1/*-
2 * Copyright (c) 2009-2010 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * This software was developed by Pawel Jakub Dawidek under sponsorship from
6 * the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: head/sbin/hastd/ebuf.c 225787 2011-09-27 08:50:37Z pjd $");
32
33#include <sys/param.h>
34
35#include <errno.h>
36#include <stdbool.h>
37#include <stdint.h>
38#include <strings.h>
39#include <unistd.h>
40
41#include <pjdlog.h>
42
43#include "ebuf.h"
44
45#ifndef PJDLOG_ASSERT
46#include <assert.h>
47#define PJDLOG_ASSERT(...) assert(__VA_ARGS__)
48#endif
49
50#define EBUF_MAGIC 0xeb0f41c
51struct ebuf {
52 /* Magic to assert the caller uses valid structure. */
53 int eb_magic;
54 /* Address where we did the allocation. */
55 unsigned char *eb_start;
56 /* Allocation end address. */
57 unsigned char *eb_end;
58 /* Start of real data. */
59 unsigned char *eb_used;
60 /* Size of real data. */
61 size_t eb_size;
62};
63
64static int ebuf_head_extend(struct ebuf *eb, size_t size);
65static int ebuf_tail_extend(struct ebuf *eb, size_t size);
66
67struct ebuf *
68ebuf_alloc(size_t size)
69{
70 struct ebuf *eb;
71 int rerrno;
72
73 eb = malloc(sizeof(*eb));
74 if (eb == NULL)
75 return (NULL);
76 size += PAGE_SIZE;
77 eb->eb_start = malloc(size);
78 if (eb->eb_start == NULL) {
79 rerrno = errno;
80 free(eb);
81 errno = rerrno;
82 return (NULL);
83 }
84 eb->eb_end = eb->eb_start + size;
85 /*
86 * We set start address for real data not at the first entry, because
87 * we want to be able to add data at the front.
88 */
89 eb->eb_used = eb->eb_start + PAGE_SIZE / 4;
90 eb->eb_size = 0;
91 eb->eb_magic = EBUF_MAGIC;
92
93 return (eb);
94}
95
96void
97ebuf_free(struct ebuf *eb)
98{
99
100 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
101
102 eb->eb_magic = 0;
103
104 free(eb->eb_start);
105 free(eb);
106}
107
108int
109ebuf_add_head(struct ebuf *eb, const void *data, size_t size)
110{
111
112 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
113
114 if (size > (size_t)(eb->eb_used - eb->eb_start)) {
115 /*
116 * We can't add more entries at the front, so we have to extend
117 * our buffer.
118 */
119 if (ebuf_head_extend(eb, size) < 0)
120 return (-1);
121 }
122 PJDLOG_ASSERT(size <= (size_t)(eb->eb_used - eb->eb_start));
123
124 eb->eb_size += size;
125 eb->eb_used -= size;
126 /*
127 * If data is NULL the caller just wants to reserve place.
128 */
129 if (data != NULL)
130 bcopy(data, eb->eb_used, size);
131
132 return (0);
133}
134
135int
136ebuf_add_tail(struct ebuf *eb, const void *data, size_t size)
137{
138
139 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
140
141 if (size > (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))) {
142 /*
143 * We can't add more entries at the back, so we have to extend
144 * our buffer.
145 */
146 if (ebuf_tail_extend(eb, size) < 0)
147 return (-1);
148 }
149 PJDLOG_ASSERT(size <=
150 (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size)));
151
152 /*
153 * If data is NULL the caller just wants to reserve space.
154 */
155 if (data != NULL)
156 bcopy(data, eb->eb_used + eb->eb_size, size);
157 eb->eb_size += size;
158
159 return (0);
160}
161
162void
163ebuf_del_head(struct ebuf *eb, size_t size)
164{
165
166 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
167 PJDLOG_ASSERT(size <= eb->eb_size);
168
169 eb->eb_used += size;
170 eb->eb_size -= size;
171}
172
173void
174ebuf_del_tail(struct ebuf *eb, size_t size)
175{
176
177 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
178 PJDLOG_ASSERT(size <= eb->eb_size);
179
180 eb->eb_size -= size;
181}
182
183/*
184 * Return pointer to the data and data size.
185 */
186void *
187ebuf_data(struct ebuf *eb, size_t *sizep)
188{
189
190 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
191
192 if (sizep != NULL)
193 *sizep = eb->eb_size;
194 return (eb->eb_size > 0 ? eb->eb_used : NULL);
195}
196
197/*
198 * Return data size.
199 */
200size_t
201ebuf_size(struct ebuf *eb)
202{
203
204 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
205
206 return (eb->eb_size);
207}
208
209/*
210 * Function adds size + (PAGE_SIZE / 4) bytes at the front of the buffer..
211 */
212static int
213ebuf_head_extend(struct ebuf *eb, size_t size)
214{
215 unsigned char *newstart, *newused;
216 size_t newsize;
217
218 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
219
220 newsize = eb->eb_end - eb->eb_start + (PAGE_SIZE / 4) + size;
221
222 newstart = malloc(newsize);
223 if (newstart == NULL)
224 return (-1);
225 newused =
226 newstart + (PAGE_SIZE / 4) + size + (eb->eb_used - eb->eb_start);
227
228 bcopy(eb->eb_used, newused, eb->eb_size);
229
230 eb->eb_start = newstart;
231 eb->eb_used = newused;
232 eb->eb_end = newstart + newsize;
233
234 return (0);
235}
236
237/*
238 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back.
239 */
240static int
241ebuf_tail_extend(struct ebuf *eb, size_t size)
242{
243 unsigned char *newstart;
244 size_t newsize;
245
246 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
247
248 newsize = eb->eb_end - eb->eb_start + size + ((3 * PAGE_SIZE) / 4);
249
250 newstart = realloc(eb->eb_start, newsize);
251 if (newstart == NULL)
252 return (-1);
253
254 eb->eb_used = newstart + (eb->eb_used - eb->eb_start);
255 eb->eb_start = newstart;
256 eb->eb_end = newstart + newsize;
257
258 return (0);
259}