1 /*- 2 * Copyright (c) 2009-2010 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Pawel Jakub Dawidek under sponsorship from 6 * the FreeBSD Foundation. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/param.h> 34 35 #include <assert.h> 36 #include <errno.h> 37 #include <stdbool.h> 38 #include <stdint.h> 39 #include <strings.h> 40 #include <unistd.h> 41 42 #include "ebuf.h" 43 44 #define EBUF_MAGIC 0xeb0f41c 45 struct ebuf { 46 /* Magic to assert the caller uses valid structure. */ 47 int eb_magic; 48 /* Address where we did the allocation. */ 49 unsigned char *eb_start; 50 /* Allocation end address. */ 51 unsigned char *eb_end; 52 /* Start of real data. */ 53 unsigned char *eb_used; 54 /* Size of real data. */ 55 size_t eb_size; 56 }; 57 58 static int ebuf_head_extend(struct ebuf *eb, size_t size); 59 static int ebuf_tail_extend(struct ebuf *eb, size_t size); 60 61 struct ebuf * 62 ebuf_alloc(size_t size) 63 { 64 struct ebuf *eb; 65 int rerrno; 66 67 eb = malloc(sizeof(*eb)); 68 if (eb == NULL) 69 return (NULL); 70 size += PAGE_SIZE; 71 eb->eb_start = malloc(size); 72 if (eb->eb_start == NULL) { 73 rerrno = errno; 74 free(eb); 75 errno = rerrno; 76 return (NULL); 77 } 78 eb->eb_end = eb->eb_start + size; 79 /* 80 * We set start address for real data not at the first entry, because 81 * we want to be able to add data at the front. 82 */ 83 eb->eb_used = eb->eb_start + PAGE_SIZE / 4; 84 eb->eb_size = 0; 85 eb->eb_magic = EBUF_MAGIC; 86 87 return (eb); 88 } 89 90 void 91 ebuf_free(struct ebuf *eb) 92 { 93 94 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 95 96 eb->eb_magic = 0; 97 98 free(eb->eb_start); 99 free(eb); 100 } 101 102 int 103 ebuf_add_head(struct ebuf *eb, const void *data, size_t size) 104 { 105 106 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 107 108 if (size > (size_t)(eb->eb_used - eb->eb_start)) { 109 /* 110 * We can't add more entries at the front, so we have to extend 111 * our buffer. 112 */ 113 if (ebuf_head_extend(eb, size) < 0) 114 return (-1); 115 } 116 assert(size <= (size_t)(eb->eb_used - eb->eb_start)); 117 118 eb->eb_size += size; 119 eb->eb_used -= size; 120 /* 121 * If data is NULL the caller just wants to reserve place. 122 */ 123 if (data != NULL) 124 bcopy(data, eb->eb_used, size); 125 126 return (0); 127 } 128 129 int 130 ebuf_add_tail(struct ebuf *eb, const void *data, size_t size) 131 { 132 133 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 134 135 if (size > (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))) { 136 /* 137 * We can't add more entries at the back, so we have to extend 138 * our buffer. 139 */ 140 if (ebuf_tail_extend(eb, size) < 0) 141 return (-1); 142 } 143 assert(size <= (size_t)(eb->eb_end - (eb->eb_used + eb->eb_size))); 144 145 /* 146 * If data is NULL the caller just wants to reserve space. 147 */ 148 if (data != NULL) 149 bcopy(data, eb->eb_used + eb->eb_size, size); 150 eb->eb_size += size; 151 152 return (0); 153 } 154 155 void 156 ebuf_del_head(struct ebuf *eb, size_t size) 157 { 158 159 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 160 assert(size <= eb->eb_size); 161 162 eb->eb_used += size; 163 eb->eb_size -= size; 164 } 165 166 void 167 ebuf_del_tail(struct ebuf *eb, size_t size) 168 { 169 170 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 171 assert(size <= eb->eb_size); 172 173 eb->eb_size -= size; 174 } 175 176 /* 177 * Return pointer to the data and data size. 178 */ 179 void * 180 ebuf_data(struct ebuf *eb, size_t *sizep) 181 { 182 183 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 184 185 if (sizep != NULL) 186 *sizep = eb->eb_size; 187 return (eb->eb_size > 0 ? eb->eb_used : NULL); 188 } 189 190 /* 191 * Return data size. 192 */ 193 size_t 194 ebuf_size(struct ebuf *eb) 195 { 196 197 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 198 199 return (eb->eb_size); 200 } 201 202 /* 203 * Function adds size + (PAGE_SIZE / 4) bytes at the front of the buffer.. 204 */ 205 static int 206 ebuf_head_extend(struct ebuf *eb, size_t size) 207 { 208 unsigned char *newstart, *newused; 209 size_t newsize; 210 211 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 212 213 newsize = eb->eb_end - eb->eb_start + (PAGE_SIZE / 4) + size; 214 215 newstart = malloc(newsize); 216 if (newstart == NULL) 217 return (-1); 218 newused = 219 newstart + (PAGE_SIZE / 4) + size + (eb->eb_used - eb->eb_start); 220 221 bcopy(eb->eb_used, newused, eb->eb_size); 222 223 eb->eb_start = newstart; 224 eb->eb_used = newused; 225 eb->eb_end = newstart + newsize; 226 227 return (0); 228 } 229 230 /* 231 * Function adds size + ((3 * PAGE_SIZE) / 4) bytes at the back. 232 */ 233 static int 234 ebuf_tail_extend(struct ebuf *eb, size_t size) 235 { 236 unsigned char *newstart; 237 size_t newsize; 238 239 assert(eb != NULL && eb->eb_magic == EBUF_MAGIC); 240 241 newsize = eb->eb_end - eb->eb_start + size + ((3 * PAGE_SIZE) / 4); 242 243 newstart = realloc(eb->eb_start, newsize); 244 if (newstart == NULL) 245 return (-1); 246 247 eb->eb_used = newstart + (eb->eb_used - eb->eb_start); 248 eb->eb_start = newstart; 249 eb->eb_end = newstart + newsize; 250 251 return (0); 252 } 253