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 #pragma once 25 #ifndef BLOB_H 26 #define BLOB_H 27 28 #ifdef __cplusplus 29 extern "C" { 30 #endif 31 32 #include <stdbool.h> 33 #include <stddef.h> 34 #include <stdint.h> 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 60 /* When done reading, the caller can ensure that everything was consumed by 61 * checking the following: 62 * 63 * 1. blob->current should be equal to blob->end, (if not, too little was 64 * read). 65 * 66 * 2. blob->overrun should be false, (otherwise, too much was read). 67 */ 68 struct blob_reader { 69 uint8_t *data; 70 uint8_t *end; 71 uint8_t *current; 72 bool overrun; 73 }; 74 75 /** 76 * Create a new, empty blob, belonging to \mem_ctx. 77 * 78 * \return The new blob, (or NULL in case of allocation failure). 79 */ 80 struct blob * 81 blob_create (void *mem_ctx); 82 83 /** 84 * Add some unstructured, fixed-size data to a blob. 85 * 86 * \return True unless allocation failed. 87 */ 88 bool 89 blob_write_bytes (struct blob *blob, const void *bytes, size_t to_write); 90 91 /** 92 * Reserve space in \blob for a number of bytes. 93 * 94 * Space will be allocated within the blob for these byes, but the bytes will 95 * be left uninitialized. The caller is expected to use the return value to 96 * write directly (and immediately) to these bytes. 97 * 98 * \note The return value is valid immediately upon return, but can be 99 * invalidated by any other call to a blob function. So the caller should call 100 * blob_reserve_byes immediately before writing through the returned pointer. 101 * 102 * This function is intended to be used when interfacing with an existing API 103 * that is not aware of the blob API, (so that blob_write_bytes cannot be 104 * called). 105 * 106 * \return A pointer to space allocated within \blob to which \to_write bytes 107 * can be written, (or NULL in case of any allocation error). 108 */ 109 uint8_t * 110 blob_reserve_bytes (struct blob *blob, size_t to_write); 111 112 /** 113 * Overwrite some data previously written to the blob. 114 * 115 * Writes data to an existing portion of the blob at an offset of \offset. 116 * This data range must have previously been written to the blob by one of the 117 * blob_write_* calls. 118 * 119 * For example usage, see blob_overwrite_uint32 120 * 121 * \return True unless the requested offset or offset+to_write lie outside 122 * the current blob's size. 123 */ 124 bool 125 blob_overwrite_bytes (struct blob *blob, 126 size_t offset, 127 const void *bytes, 128 size_t to_write); 129 130 /** 131 * Add a uint32_t to a blob. 132 * 133 * \note This function will only write to a uint32_t-aligned offset from the 134 * beginning of the blob's data, so some padding bytes may be added to the 135 * blob if this write follows some unaligned write (such as 136 * blob_write_string). 137 * 138 * \return True unless allocation failed. 139 */ 140 bool 141 blob_write_uint32 (struct blob *blob, uint32_t value); 142 143 /** 144 * Overwrite a uint32_t previously written to the blob. 145 * 146 * Writes a uint32_t value to an existing portion of the blob at an offset of 147 * \offset. This data range must have previously been written to the blob by 148 * one of the blob_write_* calls. 149 * 150 * 151 * The expected usage is something like the following pattern: 152 * 153 * size_t offset; 154 * 155 * offset = blob->size; 156 * blob_write_uint32 (blob, 0); // placeholder 157 * ... various blob write calls, writing N items ... 158 * blob_overwrite_uint32 (blob, offset, N); 159 * 160 * \return True unless the requested position or position+to_write lie outside 161 * the current blob's size. 162 */ 163 bool 164 blob_overwrite_uint32 (struct blob *blob, 165 size_t offset, 166 uint32_t value); 167 168 /** 169 * Add a uint64_t to a blob. 170 * 171 * \note This function will only write to a uint64_t-aligned offset from the 172 * beginning of the blob's data, so some padding bytes may be added to the 173 * blob if this write follows some unaligned write (such as 174 * blob_write_string). 175 * 176 * \return True unless allocation failed. 177 */ 178 bool 179 blob_write_uint64 (struct blob *blob, uint64_t value); 180 181 /** 182 * Add an intptr_t to a blob. 183 * 184 * \note This function will only write to an intptr_t-aligned offset from the 185 * beginning of the blob's data, so some padding bytes may be added to the 186 * blob if this write follows some unaligned write (such as 187 * blob_write_string). 188 * 189 * \return True unless allocation failed. 190 */ 191 bool 192 blob_write_intptr (struct blob *blob, intptr_t value); 193 194 /** 195 * Add a NULL-terminated string to a blob, (including the NULL terminator). 196 * 197 * \return True unless allocation failed. 198 */ 199 bool 200 blob_write_string (struct blob *blob, const char *str); 201 202 /** 203 * Start reading a blob, (initializing the contents of \blob for reading). 204 * 205 * After this call, the caller can use the various blob_read_* functions to 206 * read elements from the data array. 207 * 208 * For all of the blob_read_* functions, if there is insufficient data 209 * remaining, the functions will do nothing, (perhaps returning default values 210 * such as 0). The caller can detect this by noting that the blob_reader's 211 * current value is unchanged before and after the call. 212 */ 213 void 214 blob_reader_init (struct blob_reader *blob, uint8_t *data, size_t size); 215 216 /** 217 * Read some unstructured, fixed-size data from the current location, (and 218 * update the current location to just past this data). 219 * 220 * \note The memory returned belongs to the data underlying the blob reader. The 221 * caller must copy the data in order to use it after the lifetime of the data 222 * underlying the blob reader. 223 * 224 * \return The bytes read (see note above about memory lifetime). 225 */ 226 void * 227 blob_read_bytes (struct blob_reader *blob, size_t size); 228 229 /** 230 * Read some unstructured, fixed-size data from the current location, copying 231 * it to \dest (and update the current location to just past this data) 232 */ 233 void 234 blob_copy_bytes (struct blob_reader *blob, uint8_t *dest, size_t size); 235 236 /** 237 * Read a uint32_t from the current location, (and update the current location 238 * to just past this uint32_t). 239 * 240 * \note This function will only read from a uint32_t-aligned offset from the 241 * beginning of the blob's data, so some padding bytes may be skipped. 242 * 243 * \return The uint32_t read 244 */ 245 uint32_t 246 blob_read_uint32 (struct blob_reader *blob); 247 248 /** 249 * Read a uint64_t from the current location, (and update the current location 250 * to just past this uint64_t). 251 * 252 * \note This function will only read from a uint64_t-aligned offset from the 253 * beginning of the blob's data, so some padding bytes may be skipped. 254 * 255 * \return The uint64_t read 256 */ 257 uint64_t 258 blob_read_uint64 (struct blob_reader *blob); 259 260 /** 261 * Read an intptr_t value from the current location, (and update the 262 * current location to just past this intptr_t). 263 * 264 * \note This function will only read from an intptr_t-aligned offset from the 265 * beginning of the blob's data, so some padding bytes may be skipped. 266 * 267 * \return The intptr_t read 268 */ 269 intptr_t 270 blob_read_intptr (struct blob_reader *blob); 271 272 /** 273 * Read a NULL-terminated string from the current location, (and update the 274 * current location to just past this string). 275 * 276 * \note The memory returned belongs to the data underlying the blob reader. The 277 * caller must copy the string in order to use the string after the lifetime 278 * of the data underlying the blob reader. 279 * 280 * \return The string read (see note above about memory lifetime). However, if 281 * there is no NULL byte remaining within the blob, this function returns 282 * NULL. 283 */ 284 char * 285 blob_read_string (struct blob_reader *blob); 286 287 #ifdef __cplusplus 288 } 289 #endif 290 291 #endif /* BLOB_H */ 292
