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("$FreeBSD$"); 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 * 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 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 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 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 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 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 * 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 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 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 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