Annotation of src/usr.bin/tsort/tsort.c, Revision 1.21
1.21 ! jmc 1: /* $OpenBSD: tsort.c,v 1.20 2006/01/20 23:10:19 espie Exp $ */
1.15 espie 2: /* ex:ts=8 sw=4:
1.1 deraadt 3: *
1.19 espie 4: * Copyright (c) 1999-2004 Marc Espie <espie@openbsd.org>
1.1 deraadt 5: *
1.19 espie 6: * Permission to use, copy, modify, and distribute this software for any
7: * purpose with or without fee is hereby granted, provided that the above
8: * copyright notice and this permission notice appear in all copies.
9: *
10: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
1.1 deraadt 17: */
18:
1.5 espie 19: #include <assert.h>
1.1 deraadt 20: #include <ctype.h>
21: #include <err.h>
1.5 espie 22: #include <limits.h>
23: #include <stddef.h>
1.1 deraadt 24: #include <stdio.h>
1.20 espie 25: #include <stdint.h>
1.1 deraadt 26: #include <stdlib.h>
27: #include <string.h>
1.5 espie 28: #include <sysexits.h>
1.1 deraadt 29: #include <unistd.h>
1.20 espie 30: #include <ohash.h>
1.1 deraadt 31:
1.15 espie 32: /* The complexity of topological sorting is O(e), where e is the
1.5 espie 33: * size of input. While reading input, vertices have to be identified,
34: * thus add the complexity of e keys retrieval among v keys using
1.15 espie 35: * an appropriate data structure. This program uses open double hashing
36: * for that purpose. See Knuth for the expected complexity of double
1.5 espie 37: * hashing (Brent variation should probably be used if v << e, as a user
38: * option).
39: *
40: * The algorithm used for longest cycle reporting is accurate, but somewhat
41: * expensive. It may need to build all free paths of the graph (a free
42: * path is a path that never goes twice through the same node), whose
1.15 espie 43: * number can be as high as O(2^e). Usually, the number of free paths is
1.5 espie 44: * much smaller though. This program's author does not believe that a
45: * significantly better worst-case complexity algorithm exists.
46: *
47: * In case of a hints file, the set of minimal nodes is maintained as a
48: * heap. The resulting complexity is O(e+v log v) for the worst case.
49: * The average should actually be near O(e).
50: *
1.8 espie 51: * If the hints file is incomplete, there is some extra complexity incurred
52: * by make_transparent, which does propagate order values to unmarked
53: * nodes. In the worst case, make_transparent is O(e u),
54: * where u is the number of originally unmarked nodes.
55: * In practice, it is much faster.
56: *
1.5 espie 57: * The simple topological sort algorithm detects cycles. This program
1.15 espie 58: * goes further, breaking cycles through the use of simple heuristics.
59: * Each cycle break checks the whole set of nodes, hence if c cycles break
1.5 espie 60: * are needed, this is an extra cost of O(c v).
1.1 deraadt 61: *
1.5 espie 62: * Possible heuristics are as follows:
63: * - break cycle at node with lowest number of predecessors (default case),
64: * - break longest cycle at node with lowest number of predecessors,
65: * - break cycle at next node from the hints file.
1.1 deraadt 66: *
1.5 espie 67: * Except for the hints file case, which sets an explicit constraint on
1.15 espie 68: * which cycle to break, those heuristics locally result in the smallest
1.5 espie 69: * number of broken edges.
1.1 deraadt 70: *
1.5 espie 71: * Those are admittedly greedy strategies, as is the selection of the next
72: * node from the hints file amongst equivalent candidates that is used for
73: * `stable' topological sorting.
1.1 deraadt 74: */
1.5 espie 75:
76: #ifdef __GNUC__
77: #define UNUSED __attribute__((unused))
78: #else
79: #define UNUSED
80: #endif
81:
82: struct node;
83:
84: /* The set of arcs from a given node is stored as a linked list. */
85: struct link {
86: struct link *next;
87: struct node *node;
88: };
89:
1.7 espie 90: #define NO_ORDER UINT_MAX
91:
1.5 espie 92: struct node {
1.15 espie 93: unsigned int refs; /* Number of arcs left, coming into this node.
94: * Note that nodes with a null count can't
1.5 espie 95: * be part of cycles. */
96: struct link *arcs; /* List of forward arcs. */
97:
98: unsigned int order; /* Order of nodes according to a hint file. */
99:
100: /* Cycle detection algorithms build a free path of nodes. */
101: struct node *from; /* Previous node in the current path. */
102:
103: unsigned int mark; /* Mark processed nodes in cycle discovery. */
104: struct link *traverse; /* Next link to traverse when backtracking. */
105: char k[1]; /* Name of this node. */
1.1 deraadt 106: };
107:
1.5 espie 108: #define HASH_START 9
109:
110: struct array {
111: unsigned int entries;
112: struct node **t;
113: };
114:
1.12 millert 115: static void nodes_init(struct ohash *);
116: static struct node *node_lookup(struct ohash *, const char *, const char *);
117: static void usage(void);
118: static struct node *new_node(const char *, const char *);
1.5 espie 119:
1.15 espie 120: static unsigned int read_pairs(FILE *, struct ohash *, int,
1.13 millert 121: const char *, unsigned int, int);
1.12 millert 122: static void split_nodes(struct ohash *, struct array *, struct array *);
123: static void make_transparent(struct ohash *);
124: static void insert_arc(struct node *, struct node *);
1.5 espie 125:
126: #ifdef DEBUG
1.12 millert 127: static void dump_node(struct node *);
128: static void dump_array(struct array *);
129: static void dump_hash(struct ohash *);
1.5 espie 130: #endif
1.15 espie 131: static unsigned int read_hints(FILE *, struct ohash *, int,
1.13 millert 132: const char *, unsigned int);
1.12 millert 133: static struct node *find_smallest_node(struct array *);
134: static struct node *find_good_cycle_break(struct array *);
135: static void print_cycle(struct array *);
136: static struct node *find_cycle_from(struct node *, struct array *);
137: static struct node *find_predecessor(struct array *, struct node *);
138: static unsigned int traverse_node(struct node *, unsigned int, struct array *);
139: static struct node *find_longest_cycle(struct array *, struct array *);
140:
141: static void heap_down(struct array *, unsigned int);
142: static void heapify(struct array *, int);
143: static struct node *dequeue(struct array *);
144: static void enqueue(struct array *, struct node *);
1.5 espie 145:
1.1 deraadt 146:
1.5 espie 147:
148: #define erealloc(n, s) emem(realloc(n, s))
1.12 millert 149: static void *hash_alloc(size_t, void *);
150: static void hash_free(void *, size_t, void *);
151: static void* entry_alloc(size_t, void *);
152: static void *emalloc(size_t);
153: static void *emem(void *);
1.5 espie 154: #define DEBUG_TRAVERSE 0
1.15 espie 155: static struct ohash_info node_info = {
1.5 espie 156: offsetof(struct node, k), NULL, hash_alloc, hash_free, entry_alloc };
157:
158:
1.12 millert 159: int main(int, char *[]);
1.5 espie 160:
161:
162: /***
1.15 espie 163: *** Memory handling.
1.5 espie 164: ***/
165:
166: static void *
1.14 espie 167: emem(void *p)
1.5 espie 168: {
169: if (p)
170: return p;
171: else
172: errx(EX_SOFTWARE, "Memory exhausted");
173: }
174:
175: static void *
1.14 espie 176: hash_alloc(size_t s, void *u UNUSED)
1.5 espie 177: {
178: return emem(calloc(s, 1));
179: }
180:
181: static void
1.14 espie 182: hash_free(void *p, size_t s UNUSED, void *u UNUSED)
1.5 espie 183: {
184: free(p);
185: }
186:
187: static void *
1.14 espie 188: entry_alloc(size_t s, void *u UNUSED)
1.5 espie 189: {
190: return emalloc(s);
191: }
192:
193: static void *
1.14 espie 194: emalloc(size_t s)
1.1 deraadt 195: {
1.5 espie 196: return emem(malloc(s));
197: }
1.1 deraadt 198:
1.5 espie 199:
1.15 espie 200: /***
1.5 espie 201: *** Hash table.
202: ***/
203:
204: /* Inserting and finding nodes in the hash structure.
205: * We handle interval strings for efficiency wrt fgetln. */
206: static struct node *
1.14 espie 207: new_node(const char *start, const char *end)
1.5 espie 208: {
209: struct node *n;
1.1 deraadt 210:
1.5 espie 211: n = ohash_create_entry(&node_info, start, &end);
212: n->from = NULL;
213: n->arcs = NULL;
214: n->refs = 0;
215: n->mark = 0;
1.7 espie 216: n->order = NO_ORDER;
1.5 espie 217: n->traverse = NULL;
218: return n;
219: }
1.1 deraadt 220:
221:
1.15 espie 222: static void
1.14 espie 223: nodes_init(struct ohash *h)
1.5 espie 224: {
225: ohash_init(h, HASH_START, &node_info);
1.1 deraadt 226: }
227:
1.5 espie 228: static struct node *
1.14 espie 229: node_lookup(struct ohash *h, const char *start, const char *end)
1.1 deraadt 230: {
1.5 espie 231: unsigned int i;
232: struct node * n;
1.1 deraadt 233:
1.5 espie 234: i = ohash_qlookupi(h, start, &end);
1.1 deraadt 235:
1.5 espie 236: n = ohash_find(h, i);
237: if (n == NULL)
238: n = ohash_insert(h, i, new_node(start, end));
239: return n;
240: }
241:
242: #ifdef DEBUG
243: static void
1.14 espie 244: dump_node(struct node *n)
1.5 espie 245: {
246: struct link *l;
247:
248: if (n->refs == 0)
1.1 deraadt 249: return;
1.8 espie 250: printf("%s (%u/%u): ", n->k, n->order, n->refs);
1.5 espie 251: for (l = n->arcs; l != NULL; l = l->next)
252: if (n->refs != 0)
1.8 espie 253: printf("%s(%u/%u) ", l->node->k, l->node->order, l->node->refs);
1.5 espie 254: putchar('\n');
255: }
1.1 deraadt 256:
1.5 espie 257: static void
1.14 espie 258: dump_array(struct array *a)
1.5 espie 259: {
260: unsigned int i;
1.1 deraadt 261:
1.5 espie 262: for (i = 0; i < a->entries; i++)
263: dump_node(a->t[i]);
264: }
265:
1.15 espie 266: static void
1.14 espie 267: dump_hash(struct ohash *h)
1.5 espie 268: {
269: unsigned int i;
270: struct node *n;
271:
272: for (n = ohash_first(h, &i); n != NULL; n = ohash_next(h, &i))
273: dump_node(n);
274: }
275: #endif
276:
277:
278: /***
279: *** Reading data.
280: ***/
281:
1.15 espie 282: static void
1.14 espie 283: insert_arc(struct node *a, struct node *b)
1.5 espie 284: {
285: struct link *l;
286:
287: /* Check that this arc is not already present. */
288: for (l = a->arcs; l != NULL; l = l->next) {
289: if (l->node == b)
1.1 deraadt 290: return;
1.5 espie 291: }
292: b->refs++;
293: l = emalloc(sizeof(struct link));
294: l->node = b;
295: l->next = a->arcs;
296: a->arcs = l;
297: }
1.1 deraadt 298:
1.7 espie 299: static unsigned int
1.15 espie 300: read_pairs(FILE *f, struct ohash *h, int reverse, const char *name,
1.14 espie 301: unsigned int order, int hint)
1.5 espie 302: {
303: int toggle;
304: struct node *a;
305: size_t size;
306: char *str;
307:
308: toggle = 1;
309: a = NULL;
310:
311: while ((str = fgetln(f, &size)) != NULL) {
312: char *sentinel;
313:
314: sentinel = str + size;
315: for (;;) {
316: char *e;
317:
1.17 drahn 318: while (str < sentinel && isspace(*str))
1.5 espie 319: str++;
320: if (str == sentinel)
321: break;
1.17 drahn 322: for (e = str; e < sentinel && !isspace(*e); e++)
1.5 espie 323: continue;
324: if (toggle) {
325: a = node_lookup(h, str, e);
1.8 espie 326: if (a->order == NO_ORDER && hint)
1.7 espie 327: a->order = order++;
1.5 espie 328: } else {
329: struct node *b;
330:
331: b = node_lookup(h, str, e);
332: assert(a != NULL);
333: if (b != a) {
1.15 espie 334: if (reverse)
1.5 espie 335: insert_arc(b, a);
1.15 espie 336: else
1.5 espie 337: insert_arc(a, b);
338: }
339: }
340: toggle = !toggle;
341: str = e;
342: }
343: }
344: if (toggle == 0)
1.21 ! jmc 345: errx(EX_DATAERR, "odd number of node names in %s", name);
1.5 espie 346: if (!feof(f))
347: err(EX_IOERR, "error reading %s", name);
1.7 espie 348: return order;
1.5 espie 349: }
1.1 deraadt 350:
1.7 espie 351: static unsigned int
1.15 espie 352: read_hints(FILE *f, struct ohash *h, int quiet, const char *name,
1.14 espie 353: unsigned int order)
1.5 espie 354: {
355: char *str;
356: size_t size;
357:
358: while ((str = fgetln(f, &size)) != NULL) {
359: char *sentinel;
360:
361: sentinel = str + size;
362: for (;;) {
363: char *e;
364: struct node *a;
365:
1.17 drahn 366: while (str < sentinel && isspace(*str))
1.5 espie 367: str++;
368: if (str == sentinel)
369: break;
1.17 drahn 370: for (e = str; e < sentinel && !isspace(*e); e++)
1.5 espie 371: continue;
372: a = node_lookup(h, str, e);
1.7 espie 373: if (a->order != NO_ORDER) {
1.6 espie 374: if (!quiet)
375: warnx(
1.5 espie 376: "duplicate node %s in hints file %s",
377: a->k, name);
1.7 espie 378: } else
379: a->order = order++;
1.5 espie 380: str = e;
381: }
382: }
1.7 espie 383: return order;
1.5 espie 384: }
385:
386:
387: /***
1.15 espie 388: *** Standard heap handling routines.
1.5 espie 389: ***/
390:
1.15 espie 391: static void
1.14 espie 392: heap_down(struct array *h, unsigned int i)
1.5 espie 393: {
394: unsigned int j;
395: struct node *swap;
396:
397: for (; (j=2*i+1) < h->entries; i = j) {
398: if (j+1 < h->entries && h->t[j+1]->order < h->t[j]->order)
399: j++;
400: if (h->t[i]->order <= h->t[j]->order)
401: break;
402: swap = h->t[i];
403: h->t[i] = h->t[j];
404: h->t[j] = swap;
1.1 deraadt 405: }
1.5 espie 406: }
407:
1.15 espie 408: static void
1.14 espie 409: heapify(struct array *h, int verbose)
1.5 espie 410: {
411: unsigned int i;
1.1 deraadt 412:
1.6 espie 413: for (i = h->entries; i != 0;) {
1.8 espie 414: if (h->t[--i]->order == NO_ORDER && verbose)
1.6 espie 415: warnx("node %s absent from hints file", h->t[i]->k);
416: heap_down(h, i);
417: }
1.5 espie 418: }
419:
420: #define DEQUEUE(h) ( hints_flag ? dequeue(h) : (h)->t[--(h)->entries] )
1.1 deraadt 421:
1.5 espie 422: static struct node *
1.14 espie 423: dequeue(struct array *h)
1.5 espie 424: {
425: struct node *n;
426:
427: if (h->entries == 0)
428: n = NULL;
429: else {
430: n = h->t[0];
431: if (--h->entries != 0) {
432: h->t[0] = h->t[h->entries];
433: heap_down(h, 0);
434: }
435: }
436: return n;
1.1 deraadt 437: }
1.5 espie 438:
439: #define ENQUEUE(h, n) do { \
440: if (hints_flag) \
441: enqueue((h), (n)); \
442: else \
443: (h)->t[(h)->entries++] = (n); \
444: } while(0);
445:
1.15 espie 446: static void
1.14 espie 447: enqueue(struct array *h, struct node *n)
1.5 espie 448: {
449: unsigned int i, j;
450: struct node *swap;
1.1 deraadt 451:
1.5 espie 452: h->t[h->entries++] = n;
453: for (i = h->entries-1; i > 0; i = j) {
454: j = (i-1)/2;
455: if (h->t[j]->order < h->t[i]->order)
456: break;
457: swap = h->t[j];
458: h->t[j] = h->t[i];
459: h->t[i] = swap;
460: }
461: }
1.1 deraadt 462:
1.8 espie 463: /* Nodes without order should not hinder direct dependencies.
1.15 espie 464: * Iterate until no nodes are left.
1.8 espie 465: */
466: static void
1.14 espie 467: make_transparent(struct ohash *hash)
1.8 espie 468: {
469: struct node *n;
470: unsigned int i;
471: struct link *l;
472: int adjusted;
473: int bad;
474: unsigned int min;
475:
476: /* first try to solve complete nodes */
477: do {
478: adjusted = 0;
479: bad = 0;
1.15 espie 480: for (n = ohash_first(hash, &i); n != NULL;
1.8 espie 481: n = ohash_next(hash, &i)) {
482: if (n->order == NO_ORDER) {
483: min = NO_ORDER;
484:
485: for (l = n->arcs; l != NULL; l = l->next) {
486: /* unsolved node -> delay resolution */
487: if (l->node->order == NO_ORDER) {
488: bad = 1;
489: break;
490: } else if (l->node->order < min)
491: min = l->node->order;
492: }
493: if (min < NO_ORDER && l == NULL) {
494: n->order = min;
495: adjusted = 1;
496: }
497: }
498: }
499:
500: } while (adjusted);
501:
502: /* then, if incomplete nodes are left, do them */
503: if (bad) do {
504: adjusted = 0;
1.15 espie 505: for (n = ohash_first(hash, &i); n != NULL;
1.8 espie 506: n = ohash_next(hash, &i))
507: if (n->order == NO_ORDER)
508: for (l = n->arcs; l != NULL; l = l->next)
509: if (l->node->order < n->order) {
510: n->order = l->node->order;
511: adjusted = 1;
512: }
513: } while (adjusted);
514: }
515:
1.5 espie 516:
517: /***
518: *** Search through hash array for nodes.
519: ***/
520:
521: /* Split nodes into unrefed nodes/live nodes. */
522: static void
1.14 espie 523: split_nodes(struct ohash *hash, struct array *heap, struct array *remaining)
1.1 deraadt 524: {
525:
1.5 espie 526: struct node *n;
527: unsigned int i;
528:
529: heap->t = emalloc(sizeof(struct node *) * ohash_entries(hash));
1.9 espie 530: remaining->t = emalloc(sizeof(struct node *) * ohash_entries(hash));
1.5 espie 531: heap->entries = 0;
532: remaining->entries = 0;
533:
534: for (n = ohash_first(hash, &i); n != NULL; n = ohash_next(hash, &i)) {
1.15 espie 535: if (n->refs == 0)
1.5 espie 536: heap->t[heap->entries++] = n;
537: else
1.9 espie 538: remaining->t[remaining->entries++] = n;
1.5 espie 539: }
1.1 deraadt 540: }
541:
1.5 espie 542: /* Good point to break a cycle: live node with as few refs as possible. */
543: static struct node *
1.14 espie 544: find_good_cycle_break(struct array *h)
1.5 espie 545: {
546: unsigned int i;
1.15 espie 547: unsigned int best;
548: struct node *u;
1.5 espie 549:
550: best = UINT_MAX;
551: u = NULL;
552:
553: assert(h->entries != 0);
554: for (i = 0; i < h->entries; i++) {
555: struct node *n = h->t[i];
556: /* No need to look further. */
557: if (n->refs == 1)
558: return n;
559: if (n->refs != 0 && n->refs < best) {
560: best = n->refs;
561: u = n;
562: }
563: }
564: assert(u != NULL);
565: return u;
566: }
567:
568: /* Retrieve the node with the smallest order. */
1.15 espie 569: static struct node *
1.14 espie 570: find_smallest_node(struct array *h)
1.5 espie 571: {
572: unsigned int i;
573: unsigned int best;
574: struct node *u;
575:
576: best = UINT_MAX;
577: u = NULL;
578:
579: assert(h->entries != 0);
580: for (i = 0; i < h->entries; i++) {
581: struct node *n = h->t[i];
582: if (n->refs != 0 && n->order < best) {
583: best = n->order;
584: u = n;
585: }
586: }
587: assert(u != NULL);
588: return u;
589: }
590:
591:
592: /***
593: *** Graph algorithms.
594: ***/
595:
1.15 espie 596: /* Explore the nodes reachable from i to find a cycle, store it in c.
1.10 espie 597: * This may fail. */
1.15 espie 598: static struct node *
1.14 espie 599: find_cycle_from(struct node *i, struct array *c)
1.5 espie 600: {
601: struct node *n;
602:
603: n = i;
604: /* XXX Previous cycle findings may have left this pointer non-null. */
605: i->from = NULL;
606:
607: for (;;) {
608: /* Note that all marks are reversed before this code exits. */
609: n->mark = 1;
1.15 espie 610: if (n->traverse)
1.5 espie 611: n->traverse = n->traverse->next;
612: else
613: n->traverse = n->arcs;
614: /* Skip over dead nodes. */
615: while (n->traverse && n->traverse->node->refs == 0)
616: n->traverse = n->traverse->next;
617: if (n->traverse) {
618: struct node *go = n->traverse->node;
619:
620: if (go->mark) {
1.10 espie 621: c->entries = 0;
622: for (; n != NULL && n != go; n = n->from) {
623: c->t[c->entries++] = n;
624: n->mark = 0;
1.1 deraadt 625: }
1.10 espie 626: for (; n != NULL; n = n->from)
627: n->mark = 0;
628: c->t[c->entries++] = go;
629: return go;
1.5 espie 630: } else {
631: go->from = n;
632: n = go;
1.1 deraadt 633: }
1.5 espie 634: } else {
635: n->mark = 0;
636: n = n->from;
1.15 espie 637: if (n == NULL)
1.10 espie 638: return NULL;
1.5 espie 639: }
640: }
641: }
1.1 deraadt 642:
1.5 espie 643: /* Find a live predecessor of node n. This is a slow routine, as it needs
644: * to go through the whole array, but it is not needed often.
645: */
646: static struct node *
1.14 espie 647: find_predecessor(struct array *a, struct node *n)
1.5 espie 648: {
649: unsigned int i;
650:
651: for (i = 0; i < a->entries; i++) {
652: struct node *m;
1.1 deraadt 653:
1.5 espie 654: m = a->t[i];
655: if (m->refs != 0) {
656: struct link *l;
657:
658: for (l = m->arcs; l != NULL; l = l->next)
659: if (l->node == n)
660: return m;
1.1 deraadt 661: }
1.5 espie 662: }
663: assert(1 == 0);
664: return NULL;
665: }
666:
667: /* Traverse all strongly connected components reachable from node n.
668: Start numbering them at o. Return the maximum order reached.
669: Update the largest cycle found so far.
670: */
1.15 espie 671: static unsigned int
1.14 espie 672: traverse_node(struct node *n, unsigned int o, struct array *c)
1.5 espie 673: {
674: unsigned int min, max;
675:
676: n->from = NULL;
677: min = o;
678: max = ++o;
679:
680: for (;;) {
681: n->mark = o;
682: if (DEBUG_TRAVERSE)
1.11 espie 683: printf("%s(%u) ", n->k, n->mark);
1.5 espie 684: /* Find next arc to explore. */
1.15 espie 685: if (n->traverse)
1.5 espie 686: n->traverse = n->traverse->next;
687: else
688: n->traverse = n->arcs;
689: /* Skip over dead nodes. */
690: while (n->traverse && n->traverse->node->refs == 0)
691: n->traverse = n->traverse->next;
692: /* If arc left. */
693: if (n->traverse) {
694: struct node *go;
695:
696: go = n->traverse->node;
1.15 espie 697: /* Optimisation: if go->mark < min, we already
1.5 espie 698: * visited this strongly-connected component in
699: * a previous pass. Hence, this can yield no new
700: * cycle. */
701:
702: /* Not part of the current path: go for it. */
703: if (go->mark == 0 || go->mark == min) {
704: go->from = n;
705: n = go;
706: o++;
707: if (o > max)
708: max = o;
709: /* Part of the current path: check cycle length. */
710: } else if (go->mark > min) {
711: if (DEBUG_TRAVERSE)
712: printf("%d\n", o - go->mark + 1);
713: if (o - go->mark + 1 > c->entries) {
714: struct node *t;
715: unsigned int i;
716:
717: c->entries = o - go->mark + 1;
718: i = 0;
719: c->t[i++] = go;
720: for (t = n; t != go; t = t->from)
721: c->t[i++] = t;
1.1 deraadt 722: }
1.5 espie 723: }
1.1 deraadt 724:
1.5 espie 725: /* No arc left: backtrack. */
726: } else {
727: n->mark = min;
728: n = n->from;
729: if (!n)
730: return max;
731: o--;
732: }
1.1 deraadt 733: }
734: }
735:
1.5 espie 736: static void
1.14 espie 737: print_cycle(struct array *c)
1.5 espie 738: {
739: unsigned int i;
740:
741: /* Printing in reverse order, since cycle discoveries finds reverse
742: * edges. */
743: for (i = c->entries; i != 0;) {
744: i--;
745: warnx("%s", c->t[i]->k);
746: }
1.1 deraadt 747: }
748:
1.5 espie 749: static struct node *
1.14 espie 750: find_longest_cycle(struct array *h, struct array *c)
1.5 espie 751: {
752: unsigned int i;
753: unsigned int o;
754: unsigned int best;
755: struct node *n;
756: static int notfirst = 0;
757:
758: assert(h->entries != 0);
759:
760: /* No cycle found yet. */
761: c->entries = 0;
762:
763: /* Reset the set of marks, except the first time around. */
764: if (notfirst) {
1.15 espie 765: for (i = 0; i < h->entries; i++)
1.5 espie 766: h->t[i]->mark = 0;
767: } else
768: notfirst = 1;
769:
770: o = 0;
771:
772: /* Traverse the array. Each unmarked, live node heralds a
773: * new set of strongly connected components. */
774: for (i = 0; i < h->entries; i++) {
775: n = h->t[i];
776: if (n->refs != 0 && n->mark == 0) {
777: /* Each call to traverse_node uses a separate
778: * interval of numbers to mark nodes. */
779: o++;
780: o = traverse_node(n, o, c);
781: }
782: }
783:
784: assert(c->entries != 0);
785: n = c->t[0];
786: best = n->refs;
787: for (i = 0; i < c->entries; i++) {
788: if (c->t[i]->refs < best) {
789: n = c->t[i];
790: best = n->refs;
791: }
792: }
793: return n;
794: }
1.1 deraadt 795:
1.5 espie 796:
797: #define plural(n) ((n) > 1 ? "s" : "")
1.1 deraadt 798:
1.15 espie 799: int
1.14 espie 800: main(int argc, char *argv[])
1.5 espie 801: {
802: struct ohash pairs;
1.15 espie 803: int reverse_flag, quiet_flag, long_flag,
1.5 espie 804: warn_flag, hints_flag, verbose_flag;
1.7 espie 805: unsigned int order;
806:
1.8 espie 807: order = 0;
1.5 espie 808:
1.15 espie 809: reverse_flag = quiet_flag = long_flag =
1.5 espie 810: warn_flag = hints_flag = verbose_flag = 0;
811: nodes_init(&pairs);
812:
813: {
814: int c;
815:
816: while ((c = getopt(argc, argv, "h:flqrvw")) != -1) {
817: switch(c) {
818: case 'h': {
819: FILE *f;
820:
821: f = fopen(optarg, "r");
822: if (f == NULL)
823: err(EX_NOINPUT, "Can't open hint file %s",
824: optarg);
1.7 espie 825: order = read_hints(f, &pairs, quiet_flag,
826: optarg, order);
1.5 espie 827: fclose(f);
828: }
1.8 espie 829: hints_flag = 1;
830: break;
1.5 espie 831: /*FALLTHRU*/
832: case 'f':
1.8 espie 833: hints_flag = 2;
1.5 espie 834: break;
835: case 'l':
836: long_flag = 1;
837: break;
838: case 'q':
839: quiet_flag = 1;
840: break;
841: case 'r':
842: reverse_flag = 1;
843: break;
844: case 'v':
845: verbose_flag = 1;
846: break;
847: case 'w':
848: warn_flag = 1;
849: break;
850: default:
851: usage();
852: }
853: }
1.1 deraadt 854:
1.5 espie 855: argc -= optind;
856: argv += optind;
857: }
1.1 deraadt 858:
1.5 espie 859: switch(argc) {
860: case 1: {
861: FILE *f;
862:
863: f = fopen(argv[0], "r");
864: if (f == NULL)
865: err(EX_NOINPUT, "Can't open file %s", argv[1]);
1.8 espie 866: order = read_pairs(f, &pairs, reverse_flag, argv[1], order,
867: hints_flag == 2);
1.5 espie 868: fclose(f);
869: break;
870: }
871: case 0:
1.8 espie 872: order = read_pairs(stdin, &pairs, reverse_flag, "stdin",
873: order, hints_flag == 2);
1.5 espie 874: break;
875: default:
876: usage();
877: }
1.1 deraadt 878:
1.5 espie 879: {
880: struct array aux; /* Unrefed nodes/cycle reporting. */
881: struct array remaining;
882: unsigned int broken_arcs, broken_cycles;
883: unsigned int left;
884:
885: broken_arcs = 0;
886: broken_cycles = 0;
887:
1.8 espie 888: if (hints_flag)
889: make_transparent(&pairs);
1.5 espie 890: split_nodes(&pairs, &aux, &remaining);
891: ohash_delete(&pairs);
892:
893: if (hints_flag)
1.6 espie 894: heapify(&aux, verbose_flag);
1.5 espie 895:
896: left = remaining.entries + aux.entries;
897: while (left != 0) {
898:
899: /* Standard topological sort. */
900: while (aux.entries) {
901: struct link *l;
902: struct node *n;
903:
904: n = DEQUEUE(&aux);
905: printf("%s\n", n->k);
906: left--;
907: /* We can't free nodes, as we don't know which
908: * entry we can remove in the hash table. We
1.15 espie 909: * rely on refs == 0 to recognize live nodes.
1.5 espie 910: * Decrease ref count of live nodes, enter new
911: * candidates into the unrefed list. */
1.15 espie 912: for (l = n->arcs; l != NULL; l = l->next)
913: if (l->node->refs != 0 &&
1.5 espie 914: --l->node->refs == 0) {
915: ENQUEUE(&aux, l->node);
916: }
917: }
918: /* There are still cycles to break. */
919: if (left != 0) {
920: struct node *n;
921:
922: broken_cycles++;
923: /* XXX Simple cycle detection and long cycle
924: * detection are mutually exclusive. */
925:
926: if (long_flag) {
927: n = find_longest_cycle(&remaining, &aux);
928: } else {
1.10 espie 929: struct node *b;
930:
1.15 espie 931: if (hints_flag)
1.5 espie 932: n = find_smallest_node(&remaining);
1.15 espie 933: else
1.5 espie 934: n = find_good_cycle_break(&remaining);
1.10 espie 935: while ((b = find_cycle_from(n, &aux)) == NULL)
936: n = find_predecessor(&remaining, n);
937: n = b;
1.5 espie 938: }
939:
940: if (!quiet_flag) {
941: warnx("cycle in data");
942: print_cycle(&aux);
943: }
944:
945: if (verbose_flag)
946: warnx("%u edge%s broken", n->refs,
947: plural(n->refs));
948: broken_arcs += n->refs;
949: n->refs = 0;
950: /* Reinitialization, cycle reporting uses aux. */
951: aux.t[0] = n;
952: aux.entries = 1;
953: }
954: }
955: if (verbose_flag && broken_cycles != 0)
956: warnx("%u cycle%s broken, for a total of %u edge%s",
957: broken_cycles, plural(broken_cycles),
958: broken_arcs, plural(broken_arcs));
1.15 espie 959: if (warn_flag)
1.5 espie 960: exit(broken_cycles < 256 ? broken_cycles : 255);
961: else
962: exit(EX_OK);
1.1 deraadt 963: }
964: }
965:
1.5 espie 966:
967: extern char *__progname;
968:
969: static void
1.16 deraadt 970: usage(void)
1.1 deraadt 971: {
1.18 espie 972: fprintf(stderr, "Usage: %s [-flqrvw] [-h file] [file]\n", __progname);
1.5 espie 973: exit(EX_USAGE);
1.1 deraadt 974: }
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