1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2009-2010 The FreeBSD Foundation
5 * All rights reserved.
6 *
7 * This software was developed by Pawel Jakub Dawidek under sponsorship from
8 * the FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: stable/12/sbin/hastd/ebuf.c 326276 2017-11-27 15:37:16Z pfg $");
34
35 #include <sys/param.h>
36
37 #include <errno.h>
38 #include <stdbool.h>
39 #include <stdint.h>
40 #include <strings.h>
41 #include <unistd.h>
42
43 #include <pjdlog.h>
44
45 #include "ebuf.h"
46
47 #ifndef PJDLOG_ASSERT
48 #include <assert.h>
49 #define PJDLOG_ASSERT(...) assert(__VA_ARGS__)
50 #endif
51
52 #define EBUF_MAGIC 0xeb0f41c
53 struct ebuf {
54 /* Magic to assert the caller uses valid structure. */
55 int eb_magic;
56 /* Address where we did the allocation. */
57 unsigned char *eb_start;
58 /* Allocation end address. */
59 unsigned char *eb_end;
60 /* Start of real data. */
61 unsigned char *eb_used;
62 /* Size of real data. */
63 size_t eb_size;
64 };
65
66 static int ebuf_head_extend(struct ebuf *eb, size_t size);
67 static int ebuf_tail_extend(struct ebuf *eb, size_t size);
68
69 struct ebuf *
ebuf_alloc(size_t size)70 ebuf_alloc(size_t size)
71 {
72 struct ebuf *eb;
73 int rerrno;
74
75 eb = malloc(sizeof(*eb));
76 if (eb == NULL)
77 return (NULL);
78 size += PAGE_SIZE;
79 eb->eb_start = malloc(size);
80 if (eb->eb_start == NULL) {
81 rerrno = errno;
82 free(eb);
83 errno = rerrno;
84 return (NULL);
85 }
86 eb->eb_end = eb->eb_start + size;
87 /*
88 * We set start address for real data not at the first entry, because
89 * we want to be able to add data at the front.
90 */
91 eb->eb_used = eb->eb_start + PAGE_SIZE / 4;
92 eb->eb_size = 0;
93 eb->eb_magic = EBUF_MAGIC;
94
95 return (eb);
96 }
97
98 void
ebuf_free(struct ebuf * eb)99 ebuf_free(struct ebuf *eb)
100 {
101
102 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
103
104 eb->eb_magic = 0;
105
106 free(eb->eb_start);
107 free(eb);
108 }
109
110 int
ebuf_add_head(struct ebuf * eb,const void * data,size_t size)111 ebuf_add_head(struct ebuf *eb, const void *data, size_t size)
112 {
113
114 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
115
116 if (size > (size_t)(eb->eb_used - eb->eb_start)) {
117 /*
118 * We can't add more entries at the front, so we have to extend
119 * our buffer.
120 */
121 if (ebuf_head_extend(eb, size) == -1)
122 return (-1);
123 }
124 PJDLOG_ASSERT(size <= (size_t)(eb->eb_used - eb->eb_start));
125
126 eb->eb_size += size;
127 eb->eb_used -= size;
128 /*
129 * If data is NULL the caller just wants to reserve place.
130 */
131 if (data != NULL)
132 bcopy(data, eb->eb_used, size);
133
134 return (0);
135 }
136
137 int
ebuf_add_tail(struct ebuf * eb,const void * data,size_t size)138 ebuf_add_tail(struct ebuf *eb, const void *data, size_t size)
139 {
140
141 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
142
143 if (size > (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))) {
144 /*
145 * We can't add more entries at the back, so we have to extend
146 * our buffer.
147 */
148 if (ebuf_tail_extend(eb, size) == -1)
149 return (-1);
150 }
151 PJDLOG_ASSERT(size <=
152 (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size)));
153
154 /*
155 * If data is NULL the caller just wants to reserve space.
156 */
157 if (data != NULL)
158 bcopy(data, eb->eb_used + eb->eb_size, size);
159 eb->eb_size += size;
160
161 return (0);
162 }
163
164 void
ebuf_del_head(struct ebuf * eb,size_t size)165 ebuf_del_head(struct ebuf *eb, size_t size)
166 {
167
168 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
169 PJDLOG_ASSERT(size <= eb->eb_size);
170
171 eb->eb_used += size;
172 eb->eb_size -= size;
173 }
174
175 void
ebuf_del_tail(struct ebuf * eb,size_t size)176 ebuf_del_tail(struct ebuf *eb, size_t size)
177 {
178
179 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
180 PJDLOG_ASSERT(size <= eb->eb_size);
181
182 eb->eb_size -= size;
183 }
184
185 /*
186 * Return pointer to the data and data size.
187 */
188 void *
ebuf_data(struct ebuf * eb,size_t * sizep)189 ebuf_data(struct ebuf *eb, size_t *sizep)
190 {
191
192 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
193
194 if (sizep != NULL)
195 *sizep = eb->eb_size;
196 return (eb->eb_size > 0 ? eb->eb_used : NULL);
197 }
198
199 /*
200 * Return data size.
201 */
202 size_t
ebuf_size(struct ebuf * eb)203 ebuf_size(struct ebuf *eb)
204 {
205
206 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
207
208 return (eb->eb_size);
209 }
210
211 /*
212 * Function adds size + (PAGE_SIZE / 4) bytes at the front of the buffer..
213 */
214 static int
ebuf_head_extend(struct ebuf * eb,size_t size)215 ebuf_head_extend(struct ebuf *eb, size_t size)
216 {
217 unsigned char *newstart, *newused;
218 size_t newsize;
219
220 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
221
222 newsize = eb->eb_end - eb->eb_start + (PAGE_SIZE / 4) + size;
223
224 newstart = malloc(newsize);
225 if (newstart == NULL)
226 return (-1);
227 newused =
228 newstart + (PAGE_SIZE / 4) + size + (eb->eb_used - eb->eb_start);
229
230 bcopy(eb->eb_used, newused, eb->eb_size);
231
232 eb->eb_start = newstart;
233 eb->eb_used = newused;
234 eb->eb_end = newstart + newsize;
235
236 return (0);
237 }
238
239 /*
240 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back.
241 */
242 static int
ebuf_tail_extend(struct ebuf * eb,size_t size)243 ebuf_tail_extend(struct ebuf *eb, size_t size)
244 {
245 unsigned char *newstart;
246 size_t newsize;
247
248 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC);
249
250 newsize = eb->eb_end - eb->eb_start + size + ((3 * PAGE_SIZE) / 4);
251
252 newstart = realloc(eb->eb_start, newsize);
253 if (newstart == NULL)
254 return (-1);
255
256 eb->eb_used = newstart + (eb->eb_used - eb->eb_start);
257 eb->eb_start = newstart;
258 eb->eb_end = newstart + newsize;
259
260 return (0);
261 }
262