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1 | /* $RCSfile: malloc.c,v $$Revision: 4.0.1.3 $$Date: 91/11/05 17:57:40 $ |
| 8d063cd8 |
2 | * |
| 3 | * $Log: malloc.c,v $ |
| 45d8adaa |
4 | * Revision 4.0.1.3 91/11/05 17:57:40 lwall |
| 5 | * patch11: safe malloc code now integrated into Perl's malloc when possible |
| 6 | * |
| 352d5a3a |
7 | * Revision 4.0.1.2 91/06/07 11:20:45 lwall |
| 8 | * patch4: many, many itty-bitty portability fixes |
| 9 | * |
| 35c8bce7 |
10 | * Revision 4.0.1.1 91/04/11 17:48:31 lwall |
| 11 | * patch1: Configure now figures out malloc ptr type |
| 12 | * |
| fe14fcc3 |
13 | * Revision 4.0 91/03/20 01:28:52 lwall |
| 14 | * 4.0 baseline. |
| 8d063cd8 |
15 | * |
| 16 | */ |
| 17 | |
| 18 | #ifndef lint |
| 45d8adaa |
19 | /*SUPPRESS 592*/ |
| 8d063cd8 |
20 | static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83"; |
| 8d063cd8 |
21 | |
| a687059c |
22 | #ifdef DEBUGGING |
| 8d063cd8 |
23 | #define RCHECK |
| a687059c |
24 | #endif |
| 8d063cd8 |
25 | /* |
| 26 | * malloc.c (Caltech) 2/21/82 |
| 27 | * Chris Kingsley, kingsley@cit-20. |
| 28 | * |
| 29 | * This is a very fast storage allocator. It allocates blocks of a small |
| 30 | * number of different sizes, and keeps free lists of each size. Blocks that |
| 31 | * don't exactly fit are passed up to the next larger size. In this |
| 32 | * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long. |
| 33 | * This is designed for use in a program that uses vast quantities of memory, |
| 34 | * but bombs when it runs out. |
| 35 | */ |
| 36 | |
| 135863df |
37 | #include "EXTERN.h" |
| 135863df |
38 | #include "perl.h" |
| 39 | |
| 03a14243 |
40 | static findbucket(), morecore(); |
| 41 | |
| 135863df |
42 | /* I don't much care whether these are defined in sys/types.h--LAW */ |
| 43 | |
| 44 | #define u_char unsigned char |
| 45 | #define u_int unsigned int |
| 46 | #define u_short unsigned short |
| 8d063cd8 |
47 | |
| 8d063cd8 |
48 | /* |
| 49 | * The overhead on a block is at least 4 bytes. When free, this space |
| 50 | * contains a pointer to the next free block, and the bottom two bits must |
| 51 | * be zero. When in use, the first byte is set to MAGIC, and the second |
| 52 | * byte is the size index. The remaining bytes are for alignment. |
| 53 | * If range checking is enabled and the size of the block fits |
| 54 | * in two bytes, then the top two bytes hold the size of the requested block |
| 55 | * plus the range checking words, and the header word MINUS ONE. |
| 56 | */ |
| 57 | union overhead { |
| 58 | union overhead *ov_next; /* when free */ |
| c623bd54 |
59 | #if ALIGNBYTES > 4 |
| 60 | double strut; /* alignment problems */ |
| a687059c |
61 | #endif |
| 8d063cd8 |
62 | struct { |
| 63 | u_char ovu_magic; /* magic number */ |
| 64 | u_char ovu_index; /* bucket # */ |
| 65 | #ifdef RCHECK |
| 66 | u_short ovu_size; /* actual block size */ |
| 67 | u_int ovu_rmagic; /* range magic number */ |
| 68 | #endif |
| 69 | } ovu; |
| 70 | #define ov_magic ovu.ovu_magic |
| 71 | #define ov_index ovu.ovu_index |
| 72 | #define ov_size ovu.ovu_size |
| 73 | #define ov_rmagic ovu.ovu_rmagic |
| 74 | }; |
| 75 | |
| 76 | #define MAGIC 0xff /* magic # on accounting info */ |
| 378cc40b |
77 | #define OLDMAGIC 0x7f /* same after a free() */ |
| 8d063cd8 |
78 | #define RMAGIC 0x55555555 /* magic # on range info */ |
| 79 | #ifdef RCHECK |
| 80 | #define RSLOP sizeof (u_int) |
| 81 | #else |
| 82 | #define RSLOP 0 |
| 83 | #endif |
| 84 | |
| 85 | /* |
| 86 | * nextf[i] is the pointer to the next free block of size 2^(i+3). The |
| 87 | * smallest allocatable block is 8 bytes. The overhead information |
| 88 | * precedes the data area returned to the user. |
| 89 | */ |
| 90 | #define NBUCKETS 30 |
| 91 | static union overhead *nextf[NBUCKETS]; |
| 92 | extern char *sbrk(); |
| 93 | |
| 94 | #ifdef MSTATS |
| 95 | /* |
| 96 | * nmalloc[i] is the difference between the number of mallocs and frees |
| 97 | * for a given block size. |
| 98 | */ |
| 99 | static u_int nmalloc[NBUCKETS]; |
| 100 | #include <stdio.h> |
| 101 | #endif |
| 102 | |
| 103 | #ifdef debug |
| 104 | #define ASSERT(p) if (!(p)) botch("p"); else |
| 105 | static |
| 106 | botch(s) |
| 107 | char *s; |
| 108 | { |
| 109 | |
| 110 | printf("assertion botched: %s\n", s); |
| 111 | abort(); |
| 112 | } |
| 113 | #else |
| 114 | #define ASSERT(p) |
| 115 | #endif |
| 116 | |
| 45d8adaa |
117 | #ifdef safemalloc |
| 118 | static int an = 0; |
| 119 | #endif |
| 120 | |
| 35c8bce7 |
121 | MALLOCPTRTYPE * |
| 8d063cd8 |
122 | malloc(nbytes) |
| 123 | register unsigned nbytes; |
| 124 | { |
| 125 | register union overhead *p; |
| 126 | register int bucket = 0; |
| 127 | register unsigned shiftr; |
| 128 | |
| 45d8adaa |
129 | #ifdef safemalloc |
| 130 | #ifdef DEBUGGING |
| 131 | int size = nbytes; |
| 132 | #endif |
| 133 | |
| 134 | #ifdef MSDOS |
| 135 | if (nbytes > 0xffff) { |
| 136 | fprintf(stderr, "Allocation too large: %lx\n", nbytes); |
| 137 | exit(1); |
| 138 | } |
| 139 | #endif /* MSDOS */ |
| 140 | #ifdef DEBUGGING |
| 141 | if ((long)nbytes < 0) |
| 142 | fatal("panic: malloc"); |
| 143 | #endif |
| 144 | #endif /* safemalloc */ |
| 145 | |
| 8d063cd8 |
146 | /* |
| 147 | * Convert amount of memory requested into |
| 148 | * closest block size stored in hash buckets |
| 149 | * which satisfies request. Account for |
| 150 | * space used per block for accounting. |
| 151 | */ |
| 152 | nbytes += sizeof (union overhead) + RSLOP; |
| 153 | nbytes = (nbytes + 3) &~ 3; |
| 154 | shiftr = (nbytes - 1) >> 2; |
| 155 | /* apart from this loop, this is O(1) */ |
| 156 | while (shiftr >>= 1) |
| 157 | bucket++; |
| 158 | /* |
| 159 | * If nothing in hash bucket right now, |
| 160 | * request more memory from the system. |
| 161 | */ |
| 162 | if (nextf[bucket] == NULL) |
| 163 | morecore(bucket); |
| 45d8adaa |
164 | if ((p = (union overhead *)nextf[bucket]) == NULL) { |
| 165 | #ifdef safemalloc |
| 166 | fputs("Out of memory!\n", stderr); |
| 167 | exit(1); |
| 168 | #else |
| 8d063cd8 |
169 | return (NULL); |
| 45d8adaa |
170 | #endif |
| 171 | } |
| 172 | |
| 173 | #ifdef safemalloc |
| 174 | #ifdef DEBUGGING |
| 175 | # ifndef I286 |
| 176 | if (debug & 128) |
| 177 | fprintf(stderr,"0x%x: (%05d) malloc %d bytes\n",p+1,an++,size); |
| 178 | # else |
| 179 | if (debug & 128) |
| 180 | fprintf(stderr,"0x%lx: (%05d) malloc %d bytes\n",p+1,an++,size); |
| 181 | # endif |
| 182 | #endif |
| 183 | #endif /* safemalloc */ |
| 184 | |
| 8d063cd8 |
185 | /* remove from linked list */ |
| bf38876a |
186 | #ifdef RCHECK |
| 187 | if (*((int*)p) & (sizeof(union overhead) - 1)) |
| a687059c |
188 | #ifndef I286 |
| 8d063cd8 |
189 | fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",*((int*)p),p); |
| a687059c |
190 | #else |
| 191 | fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n",*((int*)p),p); |
| 192 | #endif |
| bf38876a |
193 | #endif |
| 194 | nextf[bucket] = p->ov_next; |
| 8d063cd8 |
195 | p->ov_magic = MAGIC; |
| 196 | p->ov_index= bucket; |
| 197 | #ifdef MSTATS |
| 198 | nmalloc[bucket]++; |
| 199 | #endif |
| 200 | #ifdef RCHECK |
| 201 | /* |
| 202 | * Record allocated size of block and |
| 203 | * bound space with magic numbers. |
| 204 | */ |
| 205 | if (nbytes <= 0x10000) |
| 206 | p->ov_size = nbytes - 1; |
| 207 | p->ov_rmagic = RMAGIC; |
| 208 | *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC; |
| 209 | #endif |
| 352d5a3a |
210 | return ((MALLOCPTRTYPE *)(p + 1)); |
| 8d063cd8 |
211 | } |
| 212 | |
| 213 | /* |
| 214 | * Allocate more memory to the indicated bucket. |
| 215 | */ |
| 216 | static |
| 217 | morecore(bucket) |
| a687059c |
218 | register int bucket; |
| 8d063cd8 |
219 | { |
| 220 | register union overhead *op; |
| 221 | register int rnu; /* 2^rnu bytes will be requested */ |
| 222 | register int nblks; /* become nblks blocks of the desired size */ |
| 223 | register int siz; |
| 224 | |
| 225 | if (nextf[bucket]) |
| 226 | return; |
| 227 | /* |
| 228 | * Insure memory is allocated |
| 229 | * on a page boundary. Should |
| 230 | * make getpageize call? |
| 231 | */ |
| 232 | op = (union overhead *)sbrk(0); |
| a687059c |
233 | #ifndef I286 |
| 8d063cd8 |
234 | if ((int)op & 0x3ff) |
| a687059c |
235 | (void)sbrk(1024 - ((int)op & 0x3ff)); |
| 236 | #else |
| 237 | /* The sbrk(0) call on the I286 always returns the next segment */ |
| 238 | #endif |
| 239 | |
| 240 | #ifndef I286 |
| 8d063cd8 |
241 | /* take 2k unless the block is bigger than that */ |
| 242 | rnu = (bucket <= 8) ? 11 : bucket + 3; |
| a687059c |
243 | #else |
| 244 | /* take 16k unless the block is bigger than that |
| 245 | (80286s like large segments!) */ |
| 246 | rnu = (bucket <= 11) ? 14 : bucket + 3; |
| 247 | #endif |
| 8d063cd8 |
248 | nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */ |
| 249 | if (rnu < bucket) |
| 250 | rnu = bucket; |
| 251 | op = (union overhead *)sbrk(1 << rnu); |
| 252 | /* no more room! */ |
| 253 | if ((int)op == -1) |
| 254 | return; |
| 255 | /* |
| 256 | * Round up to minimum allocation size boundary |
| 257 | * and deduct from block count to reflect. |
| 258 | */ |
| a687059c |
259 | #ifndef I286 |
| 8d063cd8 |
260 | if ((int)op & 7) { |
| 261 | op = (union overhead *)(((int)op + 8) &~ 7); |
| 262 | nblks--; |
| 263 | } |
| a687059c |
264 | #else |
| 265 | /* Again, this should always be ok on an 80286 */ |
| 266 | #endif |
| 8d063cd8 |
267 | /* |
| 268 | * Add new memory allocated to that on |
| 269 | * free list for this hash bucket. |
| 270 | */ |
| 271 | nextf[bucket] = op; |
| 272 | siz = 1 << (bucket + 3); |
| 273 | while (--nblks > 0) { |
| 274 | op->ov_next = (union overhead *)((caddr_t)op + siz); |
| 275 | op = (union overhead *)((caddr_t)op + siz); |
| 276 | } |
| 277 | } |
| 278 | |
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279 | void |
| 352d5a3a |
280 | free(mp) |
| 281 | MALLOCPTRTYPE *mp; |
| 8d063cd8 |
282 | { |
| 283 | register int size; |
| 284 | register union overhead *op; |
| 352d5a3a |
285 | char *cp = (char*)mp; |
| 8d063cd8 |
286 | |
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287 | #ifdef safemalloc |
| 288 | #ifdef DEBUGGING |
| 289 | # ifndef I286 |
| 290 | if (debug & 128) |
| 291 | fprintf(stderr,"0x%x: (%05d) free\n",cp,an++); |
| 292 | # else |
| 293 | if (debug & 128) |
| 294 | fprintf(stderr,"0x%lx: (%05d) free\n",cp,an++); |
| 295 | # endif |
| 296 | #endif |
| 297 | #endif /* safemalloc */ |
| 298 | |
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299 | if (cp == NULL) |
| 300 | return; |
| 301 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
| 302 | #ifdef debug |
| 303 | ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ |
| 304 | #else |
| 378cc40b |
305 | if (op->ov_magic != MAGIC) { |
| a687059c |
306 | warn("%s free() ignored", |
| 378cc40b |
307 | op->ov_magic == OLDMAGIC ? "Duplicate" : "Bad"); |
| 8d063cd8 |
308 | return; /* sanity */ |
| 378cc40b |
309 | } |
| 310 | op->ov_magic = OLDMAGIC; |
| 8d063cd8 |
311 | #endif |
| 312 | #ifdef RCHECK |
| 313 | ASSERT(op->ov_rmagic == RMAGIC); |
| 314 | if (op->ov_index <= 13) |
| 315 | ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC); |
| 316 | #endif |
| 317 | ASSERT(op->ov_index < NBUCKETS); |
| 318 | size = op->ov_index; |
| 319 | op->ov_next = nextf[size]; |
| 320 | nextf[size] = op; |
| 321 | #ifdef MSTATS |
| 322 | nmalloc[size]--; |
| 323 | #endif |
| 324 | } |
| 325 | |
| 326 | /* |
| 327 | * When a program attempts "storage compaction" as mentioned in the |
| 328 | * old malloc man page, it realloc's an already freed block. Usually |
| 329 | * this is the last block it freed; occasionally it might be farther |
| 330 | * back. We have to search all the free lists for the block in order |
| 331 | * to determine its bucket: 1st we make one pass thru the lists |
| 332 | * checking only the first block in each; if that fails we search |
| 378cc40b |
333 | * ``reall_srchlen'' blocks in each list for a match (the variable |
| 8d063cd8 |
334 | * is extern so the caller can modify it). If that fails we just copy |
| 335 | * however many bytes was given to realloc() and hope it's not huge. |
| 336 | */ |
| 378cc40b |
337 | int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ |
| 8d063cd8 |
338 | |
| 35c8bce7 |
339 | MALLOCPTRTYPE * |
| 352d5a3a |
340 | realloc(mp, nbytes) |
| 341 | MALLOCPTRTYPE *mp; |
| 8d063cd8 |
342 | unsigned nbytes; |
| 343 | { |
| 344 | register u_int onb; |
| 345 | union overhead *op; |
| 346 | char *res; |
| 347 | register int i; |
| 348 | int was_alloced = 0; |
| 352d5a3a |
349 | char *cp = (char*)mp; |
| 8d063cd8 |
350 | |
| 45d8adaa |
351 | #ifdef safemalloc |
| 352 | #ifdef DEBUGGING |
| 353 | int size = nbytes; |
| 354 | #endif |
| 355 | |
| 356 | #ifdef MSDOS |
| 357 | if (nbytes > 0xffff) { |
| 358 | fprintf(stderr, "Reallocation too large: %lx\n", size); |
| 359 | exit(1); |
| 360 | } |
| 361 | #endif /* MSDOS */ |
| 362 | if (!cp) |
| 363 | fatal("Null realloc"); |
| 364 | #ifdef DEBUGGING |
| 365 | if ((long)nbytes < 0) |
| 366 | fatal("panic: realloc"); |
| 367 | #endif |
| 368 | #endif /* safemalloc */ |
| 369 | |
| 8d063cd8 |
370 | if (cp == NULL) |
| 371 | return (malloc(nbytes)); |
| 372 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
| 373 | if (op->ov_magic == MAGIC) { |
| 374 | was_alloced++; |
| 375 | i = op->ov_index; |
| 376 | } else { |
| 377 | /* |
| 378 | * Already free, doing "compaction". |
| 379 | * |
| 380 | * Search for the old block of memory on the |
| 381 | * free list. First, check the most common |
| 382 | * case (last element free'd), then (this failing) |
| 378cc40b |
383 | * the last ``reall_srchlen'' items free'd. |
| 8d063cd8 |
384 | * If all lookups fail, then assume the size of |
| 385 | * the memory block being realloc'd is the |
| 386 | * smallest possible. |
| 387 | */ |
| 388 | if ((i = findbucket(op, 1)) < 0 && |
| 378cc40b |
389 | (i = findbucket(op, reall_srchlen)) < 0) |
| 8d063cd8 |
390 | i = 0; |
| 391 | } |
| 392 | onb = (1 << (i + 3)) - sizeof (*op) - RSLOP; |
| 393 | /* avoid the copy if same size block */ |
| 394 | if (was_alloced && |
| a687059c |
395 | nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) { |
| 396 | #ifdef RCHECK |
| 397 | /* |
| 398 | * Record new allocated size of block and |
| 399 | * bound space with magic numbers. |
| 400 | */ |
| 401 | if (op->ov_index <= 13) { |
| 402 | /* |
| 403 | * Convert amount of memory requested into |
| 404 | * closest block size stored in hash buckets |
| 405 | * which satisfies request. Account for |
| 406 | * space used per block for accounting. |
| 407 | */ |
| 408 | nbytes += sizeof (union overhead) + RSLOP; |
| 409 | nbytes = (nbytes + 3) &~ 3; |
| 410 | op->ov_size = nbytes - 1; |
| 411 | *((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC; |
| 412 | } |
| 413 | #endif |
| 45d8adaa |
414 | res = cp; |
| a687059c |
415 | } |
| 45d8adaa |
416 | else { |
| 417 | if ((res = (char*)malloc(nbytes)) == NULL) |
| 418 | return (NULL); |
| 419 | if (cp != res) /* common optimization */ |
| 420 | bcopy(cp, res, (int)(nbytes < onb ? nbytes : onb)); |
| 421 | if (was_alloced) |
| 422 | free(cp); |
| 423 | } |
| 424 | |
| 425 | #ifdef safemalloc |
| 426 | #ifdef DEBUGGING |
| 427 | # ifndef I286 |
| 428 | if (debug & 128) { |
| 429 | fprintf(stderr,"0x%x: (%05d) rfree\n",res,an++); |
| 430 | fprintf(stderr,"0x%x: (%05d) realloc %d bytes\n",res,an++,size); |
| 431 | } |
| 432 | # else |
| 433 | if (debug & 128) { |
| 434 | fprintf(stderr,"0x%lx: (%05d) rfree\n",res,an++); |
| 435 | fprintf(stderr,"0x%lx: (%05d) realloc %d bytes\n",res,an++,size); |
| 436 | } |
| 437 | # endif |
| 438 | #endif |
| 439 | #endif /* safemalloc */ |
| 352d5a3a |
440 | return ((MALLOCPTRTYPE*)res); |
| 8d063cd8 |
441 | } |
| 442 | |
| 443 | /* |
| 444 | * Search ``srchlen'' elements of each free list for a block whose |
| 445 | * header starts at ``freep''. If srchlen is -1 search the whole list. |
| 446 | * Return bucket number, or -1 if not found. |
| 447 | */ |
| 448 | static |
| 449 | findbucket(freep, srchlen) |
| 450 | union overhead *freep; |
| 451 | int srchlen; |
| 452 | { |
| 453 | register union overhead *p; |
| 454 | register int i, j; |
| 455 | |
| 456 | for (i = 0; i < NBUCKETS; i++) { |
| 457 | j = 0; |
| 458 | for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { |
| 459 | if (p == freep) |
| 460 | return (i); |
| 461 | j++; |
| 462 | } |
| 463 | } |
| 464 | return (-1); |
| 465 | } |
| 466 | |
| 467 | #ifdef MSTATS |
| 468 | /* |
| 469 | * mstats - print out statistics about malloc |
| 470 | * |
| 471 | * Prints two lines of numbers, one showing the length of the free list |
| 472 | * for each size category, the second showing the number of mallocs - |
| 473 | * frees for each size category. |
| 474 | */ |
| 475 | mstats(s) |
| 476 | char *s; |
| 477 | { |
| 478 | register int i, j; |
| 479 | register union overhead *p; |
| 480 | int totfree = 0, |
| 481 | totused = 0; |
| 482 | |
| 483 | fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s); |
| 484 | for (i = 0; i < NBUCKETS; i++) { |
| 485 | for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) |
| 486 | ; |
| 487 | fprintf(stderr, " %d", j); |
| 488 | totfree += j * (1 << (i + 3)); |
| 489 | } |
| 490 | fprintf(stderr, "\nused:\t"); |
| 491 | for (i = 0; i < NBUCKETS; i++) { |
| 492 | fprintf(stderr, " %d", nmalloc[i]); |
| 493 | totused += nmalloc[i] * (1 << (i + 3)); |
| 494 | } |
| 495 | fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n", |
| 496 | totused, totfree); |
| 497 | } |
| 498 | #endif |
| a687059c |
499 | #endif /* lint */ |
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