src/util/blob.c

   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 #include <string.h>
  25
  26 #include "blob.h"
  27 #include "u_math.h"
  28
  29 #ifdef HAVE_VALGRIND
  30 #include <valgrind.h>
  31 #include <memcheck.h>
  32 #define VG(x) x
  33 #else
  34 #define VG(x)
  35 #endif
  36
  37 #define BLOB_INITIAL_SIZE 4096
  38
  39 /* Ensure that \blob will be able to fit an additional object of size
  40  * \additional.  The growing (if any) will occur by doubling the existing
  41  * allocation.
  42  */
  43 static bool
  44 grow_to_fit(struct blob *blob, size_t additional)
  45 {
  46    size_t to_allocate;
  47    uint8_t *new_data;
  48
  49    if (blob->out_of_memory)
  50       return false;
  51
  52    if (blob->size + additional <= blob->allocated)
  53       return true;
  54
  55    if (blob->fixed_allocation) {
  56       blob->out_of_memory = true;
  57       return false;
  58    }
  59
  60    if (blob->allocated == 0)
  61       to_allocate = BLOB_INITIAL_SIZE;
  62    else
  63       to_allocate = blob->allocated * 2;
  64
  65    to_allocate = MAX2(to_allocate, blob->allocated + additional);
  66
  67    new_data = realloc(blob->data, to_allocate);
  68    if (new_data == NULL) {
  69       blob->out_of_memory = true;
  70       return false;
  71    }
  72
  73    blob->data = new_data;
  74    blob->allocated = to_allocate;
  75
  76    return true;
  77 }
  78
  79 /* Align the blob->size so that reading or writing a value at (blob->data +
  80  * blob->size) will result in an access aligned to a granularity of \alignment
  81  * bytes.
  82  *
  83  * \return True unless allocation fails
  84  */
  85 static bool
  86 align_blob(struct blob *blob, size_t alignment)
  87 {
  88    const size_t new_size = align64(blob->size, alignment);
  89
  90    if (blob->size < new_size) {
  91       if (!grow_to_fit(blob, new_size - blob->size))
  92          return false;
  93
  94       if (blob->data)
  95          memset(blob->data + blob->size, 0, new_size - blob->size);
  96       blob->size = new_size;
  97    }
  98
  99    return true;
 100 }
 101
 102 static void
 103 align_blob_reader(struct blob_reader *blob, size_t alignment)
 104 {
 105    blob->current = blob->data + align64(blob->current - blob->data, alignment);
 106 }
 107
 108 void
 109 blob_init(struct blob *blob)
 110 {
 111    blob->data = NULL;
 112    blob->allocated = 0;
 113    blob->size = 0;
 114    blob->fixed_allocation = false;
 115    blob->out_of_memory = false;
 116 }
 117
 118 void
 119 blob_init_fixed(struct blob *blob, void *data, size_t size)
 120 {
 121    blob->data = data;
 122    blob->allocated = size;
 123    blob->size = 0;
 124    blob->fixed_allocation = true;
 125    blob->out_of_memory = false;
 126 }
 127
 128 void
 129 blob_finish_get_buffer(struct blob *blob, void **buffer, size_t *size)
 130 {
 131    *buffer = blob->data;
 132    *size = blob->size;
 133    blob->data = NULL;
 134
 135    /* Trim the buffer. */
 136    *buffer = realloc(*buffer, *size);
 137 }
 138
 139 bool
 140 blob_overwrite_bytes(struct blob *blob,
 141                      size_t offset,
 142                      const void *bytes,
 143                      size_t to_write)
 144 {
 145    /* Detect an attempt to overwrite data out of bounds. */
 146    if (offset + to_write < offset || blob->size < offset + to_write)
 147       return false;
 148
 149    VG(VALGRIND_CHECK_MEM_IS_DEFINED(bytes, to_write));
 150
 151    if (blob->data)
 152       memcpy(blob->data + offset, bytes, to_write);
 153
 154    return true;
 155 }
 156
 157 bool
 158 blob_write_bytes(struct blob *blob, const void *bytes, size_t to_write)
 159 {
 160    if (! grow_to_fit(blob, to_write))
 161        return false;
 162
 163    VG(VALGRIND_CHECK_MEM_IS_DEFINED(bytes, to_write));
 164
 165    if (blob->data && to_write > 0)
 166       memcpy(blob->data + blob->size, bytes, to_write);
 167    blob->size += to_write;
 168
 169    return true;
 170 }
 171
 172 intptr_t
 173 blob_reserve_bytes(struct blob *blob, size_t to_write)
 174 {
 175    intptr_t ret;
 176
 177    if (! grow_to_fit (blob, to_write))
 178       return -1;
 179
 180    ret = blob->size;
 181    blob->size += to_write;
 182
 183    return ret;
 184 }
 185
 186 intptr_t
 187 blob_reserve_uint32(struct blob *blob)
 188 {
 189    align_blob(blob, sizeof(uint32_t));
 190    return blob_reserve_bytes(blob, sizeof(uint32_t));
 191 }
 192
 193 intptr_t
 194 blob_reserve_intptr(struct blob *blob)
 195 {
 196    align_blob(blob, sizeof(intptr_t));
 197    return blob_reserve_bytes(blob, sizeof(intptr_t));
 198 }
 199
 200 #define BLOB_WRITE_TYPE(name, type)                      \
 201 bool                                                     \
 202 name(struct blob *blob, type value)                      \
 203 {                                                        \
 204    align_blob(blob, sizeof(value));                      \
 205    return blob_write_bytes(blob, &value, sizeof(value)); \
 206 }
 207
 208 BLOB_WRITE_TYPE(blob_write_uint8, uint8_t)
 209 BLOB_WRITE_TYPE(blob_write_uint16, uint16_t)
 210 BLOB_WRITE_TYPE(blob_write_uint32, uint32_t)
 211 BLOB_WRITE_TYPE(blob_write_uint64, uint64_t)
 212 BLOB_WRITE_TYPE(blob_write_intptr, intptr_t)
 213
 214 #define ASSERT_ALIGNED(_offset, _align) \
 215    assert(align64((_offset), (_align)) == (_offset))
 216
 217 bool
 218 blob_overwrite_uint8 (struct blob *blob,
 219                       size_t offset,
 220                       uint8_t value)
 221 {
 222    ASSERT_ALIGNED(offset, sizeof(value));
 223    return blob_overwrite_bytes(blob, offset, &value, sizeof(value));
 224 }
 225
 226 bool
 227 blob_overwrite_uint32 (struct blob *blob,
 228                        size_t offset,
 229                        uint32_t value)
 230 {
 231    ASSERT_ALIGNED(offset, sizeof(value));
 232    return blob_overwrite_bytes(blob, offset, &value, sizeof(value));
 233 }
 234
 235 bool
 236 blob_overwrite_intptr (struct blob *blob,
 237                        size_t offset,
 238                        intptr_t value)
 239 {
 240    ASSERT_ALIGNED(offset, sizeof(value));
 241    return blob_overwrite_bytes(blob, offset, &value, sizeof(value));
 242 }
 243
 244 bool
 245 blob_write_string(struct blob *blob, const char *str)
 246 {
 247    return blob_write_bytes(blob, str, strlen(str) + 1);
 248 }
 249
 250 void
 251 blob_reader_init(struct blob_reader *blob, const void *data, size_t size)
 252 {
 253    blob->data = data;
 254    blob->end = blob->data + size;
 255    blob->current = data;
 256    blob->overrun = false;
 257 }
 258
 259 /* Check that an object of size \size can be read from this blob.
 260  *
 261  * If not, set blob->overrun to indicate that we attempted to read too far.
 262  */
 263 static bool
 264 ensure_can_read(struct blob_reader *blob, size_t size)
 265 {
 266    if (blob->overrun)
 267       return false;
 268
 269    if (blob->current <= blob->end && blob->end - blob->current >= size)
 270       return true;
 271
 272    blob->overrun = true;
 273
 274    return false;
 275 }
 276
 277 const void *
 278 blob_read_bytes(struct blob_reader *blob, size_t size)
 279 {
 280    const void *ret;
 281
 282    if (! ensure_can_read (blob, size))
 283       return NULL;
 284
 285    ret = blob->current;
 286
 287    blob->current += size;
 288
 289    return ret;
 290 }
 291
 292 void
 293 blob_copy_bytes(struct blob_reader *blob, void *dest, size_t size)
 294 {
 295    const void *bytes;
 296
 297    bytes = blob_read_bytes(blob, size);
 298    if (bytes == NULL || size == 0)
 299       return;
 300
 301    memcpy(dest, bytes, size);
 302 }
 303
 304 void
 305 blob_skip_bytes(struct blob_reader *blob, size_t size)
 306 {
 307    if (ensure_can_read (blob, size))
 308       blob->current += size;
 309 }
 310
 311 /* These next three read functions have identical form. If we add any beyond
 312  * these first three we should probably switch to generating these with a
 313  * preprocessor macro.
 314 */
 315
 316 #define BLOB_READ_TYPE(name, type)         \
 317 type                                       \
 318 name(struct blob_reader *blob)             \
 319 {                                          \
 320    type ret;                               \
 321    int size = sizeof(ret);                 \
 322    align_blob_reader(blob, size);          \
 323    if (! ensure_can_read(blob, size))      \
 324       return 0;                            \
 325    ret = *((type*) blob->current);         \
 326    blob->current += size;                  \
 327    return ret;                             \
 328 }
 329
 330 BLOB_READ_TYPE(blob_read_uint8, uint8_t)
 331 BLOB_READ_TYPE(blob_read_uint16, uint16_t)
 332 BLOB_READ_TYPE(blob_read_uint32, uint32_t)
 333 BLOB_READ_TYPE(blob_read_uint64, uint64_t)
 334 BLOB_READ_TYPE(blob_read_intptr, intptr_t)
 335
 336 char *
 337 blob_read_string(struct blob_reader *blob)
 338 {
 339    int size;
 340    char *ret;
 341    uint8_t *nul;
 342
 343    /* If we're already at the end, then this is an overrun. */
 344    if (blob->current >= blob->end) {
 345       blob->overrun = true;
 346       return NULL;
 347    }
 348
 349    /* Similarly, if there is no zero byte in the data remaining in this blob,
 350     * we also consider that an overrun.
 351     */
 352    nul = memchr(blob->current, 0, blob->end - blob->current);
 353
 354    if (nul == NULL) {
 355       blob->overrun = true;
 356       return NULL;
 357    }
 358
 359    size = nul - blob->current + 1;
 360
 361    assert(ensure_can_read(blob, size));
 362
 363    ret = (char *) blob->current;
 364
 365    blob->current += size;
 366
 367    return ret;
 368 }