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1.4 ! millert 1: /* $OpenBSD: tsort.c,v 1.3 1996/06/26 05:42:00 deraadt Exp $ */
1.2 deraadt 2: /* $NetBSD: tsort.c,v 1.11 1996/01/17 20:37:53 mycroft Exp $ */
1.1 deraadt 3:
4: /*
5: * Copyright (c) 1989, 1993, 1994
6: * The Regents of the University of California. All rights reserved.
7: *
8: * This code is derived from software contributed to Berkeley by
9: * Michael Rendell of Memorial University of Newfoundland.
10: *
11: * Redistribution and use in source and binary forms, with or without
12: * modification, are permitted provided that the following conditions
13: * are met:
14: * 1. Redistributions of source code must retain the above copyright
15: * notice, this list of conditions and the following disclaimer.
16: * 2. Redistributions in binary form must reproduce the above copyright
17: * notice, this list of conditions and the following disclaimer in the
18: * documentation and/or other materials provided with the distribution.
19: * 3. All advertising materials mentioning features or use of this software
20: * must display the following acknowledgement:
21: * This product includes software developed by the University of
22: * California, Berkeley and its contributors.
23: * 4. Neither the name of the University nor the names of its contributors
24: * may be used to endorse or promote products derived from this software
25: * without specific prior written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37: * SUCH DAMAGE.
38: */
39:
40: #ifndef lint
41: static char copyright[] =
42: "@(#) Copyright (c) 1989, 1993, 1994\n\
43: The Regents of the University of California. All rights reserved.\n";
44: #endif /* not lint */
45:
46: #ifndef lint
47: #if 0
48: static char sccsid[] = "@(#)tsort.c 8.3 (Berkeley) 5/4/95";
49: #endif
1.4 ! millert 50: static char rcsid[] = "$OpenBSD: tsort.c,v 1.3 1996/06/26 05:42:00 deraadt Exp $";
1.1 deraadt 51: #endif /* not lint */
52:
53: #include <sys/types.h>
54:
55: #include <ctype.h>
56: #include <db.h>
57: #include <err.h>
58: #include <errno.h>
59: #include <fcntl.h>
60: #include <stdio.h>
61: #include <stdlib.h>
62: #include <string.h>
63: #include <unistd.h>
64:
65: /*
66: * Topological sort. Input is a list of pairs of strings separated by
67: * white space (spaces, tabs, and/or newlines); strings are written to
68: * standard output in sorted order, one per line.
69: *
70: * usage:
71: * tsort [-l] [inputfile]
72: * If no input file is specified, standard input is read.
73: *
74: * Should be compatable with AT&T tsort HOWEVER the output is not identical
75: * (i.e. for most graphs there is more than one sorted order, and this tsort
76: * usually generates a different one then the AT&T tsort). Also, cycle
77: * reporting seems to be more accurate in this version (the AT&T tsort
78: * sometimes says a node is in a cycle when it isn't).
79: *
80: * Michael Rendell, michael@stretch.cs.mun.ca - Feb 26, '90
81: */
82: #define HASHSIZE 53 /* doesn't need to be big */
83: #define NF_MARK 0x1 /* marker for cycle detection */
84: #define NF_ACYCLIC 0x2 /* this node is cycle free */
85: #define NF_NODEST 0x4 /* Unreachable */
86:
87: typedef struct node_str NODE;
88:
89: struct node_str {
90: NODE **n_prevp; /* pointer to previous node's n_next */
91: NODE *n_next; /* next node in graph */
92: NODE **n_arcs; /* array of arcs to other nodes */
93: int n_narcs; /* number of arcs in n_arcs[] */
94: int n_arcsize; /* size of n_arcs[] array */
95: int n_refcnt; /* # of arcs pointing to this node */
96: int n_flags; /* NF_* */
97: char n_name[1]; /* name of this node */
98: };
99:
100: typedef struct _buf {
101: char *b_buf;
102: int b_bsize;
103: } BUF;
104:
105: DB *db;
106: NODE *graph, **cycle_buf, **longest_cycle;
1.2 deraadt 107: int debug, longest, quiet;
1.1 deraadt 108:
109: void add_arc __P((char *, char *));
110: int find_cycle __P((NODE *, NODE *, int, int));
111: NODE *get_node __P((char *));
112: void *grow_buf __P((void *, int));
113: void remove_node __P((NODE *));
114: void tsort __P((void));
115: void usage __P((void));
116:
117: int
118: main(argc, argv)
119: int argc;
120: char *argv[];
121: {
122: register BUF *b;
123: register int c, n;
124: FILE *fp;
125: int bsize, ch, nused;
126: BUF bufs[2];
127:
1.4 ! millert 128: while ((ch = getopt(argc, argv, "dlq")) != -1)
1.1 deraadt 129: switch (ch) {
130: case 'd':
131: debug = 1;
132: break;
133: case 'l':
134: longest = 1;
135: break;
1.2 deraadt 136: case 'q':
137: quiet = 1;
138: break;
1.1 deraadt 139: case '?':
140: default:
141: usage();
142: }
143: argc -= optind;
144: argv += optind;
145:
146: switch (argc) {
147: case 0:
148: fp = stdin;
149: break;
150: case 1:
151: if ((fp = fopen(*argv, "r")) == NULL)
152: err(1, "%s", *argv);
153: break;
154: default:
155: usage();
156: }
157:
158: for (b = bufs, n = 2; --n >= 0; b++)
159: b->b_buf = grow_buf(NULL, b->b_bsize = 1024);
160:
161: /* parse input and build the graph */
162: for (n = 0, c = getc(fp);;) {
163: while (c != EOF && isspace(c))
164: c = getc(fp);
165: if (c == EOF)
166: break;
167:
168: nused = 0;
169: b = &bufs[n];
170: bsize = b->b_bsize;
171: do {
172: b->b_buf[nused++] = c;
173: if (nused == bsize)
174: b->b_buf = grow_buf(b->b_buf, bsize *= 2);
175: c = getc(fp);
176: } while (c != EOF && !isspace(c));
177:
178: b->b_buf[nused] = '\0';
179: b->b_bsize = bsize;
180: if (n)
181: add_arc(bufs[0].b_buf, bufs[1].b_buf);
182: n = !n;
183: }
184: (void)fclose(fp);
185: if (n)
186: errx(1, "odd data count");
187:
188: /* do the sort */
189: tsort();
190: exit(0);
191: }
192:
193: /* double the size of oldbuf and return a pointer to the new buffer. */
194: void *
195: grow_buf(bp, size)
196: void *bp;
197: int size;
198: {
199: if ((bp = realloc(bp, (u_int)size)) == NULL)
200: err(1, NULL);
201: return (bp);
202: }
203:
204: /*
205: * add an arc from node s1 to node s2 in the graph. If s1 or s2 are not in
206: * the graph, then add them.
207: */
208: void
209: add_arc(s1, s2)
210: char *s1, *s2;
211: {
212: register NODE *n1;
213: NODE *n2;
214: int bsize, i;
215:
216: n1 = get_node(s1);
217:
218: if (!strcmp(s1, s2))
219: return;
220:
221: n2 = get_node(s2);
222:
223: /*
224: * Check if this arc is already here.
225: */
226: for (i = 0; i < n1->n_narcs; i++)
227: if (n1->n_arcs[i] == n2)
228: return;
229: /*
230: * Add it.
231: */
232: if (n1->n_narcs == n1->n_arcsize) {
233: if (!n1->n_arcsize)
234: n1->n_arcsize = 10;
235: bsize = n1->n_arcsize * sizeof(*n1->n_arcs) * 2;
236: n1->n_arcs = grow_buf(n1->n_arcs, bsize);
237: n1->n_arcsize = bsize / sizeof(*n1->n_arcs);
238: }
239: n1->n_arcs[n1->n_narcs++] = n2;
240: ++n2->n_refcnt;
241: }
242:
243: /* Find a node in the graph (insert if not found) and return a pointer to it. */
244: NODE *
245: get_node(name)
246: char *name;
247: {
248: DBT data, key;
249: NODE *n;
250:
251: if (db == NULL &&
252: (db = dbopen(NULL, O_RDWR, 0, DB_HASH, NULL)) == NULL)
253: err(1, "db: %s", name);
254:
255: key.data = name;
256: key.size = strlen(name) + 1;
257:
258: switch ((*db->get)(db, &key, &data, 0)) {
259: case 0:
260: bcopy(data.data, &n, sizeof(n));
261: return (n);
262: case 1:
263: break;
264: default:
265: case -1:
266: err(1, "db: %s", name);
267: }
268:
269: if ((n = malloc(sizeof(NODE) + key.size)) == NULL)
270: err(1, NULL);
271:
272: n->n_narcs = 0;
273: n->n_arcsize = 0;
274: n->n_arcs = NULL;
275: n->n_refcnt = 0;
276: n->n_flags = 0;
277: bcopy(name, n->n_name, key.size);
278:
279: /* Add to linked list. */
280: if ((n->n_next = graph) != NULL)
281: graph->n_prevp = &n->n_next;
282: n->n_prevp = &graph;
283: graph = n;
284:
285: /* Add to hash table. */
286: data.data = &n;
287: data.size = sizeof(n);
288: if ((*db->put)(db, &key, &data, 0))
289: err(1, "db: %s", name);
290: return (n);
291: }
292:
293:
294: /*
295: * Clear the NODEST flag from all nodes.
296: */
297: void
298: clear_cycle()
299: {
300: NODE *n;
301:
302: for (n = graph; n != NULL; n = n->n_next)
303: n->n_flags &= ~NF_NODEST;
304: }
305:
306: /* do topological sort on graph */
307: void
308: tsort()
309: {
310: register NODE *n, *next;
311: register int cnt, i;
312:
313: while (graph != NULL) {
314: /*
315: * Keep getting rid of simple cases until there are none left,
316: * if there are any nodes still in the graph, then there is
317: * a cycle in it.
318: */
319: do {
320: for (cnt = 0, n = graph; n != NULL; n = next) {
321: next = n->n_next;
322: if (n->n_refcnt == 0) {
323: remove_node(n);
324: ++cnt;
325: }
326: }
327: } while (graph != NULL && cnt);
328:
329: if (graph == NULL)
330: break;
331:
332: if (!cycle_buf) {
333: /*
334: * Allocate space for two cycle logs - one to be used
335: * as scratch space, the other to save the longest
336: * cycle.
337: */
338: for (cnt = 0, n = graph; n != NULL; n = n->n_next)
339: ++cnt;
340: cycle_buf = malloc((u_int)sizeof(NODE *) * cnt);
341: longest_cycle = malloc((u_int)sizeof(NODE *) * cnt);
342: if (cycle_buf == NULL || longest_cycle == NULL)
343: err(1, NULL);
344: }
345: for (n = graph; n != NULL; n = n->n_next)
346: if (!(n->n_flags & NF_ACYCLIC))
347: if (cnt = find_cycle(n, n, 0, 0)) {
1.2 deraadt 348: if (!quiet) {
349: warnx("cycle in data");
350: for (i = 0; i < cnt; i++)
351: warnx("%s",
352: longest_cycle[i]->n_name);
353: }
1.1 deraadt 354: remove_node(n);
355: clear_cycle();
356: break;
357: } else {
358: /* to avoid further checks */
359: n->n_flags |= NF_ACYCLIC;
360: clear_cycle();
361: }
362:
363: if (n == NULL)
364: errx(1, "internal error -- could not find cycle");
365: }
366: }
367:
368: /* print node and remove from graph (does not actually free node) */
369: void
370: remove_node(n)
371: register NODE *n;
372: {
373: register NODE **np;
374: register int i;
375:
376: (void)printf("%s\n", n->n_name);
377: for (np = n->n_arcs, i = n->n_narcs; --i >= 0; np++)
378: --(*np)->n_refcnt;
379: n->n_narcs = 0;
380: *n->n_prevp = n->n_next;
381: if (n->n_next)
382: n->n_next->n_prevp = n->n_prevp;
383: }
384:
385:
386: /* look for the longest? cycle from node from to node to. */
387: int
388: find_cycle(from, to, longest_len, depth)
389: NODE *from, *to;
390: int depth, longest_len;
391: {
392: register NODE **np;
393: register int i, len;
394:
395: /*
396: * avoid infinite loops and ignore portions of the graph known
397: * to be acyclic
398: */
399: if (from->n_flags & (NF_NODEST|NF_MARK|NF_ACYCLIC))
400: return (0);
401: from->n_flags |= NF_MARK;
402:
403: for (np = from->n_arcs, i = from->n_narcs; --i >= 0; np++) {
404: cycle_buf[depth] = *np;
405: if (*np == to) {
406: if (depth + 1 > longest_len) {
407: longest_len = depth + 1;
408: (void)memcpy((char *)longest_cycle,
409: (char *)cycle_buf,
410: longest_len * sizeof(NODE *));
411: }
412: } else {
413: if ((*np)->n_flags & (NF_MARK|NF_ACYCLIC|NF_NODEST))
414: continue;
415: len = find_cycle(*np, to, longest_len, depth + 1);
416:
417: if (debug)
418: (void)printf("%*s %s->%s %d\n", depth, "",
419: from->n_name, to->n_name, len);
420:
421: if (len == 0)
422: (*np)->n_flags |= NF_NODEST;
423:
424: if (len > longest_len)
425: longest_len = len;
426:
427: if (len > 0 && !longest)
428: break;
429: }
430: }
431: from->n_flags &= ~NF_MARK;
432: return (longest_len);
433: }
434:
435: void
436: usage()
437: {
1.2 deraadt 438: (void)fprintf(stderr, "usage: tsort [-lq] [file]\n");
1.1 deraadt 439: exit(1);
440: }