1 /* $NetBSD: tsort.c,v 1.23 2011/09/06 18:34:37 joerg 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 1.23 2011/09/06 18:34:37 joerg 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
60 /*
61 * Topological sort. Input is a list of pairs of strings separated by
62 * white space (spaces, tabs, and/or newlines); strings are written to
63 * standard output in sorted order, one per line.
64 *
65 * usage:
66 * tsort [-l] [inputfile]
67 * If no input file is specified, standard input is read.
68 *
69 * Should be compatible with AT&T tsort HOWEVER the output is not identical
70 * (i.e. for most graphs there is more than one sorted order, and this tsort
71 * usually generates a different one then the AT&T tsort). Also, cycle
72 * reporting seems to be more accurate in this version (the AT&T tsort
73 * sometimes says a node is in a cycle when it isn't).
74 *
75 * Michael Rendell, michael@stretch.cs.mun.ca - Feb 26, '90
76 */
77 #define HASHSIZE 53 /* doesn't need to be big */
78 #define NF_MARK 0x1 /* marker for cycle detection */
79 #define NF_ACYCLIC 0x2 /* this node is cycle free */
80 #define NF_NODEST 0x4 /* Unreachable */
81
82 typedef struct node_str NODE;
83
84 struct node_str {
85 NODE **n_prevp; /* pointer to previous node's n_next */
86 NODE *n_next; /* next node in graph */
87 NODE **n_arcs; /* array of arcs to other nodes */
88 int n_narcs; /* number of arcs in n_arcs[] */
89 int n_arcsize; /* size of n_arcs[] array */
90 int n_refcnt; /* # of arcs pointing to this node */
91 int n_flags; /* NF_* */
92 char n_name[1]; /* name of this node */
93 };
94
95 typedef struct _buf {
96 char *b_buf;
97 int b_bsize;
98 } BUF;
99
100 static DB *db;
101 static NODE *graph, **cycle_buf, **longest_cycle;
102 static int debug, longest, quiet;
103
104 static void add_arc(char *, char *);
105 static void clear_cycle(void);
106 static int find_cycle(NODE *, NODE *, int, int);
107 static NODE *get_node(char *);
108 static void *grow_buf(void *, int);
109 static void remove_node(NODE *);
110 static void tsort(void);
111 __dead static void usage(void);
112
113 int
main(int argc,char * argv[])114 main(int argc, char *argv[])
115 {
116 BUF *b;
117 int c, n;
118 FILE *fp;
119 int bsize, ch, nused;
120 BUF bufs[2];
121
122 setprogname(argv[0]);
123
124 fp = NULL;
125 while ((ch = getopt(argc, argv, "dlq")) != -1)
126 switch (ch) {
127 case 'd':
128 debug = 1;
129 break;
130 case 'l':
131 longest = 1;
132 break;
133 case 'q':
134 quiet = 1;
135 break;
136 case '?':
137 default:
138 usage();
139 }
140 argc -= optind;
141 argv += optind;
142
143 switch (argc) {
144 case 0:
145 fp = stdin;
146 break;
147 case 1:
148 if ((fp = fopen(*argv, "r")) == NULL)
149 err(1, "%s", *argv);
150 break;
151 default:
152 usage();
153 }
154
155 for (b = bufs, n = 2; --n >= 0; b++)
156 b->b_buf = grow_buf(NULL, b->b_bsize = 1024);
157
158 /* parse input and build the graph */
159 for (n = 0, c = getc(fp);;) {
160 while (c != EOF && isspace(c))
161 c = getc(fp);
162 if (c == EOF)
163 break;
164
165 nused = 0;
166 b = &bufs[n];
167 bsize = b->b_bsize;
168 do {
169 b->b_buf[nused++] = c;
170 if (nused == bsize)
171 b->b_buf = grow_buf(b->b_buf, bsize *= 2);
172 c = getc(fp);
173 } while (c != EOF && !isspace(c));
174
175 b->b_buf[nused] = '\0';
176 b->b_bsize = bsize;
177 if (n)
178 add_arc(bufs[0].b_buf, bufs[1].b_buf);
179 n = !n;
180 }
181 (void)fclose(fp);
182 if (n)
183 errx(1, "odd data count");
184
185 /* do the sort */
186 tsort();
187 return(0);
188 }
189
190 /* double the size of oldbuf and return a pointer to the new buffer. */
191 static void *
grow_buf(void * bp,int size)192 grow_buf(void *bp, int size)
193 {
194 void *n;
195
196 if ((n = realloc(bp, (u_int)size)) == NULL)
197 err(1, "realloc");
198 bp = n;
199 return (bp);
200 }
201
202 /*
203 * add an arc from node s1 to node s2 in the graph. If s1 or s2 are not in
204 * the graph, then add them.
205 */
206 static void
add_arc(char * s1,char * s2)207 add_arc(char *s1, char *s2)
208 {
209 NODE *n1;
210 NODE *n2;
211 int bsize, i;
212
213 n1 = get_node(s1);
214
215 if (!strcmp(s1, s2))
216 return;
217
218 n2 = get_node(s2);
219
220 /*
221 * Check if this arc is already here.
222 */
223 for (i = 0; i < n1->n_narcs; i++)
224 if (n1->n_arcs[i] == n2)
225 return;
226 /*
227 * Add it.
228 */
229 if (n1->n_narcs == n1->n_arcsize) {
230 if (!n1->n_arcsize)
231 n1->n_arcsize = 10;
232 bsize = n1->n_arcsize * sizeof(*n1->n_arcs) * 2;
233 n1->n_arcs = grow_buf(n1->n_arcs, bsize);
234 n1->n_arcsize = bsize / sizeof(*n1->n_arcs);
235 }
236 n1->n_arcs[n1->n_narcs++] = n2;
237 ++n2->n_refcnt;
238 }
239
240 /* Find a node in the graph (insert if not found) and return a pointer to it. */
241 static NODE *
get_node(char * name)242 get_node(char *name)
243 {
244 DBT data, key;
245 NODE *n;
246
247 if (db == NULL &&
248 (db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == NULL)
249 err(1, "db: %s", name);
250
251 key.data = name;
252 key.size = strlen(name) + 1;
253
254 switch ((*db->get)(db, &key, &data, 0)) {
255 case 0:
256 (void)memmove(&n, data.data, sizeof(n));
257 return (n);
258 case 1:
259 break;
260 default:
261 case -1:
262 err(1, "db: %s", name);
263 }
264
265 if ((n = malloc(sizeof(NODE) + key.size)) == NULL)
266 err(1, "malloc");
267
268 n->n_narcs = 0;
269 n->n_arcsize = 0;
270 n->n_arcs = NULL;
271 n->n_refcnt = 0;
272 n->n_flags = 0;
273 (void)memmove(n->n_name, name, key.size);
274
275 /* Add to linked list. */
276 if ((n->n_next = graph) != NULL)
277 graph->n_prevp = &n->n_next;
278 n->n_prevp = &graph;
279 graph = n;
280
281 /* Add to hash table. */
282 data.data = &n;
283 data.size = sizeof(n);
284 if ((*db->put)(db, &key, &data, 0))
285 err(1, "db: %s", name);
286 return (n);
287 }
288
289
290 /*
291 * Clear the NODEST flag from all nodes.
292 */
293 static void
clear_cycle(void)294 clear_cycle(void)
295 {
296 NODE *n;
297
298 for (n = graph; n != NULL; n = n->n_next)
299 n->n_flags &= ~NF_NODEST;
300 }
301
302 /* do topological sort on graph */
303 static void
tsort(void)304 tsort(void)
305 {
306 NODE *n, *next;
307 int cnt, i;
308
309 while (graph != NULL) {
310 /*
311 * Keep getting rid of simple cases until there are none left,
312 * if there are any nodes still in the graph, then there is
313 * a cycle in it.
314 */
315 do {
316 for (cnt = 0, n = graph; n != NULL; n = next) {
317 next = n->n_next;
318 if (n->n_refcnt == 0) {
319 remove_node(n);
320 ++cnt;
321 }
322 }
323 } while (graph != NULL && cnt);
324
325 if (graph == NULL)
326 break;
327
328 if (!cycle_buf) {
329 /*
330 * Allocate space for two cycle logs - one to be used
331 * as scratch space, the other to save the longest
332 * cycle.
333 */
334 for (cnt = 0, n = graph; n != NULL; n = n->n_next)
335 ++cnt;
336 cycle_buf = malloc((u_int)sizeof(NODE *) * cnt);
337 longest_cycle = malloc((u_int)sizeof(NODE *) * cnt);
338 if (cycle_buf == NULL || longest_cycle == NULL)
339 err(1, "malloc");
340 }
341 for (n = graph; n != NULL; n = n->n_next) {
342 if (!(n->n_flags & NF_ACYCLIC)) {
343 if ((cnt = find_cycle(n, n, 0, 0)) != 0) {
344 if (!quiet) {
345 warnx("cycle in data");
346 for (i = 0; i < cnt; i++)
347 warnx("%s",
348 longest_cycle[i]->n_name);
349 }
350 remove_node(n);
351 clear_cycle();
352 break;
353 } else {
354 /* to avoid further checks */
355 n->n_flags |= NF_ACYCLIC;
356 clear_cycle();
357 }
358 }
359 }
360 if (n == NULL)
361 errx(1, "internal error -- could not find cycle");
362 }
363 }
364
365 /* print node and remove from graph (does not actually free node) */
366 static void
remove_node(NODE * n)367 remove_node(NODE *n)
368 {
369 NODE **np;
370 int i;
371
372 (void)printf("%s\n", n->n_name);
373 for (np = n->n_arcs, i = n->n_narcs; --i >= 0; np++)
374 --(*np)->n_refcnt;
375 n->n_narcs = 0;
376 *n->n_prevp = n->n_next;
377 if (n->n_next)
378 n->n_next->n_prevp = n->n_prevp;
379 }
380
381
382 /* look for the longest? cycle from node from to node to. */
383 static int
find_cycle(NODE * from,NODE * to,int longest_len,int depth)384 find_cycle(NODE *from, NODE *to, int longest_len, int depth)
385 {
386 NODE **np;
387 int i, len;
388
389 /*
390 * avoid infinite loops and ignore portions of the graph known
391 * to be acyclic
392 */
393 if (from->n_flags & (NF_NODEST|NF_MARK|NF_ACYCLIC))
394 return (0);
395 from->n_flags |= NF_MARK;
396
397 for (np = from->n_arcs, i = from->n_narcs; --i >= 0; np++) {
398 cycle_buf[depth] = *np;
399 if (*np == to) {
400 if (depth + 1 > longest_len) {
401 longest_len = depth + 1;
402 (void)memcpy(longest_cycle, cycle_buf,
403 longest_len * sizeof(NODE *));
404 }
405 } else {
406 if ((*np)->n_flags & (NF_MARK|NF_ACYCLIC|NF_NODEST))
407 continue;
408 len = find_cycle(*np, to, longest_len, depth + 1);
409
410 if (debug)
411 (void)printf("%*s %s->%s %d\n", depth, "",
412 from->n_name, to->n_name, len);
413
414 if (len == 0)
415 (*np)->n_flags |= NF_NODEST;
416
417 if (len > longest_len)
418 longest_len = len;
419
420 if (len > 0 && !longest)
421 break;
422 }
423 }
424 from->n_flags &= ~NF_MARK;
425 return (longest_len);
426 }
427
428 static void
usage(void)429 usage(void)
430 {
431 (void)fprintf(stderr, "usage: tsort [-lq] [file]\n");
432 exit(1);
433 }
434