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 #include <sys/param.h> 34 35 #include <errno.h> 36 #include <stdbool.h> 37 #include <stdint.h> 38 #include <strings.h> 39 #include <unistd.h> 40 41 #include <pjdlog.h> 42 43 #include "ebuf.h" 44 45 #ifndef PJDLOG_ASSERT 46 #include <assert.h> 47 #define PJDLOG_ASSERT(...) assert(__VA_ARGS__) 48 #endif 49 50 #define EBUF_MAGIC 0xeb0f41c 51 struct ebuf { 52 /* Magic to assert the caller uses valid structure. */ 53 int eb_magic; 54 /* Address where we did the allocation. */ 55 unsigned char *eb_start; 56 /* Allocation end address. */ 57 unsigned char *eb_end; 58 /* Start of real data. */ 59 unsigned char *eb_used; 60 /* Size of real data. */ 61 size_t eb_size; 62 }; 63 64 static int ebuf_head_extend(struct ebuf *eb, size_t size); 65 static int ebuf_tail_extend(struct ebuf *eb, size_t size); 66 67 struct ebuf * 68 ebuf_alloc(size_t size) 69 { 70 struct ebuf *eb; 71 size_t page_size; 72 int rerrno; 73 74 eb = malloc(sizeof(*eb)); 75 if (eb == NULL) 76 return (NULL); 77 page_size = getpagesize(); 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, page_size; 219 220 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 221 222 page_size = getpagesize(); 223 newsize = eb->eb_end - eb->eb_start + (page_size / 4) + size; 224 225 newstart = malloc(newsize); 226 if (newstart == NULL) 227 return (-1); 228 newused = 229 newstart + (page_size / 4) + size + (eb->eb_used - eb->eb_start); 230 231 bcopy(eb->eb_used, newused, eb->eb_size); 232 233 eb->eb_start = newstart; 234 eb->eb_used = newused; 235 eb->eb_end = newstart + newsize; 236 237 return (0); 238 } 239 240 /* 241 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back. 242 */ 243 static int 244 ebuf_tail_extend(struct ebuf *eb, size_t size) 245 { 246 unsigned char *newstart; 247 size_t newsize, page_size; 248 249 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 250 251 page_size = getpagesize(); 252 newsize = eb->eb_end - eb->eb_start + size + ((3 * page_size) / 4); 253 254 newstart = realloc(eb->eb_start, newsize); 255 if (newstart == NULL) 256 return (-1); 257 258 eb->eb_used = newstart + (eb->eb_used - eb->eb_start); 259 eb->eb_start = newstart; 260 eb->eb_end = newstart + newsize; 261 262 return (0); 263 } 264