randomize_fd.c revision 110723 
1/*
2 * Copyright (C) 2003 Sean Chittenden <seanc@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/games/random/randomize_fd.c 110723 2003-02-11 19:32:18Z seanc $
27 */
28
29#include "randomize_fd.h"
30
31struct rand_node *rand_root;
32struct rand_node *rand_tail;
33
34
35static
36struct rand_node *rand_node_allocate(void)
37{
38	struct rand_node *n;
39
40	n = (struct rand_node *)malloc(sizeof(struct rand_node));
41	if (n == NULL)
42		err(1, "malloc");
43
44	n->len = 0;
45	n->cp = NULL;
46	n->next = NULL;
47	return(n);
48}
49
50
51static
52void rand_node_free(struct rand_node *n)
53{
54	if (n != NULL) {
55		if (n->cp != NULL)
56			free(n->cp);
57
58		free(n);
59	}
60}
61
62
63static
64void rand_node_free_rec(struct rand_node *n)
65{
66	if (n != NULL) {
67		if (n->next != NULL)
68			rand_node_free_rec(n->next);
69
70		rand_node_free(n);
71	}
72}
73
74
75static
76struct rand_node *rand_node_append(struct rand_node *n)
77{
78	if (rand_root == NULL) {
79		rand_root = rand_tail = n;
80		return(n);
81	} else {
82		rand_tail->next = n;
83		rand_tail = n;
84
85		return(n);
86	}
87}
88
89
90int randomize_fd(int fd, int type, int unique, double denom)
91{
92	u_char *buf, *p;
93	u_int numnode, j, selected, slen;
94	struct rand_node *n, *prev;
95	int bufc, bufleft, buflen, eof, fndstr, i, len, ret;
96
97	rand_root = rand_tail = NULL;
98	bufc = bufleft = eof = fndstr = numnode = 0;
99
100	if (type == RANDOM_TYPE_UNSET)
101		type = RANDOM_TYPE_LINES;
102
103	buflen = sizeof(u_char) * MAXBSIZE;
104	buf = (u_char *)malloc(buflen);
105	if (buf == NULL)
106		err(1, "malloc");
107
108	while (!eof) {
109		/* Check to see if we have bits in the buffer */
110		if (bufleft == 0) {
111			len = read(fd, buf, buflen);
112			if (len == -1)
113				err(1, "read");
114			else if (len == 0)
115				break;
116			else if (len < buflen) {
117				buflen = len;
118				eof++;
119			}
120
121			bufleft = len;
122		}
123
124		/* Look for a newline */
125		for (i = bufc; i <= buflen; i++, bufleft--) {
126			if (i == buflen) {
127				if (fndstr) {
128					if (!eof) {
129						memmove(buf, &buf[bufc], i - bufc);
130						i = i - bufc;
131						bufc = 0;
132						len = read(fd, &buf[i], buflen - i);
133						if (len == -1)
134							err(1, "read");
135						else if (len == 0) {
136							eof++;
137							break;
138						} else if (len < buflen -i )
139							buflen = i + len;
140
141						bufleft = len;
142						fndstr = 0;
143					}
144				} else {
145					p = (u_char *)realloc(buf, buflen * 2);
146					if (p == NULL)
147						err(1, "realloc");
148
149					buf = p;
150					if (!eof) {
151						len = read(fd, &buf[i], buflen);
152						if (len == -1)
153							err(1, "read");
154						else if (len == 0) {
155							eof++;
156							break;
157						} else if (len < buflen -i )
158							buflen = len;
159
160						bufleft = len;
161					}
162
163					buflen *= 2;
164				}
165			}
166
167			if ((type == RANDOM_TYPE_LINES && buf[i] == '\n') ||
168			    (type == RANDOM_TYPE_WORDS && isspace((int)buf[i])) ||
169			    (eof && i == buflen - 1)) {
170				n = rand_node_allocate();
171				slen = i - bufc;
172				n->len = slen + 2;
173				n->cp = (u_char *)malloc(slen + 2);
174				if (n->cp == NULL)
175					err(1, "malloc");
176
177				memmove(n->cp, &buf[bufc], slen);
178				n->cp[slen] = buf[i];
179				n->cp[slen + 1] = '\0';
180				bufc = i + 1;
181				fndstr = 1;
182				rand_node_append(n);
183				numnode++;
184			}
185		}
186	}
187
188	(void)close(fd);
189
190	for (i = numnode; i > 0; i--) {
191		selected = ((int)denom * random())/(((double)RAND_MAX + 1) / numnode);
192
193		for (j = 0, prev = n = rand_root; n != NULL; j++, prev = n, n = n->next) {
194			if (j == selected) {
195				ret = printf("%.*s", n->len - 1, n->cp);
196				if (ret < 0)
197					err(1, "printf");
198				if (unique) {
199					if (n == rand_root)
200						rand_root = n->next;
201					if (n == rand_tail)
202						rand_tail = prev;
203
204					prev->next = n->next;
205					rand_node_free(n);
206					numnode--;
207					break;
208				}
209			}
210		}
211	}
212
213	fflush(stdout);
214
215	if (!unique)
216		rand_node_free_rec(rand_root);
217
218	return(0);
219}
220