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 <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 int rerrno; 72 73 eb = malloc(sizeof(*eb)); 74 if (eb == NULL) 75 return (NULL); 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; 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 */ 240 static int 241 ebuf_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