randomize_fd.c revision 301917 
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: stable/10/games/random/randomize_fd.c 301917 2016-06-15 06:27:43Z truckman $");
29
30#include <sys/types.h>
31#include <sys/param.h>
32
33#include <ctype.h>
34#include <err.h>
35#include <errno.h>
36#include <stdlib.h>
37#include <stdio.h>
38#include <string.h>
39#include <unistd.h>
40
41#include "randomize_fd.h"
42
43static struct rand_node *rand_root;
44static struct rand_node *rand_tail;
45
46static struct rand_node *
47rand_node_allocate(void)
48{
49	struct rand_node *n;
50
51	n = (struct rand_node *)malloc(sizeof(struct rand_node));
52	if (n == NULL)
53		err(1, "malloc");
54
55	n->len = 0;
56	n->cp = NULL;
57	n->next = NULL;
58	return(n);
59}
60
61static void
62rand_node_free(struct rand_node *n)
63{
64	if (n != NULL) {
65		if (n->cp != NULL)
66			free(n->cp);
67
68		free(n);
69	}
70}
71
72static void
73rand_node_free_rec(struct rand_node *n)
74{
75	if (n != NULL) {
76		if (n->next != NULL)
77			rand_node_free_rec(n->next);
78
79		rand_node_free(n);
80	}
81}
82
83static void
84rand_node_append(struct rand_node *n)
85{
86	if (rand_root == NULL)
87		rand_root = rand_tail = n;
88	else {
89		rand_tail->next = n;
90		rand_tail = n;
91	}
92}
93
94int
95randomize_fd(int fd, int type, int unique, double denom)
96{
97	u_char *buf;
98	u_int slen;
99	u_long i, j, numnode, selected;
100	struct rand_node *n, *prev;
101	int bufleft, eof, fndstr, ret;
102	size_t bufc, buflen;
103	ssize_t len;
104
105	rand_root = rand_tail = NULL;
106	bufc = i = 0;
107	bufleft = eof = fndstr = numnode = 0;
108
109	if (type == RANDOM_TYPE_UNSET)
110		type = RANDOM_TYPE_LINES;
111
112	buflen = sizeof(u_char) * MAXBSIZE;
113	buf = (u_char *)malloc(buflen);
114	if (buf == NULL)
115		err(1, "malloc");
116
117	while (!eof) {
118		/* Check to see if we have bits in the buffer */
119		if (bufleft == 0) {
120			len = read(fd, buf, buflen);
121			if (len == -1)
122				err(1, "read");
123			else if (len == 0) {
124				eof++;
125				break;
126			} else if ((size_t)len < buflen)
127				buflen = (size_t)len;
128
129			bufleft = (int)len;
130		}
131
132		/* Look for a newline */
133		for (i = bufc; i <= buflen && bufleft >= 0; i++, bufleft--) {
134			if (i == buflen) {
135				if (fndstr) {
136					if (!eof) {
137						memmove(buf, &buf[bufc], i - bufc);
138						i -= bufc;
139						bufc = 0;
140						len = read(fd, &buf[i], buflen - i);
141						if (len == -1)
142							err(1, "read");
143						else if (len == 0) {
144							eof++;
145							break;
146						} else if (len < (ssize_t)(buflen - i))
147							buflen = i + (size_t)len;
148
149						bufleft = (int)len;
150						fndstr = 0;
151					}
152				} else {
153					buflen *= 2;
154					buf = (u_char *)realloc(buf, buflen);
155					if (buf == NULL)
156						err(1, "realloc");
157
158					if (!eof) {
159						len = read(fd, &buf[i], buflen - i);
160						if (len == -1)
161							err(1, "read");
162						else if (len == 0) {
163							eof++;
164							break;
165						} else if (len < (ssize_t)(buflen - i))
166							buflen = i + (size_t)len;
167
168						bufleft = (int)len;
169					}
170
171				}
172			}
173
174			if ((type == RANDOM_TYPE_LINES && buf[i] == '\n') ||
175			    (type == RANDOM_TYPE_WORDS && isspace(buf[i])) ||
176			    (eof && i == buflen - 1)) {
177make_token:
178				if (numnode == RANDOM_MAX_PLUS1) {
179					errno = EFBIG;
180					err(1, "too many delimiters");
181				}
182				numnode++;
183				n = rand_node_allocate();
184				if (-1 != (int)i) {
185					slen = i - (u_long)bufc;
186					n->len = slen + 2;
187					n->cp = (u_char *)malloc(slen + 2);
188					if (n->cp == NULL)
189						err(1, "malloc");
190
191					memmove(n->cp, &buf[bufc], slen);
192					n->cp[slen] = buf[i];
193					n->cp[slen + 1] = '\0';
194					bufc = i + 1;
195				}
196				rand_node_append(n);
197				fndstr = 1;
198			}
199		}
200	}
201
202	/* Necessary evil to compensate for files that don't end with a newline */
203	if (bufc != i) {
204		i--;
205		goto make_token;
206	}
207
208	(void)close(fd);
209
210	free(buf);
211
212	for (i = numnode; i > 0; i--) {
213		selected = random() % numnode;
214
215		for (j = 0, prev = n = rand_root; n != NULL; j++, prev = n, n = n->next) {
216			if (j == selected) {
217				if (n->cp == NULL)
218					break;
219
220				if ((int)(denom * random() /
221					RANDOM_MAX_PLUS1) == 0) {
222					ret = printf("%.*s",
223						(int)n->len - 1, n->cp);
224					if (ret < 0)
225						err(1, "printf");
226				}
227				if (unique) {
228					if (n == rand_root)
229						rand_root = n->next;
230					if (n == rand_tail)
231						rand_tail = prev;
232
233					prev->next = n->next;
234					rand_node_free(n);
235					numnode--;
236				}
237				break;
238			}
239		}
240	}
241
242	fflush(stdout);
243
244	if (!unique)
245		rand_node_free_rec(rand_root);
246
247	return(0);
248}
249