1 /* 2 * Copyright 2014 Intel Corporation 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 21 * IN THE SOFTWARE. 22 */ 23 24 #ifndef BLOB_H 25 #define BLOB_H 26 27 #include <stdbool.h> 28 #include <stddef.h> 29 #include <stdint.h> 30 #include <stdlib.h> 31 32 #ifdef __cplusplus 33 extern "C" { 34 #endif 35 36 /* The blob functions implement a simple, low-level API for serializing and 37 * deserializing. 38 * 39 * All objects written to a blob will be serialized directly, (without any 40 * additional meta-data to describe the data written). Therefore, it is the 41 * caller's responsibility to ensure that any data can be read later, (either 42 * by knowing exactly what data is expected, or by writing to the blob 43 * sufficient meta-data to describe what has been written). 44 * 45 * A blob is efficient in that it dynamically grows by doubling in size, so 46 * allocation costs are logarithmic. 47 */ 48 49 struct blob { 50 /* The data actually written to the blob. */ 51 uint8_t *data; 52 53 /** Number of bytes that have been allocated for \c data. */ 54 size_t allocated; 55 56 /** The number of bytes that have actual data written to them. */ 57 size_t size; 58 59 /** True if \c data a fixed allocation that we cannot resize 60 * 61 * \see blob_init_fixed 62 */ 63 bool fixed_allocation; 64 65 /** 66 * True if we've ever failed to realloc or if we go pas the end of a fixed 67 * allocation blob. 68 */ 69 bool out_of_memory; 70 }; 71 72 /* When done reading, the caller can ensure that everything was consumed by 73 * checking the following: 74 * 75 * 1. blob->current should be equal to blob->end, (if not, too little was 76 * read). 77 * 78 * 2. blob->overrun should be false, (otherwise, too much was read). 79 */ 80 struct blob_reader { 81 const uint8_t *data; 82 const uint8_t *end; 83 const uint8_t *current; 84 bool overrun; 85 }; 86 87 /** 88 * Init a new, empty blob. 89 */ 90 void 91 blob_init(struct blob *blob); 92 93 /** 94 * Init a new, fixed-size blob. 95 * 96 * A fixed-size blob has a fixed block of data that will not be freed on 97 * blob_finish and will never be grown. If we hit the end, we simply start 98 * returning false from the write functions. 99 * 100 * If a fixed-size blob has a NULL data pointer then the data is written but 101 * it otherwise operates normally. This can be used to determine the size 102 * that will be required to write a given data structure. 103 */ 104 void 105 blob_init_fixed(struct blob *blob, void *data, size_t size); 106 107 /** 108 * Finish a blob and free its memory. 109 * 110 * If \blob was initialized with blob_init_fixed, the data pointer is 111 * considered to be owned by the user and will not be freed. 112 */ 113 static inline void 114 blob_finish(struct blob *blob) 115 { 116 if (!blob->fixed_allocation) 117 free(blob->data); 118 } 119 120 /** 121 * Add some unstructured, fixed-size data to a blob. 122 * 123 * \return True unless allocation failed. 124 */ 125 bool 126 blob_write_bytes(struct blob *blob, const void *bytes, size_t to_write); 127 128 /** 129 * Reserve space in \blob for a number of bytes. 130 * 131 * Space will be allocated within the blob for these byes, but the bytes will 132 * be left uninitialized. The caller is expected to use \sa 133 * blob_overwrite_bytes to write to these bytes. 134 * 135 * \return An offset to space allocated within \blob to which \to_write bytes 136 * can be written, (or -1 in case of any allocation error). 137 */ 138 intptr_t 139 blob_reserve_bytes(struct blob *blob, size_t to_write); 140 141 /** 142 * Similar to \sa blob_reserve_bytes, but only reserves an uint32_t worth of 143 * space. Note that this must be used if later reading with \sa 144 * blob_read_uint32, since it aligns the offset correctly. 145 */ 146 intptr_t 147 blob_reserve_uint32(struct blob *blob); 148 149 /** 150 * Similar to \sa blob_reserve_bytes, but only reserves an intptr_t worth of 151 * space. Note that this must be used if later reading with \sa 152 * blob_read_intptr, since it aligns the offset correctly. 153 */ 154 intptr_t 155 blob_reserve_intptr(struct blob *blob); 156 157 /** 158 * Overwrite some data previously written to the blob. 159 * 160 * Writes data to an existing portion of the blob at an offset of \offset. 161 * This data range must have previously been written to the blob by one of the 162 * blob_write_* calls. 163 * 164 * For example usage, see blob_overwrite_uint32 165 * 166 * \return True unless the requested offset or offset+to_write lie outside 167 * the current blob's size. 168 */ 169 bool 170 blob_overwrite_bytes(struct blob *blob, 171 size_t offset, 172 const void *bytes, 173 size_t to_write); 174 175 /** 176 * Add a uint32_t to a blob. 177 * 178 * \note This function will only write to a uint32_t-aligned offset from the 179 * beginning of the blob's data, so some padding bytes may be added to the 180 * blob if this write follows some unaligned write (such as 181 * blob_write_string). 182 * 183 * \return True unless allocation failed. 184 */ 185 bool 186 blob_write_uint32(struct blob *blob, uint32_t value); 187 188 /** 189 * Overwrite a uint32_t previously written to the blob. 190 * 191 * Writes a uint32_t value to an existing portion of the blob at an offset of 192 * \offset. This data range must have previously been written to the blob by 193 * one of the blob_write_* calls. 194 * 195 * 196 * The expected usage is something like the following pattern: 197 * 198 * size_t offset; 199 * 200 * offset = blob_reserve_uint32(blob); 201 * ... various blob write calls, writing N items ... 202 * blob_overwrite_uint32 (blob, offset, N); 203 * 204 * \return True unless the requested position or position+to_write lie outside 205 * the current blob's size. 206 */ 207 bool 208 blob_overwrite_uint32(struct blob *blob, 209 size_t offset, 210 uint32_t value); 211 212 /** 213 * Add a uint64_t to a blob. 214 * 215 * \note This function will only write to a uint64_t-aligned offset from the 216 * beginning of the blob's data, so some padding bytes may be added to the 217 * blob if this write follows some unaligned write (such as 218 * blob_write_string). 219 * 220 * \return True unless allocation failed. 221 */ 222 bool 223 blob_write_uint64(struct blob *blob, uint64_t value); 224 225 /** 226 * Add an intptr_t to a blob. 227 * 228 * \note This function will only write to an intptr_t-aligned offset from the 229 * beginning of the blob's data, so some padding bytes may be added to the 230 * blob if this write follows some unaligned write (such as 231 * blob_write_string). 232 * 233 * \return True unless allocation failed. 234 */ 235 bool 236 blob_write_intptr(struct blob *blob, intptr_t value); 237 238 /** 239 * Overwrite an intptr_t previously written to the blob. 240 * 241 * Writes a intptr_t value to an existing portion of the blob at an offset of 242 * \offset. This data range must have previously been written to the blob by 243 * one of the blob_write_* calls. 244 * 245 * For example usage, see blob_overwrite_uint32 246 * 247 * \return True unless the requested position or position+to_write lie outside 248 * the current blob's size. 249 */ 250 bool 251 blob_overwrite_intptr(struct blob *blob, 252 size_t offset, 253 intptr_t value); 254 255 /** 256 * Add a NULL-terminated string to a blob, (including the NULL terminator). 257 * 258 * \return True unless allocation failed. 259 */ 260 bool 261 blob_write_string(struct blob *blob, const char *str); 262 263 /** 264 * Start reading a blob, (initializing the contents of \blob for reading). 265 * 266 * After this call, the caller can use the various blob_read_* functions to 267 * read elements from the data array. 268 * 269 * For all of the blob_read_* functions, if there is insufficient data 270 * remaining, the functions will do nothing, (perhaps returning default values 271 * such as 0). The caller can detect this by noting that the blob_reader's 272 * current value is unchanged before and after the call. 273 */ 274 void 275 blob_reader_init(struct blob_reader *blob, const void *data, size_t size); 276 277 /** 278 * Read some unstructured, fixed-size data from the current location, (and 279 * update the current location to just past this data). 280 * 281 * \note The memory returned belongs to the data underlying the blob reader. The 282 * caller must copy the data in order to use it after the lifetime of the data 283 * underlying the blob reader. 284 * 285 * \return The bytes read (see note above about memory lifetime). 286 */ 287 const void * 288 blob_read_bytes(struct blob_reader *blob, size_t size); 289 290 /** 291 * Read some unstructured, fixed-size data from the current location, copying 292 * it to \dest (and update the current location to just past this data) 293 */ 294 void 295 blob_copy_bytes(struct blob_reader *blob, void *dest, size_t size); 296 297 /** 298 * Read a uint32_t from the current location, (and update the current location 299 * to just past this uint32_t). 300 * 301 * \note This function will only read from a uint32_t-aligned offset from the 302 * beginning of the blob's data, so some padding bytes may be skipped. 303 * 304 * \return The uint32_t read 305 */ 306 uint32_t 307 blob_read_uint32(struct blob_reader *blob); 308 309 /** 310 * Read a uint64_t from the current location, (and update the current location 311 * to just past this uint64_t). 312 * 313 * \note This function will only read from a uint64_t-aligned offset from the 314 * beginning of the blob's data, so some padding bytes may be skipped. 315 * 316 * \return The uint64_t read 317 */ 318 uint64_t 319 blob_read_uint64(struct blob_reader *blob); 320 321 /** 322 * Read an intptr_t value from the current location, (and update the 323 * current location to just past this intptr_t). 324 * 325 * \note This function will only read from an intptr_t-aligned offset from the 326 * beginning of the blob's data, so some padding bytes may be skipped. 327 * 328 * \return The intptr_t read 329 */ 330 intptr_t 331 blob_read_intptr(struct blob_reader *blob); 332 333 /** 334 * Read a NULL-terminated string from the current location, (and update the 335 * current location to just past this string). 336 * 337 * \note The memory returned belongs to the data underlying the blob reader. The 338 * caller must copy the string in order to use the string after the lifetime 339 * of the data underlying the blob reader. 340 * 341 * \return The string read (see note above about memory lifetime). However, if 342 * there is no NULL byte remaining within the blob, this function returns 343 * NULL. 344 */ 345 char * 346 blob_read_string(struct blob_reader *blob); 347 348 #ifdef __cplusplus 349 } 350 #endif 351 352 #endif /* BLOB_H */ 353
