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@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
main(int argc,char * argv[])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
add_arc(const char * s1,const char * s2)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 *
get_node(const char * name)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
clear_cycle(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
tsort(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
remove_node(NODE * n)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
find_cycle(NODE * from,NODE * to,size_t longest_len,size_t depth)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
usage(void)423 usage(void)
424 {
425 (void)fprintf(stderr, "Usage: %s [-dlqr] [file]\n", getprogname());
426 exit(EXIT_FAILURE);
427 }
428