fdt_region.c 20 KB

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  1. // SPDX-License-Identifier: GPL-2.0+ OR BSD-2-Clause
  2. /*
  3. * libfdt - Flat Device Tree manipulation
  4. * Copyright (C) 2013 Google, Inc
  5. * Written by Simon Glass <sjg@chromium.org>
  6. */
  7. #include <fdt_support.h>
  8. #include <linux/libfdt_env.h>
  9. #include <fdt_region.h>
  10. #ifndef USE_HOSTCC
  11. #include <fdt.h>
  12. #include <linux/libfdt.h>
  13. #else
  14. #include "fdt_host.h"
  15. #endif
  16. #define FDT_MAX_DEPTH 32
  17. static int str_in_list(const char *str, char * const list[], int count)
  18. {
  19. int i;
  20. for (i = 0; i < count; i++)
  21. if (!strcmp(list[i], str))
  22. return 1;
  23. return 0;
  24. }
  25. int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
  26. char * const exc_prop[], int exc_prop_count,
  27. struct fdt_region region[], int max_regions,
  28. char *path, int path_len, int add_string_tab)
  29. {
  30. int stack[FDT_MAX_DEPTH] = { 0 };
  31. char *end;
  32. int nextoffset = 0;
  33. uint32_t tag;
  34. int count = 0;
  35. int start = -1;
  36. int depth = -1;
  37. int want = 0;
  38. int base = fdt_off_dt_struct(fdt);
  39. bool expect_end = false;
  40. end = path;
  41. *end = '\0';
  42. do {
  43. const struct fdt_property *prop;
  44. const char *name;
  45. const char *str;
  46. int include = 0;
  47. int stop_at = 0;
  48. int offset;
  49. int len;
  50. offset = nextoffset;
  51. tag = fdt_next_tag(fdt, offset, &nextoffset);
  52. stop_at = nextoffset;
  53. /* If we see two root nodes, something is wrong */
  54. if (expect_end && tag != FDT_END)
  55. return -FDT_ERR_BADLAYOUT;
  56. switch (tag) {
  57. case FDT_PROP:
  58. include = want >= 2;
  59. stop_at = offset;
  60. prop = fdt_get_property_by_offset(fdt, offset, NULL);
  61. str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
  62. if (!str)
  63. return -FDT_ERR_BADSTRUCTURE;
  64. if (str_in_list(str, exc_prop, exc_prop_count))
  65. include = 0;
  66. break;
  67. case FDT_NOP:
  68. include = want >= 2;
  69. stop_at = offset;
  70. break;
  71. case FDT_BEGIN_NODE:
  72. depth++;
  73. if (depth == FDT_MAX_DEPTH)
  74. return -FDT_ERR_BADSTRUCTURE;
  75. name = fdt_get_name(fdt, offset, &len);
  76. /* The root node must have an empty name */
  77. if (!depth && *name)
  78. return -FDT_ERR_BADLAYOUT;
  79. if (end - path + 2 + len >= path_len)
  80. return -FDT_ERR_NOSPACE;
  81. if (end != path + 1)
  82. *end++ = '/';
  83. strcpy(end, name);
  84. end += len;
  85. stack[depth] = want;
  86. if (want == 1)
  87. stop_at = offset;
  88. if (str_in_list(path, inc, inc_count))
  89. want = 2;
  90. else if (want)
  91. want--;
  92. else
  93. stop_at = offset;
  94. include = want;
  95. break;
  96. case FDT_END_NODE:
  97. /* Depth must never go below -1 */
  98. if (depth < 0)
  99. return -FDT_ERR_BADSTRUCTURE;
  100. include = want;
  101. want = stack[depth--];
  102. while (end > path && *--end != '/')
  103. ;
  104. *end = '\0';
  105. if (depth == -1)
  106. expect_end = true;
  107. break;
  108. case FDT_END:
  109. include = 1;
  110. break;
  111. }
  112. if (include && start == -1) {
  113. /* Should we merge with previous? */
  114. if (count && count <= max_regions &&
  115. offset == region[count - 1].offset +
  116. region[count - 1].size - base)
  117. start = region[--count].offset - base;
  118. else
  119. start = offset;
  120. }
  121. if (!include && start != -1) {
  122. if (count < max_regions) {
  123. region[count].offset = base + start;
  124. region[count].size = stop_at - start;
  125. }
  126. count++;
  127. start = -1;
  128. }
  129. } while (tag != FDT_END);
  130. if (nextoffset != fdt_size_dt_struct(fdt))
  131. return -FDT_ERR_BADLAYOUT;
  132. /* Add a region for the END tag and the string table */
  133. if (count < max_regions) {
  134. region[count].offset = base + start;
  135. region[count].size = nextoffset - start;
  136. if (add_string_tab)
  137. region[count].size += fdt_size_dt_strings(fdt);
  138. }
  139. count++;
  140. return count;
  141. }
  142. /**
  143. * fdt_add_region() - Add a new region to our list
  144. * @info: State information
  145. * @offset: Start offset of region
  146. * @size: Size of region
  147. *
  148. * The region is added if there is space, but in any case we increment the
  149. * count. If permitted, and the new region overlaps the last one, we merge
  150. * them.
  151. */
  152. static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
  153. {
  154. struct fdt_region *reg;
  155. reg = info->region ? &info->region[info->count - 1] : NULL;
  156. if (info->can_merge && info->count &&
  157. info->count <= info->max_regions &&
  158. reg && offset <= reg->offset + reg->size) {
  159. reg->size = offset + size - reg->offset;
  160. } else if (info->count++ < info->max_regions) {
  161. if (reg) {
  162. reg++;
  163. reg->offset = offset;
  164. reg->size = size;
  165. if (!(offset - fdt_off_dt_struct(info->fdt)))
  166. info->have_node = true;
  167. }
  168. } else {
  169. return -1;
  170. }
  171. return 0;
  172. }
  173. static int region_list_contains_offset(struct fdt_region_state *info,
  174. const void *fdt, int target)
  175. {
  176. struct fdt_region *reg;
  177. int num;
  178. target += fdt_off_dt_struct(fdt);
  179. for (reg = info->region, num = 0; num < info->count; reg++, num++) {
  180. if (target >= reg->offset && target < reg->offset + reg->size)
  181. return 1;
  182. }
  183. return 0;
  184. }
  185. /**
  186. * fdt_add_alias_regions() - Add regions covering the aliases that we want
  187. *
  188. * The /aliases node is not automatically included by fdtgrep unless the
  189. * command-line arguments cause to be included (or not excluded). However
  190. * aliases are special in that we generally want to include those which
  191. * reference a node that fdtgrep includes.
  192. *
  193. * In fact we want to include only aliases for those nodes still included in
  194. * the fdt, and drop the other aliases since they point to nodes that will not
  195. * be present.
  196. *
  197. * This function scans the aliases and adds regions for those which we want
  198. * to keep.
  199. *
  200. * @fdt: Device tree to scan
  201. * @region: List of regions
  202. * @count: Number of regions in the list so far (i.e. starting point for this
  203. * function)
  204. * @max_regions: Maximum number of regions in @region list
  205. * @info: Place to put the region state
  206. * Return: number of regions after processing, or -FDT_ERR_NOSPACE if we did
  207. * not have enough room in the regions table for the regions we wanted to add.
  208. */
  209. int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
  210. int max_regions, struct fdt_region_state *info)
  211. {
  212. int base = fdt_off_dt_struct(fdt);
  213. int node, node_end, offset;
  214. int did_alias_header;
  215. node = fdt_subnode_offset(fdt, 0, "aliases");
  216. if (node < 0)
  217. return -FDT_ERR_NOTFOUND;
  218. /*
  219. * Find the next node so that we know where the /aliases node ends. We
  220. * need special handling if /aliases is the last node.
  221. */
  222. node_end = fdt_next_subnode(fdt, node);
  223. if (node_end == -FDT_ERR_NOTFOUND)
  224. /* Move back to the FDT_END_NODE tag of '/' */
  225. node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
  226. else if (node_end < 0) /* other error */
  227. return node_end;
  228. node_end -= sizeof(fdt32_t); /* Move to FDT_END_NODE tag of /aliases */
  229. did_alias_header = 0;
  230. info->region = region;
  231. info->count = count;
  232. info->can_merge = 0;
  233. info->max_regions = max_regions;
  234. for (offset = fdt_first_property_offset(fdt, node);
  235. offset >= 0;
  236. offset = fdt_next_property_offset(fdt, offset)) {
  237. const struct fdt_property *prop;
  238. const char *name;
  239. int target, next;
  240. prop = fdt_get_property_by_offset(fdt, offset, NULL);
  241. name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
  242. target = fdt_path_offset(fdt, name);
  243. if (!region_list_contains_offset(info, fdt, target))
  244. continue;
  245. next = fdt_next_property_offset(fdt, offset);
  246. if (next < 0)
  247. next = node_end;
  248. if (!did_alias_header) {
  249. fdt_add_region(info, base + node, 12);
  250. did_alias_header = 1;
  251. }
  252. fdt_add_region(info, base + offset, next - offset);
  253. }
  254. /* Add the FDT_END_NODE tag */
  255. if (did_alias_header)
  256. fdt_add_region(info, base + node_end, sizeof(fdt32_t));
  257. return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
  258. }
  259. /**
  260. * fdt_include_supernodes() - Include supernodes required by this node
  261. * @info: State information
  262. * @depth: Current stack depth
  263. *
  264. * When we decided to include a node or property which is not at the top
  265. * level, this function forces the inclusion of higher level nodes. For
  266. * example, given this tree:
  267. *
  268. * / {
  269. * testing {
  270. * }
  271. * }
  272. *
  273. * If we decide to include testing then we need the root node to have a valid
  274. * tree. This function adds those regions.
  275. */
  276. static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
  277. {
  278. int base = fdt_off_dt_struct(info->fdt);
  279. int start, stop_at;
  280. int i;
  281. /*
  282. * Work down the stack looking for supernodes that we didn't include.
  283. * The algortihm here is actually pretty simple, since we know that
  284. * no previous subnode had to include these nodes, or if it did, we
  285. * marked them as included (on the stack) already.
  286. */
  287. for (i = 0; i <= depth; i++) {
  288. if (!info->stack[i].included) {
  289. start = info->stack[i].offset;
  290. /* Add the FDT_BEGIN_NODE tag of this supernode */
  291. fdt_next_tag(info->fdt, start, &stop_at);
  292. if (fdt_add_region(info, base + start, stop_at - start))
  293. return -1;
  294. /* Remember that this supernode is now included */
  295. info->stack[i].included = 1;
  296. info->can_merge = 1;
  297. }
  298. /* Force (later) generation of the FDT_END_NODE tag */
  299. if (!info->stack[i].want)
  300. info->stack[i].want = WANT_NODES_ONLY;
  301. }
  302. return 0;
  303. }
  304. /*
  305. * Tracks the progress through the device tree. Everything fdt_next_region() is
  306. * called it picks up at the same state as last time, looks at info->start and
  307. * decides what region to add next
  308. */
  309. enum {
  310. FDT_DONE_NOTHING, /* Starting */
  311. FDT_DONE_MEM_RSVMAP, /* Completed mem_rsvmap region */
  312. FDT_DONE_STRUCT, /* Completed struct region */
  313. FDT_DONE_EMPTY, /* Completed checking for empty struct region */
  314. FDT_DONE_END, /* Completed the FDT_END tag */
  315. FDT_DONE_STRINGS, /* Completed the strings */
  316. FDT_DONE_ALL, /* All done */
  317. };
  318. int fdt_first_region(const void *fdt,
  319. int (*h_include)(void *priv, const void *fdt, int offset,
  320. int type, const char *data, int size),
  321. void *priv, struct fdt_region *region,
  322. char *path, int path_len, int flags,
  323. struct fdt_region_state *info)
  324. {
  325. struct fdt_region_ptrs *p = &info->ptrs;
  326. /* Set up our state */
  327. info->fdt = fdt;
  328. info->can_merge = 1;
  329. info->max_regions = 1;
  330. info->start = -1;
  331. info->have_node = false;
  332. p->want = WANT_NOTHING;
  333. p->end = path;
  334. *p->end = '\0';
  335. p->nextoffset = 0;
  336. p->depth = -1;
  337. p->done = FDT_DONE_NOTHING;
  338. return fdt_next_region(fdt, h_include, priv, region,
  339. path, path_len, flags, info);
  340. }
  341. /***********************************************************************
  342. *
  343. * Theory of operation
  344. *
  345. * Note: in this description 'included' means that a node (or other part
  346. * of the tree) should be included in the region list, i.e. it will have
  347. * a region which covers its part of the tree.
  348. *
  349. * This function maintains some state from the last time it is called.
  350. * It checks the next part of the tree that it is supposed to look at
  351. * (p.nextoffset) to see if that should be included or not. When it
  352. * finds something to include, it sets info->start to its offset. This
  353. * marks the start of the region we want to include.
  354. *
  355. * Once info->start is set to the start (i.e. not -1), we continue
  356. * scanning until we find something that we don't want included. This
  357. * will be the end of a region. At this point we can close off the
  358. * region and add it to the list. So we do so, and reset info->start
  359. * to -1.
  360. *
  361. * One complication here is that we want to merge regions. So when we
  362. * come to add another region later, we may in fact merge it with the
  363. * previous one if one ends where the other starts.
  364. *
  365. * The function fdt_add_region() will return -1 if it fails to add the
  366. * region, because we already have a region ready to be returned, and
  367. * the new one cannot be merged in with it. In this case, we must return
  368. * the region we found, and wait for another call to this function.
  369. * When it comes, we will repeat the processing of the tag and again
  370. * try to add a region. This time it will succeed.
  371. *
  372. * The current state of the pointers (stack, offset, etc.) is maintained
  373. * in a ptrs member. At the start of every loop iteration we make a copy
  374. * of it. The copy is then updated as the tag is processed. Only if we
  375. * get to the end of the loop iteration (and successfully call
  376. * fdt_add_region() if we need to) can we commit the changes we have
  377. * made to these pointers. For example, if we see an FDT_END_NODE tag,
  378. * we will decrement the depth value. But if we need to add a region
  379. * for this tag (let's say because the previous tag is included and this
  380. * FDT_END_NODE tag is not included) then we will only commit the result
  381. * if we were able to add the region. That allows us to retry again next
  382. * time.
  383. *
  384. * We keep track of a variable called 'want' which tells us what we want
  385. * to include when there is no specific information provided by the
  386. * h_include function for a particular property. This basically handles
  387. * the inclusion of properties which are pulled in by virtue of the node
  388. * they are in. So if you include a node, its properties are also
  389. * included. In this case 'want' will be WANT_NODES_AND_PROPS. The
  390. * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
  391. * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
  392. * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
  393. * included, and properties will be skipped. If WANT_NOTHING is
  394. * selected, then we will just rely on what the h_include() function
  395. * tells us.
  396. *
  397. * Using 'want' we work out 'include', which tells us whether this
  398. * current tag should be included or not. As you can imagine, if the
  399. * value of 'include' changes, that means we are on a boundary between
  400. * nodes to include and nodes to exclude. At this point we either close
  401. * off a previous region and add it to the list, or mark the start of a
  402. * new region.
  403. *
  404. * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
  405. * string list. Each of these dealt with as a whole (i.e. we create a
  406. * region for each if it is to be included). For mem_rsvmap we don't
  407. * allow it to merge with the first struct region. For the stringlist,
  408. * we don't allow it to merge with the last struct region (which
  409. * contains at minimum the FDT_END tag).
  410. *
  411. *********************************************************************/
  412. int fdt_next_region(const void *fdt,
  413. int (*h_include)(void *priv, const void *fdt, int offset,
  414. int type, const char *data, int size),
  415. void *priv, struct fdt_region *region,
  416. char *path, int path_len, int flags,
  417. struct fdt_region_state *info)
  418. {
  419. int base = fdt_off_dt_struct(fdt);
  420. int last_node = 0;
  421. const char *str;
  422. info->region = region;
  423. info->count = 0;
  424. if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
  425. (flags & FDT_REG_ADD_MEM_RSVMAP)) {
  426. /* Add the memory reserve map into its own region */
  427. if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
  428. fdt_off_dt_struct(fdt) -
  429. fdt_off_mem_rsvmap(fdt)))
  430. return 0;
  431. info->can_merge = 0; /* Don't allow merging with this */
  432. info->ptrs.done = FDT_DONE_MEM_RSVMAP;
  433. }
  434. /*
  435. * Work through the tags one by one, deciding whether each needs to
  436. * be included or not. We set the variable 'include' to indicate our
  437. * decision. 'want' is used to track what we want to include - it
  438. * allows us to pick up all the properties (and/or subnode tags) of
  439. * a node.
  440. */
  441. while (info->ptrs.done < FDT_DONE_STRUCT) {
  442. const struct fdt_property *prop;
  443. struct fdt_region_ptrs p;
  444. const char *name;
  445. int include = 0;
  446. int stop_at = 0;
  447. uint32_t tag;
  448. int offset;
  449. int val;
  450. int len;
  451. /*
  452. * Make a copy of our pointers. If we make it to the end of
  453. * this block then we will commit them back to info->ptrs.
  454. * Otherwise we can try again from the same starting state
  455. * next time we are called.
  456. */
  457. p = info->ptrs;
  458. /*
  459. * Find the tag, and the offset of the next one. If we need to
  460. * stop including tags, then by default we stop *after*
  461. * including the current tag
  462. */
  463. offset = p.nextoffset;
  464. tag = fdt_next_tag(fdt, offset, &p.nextoffset);
  465. stop_at = p.nextoffset;
  466. switch (tag) {
  467. case FDT_PROP:
  468. stop_at = offset;
  469. prop = fdt_get_property_by_offset(fdt, offset, NULL);
  470. str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
  471. val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
  472. strlen(str) + 1);
  473. if (val == -1) {
  474. include = p.want >= WANT_NODES_AND_PROPS;
  475. } else {
  476. include = val;
  477. /*
  478. * Make sure we include the } for this block.
  479. * It might be more correct to have this done
  480. * by the call to fdt_include_supernodes() in
  481. * the case where it adds the node we are
  482. * currently in, but this is equivalent.
  483. */
  484. if ((flags & FDT_REG_SUPERNODES) && val &&
  485. !p.want)
  486. p.want = WANT_NODES_ONLY;
  487. }
  488. /* Value grepping is not yet supported */
  489. break;
  490. case FDT_NOP:
  491. include = p.want >= WANT_NODES_AND_PROPS;
  492. stop_at = offset;
  493. break;
  494. case FDT_BEGIN_NODE:
  495. last_node = offset;
  496. p.depth++;
  497. if (p.depth == FDT_MAX_DEPTH)
  498. return -FDT_ERR_BADSTRUCTURE;
  499. name = fdt_get_name(fdt, offset, &len);
  500. if (p.end - path + 2 + len >= path_len)
  501. return -FDT_ERR_NOSPACE;
  502. /* Build the full path of this node */
  503. if (p.end != path + 1)
  504. *p.end++ = '/';
  505. strcpy(p.end, name);
  506. p.end += len;
  507. info->stack[p.depth].want = p.want;
  508. info->stack[p.depth].offset = offset;
  509. /*
  510. * If we are not intending to include this node unless
  511. * it matches, make sure we stop *before* its tag.
  512. */
  513. if (p.want == WANT_NODES_ONLY ||
  514. !(flags & (FDT_REG_DIRECT_SUBNODES |
  515. FDT_REG_ALL_SUBNODES))) {
  516. stop_at = offset;
  517. p.want = WANT_NOTHING;
  518. }
  519. val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
  520. p.end - path + 1);
  521. /* Include this if requested */
  522. if (val) {
  523. p.want = (flags & FDT_REG_ALL_SUBNODES) ?
  524. WANT_ALL_NODES_AND_PROPS :
  525. WANT_NODES_AND_PROPS;
  526. }
  527. /* If not requested, decay our 'p.want' value */
  528. else if (p.want) {
  529. if (p.want != WANT_ALL_NODES_AND_PROPS)
  530. p.want--;
  531. /* Not including this tag, so stop now */
  532. } else {
  533. stop_at = offset;
  534. }
  535. /*
  536. * Decide whether to include this tag, and update our
  537. * stack with the state for this node
  538. */
  539. include = p.want;
  540. info->stack[p.depth].included = include;
  541. break;
  542. case FDT_END_NODE:
  543. include = p.want;
  544. if (p.depth < 0)
  545. return -FDT_ERR_BADSTRUCTURE;
  546. /*
  547. * If we don't want this node, stop right away, unless
  548. * we are including subnodes
  549. */
  550. if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
  551. stop_at = offset;
  552. p.want = info->stack[p.depth].want;
  553. p.depth--;
  554. while (p.end > path && *--p.end != '/')
  555. ;
  556. *p.end = '\0';
  557. break;
  558. case FDT_END:
  559. /* We always include the end tag */
  560. include = 1;
  561. p.done = FDT_DONE_STRUCT;
  562. break;
  563. }
  564. /* If this tag is to be included, mark it as region start */
  565. if (include && info->start == -1) {
  566. /* Include any supernodes required by this one */
  567. if (flags & FDT_REG_SUPERNODES) {
  568. if (fdt_include_supernodes(info, p.depth))
  569. return 0;
  570. }
  571. info->start = offset;
  572. }
  573. /*
  574. * If this tag is not to be included, finish up the current
  575. * region.
  576. */
  577. if (!include && info->start != -1) {
  578. if (!info->start)
  579. info->have_node = true;
  580. if (fdt_add_region(info, base + info->start,
  581. stop_at - info->start))
  582. return 0;
  583. info->start = -1;
  584. info->can_merge = 1;
  585. }
  586. /* If we have made it this far, we can commit our pointers */
  587. info->ptrs = p;
  588. }
  589. if (info->ptrs.done < FDT_DONE_EMPTY) {
  590. /*
  591. * Handle a special case where no nodes have been written. Write
  592. * the first { so we have at least something, since
  593. * FDT_REG_SUPERNODES means that a valid tree is required. A
  594. * tree with no nodes is not valid
  595. */
  596. if ((flags & FDT_REG_SUPERNODES) && !info->have_node &&
  597. info->start) {
  598. /* Output the FDT_BEGIN_NODE and the empty name */
  599. if (fdt_add_region(info, base, 8))
  600. return 0;
  601. }
  602. info->ptrs.done++;
  603. }
  604. /* Add a region for the END tag and a separate one for string table */
  605. if (info->ptrs.done < FDT_DONE_END) {
  606. if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
  607. return -FDT_ERR_BADSTRUCTURE;
  608. /* Output the } before the end tag to finish it off */
  609. if (info->start == fdt_size_dt_struct(fdt) - 4)
  610. info->start -= 4;
  611. if (fdt_add_region(info, base + info->start,
  612. info->ptrs.nextoffset - info->start))
  613. return 0;
  614. info->ptrs.done++;
  615. }
  616. if (info->ptrs.done < FDT_DONE_STRINGS) {
  617. if (flags & FDT_REG_ADD_STRING_TAB) {
  618. info->can_merge = 0;
  619. if (fdt_off_dt_strings(fdt) <
  620. base + info->ptrs.nextoffset)
  621. return -FDT_ERR_BADLAYOUT;
  622. if (fdt_add_region(info, fdt_off_dt_strings(fdt),
  623. fdt_size_dt_strings(fdt)))
  624. return 0;
  625. }
  626. info->ptrs.done++;
  627. }
  628. return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;
  629. }