| Commit | Line | Data |
|---|
| c623bd54 |
1 | /* $Header: malloc.c,v 3.0.1.5 91/01/11 18:09:52 lwall Locked $ |
| 8d063cd8 |
2 | * |
| 3 | * $Log: malloc.c,v $ |
| c623bd54 |
4 | * Revision 3.0.1.5 91/01/11 18:09:52 lwall |
| 5 | * patch42: Configure now checks alignment requirements |
| 6 | * |
| 4e8eb4f0 |
7 | * Revision 3.0.1.4 90/11/13 15:23:45 lwall |
| 8 | * patch41: added hp malloc union overhead strut (that sounds very blue collar) |
| 9 | * |
| d9d8d8de |
10 | * Revision 3.0.1.3 90/10/16 15:27:47 lwall |
| 11 | * patch29: various portability fixes |
| 12 | * |
| bf38876a |
13 | * Revision 3.0.1.2 89/11/11 04:36:37 lwall |
| 14 | * patch2: malloc pointer corruption check made more portable |
| 15 | * |
| 03a14243 |
16 | * Revision 3.0.1.1 89/10/26 23:15:05 lwall |
| 17 | * patch1: some declarations were missing from malloc.c |
| 18 | * patch1: sparc machines had alignment problems in malloc.c |
| 19 | * |
| a687059c |
20 | * Revision 3.0 89/10/18 15:20:39 lwall |
| 21 | * 3.0 baseline |
| 8d063cd8 |
22 | * |
| 23 | */ |
| 24 | |
| 25 | #ifndef lint |
| 26 | static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83"; |
| 8d063cd8 |
27 | |
| a687059c |
28 | #ifdef DEBUGGING |
| 8d063cd8 |
29 | #define RCHECK |
| a687059c |
30 | #endif |
| 8d063cd8 |
31 | /* |
| 32 | * malloc.c (Caltech) 2/21/82 |
| 33 | * Chris Kingsley, kingsley@cit-20. |
| 34 | * |
| 35 | * This is a very fast storage allocator. It allocates blocks of a small |
| 36 | * number of different sizes, and keeps free lists of each size. Blocks that |
| 37 | * don't exactly fit are passed up to the next larger size. In this |
| 38 | * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long. |
| 39 | * This is designed for use in a program that uses vast quantities of memory, |
| 40 | * but bombs when it runs out. |
| 41 | */ |
| 42 | |
| 135863df |
43 | #include "EXTERN.h" |
| 135863df |
44 | #include "perl.h" |
| 45 | |
| 03a14243 |
46 | static findbucket(), morecore(); |
| 47 | |
| 135863df |
48 | /* I don't much care whether these are defined in sys/types.h--LAW */ |
| 49 | |
| 50 | #define u_char unsigned char |
| 51 | #define u_int unsigned int |
| 52 | #define u_short unsigned short |
| 8d063cd8 |
53 | |
| 8d063cd8 |
54 | /* |
| 55 | * The overhead on a block is at least 4 bytes. When free, this space |
| 56 | * contains a pointer to the next free block, and the bottom two bits must |
| 57 | * be zero. When in use, the first byte is set to MAGIC, and the second |
| 58 | * byte is the size index. The remaining bytes are for alignment. |
| 59 | * If range checking is enabled and the size of the block fits |
| 60 | * in two bytes, then the top two bytes hold the size of the requested block |
| 61 | * plus the range checking words, and the header word MINUS ONE. |
| 62 | */ |
| 63 | union overhead { |
| 64 | union overhead *ov_next; /* when free */ |
| c623bd54 |
65 | #if ALIGNBYTES > 4 |
| 66 | double strut; /* alignment problems */ |
| a687059c |
67 | #endif |
| 8d063cd8 |
68 | struct { |
| 69 | u_char ovu_magic; /* magic number */ |
| 70 | u_char ovu_index; /* bucket # */ |
| 71 | #ifdef RCHECK |
| 72 | u_short ovu_size; /* actual block size */ |
| 73 | u_int ovu_rmagic; /* range magic number */ |
| 74 | #endif |
| 75 | } ovu; |
| 76 | #define ov_magic ovu.ovu_magic |
| 77 | #define ov_index ovu.ovu_index |
| 78 | #define ov_size ovu.ovu_size |
| 79 | #define ov_rmagic ovu.ovu_rmagic |
| 80 | }; |
| 81 | |
| 82 | #define MAGIC 0xff /* magic # on accounting info */ |
| 378cc40b |
83 | #define OLDMAGIC 0x7f /* same after a free() */ |
| 8d063cd8 |
84 | #define RMAGIC 0x55555555 /* magic # on range info */ |
| 85 | #ifdef RCHECK |
| 86 | #define RSLOP sizeof (u_int) |
| 87 | #else |
| 88 | #define RSLOP 0 |
| 89 | #endif |
| 90 | |
| 91 | /* |
| 92 | * nextf[i] is the pointer to the next free block of size 2^(i+3). The |
| 93 | * smallest allocatable block is 8 bytes. The overhead information |
| 94 | * precedes the data area returned to the user. |
| 95 | */ |
| 96 | #define NBUCKETS 30 |
| 97 | static union overhead *nextf[NBUCKETS]; |
| 98 | extern char *sbrk(); |
| 99 | |
| 100 | #ifdef MSTATS |
| 101 | /* |
| 102 | * nmalloc[i] is the difference between the number of mallocs and frees |
| 103 | * for a given block size. |
| 104 | */ |
| 105 | static u_int nmalloc[NBUCKETS]; |
| 106 | #include <stdio.h> |
| 107 | #endif |
| 108 | |
| 109 | #ifdef debug |
| 110 | #define ASSERT(p) if (!(p)) botch("p"); else |
| 111 | static |
| 112 | botch(s) |
| 113 | char *s; |
| 114 | { |
| 115 | |
| 116 | printf("assertion botched: %s\n", s); |
| 117 | abort(); |
| 118 | } |
| 119 | #else |
| 120 | #define ASSERT(p) |
| 121 | #endif |
| 122 | |
| 123 | char * |
| 124 | malloc(nbytes) |
| 125 | register unsigned nbytes; |
| 126 | { |
| 127 | register union overhead *p; |
| 128 | register int bucket = 0; |
| 129 | register unsigned shiftr; |
| 130 | |
| 131 | /* |
| 132 | * Convert amount of memory requested into |
| 133 | * closest block size stored in hash buckets |
| 134 | * which satisfies request. Account for |
| 135 | * space used per block for accounting. |
| 136 | */ |
| 137 | nbytes += sizeof (union overhead) + RSLOP; |
| 138 | nbytes = (nbytes + 3) &~ 3; |
| 139 | shiftr = (nbytes - 1) >> 2; |
| 140 | /* apart from this loop, this is O(1) */ |
| 141 | while (shiftr >>= 1) |
| 142 | bucket++; |
| 143 | /* |
| 144 | * If nothing in hash bucket right now, |
| 145 | * request more memory from the system. |
| 146 | */ |
| 147 | if (nextf[bucket] == NULL) |
| 148 | morecore(bucket); |
| 149 | if ((p = (union overhead *)nextf[bucket]) == NULL) |
| 150 | return (NULL); |
| 151 | /* remove from linked list */ |
| bf38876a |
152 | #ifdef RCHECK |
| 153 | if (*((int*)p) & (sizeof(union overhead) - 1)) |
| a687059c |
154 | #ifndef I286 |
| 8d063cd8 |
155 | fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",*((int*)p),p); |
| a687059c |
156 | #else |
| 157 | fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n",*((int*)p),p); |
| 158 | #endif |
| bf38876a |
159 | #endif |
| 160 | nextf[bucket] = p->ov_next; |
| 8d063cd8 |
161 | p->ov_magic = MAGIC; |
| 162 | p->ov_index= bucket; |
| 163 | #ifdef MSTATS |
| 164 | nmalloc[bucket]++; |
| 165 | #endif |
| 166 | #ifdef RCHECK |
| 167 | /* |
| 168 | * Record allocated size of block and |
| 169 | * bound space with magic numbers. |
| 170 | */ |
| 171 | if (nbytes <= 0x10000) |
| 172 | p->ov_size = nbytes - 1; |
| 173 | p->ov_rmagic = RMAGIC; |
| 174 | *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC; |
| 175 | #endif |
| 176 | return ((char *)(p + 1)); |
| 177 | } |
| 178 | |
| 179 | /* |
| 180 | * Allocate more memory to the indicated bucket. |
| 181 | */ |
| 182 | static |
| 183 | morecore(bucket) |
| a687059c |
184 | register int bucket; |
| 8d063cd8 |
185 | { |
| 186 | register union overhead *op; |
| 187 | register int rnu; /* 2^rnu bytes will be requested */ |
| 188 | register int nblks; /* become nblks blocks of the desired size */ |
| 189 | register int siz; |
| 190 | |
| 191 | if (nextf[bucket]) |
| 192 | return; |
| 193 | /* |
| 194 | * Insure memory is allocated |
| 195 | * on a page boundary. Should |
| 196 | * make getpageize call? |
| 197 | */ |
| 198 | op = (union overhead *)sbrk(0); |
| a687059c |
199 | #ifndef I286 |
| 8d063cd8 |
200 | if ((int)op & 0x3ff) |
| a687059c |
201 | (void)sbrk(1024 - ((int)op & 0x3ff)); |
| 202 | #else |
| 203 | /* The sbrk(0) call on the I286 always returns the next segment */ |
| 204 | #endif |
| 205 | |
| 206 | #ifndef I286 |
| 8d063cd8 |
207 | /* take 2k unless the block is bigger than that */ |
| 208 | rnu = (bucket <= 8) ? 11 : bucket + 3; |
| a687059c |
209 | #else |
| 210 | /* take 16k unless the block is bigger than that |
| 211 | (80286s like large segments!) */ |
| 212 | rnu = (bucket <= 11) ? 14 : bucket + 3; |
| 213 | #endif |
| 8d063cd8 |
214 | nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */ |
| 215 | if (rnu < bucket) |
| 216 | rnu = bucket; |
| 217 | op = (union overhead *)sbrk(1 << rnu); |
| 218 | /* no more room! */ |
| 219 | if ((int)op == -1) |
| 220 | return; |
| 221 | /* |
| 222 | * Round up to minimum allocation size boundary |
| 223 | * and deduct from block count to reflect. |
| 224 | */ |
| a687059c |
225 | #ifndef I286 |
| 8d063cd8 |
226 | if ((int)op & 7) { |
| 227 | op = (union overhead *)(((int)op + 8) &~ 7); |
| 228 | nblks--; |
| 229 | } |
| a687059c |
230 | #else |
| 231 | /* Again, this should always be ok on an 80286 */ |
| 232 | #endif |
| 8d063cd8 |
233 | /* |
| 234 | * Add new memory allocated to that on |
| 235 | * free list for this hash bucket. |
| 236 | */ |
| 237 | nextf[bucket] = op; |
| 238 | siz = 1 << (bucket + 3); |
| 239 | while (--nblks > 0) { |
| 240 | op->ov_next = (union overhead *)((caddr_t)op + siz); |
| 241 | op = (union overhead *)((caddr_t)op + siz); |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | free(cp) |
| 246 | char *cp; |
| 247 | { |
| 248 | register int size; |
| 249 | register union overhead *op; |
| 250 | |
| 251 | if (cp == NULL) |
| 252 | return; |
| 253 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
| 254 | #ifdef debug |
| 255 | ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ |
| 256 | #else |
| 378cc40b |
257 | if (op->ov_magic != MAGIC) { |
| a687059c |
258 | warn("%s free() ignored", |
| 378cc40b |
259 | op->ov_magic == OLDMAGIC ? "Duplicate" : "Bad"); |
| 8d063cd8 |
260 | return; /* sanity */ |
| 378cc40b |
261 | } |
| 262 | op->ov_magic = OLDMAGIC; |
| 8d063cd8 |
263 | #endif |
| 264 | #ifdef RCHECK |
| 265 | ASSERT(op->ov_rmagic == RMAGIC); |
| 266 | if (op->ov_index <= 13) |
| 267 | ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC); |
| 268 | #endif |
| 269 | ASSERT(op->ov_index < NBUCKETS); |
| 270 | size = op->ov_index; |
| 271 | op->ov_next = nextf[size]; |
| 272 | nextf[size] = op; |
| 273 | #ifdef MSTATS |
| 274 | nmalloc[size]--; |
| 275 | #endif |
| 276 | } |
| 277 | |
| 278 | /* |
| 279 | * When a program attempts "storage compaction" as mentioned in the |
| 280 | * old malloc man page, it realloc's an already freed block. Usually |
| 281 | * this is the last block it freed; occasionally it might be farther |
| 282 | * back. We have to search all the free lists for the block in order |
| 283 | * to determine its bucket: 1st we make one pass thru the lists |
| 284 | * checking only the first block in each; if that fails we search |
| 378cc40b |
285 | * ``reall_srchlen'' blocks in each list for a match (the variable |
| 8d063cd8 |
286 | * is extern so the caller can modify it). If that fails we just copy |
| 287 | * however many bytes was given to realloc() and hope it's not huge. |
| 288 | */ |
| 378cc40b |
289 | int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ |
| 8d063cd8 |
290 | |
| 291 | char * |
| 292 | realloc(cp, nbytes) |
| 293 | char *cp; |
| 294 | unsigned nbytes; |
| 295 | { |
| 296 | register u_int onb; |
| 297 | union overhead *op; |
| 298 | char *res; |
| 299 | register int i; |
| 300 | int was_alloced = 0; |
| 301 | |
| 302 | if (cp == NULL) |
| 303 | return (malloc(nbytes)); |
| 304 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
| 305 | if (op->ov_magic == MAGIC) { |
| 306 | was_alloced++; |
| 307 | i = op->ov_index; |
| 308 | } else { |
| 309 | /* |
| 310 | * Already free, doing "compaction". |
| 311 | * |
| 312 | * Search for the old block of memory on the |
| 313 | * free list. First, check the most common |
| 314 | * case (last element free'd), then (this failing) |
| 378cc40b |
315 | * the last ``reall_srchlen'' items free'd. |
| 8d063cd8 |
316 | * If all lookups fail, then assume the size of |
| 317 | * the memory block being realloc'd is the |
| 318 | * smallest possible. |
| 319 | */ |
| 320 | if ((i = findbucket(op, 1)) < 0 && |
| 378cc40b |
321 | (i = findbucket(op, reall_srchlen)) < 0) |
| 8d063cd8 |
322 | i = 0; |
| 323 | } |
| 324 | onb = (1 << (i + 3)) - sizeof (*op) - RSLOP; |
| 325 | /* avoid the copy if same size block */ |
| 326 | if (was_alloced && |
| a687059c |
327 | nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) { |
| 328 | #ifdef RCHECK |
| 329 | /* |
| 330 | * Record new allocated size of block and |
| 331 | * bound space with magic numbers. |
| 332 | */ |
| 333 | if (op->ov_index <= 13) { |
| 334 | /* |
| 335 | * Convert amount of memory requested into |
| 336 | * closest block size stored in hash buckets |
| 337 | * which satisfies request. Account for |
| 338 | * space used per block for accounting. |
| 339 | */ |
| 340 | nbytes += sizeof (union overhead) + RSLOP; |
| 341 | nbytes = (nbytes + 3) &~ 3; |
| 342 | op->ov_size = nbytes - 1; |
| 343 | *((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC; |
| 344 | } |
| 345 | #endif |
| 8d063cd8 |
346 | return(cp); |
| a687059c |
347 | } |
| 8d063cd8 |
348 | if ((res = malloc(nbytes)) == NULL) |
| 349 | return (NULL); |
| 350 | if (cp != res) /* common optimization */ |
| a687059c |
351 | (void)bcopy(cp, res, (int)((nbytes < onb) ? nbytes : onb)); |
| 8d063cd8 |
352 | if (was_alloced) |
| 353 | free(cp); |
| 354 | return (res); |
| 355 | } |
| 356 | |
| 357 | /* |
| 358 | * Search ``srchlen'' elements of each free list for a block whose |
| 359 | * header starts at ``freep''. If srchlen is -1 search the whole list. |
| 360 | * Return bucket number, or -1 if not found. |
| 361 | */ |
| 362 | static |
| 363 | findbucket(freep, srchlen) |
| 364 | union overhead *freep; |
| 365 | int srchlen; |
| 366 | { |
| 367 | register union overhead *p; |
| 368 | register int i, j; |
| 369 | |
| 370 | for (i = 0; i < NBUCKETS; i++) { |
| 371 | j = 0; |
| 372 | for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { |
| 373 | if (p == freep) |
| 374 | return (i); |
| 375 | j++; |
| 376 | } |
| 377 | } |
| 378 | return (-1); |
| 379 | } |
| 380 | |
| 381 | #ifdef MSTATS |
| 382 | /* |
| 383 | * mstats - print out statistics about malloc |
| 384 | * |
| 385 | * Prints two lines of numbers, one showing the length of the free list |
| 386 | * for each size category, the second showing the number of mallocs - |
| 387 | * frees for each size category. |
| 388 | */ |
| 389 | mstats(s) |
| 390 | char *s; |
| 391 | { |
| 392 | register int i, j; |
| 393 | register union overhead *p; |
| 394 | int totfree = 0, |
| 395 | totused = 0; |
| 396 | |
| 397 | fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s); |
| 398 | for (i = 0; i < NBUCKETS; i++) { |
| 399 | for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) |
| 400 | ; |
| 401 | fprintf(stderr, " %d", j); |
| 402 | totfree += j * (1 << (i + 3)); |
| 403 | } |
| 404 | fprintf(stderr, "\nused:\t"); |
| 405 | for (i = 0; i < NBUCKETS; i++) { |
| 406 | fprintf(stderr, " %d", nmalloc[i]); |
| 407 | totused += nmalloc[i] * (1 << (i + 3)); |
| 408 | } |
| 409 | fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n", |
| 410 | totused, totfree); |
| 411 | } |
| 412 | #endif |
| a687059c |
413 | #endif /* lint */ |
projects / p5sagit/p5-mst-13.2.git / blame