rcorder.c revision 78344
1/* $NetBSD: rcorder.c,v 1.6 2000/07/19 09:58:03 enami Exp $ */ 2 3/* 4 * Copyright (c) 1998, 1999 Matthew R. Green 5 * All rights reserved. 6 * Copyright (c) 1998 7 * Perry E. Metzger. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed for the NetBSD Project 20 * by Perry E. Metzger. 21 * 4. The name of the author may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36#include <sys/types.h> 37#include <sys/stat.h> 38 39#include <err.h> 40#include <stdio.h> 41#include <stdlib.h> 42#include <string.h> 43#include <unistd.h> 44#include <util.h> 45 46#include "ealloc.h" 47#include "sprite.h" 48#include "hash.h" 49 50#ifdef DEBUG 51int debug = 0; 52# define DPRINTF(args) if (debug) { fflush(stdout); fprintf args; } 53#else 54# define DPRINTF(args) 55#endif 56 57#define REQUIRE_STR "# REQUIRE:" 58#define REQUIRE_LEN (sizeof(REQUIRE_STR) - 1) 59#define REQUIRES_STR "# REQUIRES:" 60#define REQUIRES_LEN (sizeof(REQUIRES_STR) - 1) 61#define PROVIDE_STR "# PROVIDE:" 62#define PROVIDE_LEN (sizeof(PROVIDE_STR) - 1) 63#define PROVIDES_STR "# PROVIDES:" 64#define PROVIDES_LEN (sizeof(PROVIDES_STR) - 1) 65#define BEFORE_STR "# BEFORE:" 66#define BEFORE_LEN (sizeof(BEFORE_STR) - 1) 67#define KEYWORD_STR "# KEYWORD:" 68#define KEYWORD_LEN (sizeof(KEYWORD_STR) - 1) 69#define KEYWORDS_STR "# KEYWORDS:" 70#define KEYWORDS_LEN (sizeof(KEYWORDS_STR) - 1) 71 72int exit_code; 73int file_count; 74char **file_list; 75 76typedef int bool; 77#define TRUE 1 78#define FALSE 0 79typedef bool flag; 80#define SET TRUE 81#define RESET FALSE 82 83Hash_Table provide_hash_s, *provide_hash; 84 85typedef struct provnode provnode; 86typedef struct filenode filenode; 87typedef struct f_provnode f_provnode; 88typedef struct f_reqnode f_reqnode; 89typedef struct strnodelist strnodelist; 90 91struct provnode { 92 flag head; 93 flag in_progress; 94 filenode *fnode; 95 provnode *next, *last; 96}; 97 98struct f_provnode { 99 provnode *pnode; 100 f_provnode *next; 101}; 102 103struct f_reqnode { 104 Hash_Entry *entry; 105 f_reqnode *next; 106}; 107 108struct strnodelist { 109 filenode *node; 110 strnodelist *next; 111 char s[1]; 112}; 113 114struct filenode { 115 char *filename; 116 flag in_progress; 117 filenode *next, *last; 118 f_reqnode *req_list; 119 f_provnode *prov_list; 120 strnodelist *keyword_list; 121}; 122 123filenode fn_head_s, *fn_head; 124 125strnodelist *bl_list; 126strnodelist *keep_list; 127strnodelist *skip_list; 128 129void do_file __P((filenode *fnode)); 130void strnode_add __P((strnodelist **, char *, filenode *)); 131int skip_ok __P((filenode *fnode)); 132int keep_ok __P((filenode *fnode)); 133void satisfy_req __P((f_reqnode *rnode, char *filename)); 134void crunch_file __P((char *)); 135void parse_require __P((filenode *, char *)); 136void parse_provide __P((filenode *, char *)); 137void parse_before __P((filenode *, char *)); 138void parse_keywords __P((filenode *, char *)); 139filenode *filenode_new __P((char *)); 140void add_require __P((filenode *, char *)); 141void add_provide __P((filenode *, char *)); 142void add_before __P((filenode *, char *)); 143void add_keyword __P((filenode *, char *)); 144void insert_before __P((void)); 145Hash_Entry *make_fake_provision __P((filenode *)); 146void crunch_all_files __P((void)); 147void initialize __P((void)); 148void generate_ordering __P((void)); 149int main __P((int, char *[])); 150 151int 152main(argc, argv) 153 int argc; 154 char *argv[]; 155{ 156 int ch; 157 158 while ((ch = getopt(argc, argv, "dk:s:")) != -1) 159 switch (ch) { 160 case 'd': 161#ifdef DEBUG 162 debug = 1; 163#else 164 warnx("debugging not compiled in, -d ignored"); 165#endif 166 break; 167 case 'k': 168 strnode_add(&keep_list, optarg, 0); 169 break; 170 case 's': 171 strnode_add(&skip_list, optarg, 0); 172 break; 173 default: 174 /* XXX should crunch it? */ 175 break; 176 } 177 argc -= optind; 178 argv += optind; 179 180 file_count = argc; 181 file_list = argv; 182 183 DPRINTF((stderr, "parse_args\n")); 184 initialize(); 185 DPRINTF((stderr, "initialize\n")); 186 crunch_all_files(); 187 DPRINTF((stderr, "crunch_all_files\n")); 188 generate_ordering(); 189 DPRINTF((stderr, "generate_ordering\n")); 190 191 exit(exit_code); 192} 193 194/* 195 * initialise various variables. 196 */ 197void 198initialize() 199{ 200 201 fn_head = &fn_head_s; 202 203 provide_hash = &provide_hash_s; 204 Hash_InitTable(provide_hash, file_count); 205} 206 207/* generic function to insert a new strnodelist element */ 208void 209strnode_add(listp, s, fnode) 210 strnodelist **listp; 211 char *s; 212 filenode *fnode; 213{ 214 strnodelist *ent; 215 216 ent = emalloc(sizeof *ent + strlen(s)); 217 ent->node = fnode; 218 strcpy(ent->s, s); 219 ent->next = *listp; 220 *listp = ent; 221} 222 223/* 224 * below are the functions that deal with creating the lists 225 * from the filename's given and the dependancies and provisions 226 * in each of these files. no ordering or checking is done here. 227 */ 228 229/* 230 * we have a new filename, create a new filenode structure. 231 * fill in the bits, and put it in the filenode linked list 232 */ 233filenode * 234filenode_new(filename) 235 char *filename; 236{ 237 filenode *temp; 238 239 temp = emalloc(sizeof(*temp)); 240 memset(temp, 0, sizeof(*temp)); 241 temp->filename = estrdup(filename); 242 temp->req_list = NULL; 243 temp->prov_list = NULL; 244 temp->keyword_list = NULL; 245 temp->in_progress = RESET; 246 /* 247 * link the filenode into the list of filenodes. 248 * note that the double linking means we can delete a 249 * filenode without searching for where it belongs. 250 */ 251 temp->next = fn_head->next; 252 if (temp->next != NULL) 253 temp->next->last = temp; 254 temp->last = fn_head; 255 fn_head->next = temp; 256 return (temp); 257} 258 259/* 260 * add a requirement to a filenode. 261 */ 262void 263add_require(fnode, s) 264 filenode *fnode; 265 char *s; 266{ 267 Hash_Entry *entry; 268 f_reqnode *rnode; 269 int new; 270 271 entry = Hash_CreateEntry(provide_hash, s, &new); 272 if (new) 273 Hash_SetValue(entry, NULL); 274 rnode = emalloc(sizeof(*rnode)); 275 rnode->entry = entry; 276 rnode->next = fnode->req_list; 277 fnode->req_list = rnode; 278} 279 280/* 281 * add a provision to a filenode. if this provision doesn't 282 * have a head node, create one here. 283 */ 284void 285add_provide(fnode, s) 286 filenode *fnode; 287 char *s; 288{ 289 Hash_Entry *entry; 290 f_provnode *f_pnode; 291 provnode *pnode, *head; 292 int new; 293 294 entry = Hash_CreateEntry(provide_hash, s, &new); 295 head = Hash_GetValue(entry); 296 297 /* create a head node if necessary. */ 298 if (head == NULL) { 299 head = emalloc(sizeof(*head)); 300 head->head = SET; 301 head->in_progress = RESET; 302 head->fnode = NULL; 303 head->last = head->next = NULL; 304 Hash_SetValue(entry, head); 305 } 306#if 0 307 /* 308 * Don't warn about this. We want to be able to support 309 * scripts that do two complex things: 310 * 311 * - Two independent scripts which both provide the 312 * same thing. Both scripts must be executed in 313 * any order to meet the barrier. An example: 314 * 315 * Script 1: 316 * 317 * PROVIDE: mail 318 * REQUIRE: LOGIN 319 * 320 * Script 2: 321 * 322 * PROVIDE: mail 323 * REQUIRE: LOGIN 324 * 325 * - Two interdependent scripts which both provide the 326 * same thing. Both scripts must be executed in 327 * graph order to meet the barrier. An example: 328 * 329 * Script 1: 330 * 331 * PROVIDE: nameservice dnscache 332 * REQUIRE: SERVERS 333 * 334 * Script 2: 335 * 336 * PROVIDE: nameservice nscd 337 * REQUIRE: dnscache 338 */ 339 else if (new == 0) { 340 warnx("file `%s' provides `%s'.", fnode->filename, s); 341 warnx("\tpreviously seen in `%s'.", 342 head->next->fnode->filename); 343 } 344#endif 345 346 pnode = emalloc(sizeof(*pnode)); 347 pnode->head = RESET; 348 pnode->in_progress = RESET; 349 pnode->fnode = fnode; 350 pnode->next = head->next; 351 pnode->last = head; 352 head->next = pnode; 353 if (pnode->next != NULL) 354 pnode->next->last = pnode; 355 356 f_pnode = emalloc(sizeof(*f_pnode)); 357 f_pnode->pnode = pnode; 358 f_pnode->next = fnode->prov_list; 359 fnode->prov_list = f_pnode; 360} 361 362/* 363 * put the BEFORE: lines to a list and handle them later. 364 */ 365void 366add_before(fnode, s) 367 filenode *fnode; 368 char *s; 369{ 370 strnodelist *bf_ent; 371 372 bf_ent = emalloc(sizeof *bf_ent + strlen(s)); 373 bf_ent->node = fnode; 374 strcpy(bf_ent->s, s); 375 bf_ent->next = bl_list; 376 bl_list = bf_ent; 377} 378 379/* 380 * add a key to a filenode. 381 */ 382void 383add_keyword(fnode, s) 384 filenode *fnode; 385 char *s; 386{ 387 388 strnode_add(&fnode->keyword_list, s, fnode); 389} 390 391/* 392 * loop over the rest of a REQUIRE line, giving each word to 393 * add_require() to do the real work. 394 */ 395void 396parse_require(node, buffer) 397 filenode *node; 398 char *buffer; 399{ 400 char *s; 401 402 while ((s = strsep(&buffer, " \t\n")) != NULL) 403 if (*s != '\0') 404 add_require(node, s); 405} 406 407/* 408 * loop over the rest of a PROVIDE line, giving each word to 409 * add_provide() to do the real work. 410 */ 411void 412parse_provide(node, buffer) 413 filenode *node; 414 char *buffer; 415{ 416 char *s; 417 418 while ((s = strsep(&buffer, " \t\n")) != NULL) 419 if (*s != '\0') 420 add_provide(node, s); 421} 422 423/* 424 * loop over the rest of a BEFORE line, giving each word to 425 * add_before() to do the real work. 426 */ 427void 428parse_before(node, buffer) 429 filenode *node; 430 char *buffer; 431{ 432 char *s; 433 434 while ((s = strsep(&buffer, " \t\n")) != NULL) 435 if (*s != '\0') 436 add_before(node, s); 437} 438 439/* 440 * loop over the rest of a KEYWORD line, giving each word to 441 * add_keyword() to do the real work. 442 */ 443void 444parse_keywords(node, buffer) 445 filenode *node; 446 char *buffer; 447{ 448 char *s; 449 450 while ((s = strsep(&buffer, " \t\n")) != NULL) 451 if (*s != '\0') 452 add_keyword(node, s); 453} 454 455/* 456 * given a file name, create a filenode for it, read in lines looking 457 * for provision and requirement lines, building the graphs as needed. 458 */ 459void 460crunch_file(filename) 461 char *filename; 462{ 463 FILE *fp; 464 char *buf; 465 int require_flag, provide_flag, before_flag, keywords_flag; 466 enum { BEFORE_PARSING, PARSING, PARSING_DONE } state; 467 filenode *node; 468 char delims[3] = { '\\', '\\', '\0' }; 469 struct stat st; 470 471 if ((fp = fopen(filename, "r")) == NULL) { 472 warn("could not open %s", filename); 473 return; 474 } 475 476 if (fstat(fileno(fp), &st) == -1) { 477 warn("could not stat %s", filename); 478 fclose(fp); 479 return; 480 } 481 482 if (!S_ISREG(st.st_mode)) { 483 warnx("%s is not a file", filename); 484 fclose(fp); 485 return; 486 } 487 488 node = filenode_new(filename); 489 490 /* 491 * we don't care about length, line number, don't want # for comments, 492 * and have no flags. 493 */ 494 for (state = BEFORE_PARSING; state != PARSING_DONE && 495 (buf = fparseln(fp, NULL, NULL, delims, 0)) != NULL; free(buf)) { 496 require_flag = provide_flag = before_flag = keywords_flag = 0; 497 if (strncmp(REQUIRE_STR, buf, REQUIRE_LEN) == 0) 498 require_flag = REQUIRE_LEN; 499 else if (strncmp(REQUIRES_STR, buf, REQUIRES_LEN) == 0) 500 require_flag = REQUIRES_LEN; 501 else if (strncmp(PROVIDE_STR, buf, PROVIDE_LEN) == 0) 502 provide_flag = PROVIDE_LEN; 503 else if (strncmp(PROVIDES_STR, buf, PROVIDES_LEN) == 0) 504 provide_flag = PROVIDES_LEN; 505 else if (strncmp(BEFORE_STR, buf, BEFORE_LEN) == 0) 506 before_flag = BEFORE_LEN; 507 else if (strncmp(KEYWORD_STR, buf, KEYWORD_LEN) == 0) 508 keywords_flag = KEYWORD_LEN; 509 else if (strncmp(KEYWORDS_STR, buf, KEYWORDS_LEN) == 0) 510 keywords_flag = KEYWORDS_LEN; 511 else { 512 if (state == PARSING) 513 state = PARSING_DONE; 514 continue; 515 } 516 517 state = PARSING; 518 if (require_flag) 519 parse_require(node, buf + require_flag); 520 else if (provide_flag) 521 parse_provide(node, buf + provide_flag); 522 else if (before_flag) 523 parse_before(node, buf + before_flag); 524 else if (keywords_flag) 525 parse_keywords(node, buf + keywords_flag); 526 } 527 fclose(fp); 528} 529 530Hash_Entry * 531make_fake_provision(node) 532 filenode *node; 533{ 534 Hash_Entry *entry; 535 f_provnode *f_pnode; 536 provnode *head, *pnode; 537 static int i = 0; 538 int new; 539 char buffer[30]; 540 541 do { 542 snprintf(buffer, sizeof buffer, "fake_prov_%08d", i++); 543 entry = Hash_CreateEntry(provide_hash, buffer, &new); 544 } while (new == 0); 545 head = emalloc(sizeof(*head)); 546 head->head = SET; 547 head->in_progress = RESET; 548 head->fnode = NULL; 549 head->last = head->next = NULL; 550 Hash_SetValue(entry, head); 551 552 pnode = emalloc(sizeof(*pnode)); 553 pnode->head = RESET; 554 pnode->in_progress = RESET; 555 pnode->fnode = node; 556 pnode->next = head->next; 557 pnode->last = head; 558 head->next = pnode; 559 if (pnode->next != NULL) 560 pnode->next->last = pnode; 561 562 f_pnode = emalloc(sizeof(*f_pnode)); 563 f_pnode->pnode = pnode; 564 f_pnode->next = node->prov_list; 565 node->prov_list = f_pnode; 566 567 return (entry); 568} 569 570/* 571 * go through the BEFORE list, inserting requirements into the graph(s) 572 * as required. in the before list, for each entry B, we have a file F 573 * and a string S. we create a "fake" provision (P) that F provides. 574 * for each entry in the provision list for S, add a requirement to 575 * that provisions filenode for P. 576 */ 577void 578insert_before() 579{ 580 Hash_Entry *entry, *fake_prov_entry; 581 provnode *pnode; 582 f_reqnode *rnode; 583 strnodelist *bl; 584 int new; 585 586 while (bl_list != NULL) { 587 bl = bl_list->next; 588 589 fake_prov_entry = make_fake_provision(bl_list->node); 590 591 entry = Hash_CreateEntry(provide_hash, bl_list->s, &new); 592 if (new == 1) 593 warnx("file `%s' is before unknown provision `%s'", bl_list->node->filename, bl_list->s); 594 595 for (pnode = Hash_GetValue(entry); pnode; pnode = pnode->next) { 596 if (pnode->head) 597 continue; 598 599 rnode = emalloc(sizeof(*rnode)); 600 rnode->entry = fake_prov_entry; 601 rnode->next = pnode->fnode->req_list; 602 pnode->fnode->req_list = rnode; 603 } 604 605 free(bl_list); 606 bl_list = bl; 607 } 608} 609 610/* 611 * loop over all the files calling crunch_file() on them to do the 612 * real work. after we have built all the nodes, insert the BEFORE: 613 * lines into graph(s). 614 */ 615void 616crunch_all_files() 617{ 618 int i; 619 620 for (i = 0; i < file_count; i++) 621 crunch_file(file_list[i]); 622 insert_before(); 623} 624 625/* 626 * below are the functions that traverse the graphs we have built 627 * finding out the desired ordering, printing each file in turn. 628 * if missing requirements, or cyclic graphs are detected, a 629 * warning will be issued, and we will continue on.. 630 */ 631 632/* 633 * given a requirement node (in a filename) we attempt to satisfy it. 634 * we do some sanity checking first, to ensure that we have providers, 635 * aren't already satisfied and aren't already being satisfied (ie, 636 * cyclic). if we pass all this, we loop over the provision list 637 * calling do_file() (enter recursion) for each filenode in this 638 * provision. 639 */ 640void 641satisfy_req(rnode, filename) 642 f_reqnode *rnode; 643 char *filename; 644{ 645 Hash_Entry *entry; 646 provnode *head; 647 648 entry = rnode->entry; 649 head = Hash_GetValue(entry); 650 651 if (head == NULL) { 652 warnx("requirement `%s' in file `%s' has no providers.", 653 Hash_GetKey(entry), filename); 654 exit_code = 1; 655 return; 656 } 657 658 /* return if the requirement is already satisfied. */ 659 if (head->next == NULL) 660 return; 661 662 /* 663 * if list is marked as in progress, 664 * print that there is a circular dependency on it and abort 665 */ 666 if (head->in_progress == SET) { 667 warnx("Circular dependency on provision `%s' in file `%s'.", 668 Hash_GetKey(entry), filename); 669 exit_code = 1; 670 return; 671 } 672 673 head->in_progress = SET; 674 675 /* 676 * while provision_list is not empty 677 * do_file(first_member_of(provision_list)); 678 */ 679 while (head->next != NULL) 680 do_file(head->next->fnode); 681} 682 683int 684skip_ok(fnode) 685 filenode *fnode; 686{ 687 strnodelist *s; 688 strnodelist *k; 689 690 for (s = skip_list; s; s = s->next) 691 for (k = fnode->keyword_list; k; k = k->next) 692 if (strcmp(k->s, s->s) == 0) 693 return (0); 694 695 return (1); 696} 697 698int 699keep_ok(fnode) 700 filenode *fnode; 701{ 702 strnodelist *s; 703 strnodelist *k; 704 705 for (s = keep_list; s; s = s->next) 706 for (k = fnode->keyword_list; k; k = k->next) 707 if (strcmp(k->s, s->s) == 0) 708 return (1); 709 710 /* an empty keep_list means every one */ 711 return (!keep_list); 712} 713 714/* 715 * given a filenode, we ensure we are not a cyclic graph. if this 716 * is ok, we loop over the filenodes requirements, calling satisfy_req() 717 * for each of them.. once we have done this, remove this filenode 718 * from each provision table, as we are now done. 719 */ 720void 721do_file(fnode) 722 filenode *fnode; 723{ 724 f_reqnode *r, *r_tmp; 725 f_provnode *p, *p_tmp; 726 provnode *pnode; 727 int was_set; 728 729 DPRINTF((stderr, "do_file on %s.\n", fnode->filename)); 730 731 /* 732 * if fnode is marked as in progress, 733 * print that fnode; is circularly depended upon and abort. 734 */ 735 if (fnode->in_progress == SET) { 736 warnx("Circular dependency on file `%s'.", 737 fnode->filename); 738 was_set = exit_code = 1; 739 } else 740 was_set = 0; 741 742 /* mark fnode */ 743 fnode->in_progress = SET; 744 745 /* 746 * for each requirement of fnode -> r 747 * satisfy_req(r, filename) 748 */ 749 r = fnode->req_list; 750 while (r != NULL) { 751 r_tmp = r; 752 satisfy_req(r, fnode->filename); 753 r = r->next; 754 free(r_tmp); 755 } 756 fnode->req_list = NULL; 757 758 /* 759 * for each provision of fnode -> p 760 * remove fnode from provision list for p in hash table 761 */ 762 p = fnode->prov_list; 763 while (p != NULL) { 764 p_tmp = p; 765 pnode = p->pnode; 766 if (pnode->next != NULL) { 767 pnode->next->last = pnode->last; 768 } 769 if (pnode->last != NULL) { 770 pnode->last->next = pnode->next; 771 } 772 free(pnode); 773 p = p->next; 774 free(p_tmp); 775 } 776 fnode->prov_list = NULL; 777 778 /* do_it(fnode) */ 779 DPRINTF((stderr, "next do: ")); 780 781 /* if we were already in progress, don't print again */ 782 if (was_set == 0 && skip_ok(fnode) && keep_ok(fnode)) 783 printf("%s\n", fnode->filename); 784 785 if (fnode->next != NULL) { 786 fnode->next->last = fnode->last; 787 } 788 if (fnode->last != NULL) { 789 fnode->last->next = fnode->next; 790 } 791 792 DPRINTF((stderr, "nuking %s\n", fnode->filename)); 793 free(fnode->filename); 794 free(fnode); 795} 796 797void 798generate_ordering() 799{ 800 801 /* 802 * while there remain undone files{f}, 803 * pick an arbitrary f, and do_file(f) 804 * Note that the first file in the file list is perfectly 805 * arbitrary, and easy to find, so we use that. 806 */ 807 808 /* 809 * N.B.: the file nodes "self delete" after they execute, so 810 * after each iteration of the loop, the head will be pointing 811 * to something totally different. The loop ends up being 812 * executed only once for every strongly connected set of 813 * nodes. 814 */ 815 while (fn_head->next != NULL) { 816 DPRINTF((stderr, "generate on %s\n", fn_head->next->filename)); 817 do_file(fn_head->next); 818 } 819} 820