1 /*
2 * Copyright (c) 1989, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Michael Rendell of Memorial University of Newfoundland.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #ifndef lint
34 static const char copyright[] =
35 "@(#) Copyright (c) 1989, 1993, 1994\n\
36 The Regents of the University of California. All rights reserved.\n";
37 #endif /* not lint */
38
39 #ifndef lint
40 static const char sccsid[] = "@(#)tsort.c 8.3 (Berkeley) 5/4/95";
41 #endif /* not lint */
42
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD: stable/9/usr.bin/tsort/tsort.c 216370 2010-12-11 08:32:16Z joel $");
45
46 #include <sys/types.h>
47
48 #include <ctype.h>
49 #include <db.h>
50 #include <err.h>
51 #include <errno.h>
52 #include <fcntl.h>
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <string.h>
56 #include <unistd.h>
57
58 /*
59 * Topological sort. Input is a list of pairs of strings separated by
60 * white space (spaces, tabs, and/or newlines); strings are written to
61 * standard output in sorted order, one per line.
62 *
63 * usage:
64 * tsort [-dlq] [inputfile]
65 * If no input file is specified, standard input is read.
66 *
67 * Should be compatible with AT&T tsort HOWEVER the output is not identical
68 * (i.e. for most graphs there is more than one sorted order, and this tsort
69 * usually generates a different one then the AT&T tsort). Also, cycle
70 * reporting seems to be more accurate in this version (the AT&T tsort
71 * sometimes says a node is in a cycle when it isn't).
72 *
73 * Michael Rendell, michael@stretch.cs.mun.ca - Feb 26, '90
74 */
75
76 #define NF_MARK 0x1 /* marker for cycle detection */
77 #define NF_ACYCLIC 0x2 /* this node is cycle free */
78 #define NF_NODEST 0x4 /* Unreachable */
79
80
81 typedef struct node_str NODE;
82
83 struct node_str {
84 NODE **n_prevp; /* pointer to previous node's n_next */
85 NODE *n_next; /* next node in graph */
86 NODE **n_arcs; /* array of arcs to other nodes */
87 int n_narcs; /* number of arcs in n_arcs[] */
88 int n_arcsize; /* size of n_arcs[] array */
89 int n_refcnt; /* # of arcs pointing to this node */
90 int n_flags; /* NF_* */
91 char n_name[1]; /* name of this node */
92 };
93
94 typedef struct _buf {
95 char *b_buf;
96 int b_bsize;
97 } BUF;
98
99 DB *db;
100 NODE *graph, **cycle_buf, **longest_cycle;
101 int debug, longest, quiet;
102
103 void add_arc(char *, char *);
104 int find_cycle(NODE *, NODE *, int, int);
105 NODE *get_node(char *);
106 void *grow_buf(void *, size_t);
107 void remove_node(NODE *);
108 void clear_cycle(void);
109 void tsort(void);
110 void usage(void);
111
112 int
main(int argc,char * argv[])113 main(int argc, char *argv[])
114 {
115 BUF *b;
116 int c, n;
117 FILE *fp;
118 int bsize, ch, nused;
119 BUF bufs[2];
120
121 fp = NULL;
122 while ((ch = getopt(argc, argv, "dlq")) != -1)
123 switch (ch) {
124 case 'd':
125 debug = 1;
126 break;
127 case 'l':
128 longest = 1;
129 break;
130 case 'q':
131 quiet = 1;
132 break;
133 case '?':
134 default:
135 usage();
136 }
137 argc -= optind;
138 argv += optind;
139
140 switch (argc) {
141 case 0:
142 fp = stdin;
143 break;
144 case 1:
145 if ((fp = fopen(*argv, "r")) == NULL)
146 err(1, "%s", *argv);
147 break;
148 default:
149 usage();
150 }
151
152 for (b = bufs, n = 2; --n >= 0; b++)
153 b->b_buf = grow_buf(NULL, b->b_bsize = 1024);
154
155 /* parse input and build the graph */
156 for (n = 0, c = getc(fp);;) {
157 while (c != EOF && isspace(c))
158 c = getc(fp);
159 if (c == EOF)
160 break;
161
162 nused = 0;
163 b = &bufs[n];
164 bsize = b->b_bsize;
165 do {
166 b->b_buf[nused++] = c;
167 if (nused == bsize)
168 b->b_buf = grow_buf(b->b_buf, bsize *= 2);
169 c = getc(fp);
170 } while (c != EOF && !isspace(c));
171
172 b->b_buf[nused] = '\0';
173 b->b_bsize = bsize;
174 if (n)
175 add_arc(bufs[0].b_buf, bufs[1].b_buf);
176 n = !n;
177 }
178 (void)fclose(fp);
179 if (n)
180 errx(1, "odd data count");
181
182 /* do the sort */
183 tsort();
184 exit(0);
185 }
186
187 /* double the size of oldbuf and return a pointer to the new buffer. */
188 void *
grow_buf(void * bp,size_t size)189 grow_buf(void *bp, size_t size)
190 {
191 if ((bp = realloc(bp, size)) == NULL)
192 err(1, NULL);
193 return (bp);
194 }
195
196 /*
197 * add an arc from node s1 to node s2 in the graph. If s1 or s2 are not in
198 * the graph, then add them.
199 */
200 void
add_arc(char * s1,char * s2)201 add_arc(char *s1, char *s2)
202 {
203 NODE *n1;
204 NODE *n2;
205 int bsize, i;
206
207 n1 = get_node(s1);
208
209 if (!strcmp(s1, s2))
210 return;
211
212 n2 = get_node(s2);
213
214 /*
215 * Check if this arc is already here.
216 */
217 for (i = 0; i < n1->n_narcs; i++)
218 if (n1->n_arcs[i] == n2)
219 return;
220 /*
221 * Add it.
222 */
223 if (n1->n_narcs == n1->n_arcsize) {
224 if (!n1->n_arcsize)
225 n1->n_arcsize = 10;
226 bsize = n1->n_arcsize * sizeof(*n1->n_arcs) * 2;
227 n1->n_arcs = grow_buf(n1->n_arcs, bsize);
228 n1->n_arcsize = bsize / sizeof(*n1->n_arcs);
229 }
230 n1->n_arcs[n1->n_narcs++] = n2;
231 ++n2->n_refcnt;
232 }
233
234 /* Find a node in the graph (insert if not found) and return a pointer to it. */
235 NODE *
get_node(char * name)236 get_node(char *name)
237 {
238 DBT data, key;
239 NODE *n;
240
241 if (db == NULL &&
242 (db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == NULL)
243 err(1, "db: %s", name);
244
245 key.data = name;
246 key.size = strlen(name) + 1;
247
248 switch ((*db->get)(db, &key, &data, 0)) {
249 case 0:
250 bcopy(data.data, &n, sizeof(n));
251 return (n);
252 case 1:
253 break;
254 default:
255 case -1:
256 err(1, "db: %s", name);
257 }
258
259 if ((n = malloc(sizeof(NODE) + key.size)) == NULL)
260 err(1, NULL);
261
262 n->n_narcs = 0;
263 n->n_arcsize = 0;
264 n->n_arcs = NULL;
265 n->n_refcnt = 0;
266 n->n_flags = 0;
267 bcopy(name, n->n_name, key.size);
268
269 /* Add to linked list. */
270 if ((n->n_next = graph) != NULL)
271 graph->n_prevp = &n->n_next;
272 n->n_prevp = &graph;
273 graph = n;
274
275 /* Add to hash table. */
276 data.data = &n;
277 data.size = sizeof(n);
278 if ((*db->put)(db, &key, &data, 0))
279 err(1, "db: %s", name);
280 return (n);
281 }
282
283
284 /*
285 * Clear the NODEST flag from all nodes.
286 */
287 void
clear_cycle(void)288 clear_cycle(void)
289 {
290 NODE *n;
291
292 for (n = graph; n != NULL; n = n->n_next)
293 n->n_flags &= ~NF_NODEST;
294 }
295
296 /* do topological sort on graph */
297 void
tsort(void)298 tsort(void)
299 {
300 NODE *n, *next;
301 int cnt, i;
302
303 while (graph != NULL) {
304 /*
305 * Keep getting rid of simple cases until there are none left,
306 * if there are any nodes still in the graph, then there is
307 * a cycle in it.
308 */
309 do {
310 for (cnt = 0, n = graph; n != NULL; n = next) {
311 next = n->n_next;
312 if (n->n_refcnt == 0) {
313 remove_node(n);
314 ++cnt;
315 }
316 }
317 } while (graph != NULL && cnt);
318
319 if (graph == NULL)
320 break;
321
322 if (!cycle_buf) {
323 /*
324 * Allocate space for two cycle logs - one to be used
325 * as scratch space, the other to save the longest
326 * cycle.
327 */
328 for (cnt = 0, n = graph; n != NULL; n = n->n_next)
329 ++cnt;
330 cycle_buf = malloc(sizeof(NODE *) * cnt);
331 longest_cycle = malloc(sizeof(NODE *) * cnt);
332 if (cycle_buf == NULL || longest_cycle == NULL)
333 err(1, NULL);
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))) {
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 void
remove_node(NODE * n)361 remove_node(NODE *n)
362 {
363 NODE **np;
364 int 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 int
find_cycle(NODE * from,NODE * to,int longest_len,int depth)378 find_cycle(NODE *from, NODE *to, int longest_len, int depth)
379 {
380 NODE **np;
381 int 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((char *)longest_cycle,
397 (char *)cycle_buf,
398 longest_len * sizeof(NODE *));
399 }
400 } else {
401 if ((*np)->n_flags & (NF_MARK|NF_ACYCLIC|NF_NODEST))
402 continue;
403 len = find_cycle(*np, to, longest_len, depth + 1);
404
405 if (debug)
406 (void)printf("%*s %s->%s %d\n", depth, "",
407 from->n_name, to->n_name, len);
408
409 if (len == 0)
410 (*np)->n_flags |= NF_NODEST;
411
412 if (len > longest_len)
413 longest_len = len;
414
415 if (len > 0 && !longest)
416 break;
417 }
418 }
419 from->n_flags &= ~NF_MARK;
420 return (longest_len);
421 }
422
423 void
usage(void)424 usage(void)
425 {
426 (void)fprintf(stderr, "usage: tsort [-dlq] [file]\n");
427 exit(1);
428 }
429