1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 size_t page_size; 74 int rerrno; 75 76 eb = malloc(sizeof(*eb)); 77 if (eb == NULL) 78 return (NULL); 79 page_size = getpagesize(); 80 size += page_size; 81 eb->eb_start = malloc(size); 82 if (eb->eb_start == NULL) { 83 rerrno = errno; 84 free(eb); 85 errno = rerrno; 86 return (NULL); 87 } 88 eb->eb_end = eb->eb_start + size; 89 /* 90 * We set start address for real data not at the first entry, because 91 * we want to be able to add data at the front. 92 */ 93 eb->eb_used = eb->eb_start + page_size / 4; 94 eb->eb_size = 0; 95 eb->eb_magic = EBUF_MAGIC; 96 97 return (eb); 98 } 99 100 void 101 ebuf_free(struct ebuf *eb) 102 { 103 104 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 105 106 eb->eb_magic = 0; 107 108 free(eb->eb_start); 109 free(eb); 110 } 111 112 int 113 ebuf_add_head(struct ebuf *eb, const void *data, size_t size) 114 { 115 116 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 117 118 if (size > (size_t)(eb->eb_used - eb->eb_start)) { 119 /* 120 * We can't add more entries at the front, so we have to extend 121 * our buffer. 122 */ 123 if (ebuf_head_extend(eb, size) == -1) 124 return (-1); 125 } 126 PJDLOG_ASSERT(size <= (size_t)(eb->eb_used - eb->eb_start)); 127 128 eb->eb_size += size; 129 eb->eb_used -= size; 130 /* 131 * If data is NULL the caller just wants to reserve place. 132 */ 133 if (data != NULL) 134 bcopy(data, eb->eb_used, size); 135 136 return (0); 137 } 138 139 int 140 ebuf_add_tail(struct ebuf *eb, const void *data, size_t size) 141 { 142 143 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 144 145 if (size > (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))) { 146 /* 147 * We can't add more entries at the back, so we have to extend 148 * our buffer. 149 */ 150 if (ebuf_tail_extend(eb, size) == -1) 151 return (-1); 152 } 153 PJDLOG_ASSERT(size <= 154 (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))); 155 156 /* 157 * If data is NULL the caller just wants to reserve space. 158 */ 159 if (data != NULL) 160 bcopy(data, eb->eb_used + eb->eb_size, size); 161 eb->eb_size += size; 162 163 return (0); 164 } 165 166 void 167 ebuf_del_head(struct ebuf *eb, size_t size) 168 { 169 170 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 171 PJDLOG_ASSERT(size <= eb->eb_size); 172 173 eb->eb_used += size; 174 eb->eb_size -= size; 175 } 176 177 void 178 ebuf_del_tail(struct ebuf *eb, size_t size) 179 { 180 181 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 182 PJDLOG_ASSERT(size <= eb->eb_size); 183 184 eb->eb_size -= size; 185 } 186 187 /* 188 * Return pointer to the data and data size. 189 */ 190 void * 191 ebuf_data(struct ebuf *eb, size_t *sizep) 192 { 193 194 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 195 196 if (sizep != NULL) 197 *sizep = eb->eb_size; 198 return (eb->eb_size > 0 ? eb->eb_used : NULL); 199 } 200 201 /* 202 * Return data size. 203 */ 204 size_t 205 ebuf_size(struct ebuf *eb) 206 { 207 208 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 209 210 return (eb->eb_size); 211 } 212 213 /* 214 * Function adds size + (PAGE_SIZE / 4) bytes at the front of the buffer.. 215 */ 216 static int 217 ebuf_head_extend(struct ebuf *eb, size_t size) 218 { 219 unsigned char *newstart, *newused; 220 size_t newsize, page_size; 221 222 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 223 224 page_size = getpagesize(); 225 newsize = eb->eb_end - eb->eb_start + (page_size / 4) + size; 226 227 newstart = malloc(newsize); 228 if (newstart == NULL) 229 return (-1); 230 newused = 231 newstart + (page_size / 4) + size + (eb->eb_used - eb->eb_start); 232 233 bcopy(eb->eb_used, newused, eb->eb_size); 234 235 eb->eb_start = newstart; 236 eb->eb_used = newused; 237 eb->eb_end = newstart + newsize; 238 239 return (0); 240 } 241 242 /* 243 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back. 244 */ 245 static int 246 ebuf_tail_extend(struct ebuf *eb, size_t size) 247 { 248 unsigned char *newstart; 249 size_t newsize, page_size; 250 251 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 252 253 page_size = getpagesize(); 254 newsize = eb->eb_end - eb->eb_start + size + ((3 * page_size) / 4); 255 256 newstart = realloc(eb->eb_start, newsize); 257 if (newstart == NULL) 258 return (-1); 259 260 eb->eb_used = newstart + (eb->eb_used - eb->eb_start); 261 eb->eb_start = newstart; 262 eb->eb_end = newstart + newsize; 263 264 return (0); 265 } 266