randomize_fd.c revision 181410 
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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/games/random/randomize_fd.c 181410 2008-08-08 01:42:17Z ache $");
29
30#include <sys/types.h>
31#include <sys/param.h>
32
33#include <ctype.h>
34#include <err.h>
35#include <stdlib.h>
36#include <stdio.h>
37#include <string.h>
38#include <unistd.h>
39
40#include "randomize_fd.h"
41
42static struct rand_node *rand_root;
43static struct rand_node *rand_tail;
44
45static struct rand_node *
46rand_node_allocate(void)
47{
48	struct rand_node *n;
49
50	n = (struct rand_node *)malloc(sizeof(struct rand_node));
51	if (n == NULL)
52		err(1, "malloc");
53
54	n->len = 0;
55	n->cp = NULL;
56	n->next = NULL;
57	return(n);
58}
59
60static void
61rand_node_free(struct rand_node *n)
62{
63	if (n != NULL) {
64		if (n->cp != NULL)
65			free(n->cp);
66
67		free(n);
68	}
69}
70
71static void
72rand_node_free_rec(struct rand_node *n)
73{
74	if (n != NULL) {
75		if (n->next != NULL)
76			rand_node_free_rec(n->next);
77
78		rand_node_free(n);
79	}
80}
81
82static void
83rand_node_append(struct rand_node *n)
84{
85	if (rand_root == NULL)
86		rand_root = rand_tail = n;
87	else {
88		rand_tail->next = n;
89		rand_tail = n;
90	}
91}
92
93int
94randomize_fd(int fd, int type, int unique, double denom)
95{
96	u_char *buf;
97	u_int numnode, j, selected, slen;
98	struct rand_node *n, *prev;
99	int bufleft, eof, fndstr, ret;
100	size_t bufc, buflen, i;
101	ssize_t len;
102
103	rand_root = rand_tail = NULL;
104	bufc = i = 0;
105	bufleft = eof = fndstr = numnode = ret = 0;
106
107	if (type == RANDOM_TYPE_UNSET)
108		type = RANDOM_TYPE_LINES;
109
110	buflen = sizeof(u_char) * MAXBSIZE;
111	buf = (u_char *)malloc(buflen);
112	if (buf == NULL)
113		err(1, "malloc");
114
115	while (!eof) {
116		/* Check to see if we have bits in the buffer */
117		if (bufleft == 0) {
118			len = read(fd, buf, buflen);
119			if (len == -1)
120				err(1, "read");
121			else if (len == 0) {
122				eof++;
123				break;
124			} else if ((size_t)len < buflen)
125				buflen = (size_t)len;
126
127			bufleft = (int)len;
128		}
129
130		/* Look for a newline */
131		for (i = bufc; i <= buflen && bufleft >= 0; i++, bufleft--) {
132			if (i == buflen) {
133				if (fndstr) {
134					if (!eof) {
135						memmove(buf, &buf[bufc], i - bufc);
136						i -= bufc;
137						bufc = 0;
138						len = read(fd, &buf[i], buflen - i);
139						if (len == -1)
140							err(1, "read");
141						else if (len == 0) {
142							eof++;
143							break;
144						} else if (len < (ssize_t)(buflen - i))
145							buflen = i + (size_t)len;
146
147						bufleft = (int)len;
148						fndstr = 0;
149					}
150				} else {
151					buflen *= 2;
152					buf = (u_char *)realloc(buf, buflen);
153					if (buf == NULL)
154						err(1, "realloc");
155
156					if (!eof) {
157						len = read(fd, &buf[i], buflen - i);
158						if (len == -1)
159							err(1, "read");
160						else if (len == 0) {
161							eof++;
162							break;
163						} else if (len < (ssize_t)(buflen - i))
164							buflen = i + (size_t)len;
165
166						bufleft = (int)len;
167					}
168
169				}
170			}
171
172			if ((type == RANDOM_TYPE_LINES && buf[i] == '\n') ||
173			    (type == RANDOM_TYPE_WORDS && isspace(buf[i])) ||
174			    (eof && i == buflen - 1)) {
175			make_token:
176				n = rand_node_allocate();
177				if (-1 != (int)i) {
178					slen = i - (u_long)bufc;
179					n->len = slen + 2;
180					n->cp = (u_char *)malloc(slen + 2);
181					if (n->cp == NULL)
182						err(1, "malloc");
183
184					memmove(n->cp, &buf[bufc], slen);
185					n->cp[slen] = buf[i];
186					n->cp[slen + 1] = '\0';
187					bufc = i + 1;
188				}
189				rand_node_append(n);
190				fndstr = 1;
191				numnode++;
192			}
193		}
194	}
195
196	(void)close(fd);
197
198	/* Necessary evil to compensate for files that don't end with a newline */
199	if (bufc != i) {
200		i--;
201		goto make_token;
202	}
203
204	for (i = numnode; i > 0; i--) {
205		selected = ((int)denom * random())/(RANDOM_MAX / numnode);
206
207		for (j = 0, prev = n = rand_root; n != NULL; j++, prev = n, n = n->next) {
208			if (j == selected) {
209				if (n->cp == NULL)
210					break;
211
212				ret = printf("%.*s", (int)n->len - 1, n->cp);
213				if (ret < 0)
214					err(1, "printf");
215				if (unique) {
216					if (n == rand_root)
217						rand_root = n->next;
218					if (n == rand_tail)
219						rand_tail = prev;
220
221					prev->next = n->next;
222					rand_node_free(n);
223					numnode--;
224					break;
225				}
226			}
227		}
228	}
229
230	fflush(stdout);
231
232	if (!unique)
233		rand_node_free_rec(rand_root);
234
235	return(0);
236}
237