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 #include <sys/param.h>
32
33 #ifdef HAVE_HEADER_MACHINE_VMPARAM_H
34 #include <machine/vmparam.h>
35 #elif defined(HAVE_HEADER_SYS_USER_H)
36 #include <sys/user.h>
37 #endif
38
39 #include <assert.h>
40 #include <errno.h>
41 #include <stdbool.h>
42 #include <stdint.h>
43 #include <strings.h>
44 #include <unistd.h>
45
46 #include "ebuf.h"
47
48 #define EBUF_MAGIC 0xeb0f41c
49 struct ebuf {
50 /* Magic to assert the caller uses valid structure. */
51 int eb_magic;
52 /* Address where we did the allocation. */
53 unsigned char *eb_start;
54 /* Allocation end address. */
55 unsigned char *eb_end;
56 /* Start of real data. */
57 unsigned char *eb_used;
58 /* Size of real data. */
59 size_t eb_size;
60 };
61
62 static int ebuf_head_extend(struct ebuf *eb, size_t size);
63 static int ebuf_tail_extend(struct ebuf *eb, size_t size);
64
65 struct ebuf *
ebuf_alloc(size_t size)66 ebuf_alloc(size_t size)
67 {
68 struct ebuf *eb;
69 int rerrno;
70
71 eb = malloc(sizeof(*eb));
72 if (eb == NULL)
73 return (NULL);
74 size += PAGE_SIZE;
75 eb->eb_start = malloc(size);
76 if (eb->eb_start == NULL) {
77 rerrno = errno;
78 free(eb);
79 errno = rerrno;
80 return (NULL);
81 }
82 eb->eb_end = eb->eb_start + size;
83 /*
84 * We set start address for real data not at the first entry, because
85 * we want to be able to add data at the front.
86 */
87 eb->eb_used = eb->eb_start + PAGE_SIZE / 4;
88 eb->eb_size = 0;
89 eb->eb_magic = EBUF_MAGIC;
90
91 return (eb);
92 }
93
94 void
ebuf_free(struct ebuf * eb)95 ebuf_free(struct ebuf *eb)
96 {
97
98 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
99
100 eb->eb_magic = 0;
101
102 free(eb->eb_start);
103 free(eb);
104 }
105
106 int
ebuf_add_head(struct ebuf * eb,const void * data,size_t size)107 ebuf_add_head(struct ebuf *eb, const void *data, size_t size)
108 {
109
110 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
111
112 if (size > (size_t)(eb->eb_used - eb->eb_start)) {
113 /*
114 * We can't add more entries at the front, so we have to extend
115 * our buffer.
116 */
117 if (ebuf_head_extend(eb, size) < 0)
118 return (-1);
119 }
120 assert(size <= (size_t)(eb->eb_used - eb->eb_start));
121
122 eb->eb_size += size;
123 eb->eb_used -= size;
124 /*
125 * If data is NULL the caller just wants to reserve place.
126 */
127 if (data != NULL)
128 bcopy(data, eb->eb_used, size);
129
130 return (0);
131 }
132
133 int
ebuf_add_tail(struct ebuf * eb,const void * data,size_t size)134 ebuf_add_tail(struct ebuf *eb, const void *data, size_t size)
135 {
136
137 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
138
139 if (size > (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))) {
140 /*
141 * We can't add more entries at the back, so we have to extend
142 * our buffer.
143 */
144 if (ebuf_tail_extend(eb, size) < 0)
145 return (-1);
146 }
147 assert(size <= (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size)));
148
149 /*
150 * If data is NULL the caller just wants to reserve space.
151 */
152 if (data != NULL)
153 bcopy(data, eb->eb_used + eb->eb_size, size);
154 eb->eb_size += size;
155
156 return (0);
157 }
158
159 void
ebuf_del_head(struct ebuf * eb,size_t size)160 ebuf_del_head(struct ebuf *eb, size_t size)
161 {
162
163 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
164 assert(size <= eb->eb_size);
165
166 eb->eb_used += size;
167 eb->eb_size -= size;
168 }
169
170 void
ebuf_del_tail(struct ebuf * eb,size_t size)171 ebuf_del_tail(struct ebuf *eb, size_t size)
172 {
173
174 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
175 assert(size <= eb->eb_size);
176
177 eb->eb_size -= size;
178 }
179
180 /*
181 * Return pointer to the data and data size.
182 */
183 void *
ebuf_data(struct ebuf * eb,size_t * sizep)184 ebuf_data(struct ebuf *eb, size_t *sizep)
185 {
186
187 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
188
189 if (sizep != NULL)
190 *sizep = eb->eb_size;
191 return (eb->eb_size > 0 ? eb->eb_used : NULL);
192 }
193
194 /*
195 * Return data size.
196 */
197 size_t
ebuf_size(struct ebuf * eb)198 ebuf_size(struct ebuf *eb)
199 {
200
201 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
202
203 return (eb->eb_size);
204 }
205
206 /*
207 * Function adds size + (PAGE_SIZE / 4) bytes at the front of the buffer..
208 */
209 static int
ebuf_head_extend(struct ebuf * eb,size_t size)210 ebuf_head_extend(struct ebuf *eb, size_t size)
211 {
212 unsigned char *newstart, *newused;
213 size_t newsize;
214
215 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
216
217 newsize = eb->eb_end - eb->eb_start + (PAGE_SIZE / 4) + size;
218
219 newstart = malloc(newsize);
220 if (newstart == NULL)
221 return (-1);
222 newused =
223 newstart + (PAGE_SIZE / 4) + size + (eb->eb_used - eb->eb_start);
224
225 bcopy(eb->eb_used, newused, eb->eb_size);
226
227 eb->eb_start = newstart;
228 eb->eb_used = newused;
229 eb->eb_end = newstart + newsize;
230
231 return (0);
232 }
233
234 /*
235 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back.
236 */
237 static int
ebuf_tail_extend(struct ebuf * eb,size_t size)238 ebuf_tail_extend(struct ebuf *eb, size_t size)
239 {
240 unsigned char *newstart;
241 size_t newsize;
242
243 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC);
244
245 newsize = eb->eb_end - eb->eb_start + size + ((3 * PAGE_SIZE) / 4);
246
247 newstart = realloc(eb->eb_start, newsize);
248 if (newstart == NULL)
249 return (-1);
250
251 eb->eb_used = newstart + (eb->eb_used - eb->eb_start);
252 eb->eb_start = newstart;
253 eb->eb_end = newstart + newsize;
254
255 return (0);
256 }
257