ebuf.c revision 225787
153790Sobrien/*- 253790Sobrien * Copyright (c) 2009-2010 The FreeBSD Foundation 353790Sobrien * All rights reserved. 453790Sobrien * 586266Sgroudier * This software was developed by Pawel Jakub Dawidek under sponsorship from 653790Sobrien * the FreeBSD Foundation. 753790Sobrien * 862422Sgroudier * Redistribution and use in source and binary forms, with or without 962422Sgroudier * modification, are permitted provided that the following conditions 1053790Sobrien * are met: 1153790Sobrien * 1. Redistributions of source code must retain the above copyright 1253790Sobrien * notice, this list of conditions and the following disclaimer. 1353790Sobrien * 2. Redistributions in binary form must reproduce the above copyright 1453790Sobrien * notice, this list of conditions and the following disclaimer in the 1553790Sobrien * documentation and/or other materials provided with the distribution. 1653790Sobrien * 1753790Sobrien * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 1853790Sobrien * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1953790Sobrien * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2053790Sobrien * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 2153790Sobrien * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2253790Sobrien * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2353790Sobrien * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2453790Sobrien * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2553790Sobrien * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2653790Sobrien * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2753790Sobrien * SUCH DAMAGE. 2853790Sobrien */ 2953790Sobrien 3053790Sobrien#include <sys/cdefs.h> 3153790Sobrien__FBSDID("$FreeBSD: head/sbin/hastd/ebuf.c 225787 2011-09-27 08:50:37Z pjd $"); 3253790Sobrien 3353790Sobrien#include <sys/param.h> 3453790Sobrien 3553790Sobrien#include <errno.h> 3653790Sobrien#include <stdbool.h> 3753790Sobrien#include <stdint.h> 3853790Sobrien#include <strings.h> 3953790Sobrien#include <unistd.h> 4053790Sobrien 4153790Sobrien#include <pjdlog.h> 4253790Sobrien 4353790Sobrien#include "ebuf.h" 4453790Sobrien 4553790Sobrien#ifndef PJDLOG_ASSERT 4653790Sobrien#include <assert.h> 4753790Sobrien#define PJDLOG_ASSERT(...) assert(__VA_ARGS__) 4853790Sobrien#endif 4953790Sobrien 5053790Sobrien#define EBUF_MAGIC 0xeb0f41c 5153790Sobrienstruct ebuf { 5253790Sobrien /* Magic to assert the caller uses valid structure. */ 5353790Sobrien int eb_magic; 5453790Sobrien /* Address where we did the allocation. */ 5553790Sobrien unsigned char *eb_start; 5659868Speter /* Allocation end address. */ 5759868Speter unsigned char *eb_end; 5853790Sobrien /* Start of real data. */ 5953790Sobrien unsigned char *eb_used; 6062422Sgroudier /* Size of real data. */ 6162422Sgroudier size_t eb_size; 6262422Sgroudier}; 6362422Sgroudier 6462422Sgroudierstatic int ebuf_head_extend(struct ebuf *eb, size_t size); 6562422Sgroudierstatic int ebuf_tail_extend(struct ebuf *eb, size_t size); 6662422Sgroudier 6762422Sgroudierstruct ebuf * 6862422Sgroudierebuf_alloc(size_t size) 6953790Sobrien{ 7062422Sgroudier struct ebuf *eb; 7162422Sgroudier int rerrno; 7262422Sgroudier 7362422Sgroudier eb = malloc(sizeof(*eb)); 7453790Sobrien if (eb == NULL) 7562422Sgroudier return (NULL); 7653790Sobrien size += PAGE_SIZE; 7762422Sgroudier eb->eb_start = malloc(size); 7886266Sgroudier 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} 260