1 /* $NetBSD: tsort.c,v 1.26 2021/02/06 16:02:16 dbj Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Michael Rendell of Memorial University of Newfoundland. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if HAVE_NBTOOL_CONFIG_H 36 #include "nbtool_config.h" 37 #endif 38 39 #include <sys/cdefs.h> 40 #if !defined(lint) 41 __COPYRIGHT("@(#) Copyright (c) 1989, 1993, 1994\ 42 The Regents of the University of California. All rights reserved."); 43 #if 0 44 static char sccsid[] = "@(#)tsort.c 8.3 (Berkeley) 5/4/95"; 45 #endif 46 __RCSID("$NetBSD: tsort.c,v 1.26 2021/02/06 16:02:16 dbj Exp $"); 47 #endif /* not lint */ 48 49 #include <sys/types.h> 50 #include <ctype.h> 51 #include <db.h> 52 #include <err.h> 53 #include <errno.h> 54 #include <fcntl.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 #if !HAVE_NBTOOL_CONFIG_H 60 #include <util.h> 61 #endif 62 63 /* 64 * Topological sort. Input is a list of pairs of strings separated by 65 * white space (spaces, tabs, and/or newlines); strings are written to 66 * standard output in sorted order, one per line. 67 * 68 * usage: 69 * tsort [-l] [inputfile] 70 * If no input file is specified, standard input is read. 71 * 72 * Should be compatible with AT&T tsort HOWEVER the output is not identical 73 * (i.e. for most graphs there is more than one sorted order, and this tsort 74 * usually generates a different one than the AT&T tsort). Also, cycle 75 * reporting seems to be more accurate in this version (the AT&T tsort 76 * sometimes says a node is in a cycle when it isn't). 77 * 78 * Michael Rendell, michael (at) stretch.cs.mun.ca - Feb 26, '90 79 */ 80 #define HASHSIZE 53 /* doesn't need to be big */ 81 #define NF_MARK 0x1 /* marker for cycle detection */ 82 #define NF_ACYCLIC 0x2 /* this node is cycle free */ 83 #define NF_NODEST 0x4 /* Unreachable */ 84 85 typedef struct node_str NODE; 86 87 struct node_str { 88 NODE **n_prevp; /* pointer to previous node's n_next */ 89 NODE *n_next; /* next node in graph */ 90 NODE **n_arcs; /* array of arcs to other nodes */ 91 size_t n_narcs; /* number of arcs in n_arcs[] */ 92 size_t n_arcsize; /* size of n_arcs[] array */ 93 size_t n_refcnt; /* # of arcs pointing to this node */ 94 int n_flags; /* NF_* */ 95 char n_name[1]; /* name of this node */ 96 }; 97 98 typedef struct _buf { 99 char *b_buf; 100 size_t b_bsize; 101 } BUF; 102 103 static DB *db; 104 static NODE *graph, **cycle_buf, **longest_cycle; 105 static int debug, longest, quiet, reverse; 106 107 static void add_arc(const char *, const char *); 108 static void clear_cycle(void); 109 static size_t find_cycle(NODE *, NODE *, size_t, size_t); 110 static NODE *get_node(const char *); 111 static void remove_node(NODE *); 112 static void tsort(void); 113 __dead static void usage(void); 114 115 int 116 main(int argc, char *argv[]) 117 { 118 BUF *b; 119 int c, n, ch; 120 FILE *fp; 121 size_t bsize, nused; 122 BUF bufs[2]; 123 124 setprogname(argv[0]); 125 126 fp = NULL; 127 while ((ch = getopt(argc, argv, "dlqr")) != -1) 128 switch (ch) { 129 case 'd': 130 debug = 1; 131 break; 132 case 'l': 133 longest = 1; 134 break; 135 case 'q': 136 quiet = 1; 137 break; 138 case 'r': 139 reverse = 1; 140 break; 141 case '?': 142 default: 143 usage(); 144 } 145 argc -= optind; 146 argv += optind; 147 148 switch (argc) { 149 case 0: 150 fp = stdin; 151 break; 152 case 1: 153 if ((fp = fopen(*argv, "r")) == NULL) 154 err(EXIT_FAILURE, "%s", *argv); 155 break; 156 default: 157 usage(); 158 } 159 160 for (b = bufs, n = 2; n-- > 0; b++) 161 b->b_buf = erealloc(NULL, b->b_bsize = 1024); 162 163 /* parse input and build the graph */ 164 for (n = 0, c = getc(fp);;) { 165 while (c != EOF && isspace(c)) 166 c = getc(fp); 167 if (c == EOF) 168 break; 169 170 nused = 0; 171 b = &bufs[n]; 172 bsize = b->b_bsize; 173 do { 174 b->b_buf[nused++] = (char)c; 175 if (nused == bsize) 176 b->b_buf = erealloc(b->b_buf, bsize *= 2); 177 c = getc(fp); 178 } while (c != EOF && !isspace(c)); 179 180 b->b_buf[nused] = '\0'; 181 b->b_bsize = bsize; 182 if (n) { 183 if (reverse) 184 add_arc(bufs[1].b_buf, bufs[0].b_buf); 185 else 186 add_arc(bufs[0].b_buf, bufs[1].b_buf); 187 } 188 n = !n; 189 } 190 (void)fclose(fp); 191 if (n) 192 errx(EXIT_FAILURE, "odd data count"); 193 194 /* do the sort */ 195 tsort(); 196 return EXIT_SUCCESS; 197 } 198 199 /* 200 * add an arc from node s1 to node s2 in the graph. If s1 or s2 are not in 201 * the graph, then add them. 202 */ 203 static void 204 add_arc(const char *s1, const char *s2) 205 { 206 NODE *n1; 207 NODE *n2; 208 size_t bsize, i; 209 210 n1 = get_node(s1); 211 212 if (strcmp(s1, s2) == 0) 213 return; 214 215 n2 = get_node(s2); 216 217 /* 218 * Check if this arc is already here. 219 */ 220 for (i = 0; i < n1->n_narcs; i++) 221 if (n1->n_arcs[i] == n2) 222 return; 223 /* 224 * Add it. 225 */ 226 if (n1->n_narcs == n1->n_arcsize) { 227 if (!n1->n_arcsize) 228 n1->n_arcsize = 10; 229 bsize = n1->n_arcsize * sizeof(*n1->n_arcs) * 2; 230 n1->n_arcs = erealloc(n1->n_arcs, bsize); 231 n1->n_arcsize = bsize / sizeof(*n1->n_arcs); 232 } 233 n1->n_arcs[n1->n_narcs++] = n2; 234 ++n2->n_refcnt; 235 } 236 237 /* Find a node in the graph (insert if not found) and return a pointer to it. */ 238 static NODE * 239 get_node(const char *name) 240 { 241 DBT data, key; 242 NODE *n; 243 244 if (db == NULL && 245 (db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == NULL) 246 err(EXIT_FAILURE, "db: %s", name); 247 248 key.data = __UNCONST(name); 249 key.size = strlen(name) + 1; 250 251 switch ((*db->get)(db, &key, &data, 0)) { 252 case 0: 253 (void)memmove(&n, data.data, sizeof(n)); 254 return n; 255 case 1: 256 break; 257 default: 258 case -1: 259 err(EXIT_FAILURE, "db: %s", name); 260 } 261 262 n = emalloc(sizeof(NODE) + key.size); 263 264 n->n_narcs = 0; 265 n->n_arcsize = 0; 266 n->n_arcs = NULL; 267 n->n_refcnt = 0; 268 n->n_flags = 0; 269 (void)memmove(n->n_name, name, key.size); 270 271 /* Add to linked list. */ 272 if ((n->n_next = graph) != NULL) 273 graph->n_prevp = &n->n_next; 274 n->n_prevp = &graph; 275 graph = n; 276 277 /* Add to hash table. */ 278 data.data = &n; 279 data.size = sizeof(n); 280 if ((*db->put)(db, &key, &data, 0)) 281 err(EXIT_FAILURE, "db: %s", name); 282 return n; 283 } 284 285 286 /* 287 * Clear the NODEST flag from all nodes. 288 */ 289 static void 290 clear_cycle(void) 291 { 292 NODE *n; 293 294 for (n = graph; n != NULL; n = n->n_next) 295 n->n_flags &= ~NF_NODEST; 296 } 297 298 /* do topological sort on graph */ 299 static void 300 tsort(void) 301 { 302 NODE *n, *next; 303 size_t cnt, i; 304 305 while (graph != NULL) { 306 /* 307 * Keep getting rid of simple cases until there are none left, 308 * if there are any nodes still in the graph, then there is 309 * a cycle in it. 310 */ 311 do { 312 for (cnt = 0, n = graph; n != NULL; n = next) { 313 next = n->n_next; 314 if (n->n_refcnt == 0) { 315 remove_node(n); 316 ++cnt; 317 } 318 } 319 } while (graph != NULL && cnt); 320 321 if (graph == NULL) 322 break; 323 324 if (!cycle_buf) { 325 /* 326 * Allocate space for two cycle logs - one to be used 327 * as scratch space, the other to save the longest 328 * cycle. 329 */ 330 for (cnt = 0, n = graph; n != NULL; n = n->n_next) 331 ++cnt; 332 cycle_buf = ecalloc(cnt, sizeof(*cycle_buf)); 333 longest_cycle = ecalloc(cnt, sizeof(*longest_cycle)); 334 } 335 for (n = graph; n != NULL; n = n->n_next) { 336 if (!(n->n_flags & NF_ACYCLIC)) { 337 if ((cnt = find_cycle(n, n, 0, 0)) != 0) { 338 if (!quiet) { 339 warnx("cycle in data"); 340 for (i = 0; i < cnt; i++) 341 warnx("%s", 342 longest_cycle[i]->n_name); 343 } 344 remove_node(n); 345 clear_cycle(); 346 break; 347 } else { 348 /* to avoid further checks */ 349 n->n_flags |= NF_ACYCLIC; 350 clear_cycle(); 351 } 352 } 353 } 354 if (n == NULL) 355 errx(1, "internal error -- could not find cycle"); 356 } 357 } 358 359 /* print node and remove from graph (does not actually free node) */ 360 static void 361 remove_node(NODE *n) 362 { 363 NODE **np; 364 size_t i; 365 366 (void)printf("%s\n", n->n_name); 367 for (np = n->n_arcs, i = n->n_narcs; i-- > 0; np++) 368 --(*np)->n_refcnt; 369 n->n_narcs = 0; 370 *n->n_prevp = n->n_next; 371 if (n->n_next) 372 n->n_next->n_prevp = n->n_prevp; 373 } 374 375 376 /* look for the longest? cycle from node from to node to. */ 377 static size_t 378 find_cycle(NODE *from, NODE *to, size_t longest_len, size_t depth) 379 { 380 NODE **np; 381 size_t i, len; 382 383 /* 384 * avoid infinite loops and ignore portions of the graph known 385 * to be acyclic 386 */ 387 if (from->n_flags & (NF_NODEST|NF_MARK|NF_ACYCLIC)) 388 return 0; 389 from->n_flags |= NF_MARK; 390 391 for (np = from->n_arcs, i = from->n_narcs; i-- > 0; np++) { 392 cycle_buf[depth] = *np; 393 if (*np == to) { 394 if (depth + 1 > longest_len) { 395 longest_len = depth + 1; 396 (void)memcpy(longest_cycle, cycle_buf, 397 longest_len * sizeof(NODE *)); 398 } 399 } else { 400 if ((*np)->n_flags & (NF_MARK|NF_ACYCLIC|NF_NODEST)) 401 continue; 402 len = find_cycle(*np, to, longest_len, depth + 1); 403 404 if (debug) 405 (void)printf("%*s %s->%s %zu\n", (int)depth, "", 406 from->n_name, to->n_name, len); 407 408 if (len == 0) 409 (*np)->n_flags |= NF_NODEST; 410 411 if (len > longest_len) 412 longest_len = len; 413 414 if (len > 0 && !longest) 415 break; 416 } 417 } 418 from->n_flags &= ~NF_MARK; 419 return longest_len; 420 } 421 422 static void 423 usage(void) 424 { 425 (void)fprintf(stderr, "Usage: %s [-dlqr] [file]\n", getprogname()); 426 exit(EXIT_FAILURE); 427 } 428
Indexes created Sat Sep 20 22:09:52 GMT 2025