Net2/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, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#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 5.3 (Berkeley) 6/1/90";
#endif /* not lint */
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
#include <string.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);
}