1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2009-2010 The FreeBSD Foundation 5 * 6 * This software was developed by Pawel Jakub Dawidek under sponsorship from 7 * the FreeBSD Foundation. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/param.h> 32 33 #include <errno.h> 34 #include <stdbool.h> 35 #include <stdint.h> 36 #include <strings.h> 37 #include <unistd.h> 38 39 #include <pjdlog.h> 40 41 #include "ebuf.h" 42 43 #ifndef PJDLOG_ASSERT 44 #include <assert.h> 45 #define PJDLOG_ASSERT(...) assert(__VA_ARGS__) 46 #endif 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 * 66 ebuf_alloc(size_t size) 67 { 68 struct ebuf *eb; 69 size_t page_size; 70 int rerrno; 71 72 eb = malloc(sizeof(*eb)); 73 if (eb == NULL) 74 return (NULL); 75 page_size = getpagesize(); 76 size += page_size; 77 eb->eb_start = malloc(size); 78 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 96 void 97 ebuf_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 } 107 108 int 109 ebuf_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) == -1) 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 } 134 135 int 136 ebuf_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) == -1) 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 } 161 162 void 163 ebuf_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 } 172 173 void 174 ebuf_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 */ 186 void * 187 ebuf_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 */ 200 size_t 201 ebuf_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 */ 212 static int 213 ebuf_head_extend(struct ebuf *eb, size_t size) 214 { 215 unsigned char *newstart, *newused; 216 size_t newsize, page_size; 217 218 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 219 220 page_size = getpagesize(); 221 newsize = eb->eb_end - eb->eb_start + (page_size / 4) + size; 222 223 newstart = malloc(newsize); 224 if (newstart == NULL) 225 return (-1); 226 newused = 227 newstart + (page_size / 4) + size + (eb->eb_used - eb->eb_start); 228 229 bcopy(eb->eb_used, newused, eb->eb_size); 230 231 eb->eb_start = newstart; 232 eb->eb_used = newused; 233 eb->eb_end = newstart + newsize; 234 235 return (0); 236 } 237 238 /* 239 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back. 240 */ 241 static int 242 ebuf_tail_extend(struct ebuf *eb, size_t size) 243 { 244 unsigned char *newstart; 245 size_t newsize, page_size; 246 247 PJDLOG_ASSERT(eb != NULL && eb->eb_magic == EBUF_MAGIC); 248 249 page_size = getpagesize(); 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