| 1 | /* $Cambridge: exim/src/src/store.c,v 1.5 2009/11/16 19:50:37 nm4 Exp $ */ |
| 2 | |
| 3 | /************************************************* |
| 4 | * Exim - an Internet mail transport agent * |
| 5 | *************************************************/ |
| 6 | |
| 7 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
| 8 | /* See the file NOTICE for conditions of use and distribution. */ |
| 9 | |
| 10 | /* Exim gets and frees all its store through these functions. In the original |
| 11 | implementation there was a lot of mallocing and freeing of small bits of store. |
| 12 | The philosophy has now changed to a scheme which includes the concept of |
| 13 | "stacking pools" of store. For the short-lived processes, there isn't any real |
| 14 | need to do any garbage collection, but the stack concept allows quick resetting |
| 15 | in places where this seems sensible. |
| 16 | |
| 17 | Obviously the long-running processes (the daemon, the queue runner, and eximon) |
| 18 | must take care not to eat store. |
| 19 | |
| 20 | The following different types of store are recognized: |
| 21 | |
| 22 | . Long-lived, large blocks: This is implemented by retaining the original |
| 23 | malloc/free functions, and it used for permanent working buffers and for |
| 24 | getting blocks to cut up for the other types. |
| 25 | |
| 26 | . Long-lived, small blocks: This is used for blocks that have to survive until |
| 27 | the process exits. It is implemented as a stacking pool (POOL_PERM). This is |
| 28 | functionally the same as store_malloc(), except that the store can't be |
| 29 | freed, but I expect it to be more efficient for handling small blocks. |
| 30 | |
| 31 | . Short-lived, short blocks: Most of the dynamic store falls into this |
| 32 | category. It is implemented as a stacking pool (POOL_MAIN) which is reset |
| 33 | after accepting a message when multiple messages are received by a single |
| 34 | process. Resetting happens at some other times as well, usually fairly |
| 35 | locally after some specific processing that needs working store. |
| 36 | |
| 37 | . There is a separate pool (POOL_SEARCH) that is used only for lookup storage. |
| 38 | This means it can be freed when search_tidyup() is called to close down all |
| 39 | the lookup caching. |
| 40 | */ |
| 41 | |
| 42 | |
| 43 | #include "exim.h" |
| 44 | #include "memcheck.h" |
| 45 | |
| 46 | |
| 47 | /* We need to know how to align blocks of data for general use. I'm not sure |
| 48 | how to get an alignment factor in general. In the current world, a value of 8 |
| 49 | is probably right, and this is sizeof(double) on some systems and sizeof(void |
| 50 | *) on others, so take the larger of those. Since everything in this expression |
| 51 | is a constant, the compiler should optimize it to a simple constant wherever it |
| 52 | appears (I checked that gcc does do this). */ |
| 53 | |
| 54 | #define alignment \ |
| 55 | ((sizeof(void *) > sizeof(double))? sizeof(void *) : sizeof(double)) |
| 56 | |
| 57 | /* Size of block to get from malloc to carve up into smaller ones. This |
| 58 | must be a multiple of the alignment. We assume that 8192 is going to be |
| 59 | suitably aligned. */ |
| 60 | |
| 61 | #define STORE_BLOCK_SIZE 8192 |
| 62 | |
| 63 | /* store_reset() will not free the following block if the last used block has |
| 64 | less than this much left in it. */ |
| 65 | |
| 66 | #define STOREPOOL_MIN_SIZE 256 |
| 67 | |
| 68 | /* Structure describing the beginning of each big block. */ |
| 69 | |
| 70 | typedef struct storeblock { |
| 71 | struct storeblock *next; |
| 72 | size_t length; |
| 73 | } storeblock; |
| 74 | |
| 75 | /* Just in case we find ourselves on a system where the structure above has a |
| 76 | length that is not a multiple of the alignment, set up a macro for the padded |
| 77 | length. */ |
| 78 | |
| 79 | #define ALIGNED_SIZEOF_STOREBLOCK \ |
| 80 | (((sizeof(storeblock) + alignment - 1) / alignment) * alignment) |
| 81 | |
| 82 | /* Variables holding data for the local pools of store. The current pool number |
| 83 | is held in store_pool, which is global so that it can be changed from outside. |
| 84 | Setting the initial length values to -1 forces a malloc for the first call, |
| 85 | even if the length is zero (which is used for getting a point to reset to). */ |
| 86 | |
| 87 | int store_pool = POOL_PERM; |
| 88 | |
| 89 | static storeblock *chainbase[3] = { NULL, NULL, NULL }; |
| 90 | static storeblock *current_block[3] = { NULL, NULL, NULL }; |
| 91 | static void *next_yield[3] = { NULL, NULL, NULL }; |
| 92 | static int yield_length[3] = { -1, -1, -1 }; |
| 93 | |
| 94 | /* pool_malloc holds the amount of memory used by the store pools; this goes up |
| 95 | and down as store is reset or released. nonpool_malloc is the total got by |
| 96 | malloc from other calls; this doesn't go down because it is just freed by |
| 97 | pointer. */ |
| 98 | |
| 99 | static int pool_malloc = 0; |
| 100 | static int nonpool_malloc = 0; |
| 101 | |
| 102 | /* This variable is set by store_get() to its yield, and by store_reset() to |
| 103 | NULL. This enables string_cat() to optimize its store handling for very long |
| 104 | strings. That's why the variable is global. */ |
| 105 | |
| 106 | void *store_last_get[3] = { NULL, NULL, NULL }; |
| 107 | |
| 108 | |
| 109 | |
| 110 | /************************************************* |
| 111 | * Get a block from the current pool * |
| 112 | *************************************************/ |
| 113 | |
| 114 | /* Running out of store is a total disaster. This function is called via the |
| 115 | macro store_get(). It passes back a block of store within the current big |
| 116 | block, getting a new one if necessary. The address is saved in |
| 117 | store_last_was_get. |
| 118 | |
| 119 | Arguments: |
| 120 | size amount wanted |
| 121 | filename source file from which called |
| 122 | linenumber line number in source file. |
| 123 | |
| 124 | Returns: pointer to store (panic on malloc failure) |
| 125 | */ |
| 126 | |
| 127 | void * |
| 128 | store_get_3(int size, const char *filename, int linenumber) |
| 129 | { |
| 130 | /* Round up the size to a multiple of the alignment. Although this looks a |
| 131 | messy statement, because "alignment" is a constant expression, the compiler can |
| 132 | do a reasonable job of optimizing, especially if the value of "alignment" is a |
| 133 | power of two. I checked this with -O2, and gcc did very well, compiling it to 4 |
| 134 | instructions on a Sparc (alignment = 8). */ |
| 135 | |
| 136 | if (size % alignment != 0) size += alignment - (size % alignment); |
| 137 | |
| 138 | /* If there isn't room in the current block, get a new one. The minimum |
| 139 | size is STORE_BLOCK_SIZE, and we would expect this to be the norm, since |
| 140 | these functions are mostly called for small amounts of store. */ |
| 141 | |
| 142 | if (size > yield_length[store_pool]) |
| 143 | { |
| 144 | int length = (size <= STORE_BLOCK_SIZE)? STORE_BLOCK_SIZE : size; |
| 145 | int mlength = length + ALIGNED_SIZEOF_STOREBLOCK; |
| 146 | storeblock *newblock = NULL; |
| 147 | |
| 148 | /* Sometimes store_reset() may leave a block for us; check if we can use it */ |
| 149 | |
| 150 | if (current_block[store_pool] != NULL && |
| 151 | current_block[store_pool]->next != NULL) |
| 152 | { |
| 153 | newblock = current_block[store_pool]->next; |
| 154 | if (newblock->length < length) |
| 155 | { |
| 156 | /* Give up on this block, because it's too small */ |
| 157 | store_free(newblock); |
| 158 | newblock = NULL; |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | /* If there was no free block, get a new one */ |
| 163 | |
| 164 | if (newblock == NULL) |
| 165 | { |
| 166 | pool_malloc += mlength; /* Used in pools */ |
| 167 | nonpool_malloc -= mlength; /* Exclude from overall total */ |
| 168 | newblock = store_malloc(mlength); |
| 169 | newblock->next = NULL; |
| 170 | newblock->length = length; |
| 171 | if (chainbase[store_pool] == NULL) chainbase[store_pool] = newblock; |
| 172 | else current_block[store_pool]->next = newblock; |
| 173 | } |
| 174 | |
| 175 | current_block[store_pool] = newblock; |
| 176 | yield_length[store_pool] = newblock->length; |
| 177 | next_yield[store_pool] = |
| 178 | (void *)((char *)current_block[store_pool] + ALIGNED_SIZEOF_STOREBLOCK); |
| 179 | VALGRIND_MAKE_MEM_NOACCESS(next_yield[store_pool], yield_length[store_pool]); |
| 180 | } |
| 181 | |
| 182 | /* There's (now) enough room in the current block; the yield is the next |
| 183 | pointer. */ |
| 184 | |
| 185 | store_last_get[store_pool] = next_yield[store_pool]; |
| 186 | |
| 187 | /* Cut out the debugging stuff for utilities, but stop picky compilers from |
| 188 | giving warnings. */ |
| 189 | |
| 190 | #ifdef COMPILE_UTILITY |
| 191 | filename = filename; |
| 192 | linenumber = linenumber; |
| 193 | #else |
| 194 | DEBUG(D_memory) |
| 195 | { |
| 196 | if (running_in_test_harness) |
| 197 | debug_printf("---%d Get %5d\n", store_pool, size); |
| 198 | else |
| 199 | debug_printf("---%d Get %6p %5d %-14s %4d\n", store_pool, |
| 200 | store_last_get[store_pool], size, filename, linenumber); |
| 201 | } |
| 202 | #endif /* COMPILE_UTILITY */ |
| 203 | |
| 204 | VALGRIND_MAKE_MEM_UNDEFINED(store_last_get[store_pool], size); |
| 205 | /* Update next pointer and number of bytes left in the current block. */ |
| 206 | |
| 207 | next_yield[store_pool] = (void *)((char *)next_yield[store_pool] + size); |
| 208 | yield_length[store_pool] -= size; |
| 209 | |
| 210 | return store_last_get[store_pool]; |
| 211 | } |
| 212 | |
| 213 | |
| 214 | |
| 215 | /************************************************* |
| 216 | * Get a block from the PERM pool * |
| 217 | *************************************************/ |
| 218 | |
| 219 | /* This is just a convenience function, useful when just a single block is to |
| 220 | be obtained. |
| 221 | |
| 222 | Arguments: |
| 223 | size amount wanted |
| 224 | filename source file from which called |
| 225 | linenumber line number in source file. |
| 226 | |
| 227 | Returns: pointer to store (panic on malloc failure) |
| 228 | */ |
| 229 | |
| 230 | void * |
| 231 | store_get_perm_3(int size, const char *filename, int linenumber) |
| 232 | { |
| 233 | void *yield; |
| 234 | int old_pool = store_pool; |
| 235 | store_pool = POOL_PERM; |
| 236 | yield = store_get_3(size, filename, linenumber); |
| 237 | store_pool = old_pool; |
| 238 | return yield; |
| 239 | } |
| 240 | |
| 241 | |
| 242 | |
| 243 | /************************************************* |
| 244 | * Extend a block if it is at the top * |
| 245 | *************************************************/ |
| 246 | |
| 247 | /* While reading strings of unknown length, it is often the case that the |
| 248 | string is being read into the block at the top of the stack. If it needs to be |
| 249 | extended, it is more efficient just to extend the top block rather than |
| 250 | allocate a new block and then have to copy the data. This function is provided |
| 251 | for the use of string_cat(), but of course can be used elsewhere too. |
| 252 | |
| 253 | Arguments: |
| 254 | ptr pointer to store block |
| 255 | oldsize current size of the block, as requested by user |
| 256 | newsize new size required |
| 257 | filename source file from which called |
| 258 | linenumber line number in source file |
| 259 | |
| 260 | Returns: TRUE if the block is at the top of the stack and has been |
| 261 | extended; FALSE if it isn't at the top of the stack, or cannot |
| 262 | be extended |
| 263 | */ |
| 264 | |
| 265 | BOOL |
| 266 | store_extend_3(void *ptr, int oldsize, int newsize, const char *filename, |
| 267 | int linenumber) |
| 268 | { |
| 269 | int inc = newsize - oldsize; |
| 270 | int rounded_oldsize = oldsize; |
| 271 | |
| 272 | if (rounded_oldsize % alignment != 0) |
| 273 | rounded_oldsize += alignment - (rounded_oldsize % alignment); |
| 274 | |
| 275 | if ((char *)ptr + rounded_oldsize != (char *)(next_yield[store_pool]) || |
| 276 | inc > yield_length[store_pool] + rounded_oldsize - oldsize) |
| 277 | return FALSE; |
| 278 | |
| 279 | /* Cut out the debugging stuff for utilities, but stop picky compilers from |
| 280 | giving warnings. */ |
| 281 | |
| 282 | #ifdef COMPILE_UTILITY |
| 283 | filename = filename; |
| 284 | linenumber = linenumber; |
| 285 | #else |
| 286 | DEBUG(D_memory) |
| 287 | { |
| 288 | if (running_in_test_harness) |
| 289 | debug_printf("---%d Ext %5d\n", store_pool, newsize); |
| 290 | else |
| 291 | debug_printf("---%d Ext %6p %5d %-14s %4d\n", store_pool, ptr, newsize, |
| 292 | filename, linenumber); |
| 293 | } |
| 294 | #endif /* COMPILE_UTILITY */ |
| 295 | |
| 296 | if (newsize % alignment != 0) newsize += alignment - (newsize % alignment); |
| 297 | next_yield[store_pool] = (char *)ptr + newsize; |
| 298 | yield_length[store_pool] -= newsize - rounded_oldsize; |
| 299 | VALGRIND_MAKE_MEM_UNDEFINED(ptr + oldsize, inc); |
| 300 | return TRUE; |
| 301 | } |
| 302 | |
| 303 | |
| 304 | |
| 305 | |
| 306 | /************************************************* |
| 307 | * Back up to a previous point on the stack * |
| 308 | *************************************************/ |
| 309 | |
| 310 | /* This function resets the next pointer, freeing any subsequent whole blocks |
| 311 | that are now unused. Normally it is given a pointer that was the yield of a |
| 312 | call to store_get, and is therefore aligned, but it may be given an offset |
| 313 | after such a pointer in order to release the end of a block and anything that |
| 314 | follows. |
| 315 | |
| 316 | Arguments: |
| 317 | ptr place to back up to |
| 318 | filename source file from which called |
| 319 | linenumber line number in source file |
| 320 | |
| 321 | Returns: nothing |
| 322 | */ |
| 323 | |
| 324 | void |
| 325 | store_reset_3(void *ptr, const char *filename, int linenumber) |
| 326 | { |
| 327 | storeblock *bb; |
| 328 | storeblock *b = current_block[store_pool]; |
| 329 | char *bc = (char *)b + ALIGNED_SIZEOF_STOREBLOCK; |
| 330 | int newlength; |
| 331 | |
| 332 | /* Last store operation was not a get */ |
| 333 | |
| 334 | store_last_get[store_pool] = NULL; |
| 335 | |
| 336 | /* See if the place is in the current block - as it often will be. Otherwise, |
| 337 | search for the block in which it lies. */ |
| 338 | |
| 339 | if ((char *)ptr < bc || (char *)ptr > bc + b->length) |
| 340 | { |
| 341 | for (b = chainbase[store_pool]; b != NULL; b = b->next) |
| 342 | { |
| 343 | bc = (char *)b + ALIGNED_SIZEOF_STOREBLOCK; |
| 344 | if ((char *)ptr >= bc && (char *)ptr <= bc + b->length) break; |
| 345 | } |
| 346 | if (b == NULL) |
| 347 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "internal error: store_reset(%d) " |
| 348 | "failed: pool=%d %-14s %4d", ptr, store_pool, filename, linenumber); |
| 349 | } |
| 350 | |
| 351 | /* Back up, rounding to the alignment if necessary. When testing, flatten |
| 352 | the released memory. */ |
| 353 | |
| 354 | newlength = bc + b->length - (char *)ptr; |
| 355 | #ifndef COMPILE_UTILITY |
| 356 | if (running_in_test_harness) memset(ptr, 0xF0, newlength); |
| 357 | #endif |
| 358 | VALGRIND_MAKE_MEM_NOACCESS(ptr, newlength); |
| 359 | yield_length[store_pool] = newlength - (newlength % alignment); |
| 360 | next_yield[store_pool] = (char *)ptr + (newlength % alignment); |
| 361 | current_block[store_pool] = b; |
| 362 | |
| 363 | /* Free any subsequent block. Do NOT free the first successor, if our |
| 364 | current block has less than 256 bytes left. This should prevent us from |
| 365 | flapping memory. However, keep this block only when it has the default size. */ |
| 366 | |
| 367 | if (yield_length[store_pool] < STOREPOOL_MIN_SIZE && |
| 368 | b->next != NULL && |
| 369 | b->next->length == STORE_BLOCK_SIZE) |
| 370 | { |
| 371 | b = b->next; |
| 372 | VALGRIND_MAKE_MEM_NOACCESS((char *)b + ALIGNED_SIZEOF_STOREBLOCK, b->length - ALIGNED_SIZEOF_STOREBLOCK); |
| 373 | } |
| 374 | |
| 375 | bb = b->next; |
| 376 | b->next = NULL; |
| 377 | |
| 378 | while (bb != NULL) |
| 379 | { |
| 380 | b = bb; |
| 381 | bb = bb->next; |
| 382 | pool_malloc -= b->length + ALIGNED_SIZEOF_STOREBLOCK; |
| 383 | store_free_3(b, filename, linenumber); |
| 384 | } |
| 385 | |
| 386 | /* Cut out the debugging stuff for utilities, but stop picky compilers from |
| 387 | giving warnings. */ |
| 388 | |
| 389 | #ifdef COMPILE_UTILITY |
| 390 | filename = filename; |
| 391 | linenumber = linenumber; |
| 392 | #else |
| 393 | DEBUG(D_memory) |
| 394 | { |
| 395 | if (running_in_test_harness) |
| 396 | debug_printf("---%d Rst ** %d\n", store_pool, pool_malloc); |
| 397 | else |
| 398 | debug_printf("---%d Rst %6p ** %-14s %4d %d\n", store_pool, ptr, |
| 399 | filename, linenumber, pool_malloc); |
| 400 | } |
| 401 | #endif /* COMPILE_UTILITY */ |
| 402 | } |
| 403 | |
| 404 | |
| 405 | |
| 406 | |
| 407 | |
| 408 | /************************************************ |
| 409 | * Release store * |
| 410 | ************************************************/ |
| 411 | |
| 412 | /* This function is specifically provided for use when reading very |
| 413 | long strings, e.g. header lines. When the string gets longer than a |
| 414 | complete block, it gets copied to a new block. It is helpful to free |
| 415 | the old block iff the previous copy of the string is at its start, |
| 416 | and therefore the only thing in it. Otherwise, for very long strings, |
| 417 | dead store can pile up somewhat disastrously. This function checks that |
| 418 | the pointer it is given is the first thing in a block, and if so, |
| 419 | releases that block. |
| 420 | |
| 421 | Arguments: |
| 422 | block block of store to consider |
| 423 | filename source file from which called |
| 424 | linenumber line number in source file |
| 425 | |
| 426 | Returns: nothing |
| 427 | */ |
| 428 | |
| 429 | void |
| 430 | store_release_3(void *block, const char *filename, int linenumber) |
| 431 | { |
| 432 | storeblock *b; |
| 433 | |
| 434 | /* It will never be the first block, so no need to check that. */ |
| 435 | |
| 436 | for (b = chainbase[store_pool]; b != NULL; b = b->next) |
| 437 | { |
| 438 | storeblock *bb = b->next; |
| 439 | if (bb != NULL && (char *)block == (char *)bb + ALIGNED_SIZEOF_STOREBLOCK) |
| 440 | { |
| 441 | b->next = bb->next; |
| 442 | pool_malloc -= bb->length + ALIGNED_SIZEOF_STOREBLOCK; |
| 443 | |
| 444 | /* Cut out the debugging stuff for utilities, but stop picky compilers |
| 445 | from giving warnings. */ |
| 446 | |
| 447 | #ifdef COMPILE_UTILITY |
| 448 | filename = filename; |
| 449 | linenumber = linenumber; |
| 450 | #else |
| 451 | DEBUG(D_memory) |
| 452 | { |
| 453 | if (running_in_test_harness) |
| 454 | debug_printf("-Release %d\n", pool_malloc); |
| 455 | else |
| 456 | debug_printf("-Release %6p %-20s %4d %d\n", (void *)bb, filename, |
| 457 | linenumber, pool_malloc); |
| 458 | } |
| 459 | if (running_in_test_harness) |
| 460 | memset(bb, 0xF0, bb->length+ALIGNED_SIZEOF_STOREBLOCK); |
| 461 | #endif /* COMPILE_UTILITY */ |
| 462 | |
| 463 | free(bb); |
| 464 | return; |
| 465 | } |
| 466 | } |
| 467 | } |
| 468 | |
| 469 | |
| 470 | |
| 471 | |
| 472 | /************************************************* |
| 473 | * Malloc store * |
| 474 | *************************************************/ |
| 475 | |
| 476 | /* Running out of store is a total disaster for exim. Some malloc functions |
| 477 | do not run happily on very small sizes, nor do they document this fact. This |
| 478 | function is called via the macro store_malloc(). |
| 479 | |
| 480 | Arguments: |
| 481 | size amount of store wanted |
| 482 | filename source file from which called |
| 483 | linenumber line number in source file |
| 484 | |
| 485 | Returns: pointer to gotten store (panic on failure) |
| 486 | */ |
| 487 | |
| 488 | void * |
| 489 | store_malloc_3(int size, const char *filename, int linenumber) |
| 490 | { |
| 491 | void *yield; |
| 492 | |
| 493 | if (size < 16) size = 16; |
| 494 | yield = malloc((size_t)size); |
| 495 | |
| 496 | if (yield == NULL) |
| 497 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to malloc %d bytes of memory: " |
| 498 | "called from line %d of %s", size, linenumber, filename); |
| 499 | |
| 500 | nonpool_malloc += size; |
| 501 | |
| 502 | /* Cut out the debugging stuff for utilities, but stop picky compilers from |
| 503 | giving warnings. */ |
| 504 | |
| 505 | #ifdef COMPILE_UTILITY |
| 506 | filename = filename; |
| 507 | linenumber = linenumber; |
| 508 | #else |
| 509 | |
| 510 | /* If running in test harness, spend time making sure all the new store |
| 511 | is not filled with zeros so as to catch problems. */ |
| 512 | |
| 513 | if (running_in_test_harness) |
| 514 | { |
| 515 | memset(yield, 0xF0, (size_t)size); |
| 516 | DEBUG(D_memory) debug_printf("--Malloc %5d %d %d\n", size, pool_malloc, |
| 517 | nonpool_malloc); |
| 518 | } |
| 519 | else |
| 520 | { |
| 521 | DEBUG(D_memory) debug_printf("--Malloc %6p %5d %-14s %4d %d %d\n", yield, |
| 522 | size, filename, linenumber, pool_malloc, nonpool_malloc); |
| 523 | } |
| 524 | #endif /* COMPILE_UTILITY */ |
| 525 | |
| 526 | return yield; |
| 527 | } |
| 528 | |
| 529 | |
| 530 | /************************************************ |
| 531 | * Free store * |
| 532 | ************************************************/ |
| 533 | |
| 534 | /* This function is called by the macro store_free(). |
| 535 | |
| 536 | Arguments: |
| 537 | block block of store to free |
| 538 | filename source file from which called |
| 539 | linenumber line number in source file |
| 540 | |
| 541 | Returns: nothing |
| 542 | */ |
| 543 | |
| 544 | void |
| 545 | store_free_3(void *block, const char *filename, int linenumber) |
| 546 | { |
| 547 | #ifdef COMPILE_UTILITY |
| 548 | filename = filename; |
| 549 | linenumber = linenumber; |
| 550 | #else |
| 551 | DEBUG(D_memory) |
| 552 | { |
| 553 | if (running_in_test_harness) |
| 554 | debug_printf("----Free\n"); |
| 555 | else |
| 556 | debug_printf("----Free %6p %-20s %4d\n", block, filename, linenumber); |
| 557 | } |
| 558 | #endif /* COMPILE_UTILITY */ |
| 559 | free(block); |
| 560 | } |
| 561 | |
| 562 | /* End of store.c */ |