnu.org/onlinedocs/gcc-3.2.1/gcc/Function-Attributes.html
64 */
65 #if defined(__GNUC__) && __GNUC__ >= 4
66 #define WL_PRINTF(x, y) __attribute__((__format__(__printf__, x, y)))
67 #else
68 #define WL_PRINTF(x, y)
69 #endif
70
71 /**
72 * Protocol message signature
73 *
74 * A wl_message describes the signature of an actual protocol message, such as a
75 * request or event, that adheres to the Wayland protocol wire format. The
76 * protocol implementation uses a wl_message within its demarshal machinery for
77 * decoding messages between a compositor and its clients. In a sense, a
78 * wl_message is to a protocol message like a class is to an object.
79 *
80 * The `name` of a wl_message is the name of the corresponding protocol message.
81 * The `signature` is an ordered list of symbols representing the data types
82 * of message arguments and, optionally, a protocol version and indicators for
83 * nullability. A leading integer in the `signature` indicates the _since_
84 * version of the protocol message. A `?` preceding a data type symbol indicates
85 * that the following argument type is nullable. When no arguments accompany a
86 * message, `signature` is an empty string.
87 *
88 * * `i`: int
89 * * `u`: uint
90 * * `f`: fixed
91 * * `s`: string
92 * * `o`: object
93 * * `n`: new_id
94 * * `a`: array
95 * * `h`: fd
96 * * `?`: following argument is nullable
97 *
98 * While demarshaling primitive arguments is straightforward, when demarshaling
99 * messages containing `object` or `new_id` arguments, the protocol
100 * implementation often must determine the type of the object. The `types` of a
101 * wl_message is an array of wl_interface references that correspond to `o` and
102 * `n` arguments in `signature`, with `NULL` placeholders for arguments with
103 * non-object types.
104 *
105 * Consider the protocol event wl_display `delete_id` that has a single `uint`
106 * argument. The wl_message is:
107 *
108 * \code
109 * { "delete_id", "u", [NULL] }
110 * \endcode
111 *
112 * Here, the message `name` is `"delete_id"`, the `signature` is `"u"`, and the
113 * argument `types` is `[NULL]`, indicating that the `uint` argument has no
114 * corresponding wl_interface since it is a primitive argument.
115 *
116 * In contrast, consider a `wl_foo` interface supporting protocol request `bar`
117 * that has existed since version 2, and has two arguments: a `uint` and an
118 * object of type `wl_baz_interface` that may be `NULL`. Such a `wl_message`
119 * might be:
120 *
121 * \code
122 * { "bar", "2u?o", [NULL, &wl_baz_interface] }
123 * \endcode
124 *
125 * Here, the message `name` is `"bar"`, and the `signature` is `"2u?o"`. Notice
126 * how the `2` indicates the protocol version, the `u` indicates the first
127 * argument type is `uint`, and the `?o` indicates that the second argument
128 * is an object that may be `NULL`. Lastly, the argument `types` array indicates
129 * that no wl_interface corresponds to the first argument, while the type
130 * `wl_baz_interface` corresponds to the second argument.
131 *
132 * \sa wl_argument
133 * \sa wl_interface
134 * \sa <a href="https://wayland.freedesktop.org/docs/html/ch04.html#sect-Protocol-Wire-Format">Wire Format</a>
135 */
136 struct wl_message {
137 /** Message name */
138 const char *name;
139 /** Message signature */
140 const char *signature;
141 /** Object argument interfaces */
142 const struct wl_interface **types;
143 };
144
145 struct wl_interface {
146 const char *name;
147 int version;
148 int method_count;
149 const struct wl_message *methods;
150 int event_count;
151 const struct wl_message *events;
152 };
153
154 /** \class wl_list
155 *
156 * \brief Doubly-linked list
157 *
158 * On its own, an instance of `struct wl_list` represents the sentinel head of
159 * a doubly-linked list, and must be initialized using wl_list_init().
160 * When empty, the list head's `next` and `prev` members point to the list head
161 * itself, otherwise `next` references the first element in the list, and `prev`
162 * refers to the last element in the list.
163 *
164 * Use the `struct wl_list` type to represent both the list head and the links
165 * between elements within the list. Use wl_list_empty() to determine if the
166 * list is empty in O(1).
167 *
168 * All elements in the list must be of the same type. The element type must have
169 * a `struct wl_list` member, often named `link` by convention. Prior to
170 * insertion, there is no need to initialize an element's `link` - invoking
171 * wl_list_init() on an individual list element's `struct wl_list` member is
172 * unnecessary if the very next operation is wl_list_insert(). However, a
173 * common idiom is to initialize an element's `link` prior to removal - ensure
174 * safety by invoking wl_list_init() before wl_list_remove().
175 *
176 * Consider a list reference `struct wl_list foo_list`, an element type as
177 * `struct element`, and an element's link member as `struct wl_list link`.
178 *
179 * The following code initializes a list and adds three elements to it.
180 *
181 * \code
182 * struct wl_list foo_list;
183 *
184 * struct element {
185 * int foo;
186 * struct wl_list link;
187 * };
188 * struct element e1, e2, e3;
189 *
190 * wl_list_init(&foo_list);
191 * wl_list_insert(&foo_list, &e1.link); // e1 is the first element
192 * wl_list_insert(&foo_list, &e2.link); // e2 is now the first element
193 * wl_list_insert(&e2.link, &e3.link); // insert e3 after e2
194 * \endcode
195 *
196 * The list now looks like <em>[e2, e3, e1]</em>.
197 *
198 * The `wl_list` API provides some iterator macros. For example, to iterate
199 * a list in ascending order:
200 *
201 * \code
202 * struct element *e;
203 * wl_list_for_each(e, foo_list, link) {
204 * do_something_with_element(e);
205 * }
206 * \endcode
207 *
208 * See the documentation of each iterator for details.
209 * \sa http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/linux/list.h
210 */
211 struct wl_list {
212 struct wl_list *prev;
213 struct wl_list *next;
214 };
215
216 /**
217 * Initializes the list.
218 *
219 * \param list List to initialize
220 *
221 * \memberof wl_list
222 */
223 void
224 wl_list_init(struct wl_list *list);
225
226 /**
227 * Inserts an element into the list, after the element represented by \p list.
228 * When \p list is a reference to the list itself (the head), set the containing
229 * struct of \p elm as the first element in the list.
230 *
231 * \note If \p elm is already part of a list, inserting it again will lead to
232 * list corruption.
233 *
234 * \param list List element after which the new element is inserted
235 * \param elm Link of the containing struct to insert into the list
236 *
237 * \memberof wl_list
238 */
239 void
240 wl_list_insert(struct wl_list *list, struct wl_list *elm);
241
242 /**
243 * Removes an element from the list.
244 *
245 * \note This operation leaves \p elm in an invalid state.
246 *
247 * \param elm Link of the containing struct to remove from the list
248 *
249 * \memberof wl_list
250 */
251 void
252 wl_list_remove(struct wl_list *elm);
253
254 /**
255 * Determines the length of the list.
256 *
257 * \note This is an O(n) operation.
258 *
259 * \param list List whose length is to be determined
260 *
261 * \return Number of elements in the list
262 *
263 * \memberof wl_list
264 */
265 int
266 wl_list_length(const struct wl_list *list);
267
268 /**
269 * Determines if the list is empty.
270 *
271 * \param list List whose emptiness is to be determined
272 *
273 * \return 1 if empty, or 0 if not empty
274 *
275 * \memberof wl_list
276 */
277 int
278 wl_list_empty(const struct wl_list *list);
279
280 /**
281 * Inserts all of the elements of one list into another, after the element
282 * represented by \p list.
283 *
284 * \note This leaves \p other in an invalid state.
285 *
286 * \param list List element after which the other list elements will be inserted
287 * \param other List of elements to insert
288 *
289 * \memberof wl_list
290 */
291 void
292 wl_list_insert_list(struct wl_list *list, struct wl_list *other);
293
294 /**
295 * Retrieves a pointer to a containing struct, given a member name.
296 *
297 * This macro allows "conversion" from a pointer to a member to its containing
298 * struct. This is useful if you have a contained item like a wl_list,
299 * wl_listener, or wl_signal, provided via a callback or other means, and would
300 * like to retrieve the struct that contains it.
301 *
302 * To demonstrate, the following example retrieves a pointer to
303 * `example_container` given only its `destroy_listener` member:
304 *
305 * \code
306 * struct example_container {
307 * struct wl_listener destroy_listener;
308 * // other members...
309 * };
310 *
311 * void example_container_destroy(struct wl_listener *listener, void *data)
312 * {
313 * struct example_container *ctr;
314 *
315 * ctr = wl_container_of(listener, ctr, destroy_listener);
316 * // destroy ctr...
317 * }
318 * \endcode
319 *
320 * \note `sample` need not be a valid pointer. A null or uninitialised pointer
321 * is sufficient.
322 *
323 * \param ptr Valid pointer to the contained member
324 * \param sample Pointer to a struct whose type contains \p ptr
325 * \param member Named location of \p ptr within the \p sample type
326 *
327 * \return The container for the specified pointer
328 */
329 #define wl_container_of(ptr, sample, member) \
330 (__typeof__(sample))((char *)(ptr) - \
331 offsetof(__typeof__(*sample), member))
332
333 /**
334 * Iterates over a list.
335 *
336 * This macro expresses a for-each iterator for wl_list. Given a list and
337 * wl_list link member name (often named `link` by convention), this macro
338 * assigns each element in the list to \p pos, which can then be referenced in
339 * a trailing code block. For example, given a wl_list of `struct message`
340 * elements:
341 *
342 * \code
343 * struct message {
344 * char *contents;
345 * wl_list link;
346 * };
347 *
348 * struct wl_list *message_list;
349 * // Assume message_list now "contains" many messages
350 *
351 * struct message *m;
352 * wl_list_for_each(m, message_list, link) {
353 * do_something_with_message(m);
354 * }
355 * \endcode
356 *
357 * \param pos Cursor that each list element will be assigned to
358 * \param head Head of the list to iterate over
359 * \param member Name of the link member within the element struct
360 *
361 * \relates wl_list
362 */
363 #define wl_list_for_each(pos, head, member) \
364 for (pos = wl_container_of((head)->next, pos, member); \
365 &pos->member != (head); \
366 pos = wl_container_of(pos->member.next, pos, member))
367
368 /**
369 * Iterates over a list, safe against removal of the list element.
370 *
371 * \note Only removal of the current element, \p pos, is safe. Removing
372 * any other element during traversal may lead to a loop malfunction.
373 *
374 * \sa wl_list_for_each()
375 *
376 * \param pos Cursor that each list element will be assigned to
377 * \param tmp Temporary pointer of the same type as \p pos
378 * \param head Head of the list to iterate over
379 * \param member Name of the link member within the element struct
380 *
381 * \relates wl_list
382 */
383 #define wl_list_for_each_safe(pos, tmp, head, member) \
384 for (pos = wl_container_of((head)->next, pos, member), \
385 tmp = wl_container_of((pos)->member.next, tmp, member); \
386 &pos->member != (head); \
387 pos = tmp, \
388 tmp = wl_container_of(pos->member.next, tmp, member))
389
390 /**
391 * Iterates backwards over a list.
392 *
393 * \sa wl_list_for_each()
394 *
395 * \param pos Cursor that each list element will be assigned to
396 * \param head Head of the list to iterate over
397 * \param member Name of the link member within the element struct
398 *
399 * \relates wl_list
400 */
401 #define wl_list_for_each_reverse(pos, head, member) \
402 for (pos = wl_container_of((head)->prev, pos, member); \
403 &pos->member != (head); \
404 pos = wl_container_of(pos->member.prev, pos, member))
405
406 /**
407 * Iterates backwards over a list, safe against removal of the list element.
408 *
409 * \note Only removal of the current element, \p pos, is safe. Removing
410 * any other element during traversal may lead to a loop malfunction.
411 *
412 * \sa wl_list_for_each()
413 *
414 * \param pos Cursor that each list element will be assigned to
415 * \param tmp Temporary pointer of the same type as \p pos
416 * \param head Head of the list to iterate over
417 * \param member Name of the link member within the element struct
418 *
419 * \relates wl_list
420 */
421 #define wl_list_for_each_reverse_safe(pos, tmp, head, member) \
422 for (pos = wl_container_of((head)->prev, pos, member), \
423 tmp = wl_container_of((pos)->member.prev, tmp, member); \
424 &pos->member != (head); \
425 pos = tmp, \
426 tmp = wl_container_of(pos->member.prev, tmp, member))
427
428 /**
429 * \class wl_array
430 *
431 * Dynamic array
432 *
433 * A wl_array is a dynamic array that can only grow until released. It is
434 * intended for relatively small allocations whose size is variable or not known
435 * in advance. While construction of a wl_array does not require all elements to
436 * be of the same size, wl_array_for_each() does require all elements to have
437 * the same type and size.
438 *
439 */
440 struct wl_array {
441 size_t size;
442 size_t alloc;
443 void *data;
444 };
445
446 /**
447 * Initializes the array.
448 *
449 * \param array Array to initialize
450 *
451 * \memberof wl_array
452 */
453 void
454 wl_array_init(struct wl_array *array);
455
456 /**
457 * Releases the array data.
458 *
459 * \note Leaves the array in an invalid state.
460 *
461 * \param array Array whose data is to be released
462 *
463 * \memberof wl_array
464 */
465 void
466 wl_array_release(struct wl_array *array);
467
468 /**
469 * Increases the size of the array by \p size bytes.
470 *
471 * \param array Array whose size is to be increased
472 * \param size Number of bytes to increase the size of the array by
473 *
474 * \return A pointer to the beginning of the newly appended space, or NULL when
475 * resizing fails.
476 *
477 * \memberof wl_array
478 */
479 void *
480 wl_array_add(struct wl_array *array, size_t size);
481
482 /**
483 * Copies the contents of \p source to \p array.
484 *
485 * \param array Destination array to copy to
486 * \param source Source array to copy from
487 *
488 * \return 0 on success, or -1 on failure
489 *
490 * \memberof wl_array
491 */
492 int
493 wl_array_copy(struct wl_array *array, struct wl_array *source);
494
495 /**
496 * Iterates over an array.
497 *
498 * This macro expresses a for-each iterator for wl_array. It assigns each
499 * element in the array to \p pos, which can then be referenced in a trailing
500 * code block. \p pos must be a pointer to the array element type, and all
501 * array elements must be of the same type and size.
502 *
503 * \param pos Cursor that each array element will be assigned to
504 * \param array Array to iterate over
505 *
506 * \relates wl_array
507 * \sa wl_list_for_each()
508 */
509 #define wl_array_for_each(pos, array) \
510 for (pos = (array)->data; \
511 (const char *) pos < ((const char *) (array)->data + (array)->size); \
512 (pos)++)
513
514 /**
515 * Fixed-point number
516 *
517 * A `wl_fixed_t` is a 24.8 signed fixed-point number with a sign bit, 23 bits
518 * of integer precision and 8 bits of decimal precision. Consider `wl_fixed_t`
519 * as an opaque struct with methods that facilitate conversion to and from
520 * `double` and `int` types.
521 */
522 typedef int32_t wl_fixed_t;
523
524 /**
525 * Converts a fixed-point number to a floating-point number.
526 *
527 * \param f Fixed-point number to convert
528 *
529 * \return Floating-point representation of the fixed-point argument
530 */
531 static inline double
wl_fixed_to_double(wl_fixed_t f)532 wl_fixed_to_double(wl_fixed_t f)
533 {
534 union {
535 double d;
536 int64_t i;
537 } u;
538
539 u.i = ((1023LL + 44LL) << 52) + (1LL << 51) + f;
540
541 return u.d - (3LL << 43);
542 }
543
544 /**
545 * Converts a floating-point number to a fixed-point number.
546 *
547 * \param d Floating-point number to convert
548 *
549 * \return Fixed-point representation of the floating-point argument
550 */
551 static inline wl_fixed_t
wl_fixed_from_double(double d)552 wl_fixed_from_double(double d)
553 {
554 union {
555 double d;
556 int64_t i;
557 } u;
558
559 u.d = d + (3LL << (51 - 8));
560
561 return u.i;
562 }
563
564 /**
565 * Converts a fixed-point number to an integer.
566 *
567 * \param f Fixed-point number to convert
568 *
569 * \return Integer component of the fixed-point argument
570 */
571 static inline int
wl_fixed_to_int(wl_fixed_t f)572 wl_fixed_to_int(wl_fixed_t f)
573 {
574 return f / 256;
575 }
576
577 /**
578 * Converts an integer to a fixed-point number.
579 *
580 * \param i Integer to convert
581 *
582 * \return Fixed-point representation of the integer argument
583 */
584 static inline wl_fixed_t
wl_fixed_from_int(int i)585 wl_fixed_from_int(int i)
586 {
587 return i * 256;
588 }
589
590 /**
591 * \brief A union representing all of the basic data types that can be passed
592 * along the wayland wire format.
593 *
594 * This union represents all of the basic data types that can be passed in the
595 * wayland wire format. It is used by dispatchers and runtime-friendly
596 * versions of the event and request marshaling functions.
597 */
598 union wl_argument {
599 int32_t i; /**< signed integer */
600 uint32_t u; /**< unsigned integer */
601 wl_fixed_t f; /**< fixed point */
602 const char *s; /**< string */
603 struct wl_object *o; /**< object */
604 uint32_t n; /**< new_id */
605 struct wl_array *a; /**< array */
606 int32_t h; /**< file descriptor */
607 };
608
609 /**
610 * \brief A function pointer type for a dispatcher.
611 *
612 * A dispatcher is a function that handles the emitting of callbacks in client
613 * code. For programs directly using the C library, this is done by using
614 * libffi to call function pointers. When binding to languages other than C,
615 * dispatchers provide a way to abstract the function calling process to be
616 * friendlier to other function calling systems.
617 *
618 * A dispatcher takes five arguments: The first is the dispatcher-specific
619 * implementation data associated with the target object. The second is the
620 * object on which the callback is being invoked (either wl_proxy or
621 * wl_resource). The third and fourth arguments are the opcode the wl_message
622 * structure corresponding to the callback being emitted. The final argument
623 * is an array of arguments received from the other process via the wire
624 * protocol.
625 */
626 typedef int (*wl_dispatcher_func_t)(const void *, void *, uint32_t,
627 const struct wl_message *,
628 union wl_argument *);
629
630 typedef void (*wl_log_func_t)(const char *, va_list) WL_PRINTF(1, 0);
631
632 /** \enum wl_iterator_result
633 *
634 * This enum represents the return value of an iterator function.
635 */
636 enum wl_iterator_result {
637 /** Stop the iteration */
638 WL_ITERATOR_STOP,
639 /** Continue the iteration */
640 WL_ITERATOR_CONTINUE
641 };
642
643 #ifdef __cplusplus
644 }
645 #endif
646
647 #endif
648