[unix-history] / usr / src / usr.bin / tsort / tsort.c

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Michael Rendell of Memorial University of Newfoundland.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)tsort.c	5.1 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
#include <strings.h>

/*
 *  Topological sort.  Input is a list of pairs of strings seperated by
 *  white space (spaces, tabs, and/or newlines); strings are written to
 *  standard output in sorted order, one per line.
 *
 *  usage:
 *     tsort [inputfile]
 *  If no input file is specified, standard input is read.
 *
 *  Should be compatable with AT&T tsort HOWEVER the output is not identical
 *  (i.e. for most graphs there is more than one sorted order, and this tsort
 *  usually generates a different one then the AT&T tsort).  Also, cycle
 *  reporting seems to be more accurate in this version (the AT&T tsort
 *  sometimes says a node is in a cycle when it isn't).
 *
 *  Michael Rendell, michael@stretch.cs.mun.ca - Feb 26, '90
 */
#define	HASHSIZE	53		/* doesn't need to be big */
#define	NF_MARK		0x1		/* marker for cycle detection */
#define	NF_ACYCLIC	0x2		/* this node is cycle free */

typedef struct node_str NODE;

struct node_str {
	char *n_name;			/* name of this node */
	NODE **n_prevp;			/* pointer to previous node's n_next */
	NODE *n_next;			/* next node in graph */
	NODE *n_hash;			/* next node in hash table */
	int n_narcs;			/* number of arcs in n_arcs[] */
	int n_arcsize;			/* size of n_arcs[] array */
	NODE **n_arcs;			/* array of arcs to other nodes */
	int n_refcnt;			/* # of arcs pointing to this node */
	int n_flags;			/* NF_* */
};

typedef struct _buf {
	char *b_buf;
	int b_bsize;
} BUF;

NODE *add_node(), *find_node();
void add_arc(), no_memory(), remove_node(), tsort();
char *grow_buf(), *malloc();

extern int errno;
NODE *graph;
NODE *hashtable[HASHSIZE];
NODE **cycle_buf;
NODE **longest_cycle;

main(argc, argv)
	int argc;
	char **argv;
{
	register BUF *b;
	register int c, n;
	FILE *fp;
	int bsize, nused;
	BUF bufs[2];

	if (argc < 2)
		fp = stdin;
	else if (argc == 2) {
		(void)fprintf(stderr, "usage: tsort [ inputfile ]\n");
		exit(1);
	} else if (!(fp = fopen(argv[1], "r"))) {
		(void)fprintf(stderr, "tsort: %s.\n", strerror(errno));
		exit(1);
	}

	for (b = bufs, n = 2; --n >= 0; b++)
		b->b_buf = grow_buf((char *)NULL, b->b_bsize = 1024);

	/* parse input and build the graph */
	for (n = 0, c = getc(fp);;) {
		while (c != EOF && isspace(c))
			c = getc(fp);
		if (c == EOF)
			break;

		nused = 0;
		b = &bufs[n];
		bsize = b->b_bsize;
		do {
			b->b_buf[nused++] = c;
			if (nused == bsize) {
				bsize *= 2;
				b->b_buf = grow_buf(b->b_buf, bsize);
			}
			c = getc(fp);
		} while (c != EOF && !isspace(c));

		b->b_buf[nused] = '\0';
		b->b_bsize = bsize;
		if (n)
			add_arc(bufs[0].b_buf, bufs[1].b_buf);
		n = !n;
	}
	(void)fclose(fp);
	if (n) {
		(void)fprintf(stderr, "tsort: odd data count.\n");
		exit(1);
	}

	/* do the sort */
	tsort();
	exit(0);
}

/* double the size of oldbuf and return a pointer to the new buffer. */
char *
grow_buf(bp, size)
	char *bp;
	int size;
{
	char *realloc();

	if (!(bp = realloc(bp, (u_int)size)))
		no_memory();
	return(bp);
}

/*
 * add an arc from node s1 to node s2 in the graph.  If s1 or s2 are not in
 * the graph, then add them.
 */
void
add_arc(s1, s2)
	char *s1, *s2;
{
	register NODE *n1;
	NODE *n2;
	int bsize;

	n1 = find_node(s1);
	if (!n1)
		n1 = add_node(s1);

	if (!strcmp(s1, s2))
		return;

	n2 = find_node(s2);
	if (!n2)
		n2 = add_node(s2);

	/*
	 * could check to see if this arc is here already, but it isn't
	 * worth the bother -- there usually isn't and it doesn't hurt if
	 * there is (I think :-).
	 */
	if (n1->n_narcs == n1->n_arcsize) {
		if (!n1->n_arcsize)
			n1->n_arcsize = 10;
		bsize = n1->n_arcsize * sizeof(*n1->n_arcs) * 2;
		n1->n_arcs = (NODE **)grow_buf((char *)n1->n_arcs, bsize);
		n1->n_arcsize = bsize / sizeof(*n1->n_arcs);
	}
	n1->n_arcs[n1->n_narcs++] = n2;
	++n2->n_refcnt;
}

hash_string(s)
	char *s;
{
	register int hash, i;

	for (hash = 0, i = 1; *s; s++, i++)
		hash += *s * i;
	return(hash % HASHSIZE);
}

/*
 * find a node in the graph and return a pointer to it - returns null if not
 * found.
 */
NODE *
find_node(name)
	char *name;
{
	register NODE *n;

	for (n = hashtable[hash_string(name)]; n; n = n->n_hash)
		if (!strcmp(n->n_name, name))
			return(n);
	return((NODE *)NULL);
}

/* Add a node to the graph and return a pointer to it. */
NODE *
add_node(name)
	char *name;
{
	register NODE *n;
	int hash;

	if (!(n = (NODE *)malloc(sizeof(NODE))) || !(n->n_name = strdup(name)))
		no_memory();

	n->n_narcs = 0;
	n->n_arcsize = 0;
	n->n_arcs = (NODE **)NULL;
	n->n_refcnt = 0;
	n->n_flags = 0;

	/* add to linked list */
	if (n->n_next = graph)
		graph->n_prevp = &n->n_next;
	n->n_prevp = &graph;
	graph = n;

	/* add to hash table */
	hash = hash_string(name);
	n->n_hash = hashtable[hash];
	hashtable[hash] = n;
	return(n);
}

/* do topological sort on graph */
void
tsort()
{
	register NODE *n, *next;
	register int cnt;

	while (graph) {
		/*
		 * keep getting rid of simple cases until there are none left,
		 * if there are any nodes still in the graph, then there is
		 * a cycle in it.
		 */
		do {
			for (cnt = 0, n = graph; n; n = next) {
				next = n->n_next;
				if (n->n_refcnt == 0) {
					remove_node(n);
					++cnt;
				}
			}
		} while (graph && cnt);

		if (!graph)
			break;

		if (!cycle_buf) {
			/*
			 * allocate space for two cycle logs - one to be used
			 * as scratch space, the other to save the longest
			 * cycle.
			 */
			for (cnt = 0, n = graph; n; n = n->n_next)
				++cnt;
			cycle_buf =
			    (NODE **)malloc((u_int)sizeof(NODE *) * cnt);
			longest_cycle =
			    (NODE **)malloc((u_int)sizeof(NODE *) * cnt);
			if (!cycle_buf || !longest_cycle)
				no_memory();
		}
		for (n = graph; n; n = n->n_next)
			if (!(n->n_flags & NF_ACYCLIC)) {
				if (cnt = find_cycle(n, n, 0, 0)) {
					register int i;

					(void)fprintf(stderr,
					    "tsort: cycle in data.\n");
					for (i = 0; i < cnt; i++)
						(void)fprintf(stderr,
				"tsort: %s.\n", longest_cycle[i]->n_name);
					remove_node(n);
					break;
				} else
					/* to avoid further checks */
					n->n_flags  = NF_ACYCLIC;
			}

		if (!n) {
			(void)fprintf(stderr,
			    "tsort: internal error -- could not find cycle.\n");
			exit(1);
		}
	}
}

/* print node and remove from graph (does not actually free node) */
void
remove_node(n)
	register NODE *n;
{
	register NODE **np;
	register int i;

	(void)printf("%s\n", n->n_name);
	for (np = n->n_arcs, i = n->n_narcs; --i >= 0; np++)
		--(*np)->n_refcnt;
	n->n_narcs = 0;
	*n->n_prevp = n->n_next;
	if (n->n_next)
		n->n_next->n_prevp = n->n_prevp;
}

/* look for the longest cycle from node from to node to. */
find_cycle(from, to, longest_len, depth)
	NODE *from, *to;
	int depth, longest_len;
{
	register NODE **np;
	register int i, len;

	/*
	 * avoid infinite loops and ignore portions of the graph known
	 * to be acyclic
	 */
	if (from->n_flags & (NF_MARK|NF_ACYCLIC))
		return(0);
	from->n_flags = NF_MARK;

	for (np = from->n_arcs, i = from->n_narcs; --i >= 0; np++) {
		cycle_buf[depth] = *np;
		if (*np == to) {
			if (depth + 1 > longest_len) {
				longest_len = depth + 1;
				(void)memcpy((char *)longest_cycle,
				    (char *)cycle_buf,
				    longest_len * sizeof(NODE *));
			}
		} else {
			len = find_cycle(*np, to, longest_len, depth + 1);
			if (len > longest_len)
				longest_len = len;
		}
	}
	from->n_flags &= ~NF_MARK;
	return(longest_len);
}

void
no_memory()
{
	(void)fprintf(stderr, "tsort: %s.\n", strerror(ENOMEM));
	exit(1);
}
Commit	Line	Data
3ff38436 KB	1	/*
	2	* Copyright (c) 1989 The Regents of the University of California.
	3	* 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 are permitted
	9	* provided that the above copyright notice and this paragraph are
	10	* duplicated in all such forms and that any documentation,
	11	* advertising materials, and other materials related to such
	12	* distribution and use acknowledge that the software was developed
	13	* by the University of California, Berkeley. The name of the
	14	* University may not be used to endorse or promote products derived
	15	* from this software without specific prior written permission.
	16	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	17	* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	18	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	19	*/
	20
	21	#ifndef lint
	22	char copyright[] =
	23	"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
	24	All rights reserved.\n";
	25	#endif /* not lint */
	26
	27	#ifndef lint
	28	static char sccsid[] = "@(#)tsort.c 5.1 (Berkeley) %G%";
	29	#endif /* not lint */
	30
	31	#include <sys/types.h>
	32	#include <errno.h>
4a5cb176	33	#include <stdio.h>
3ff38436 KB	34	#include <ctype.h>
3ff38436 KB	35	#include <strings.h>
dc5d5eb8	36
3ff38436 KB	37	/*
	38	* Topological sort. Input is a list of pairs of strings seperated by
	39	* white space (spaces, tabs, and/or newlines); strings are written to
	40	* standard output in sorted order, one per line.
	41	*
	42	* usage:
	43	* tsort [inputfile]
	44	* If no input file is specified, standard input is read.
	45	*
	46	* Should be compatable with AT&T tsort HOWEVER the output is not identical
	47	* (i.e. for most graphs there is more than one sorted order, and this tsort
	48	* usually generates a different one then the AT&T tsort). Also, cycle
	49	* reporting seems to be more accurate in this version (the AT&T tsort
	50	* sometimes says a node is in a cycle when it isn't).
	51	*
	52	* Michael Rendell, michael@stretch.cs.mun.ca - Feb 26, '90
	53	*/
	54	#define HASHSIZE 53 /* doesn't need to be big */
	55	#define NF_MARK 0x1 /* marker for cycle detection */
	56	#define NF_ACYCLIC 0x2 /* this node is cycle free */
dc5d5eb8	57
3ff38436 KB	58	typedef struct node_str NODE;
	59
	60	struct node_str {
	61	char n_name; / name of this node */
	62	NODE *n_prevp; / pointer to previous node's n_next */
	63	NODE n_next; / next node in graph */
	64	NODE n_hash; / next node in hash table */
	65	int n_narcs; /* number of arcs in n_arcs[] */
	66	int n_arcsize; /* size of n_arcs[] array */
	67	NODE *n_arcs; / array of arcs to other nodes */
	68	int n_refcnt; /* # of arcs pointing to this node */
	69	int n_flags; /* NF_* */
dc5d5eb8 BJ	70	};
dc5d5eb8 BJ	71
3ff38436 KB	72	typedef struct _buf {
	73	char *b_buf;
	74	int b_bsize;
	75	} BUF;
	76
	77	NODE add_node(), find_node();
	78	void add_arc(), no_memory(), remove_node(), tsort();
	79	char grow_buf(), malloc();
	80
	81	extern int errno;
	82	NODE *graph;
	83	NODE *hashtable[HASHSIZE];
	84	NODE **cycle_buf;
	85	NODE **longest_cycle;
	86
	87	main(argc, argv)
	88	int argc;
	89	char **argv;
dc5d5eb8	90	{
3ff38436 KB	91	register BUF *b;
	92	register int c, n;
	93	FILE *fp;
	94	int bsize, nused;
	95	BUF bufs[2];
	96
	97	if (argc < 2)
	98	fp = stdin;
	99	else if (argc == 2) {
	100	(void)fprintf(stderr, "usage: tsort [ inputfile ]\n");
	101	exit(1);
	102	} else if (!(fp = fopen(argv[1], "r"))) {
	103	(void)fprintf(stderr, "tsort: %s.\n", strerror(errno));
	104	exit(1);
dc5d5eb8	105	}
3ff38436 KB	106
	107	for (b = bufs, n = 2; --n >= 0; b++)
	108	b->b_buf = grow_buf((char *)NULL, b->b_bsize = 1024);
	109
	110	/* parse input and build the graph */
	111	for (n = 0, c = getc(fp);;) {
	112	while (c != EOF && isspace(c))
	113	c = getc(fp);
	114	if (c == EOF)
dc5d5eb8	115	break;
3ff38436 KB	116
	117	nused = 0;
	118	b = &bufs[n];
	119	bsize = b->b_bsize;
	120	do {
	121	b->b_buf[nused++] = c;
	122	if (nused == bsize) {
	123	bsize *= 2;
	124	b->b_buf = grow_buf(b->b_buf, bsize);
dc5d5eb8	125	}
3ff38436 KB	126	c = getc(fp);
	127	} while (c != EOF && !isspace(c));
	128
	129	b->b_buf[nused] = '\0';
	130	b->b_bsize = bsize;
	131	if (n)
	132	add_arc(bufs[0].b_buf, bufs[1].b_buf);
	133	n = !n;
	134	}
	135	(void)fclose(fp);
	136	if (n) {
	137	(void)fprintf(stderr, "tsort: odd data count.\n");
	138	exit(1);
dc5d5eb8	139	}
3ff38436 KB	140
	141	/* do the sort */
	142	tsort();
2afd1306	143	exit(0);
dc5d5eb8 BJ	144	}
dc5d5eb8 BJ	145
3ff38436 KB	146	/* double the size of oldbuf and return a pointer to the new buffer. */
	147	char *
	148	grow_buf(bp, size)
	149	char *bp;
	150	int size;
dc5d5eb8	151	{
3ff38436 KB	152	char *realloc();
	153
	154	if (!(bp = realloc(bp, (u_int)size)))
	155	no_memory();
	156	return(bp);
dc5d5eb8 BJ	157	}
dc5d5eb8 BJ	158
3ff38436 KB	159	/*
	160	* add an arc from node s1 to node s2 in the graph. If s1 or s2 are not in
	161	* the graph, then add them.
	162	*/
	163	void
	164	add_arc(s1, s2)
	165	char s1, s2;
dc5d5eb8	166	{
3ff38436 KB	167	register NODE *n1;
	168	NODE *n2;
	169	int bsize;
	170
	171	n1 = find_node(s1);
	172	if (!n1)
	173	n1 = add_node(s1);
	174
	175	if (!strcmp(s1, s2))
	176	return;
	177
	178	n2 = find_node(s2);
	179	if (!n2)
	180	n2 = add_node(s2);
	181
	182	/*
	183	* could check to see if this arc is here already, but it isn't
	184	* worth the bother -- there usually isn't and it doesn't hurt if
	185	* there is (I think :-).
	186	*/
	187	if (n1->n_narcs == n1->n_arcsize) {
	188	if (!n1->n_arcsize)
	189	n1->n_arcsize = 10;
	190	bsize = n1->n_arcsize * sizeof(n1->n_arcs) 2;
	191	n1->n_arcs = (NODE *)grow_buf((char )n1->n_arcs, bsize);
	192	n1->n_arcsize = bsize / sizeof(*n1->n_arcs);
	193	}
	194	n1->n_arcs[n1->n_narcs++] = n2;
	195	++n2->n_refcnt;
dc5d5eb8 BJ	196	}
dc5d5eb8 BJ	197
3ff38436 KB	198	hash_string(s)
3ff38436 KB	199	char *s;
dc5d5eb8	200	{
3ff38436 KB	201	register int hash, i;
	202
	203	for (hash = 0, i = 1; *s; s++, i++)
	204	hash += s i;
	205	return(hash % HASHSIZE);
dc5d5eb8 BJ	206	}
dc5d5eb8 BJ	207
3ff38436 KB	208	/*
	209	* find a node in the graph and return a pointer to it - returns null if not
	210	* found.
	211	*/
	212	NODE *
	213	find_node(name)
	214	char *name;
dc5d5eb8	215	{
3ff38436 KB	216	register NODE *n;
	217
	218	for (n = hashtable[hash_string(name)]; n; n = n->n_hash)
	219	if (!strcmp(n->n_name, name))
	220	return(n);
	221	return((NODE *)NULL);
dc5d5eb8 BJ	222	}
dc5d5eb8 BJ	223
3ff38436 KB	224	/* Add a node to the graph and return a pointer to it. */
	225	NODE *
	226	add_node(name)
	227	char *name;
dc5d5eb8	228	{
3ff38436 KB	229	register NODE *n;
	230	int hash;
	231
	232	if (!(n = (NODE *)malloc(sizeof(NODE))) \|\| !(n->n_name = strdup(name)))
	233	no_memory();
	234
	235	n->n_narcs = 0;
	236	n->n_arcsize = 0;
	237	n->n_arcs = (NODE **)NULL;
	238	n->n_refcnt = 0;
	239	n->n_flags = 0;
	240
	241	/* add to linked list */
	242	if (n->n_next = graph)
	243	graph->n_prevp = &n->n_next;
	244	n->n_prevp = &graph;
	245	graph = n;
	246
	247	/* add to hash table */
	248	hash = hash_string(name);
	249	n->n_hash = hashtable[hash];
	250	hashtable[hash] = n;
	251	return(n);
dc5d5eb8 BJ	252	}
dc5d5eb8 BJ	253
3ff38436 KB	254	/* do topological sort on graph */
	255	void
	256	tsort()
dc5d5eb8	257	{
3ff38436 KB	258	register NODE n, next;
	259	register int cnt;
	260
	261	while (graph) {
	262	/*
	263	* keep getting rid of simple cases until there are none left,
	264	* if there are any nodes still in the graph, then there is
	265	* a cycle in it.
	266	*/
	267	do {
	268	for (cnt = 0, n = graph; n; n = next) {
	269	next = n->n_next;
	270	if (n->n_refcnt == 0) {
	271	remove_node(n);
	272	++cnt;
	273	}
	274	}
	275	} while (graph && cnt);
	276
	277	if (!graph)
	278	break;
	279
	280	if (!cycle_buf) {
	281	/*
	282	* allocate space for two cycle logs - one to be used
	283	* as scratch space, the other to save the longest
	284	* cycle.
	285	*/
	286	for (cnt = 0, n = graph; n; n = n->n_next)
	287	++cnt;
	288	cycle_buf =
	289	(NODE *)malloc((u_int)sizeof(NODE ) * cnt);
	290	longest_cycle =
	291	(NODE *)malloc((u_int)sizeof(NODE ) * cnt);
	292	if (!cycle_buf \|\| !longest_cycle)
	293	no_memory();
	294	}
	295	for (n = graph; n; n = n->n_next)
	296	if (!(n->n_flags & NF_ACYCLIC)) {
	297	if (cnt = find_cycle(n, n, 0, 0)) {
	298	register int i;
	299
	300	(void)fprintf(stderr,
	301	"tsort: cycle in data.\n");
	302	for (i = 0; i < cnt; i++)
	303	(void)fprintf(stderr,
	304	"tsort: %s.\n", longest_cycle[i]->n_name);
	305	remove_node(n);
	306	break;
	307	} else
	308	/* to avoid further checks */
	309	n->n_flags = NF_ACYCLIC;
	310	}
	311
	312	if (!n) {
	313	(void)fprintf(stderr,
	314	"tsort: internal error -- could not find cycle.\n");
	315	exit(1);
	316	}
	317	}
dc5d5eb8 BJ	318	}
dc5d5eb8 BJ	319
3ff38436 KB	320	/* print node and remove from graph (does not actually free node) */
	321	void
	322	remove_node(n)
	323	register NODE *n;
dc5d5eb8	324	{
3ff38436 KB	325	register NODE **np;
	326	register int i;
	327
	328	(void)printf("%s\n", n->n_name);
	329	for (np = n->n_arcs, i = n->n_narcs; --i >= 0; np++)
	330	--(*np)->n_refcnt;
	331	n->n_narcs = 0;
	332	*n->n_prevp = n->n_next;
	333	if (n->n_next)
	334	n->n_next->n_prevp = n->n_prevp;
dc5d5eb8 BJ	335	}
dc5d5eb8 BJ	336
3ff38436 KB	337	/* look for the longest cycle from node from to node to. */
	338	find_cycle(from, to, longest_len, depth)
	339	NODE from, to;
	340	int depth, longest_len;
dc5d5eb8	341	{
3ff38436 KB	342	register NODE **np;
	343	register int i, len;
	344
	345	/*
	346	* avoid infinite loops and ignore portions of the graph known
	347	* to be acyclic
	348	*/
	349	if (from->n_flags & (NF_MARK\|NF_ACYCLIC))
	350	return(0);
	351	from->n_flags = NF_MARK;
	352
	353	for (np = from->n_arcs, i = from->n_narcs; --i >= 0; np++) {
	354	cycle_buf[depth] = *np;
	355	if (*np == to) {
	356	if (depth + 1 > longest_len) {
	357	longest_len = depth + 1;
	358	(void)memcpy((char *)longest_cycle,
	359	(char *)cycle_buf,
	360	longest_len * sizeof(NODE *));
	361	}
	362	} else {
	363	len = find_cycle(*np, to, longest_len, depth + 1);
	364	if (len > longest_len)
	365	longest_len = len;
dc5d5eb8 BJ	366	}
dc5d5eb8 BJ	367	}
3ff38436 KB	368	from->n_flags &= ~NF_MARK;
	369	return(longest_len);
	370	}
	371
	372	void
	373	no_memory()
	374	{
	375	(void)fprintf(stderr, "tsort: %s.\n", strerror(ENOMEM));
	376	exit(1);
dc5d5eb8	377	}