Commit | Line | Data |
---|---|---|
a0d0e21e | 1 | /* malloc.c |
8d063cd8 | 2 | * |
8d063cd8 LW |
3 | */ |
4 | ||
5 | #ifndef lint | |
a687059c | 6 | #ifdef DEBUGGING |
8d063cd8 | 7 | #define RCHECK |
a687059c | 8 | #endif |
8d063cd8 LW |
9 | /* |
10 | * malloc.c (Caltech) 2/21/82 | |
11 | * Chris Kingsley, kingsley@cit-20. | |
12 | * | |
13 | * This is a very fast storage allocator. It allocates blocks of a small | |
14 | * number of different sizes, and keeps free lists of each size. Blocks that | |
15 | * don't exactly fit are passed up to the next larger size. In this | |
16 | * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long. | |
17 | * This is designed for use in a program that uses vast quantities of memory, | |
18 | * but bombs when it runs out. | |
19 | */ | |
20 | ||
135863df | 21 | #include "EXTERN.h" |
135863df AB |
22 | #include "perl.h" |
23 | ||
24 | /* I don't much care whether these are defined in sys/types.h--LAW */ | |
25 | ||
26 | #define u_char unsigned char | |
27 | #define u_int unsigned int | |
28 | #define u_short unsigned short | |
8d063cd8 | 29 | |
8d063cd8 LW |
30 | /* |
31 | * The overhead on a block is at least 4 bytes. When free, this space | |
32 | * contains a pointer to the next free block, and the bottom two bits must | |
33 | * be zero. When in use, the first byte is set to MAGIC, and the second | |
34 | * byte is the size index. The remaining bytes are for alignment. | |
35 | * If range checking is enabled and the size of the block fits | |
36 | * in two bytes, then the top two bytes hold the size of the requested block | |
37 | * plus the range checking words, and the header word MINUS ONE. | |
38 | */ | |
39 | union overhead { | |
40 | union overhead *ov_next; /* when free */ | |
85e6fe83 | 41 | #if MEM_ALIGNBYTES > 4 |
c623bd54 | 42 | double strut; /* alignment problems */ |
a687059c | 43 | #endif |
8d063cd8 LW |
44 | struct { |
45 | u_char ovu_magic; /* magic number */ | |
46 | u_char ovu_index; /* bucket # */ | |
47 | #ifdef RCHECK | |
48 | u_short ovu_size; /* actual block size */ | |
49 | u_int ovu_rmagic; /* range magic number */ | |
50 | #endif | |
51 | } ovu; | |
52 | #define ov_magic ovu.ovu_magic | |
53 | #define ov_index ovu.ovu_index | |
54 | #define ov_size ovu.ovu_size | |
55 | #define ov_rmagic ovu.ovu_rmagic | |
56 | }; | |
57 | ||
a0d0e21e LW |
58 | #ifdef debug |
59 | static void botch _((char *s)); | |
60 | #endif | |
61 | static void morecore _((int bucket)); | |
62 | static int findbucket _((union overhead *freep, int srchlen)); | |
63 | ||
8d063cd8 LW |
64 | #define MAGIC 0xff /* magic # on accounting info */ |
65 | #define RMAGIC 0x55555555 /* magic # on range info */ | |
66 | #ifdef RCHECK | |
67 | #define RSLOP sizeof (u_int) | |
68 | #else | |
69 | #define RSLOP 0 | |
70 | #endif | |
71 | ||
72 | /* | |
73 | * nextf[i] is the pointer to the next free block of size 2^(i+3). The | |
74 | * smallest allocatable block is 8 bytes. The overhead information | |
75 | * precedes the data area returned to the user. | |
76 | */ | |
77 | #define NBUCKETS 30 | |
78 | static union overhead *nextf[NBUCKETS]; | |
79 | extern char *sbrk(); | |
80 | ||
c07a80fd | 81 | #ifdef DEBUGGING_MSTATS |
8d063cd8 LW |
82 | /* |
83 | * nmalloc[i] is the difference between the number of mallocs and frees | |
84 | * for a given block size. | |
85 | */ | |
86 | static u_int nmalloc[NBUCKETS]; | |
87 | #include <stdio.h> | |
88 | #endif | |
89 | ||
90 | #ifdef debug | |
91 | #define ASSERT(p) if (!(p)) botch("p"); else | |
ee0007ab | 92 | static void |
8d063cd8 LW |
93 | botch(s) |
94 | char *s; | |
95 | { | |
96 | ||
97 | printf("assertion botched: %s\n", s); | |
98 | abort(); | |
99 | } | |
100 | #else | |
101 | #define ASSERT(p) | |
102 | #endif | |
103 | ||
2304df62 | 104 | Malloc_t |
8d063cd8 | 105 | malloc(nbytes) |
ee0007ab | 106 | register MEM_SIZE nbytes; |
8d063cd8 LW |
107 | { |
108 | register union overhead *p; | |
109 | register int bucket = 0; | |
ee0007ab | 110 | register MEM_SIZE shiftr; |
8d063cd8 | 111 | |
45d8adaa LW |
112 | #ifdef safemalloc |
113 | #ifdef DEBUGGING | |
ee0007ab | 114 | MEM_SIZE size = nbytes; |
45d8adaa LW |
115 | #endif |
116 | ||
117 | #ifdef MSDOS | |
118 | if (nbytes > 0xffff) { | |
ee0007ab | 119 | fprintf(stderr, "Allocation too large: %lx\n", (long)nbytes); |
79072805 | 120 | my_exit(1); |
45d8adaa LW |
121 | } |
122 | #endif /* MSDOS */ | |
123 | #ifdef DEBUGGING | |
124 | if ((long)nbytes < 0) | |
463ee0b2 | 125 | croak("panic: malloc"); |
45d8adaa LW |
126 | #endif |
127 | #endif /* safemalloc */ | |
128 | ||
8d063cd8 LW |
129 | /* |
130 | * Convert amount of memory requested into | |
131 | * closest block size stored in hash buckets | |
132 | * which satisfies request. Account for | |
133 | * space used per block for accounting. | |
134 | */ | |
135 | nbytes += sizeof (union overhead) + RSLOP; | |
136 | nbytes = (nbytes + 3) &~ 3; | |
137 | shiftr = (nbytes - 1) >> 2; | |
138 | /* apart from this loop, this is O(1) */ | |
139 | while (shiftr >>= 1) | |
140 | bucket++; | |
141 | /* | |
142 | * If nothing in hash bucket right now, | |
143 | * request more memory from the system. | |
144 | */ | |
145 | if (nextf[bucket] == NULL) | |
146 | morecore(bucket); | |
45d8adaa LW |
147 | if ((p = (union overhead *)nextf[bucket]) == NULL) { |
148 | #ifdef safemalloc | |
ee0007ab LW |
149 | if (!nomemok) { |
150 | fputs("Out of memory!\n", stderr); | |
79072805 | 151 | my_exit(1); |
ee0007ab | 152 | } |
45d8adaa | 153 | #else |
8d063cd8 | 154 | return (NULL); |
45d8adaa LW |
155 | #endif |
156 | } | |
157 | ||
158 | #ifdef safemalloc | |
a0d0e21e LW |
159 | DEBUG_m(fprintf(stderr,"0x%lx: (%05d) malloc %ld bytes\n", |
160 | (unsigned long)(p+1),an++,(long)size)); | |
45d8adaa LW |
161 | #endif /* safemalloc */ |
162 | ||
8d063cd8 | 163 | /* remove from linked list */ |
bf38876a LW |
164 | #ifdef RCHECK |
165 | if (*((int*)p) & (sizeof(union overhead) - 1)) | |
a0d0e21e LW |
166 | fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n", |
167 | (unsigned long)*((int*)p),(unsigned long)p); | |
bf38876a LW |
168 | #endif |
169 | nextf[bucket] = p->ov_next; | |
8d063cd8 LW |
170 | p->ov_magic = MAGIC; |
171 | p->ov_index= bucket; | |
c07a80fd | 172 | #ifdef DEBUGGING_MSTATS |
8d063cd8 LW |
173 | nmalloc[bucket]++; |
174 | #endif | |
175 | #ifdef RCHECK | |
176 | /* | |
177 | * Record allocated size of block and | |
178 | * bound space with magic numbers. | |
179 | */ | |
180 | if (nbytes <= 0x10000) | |
181 | p->ov_size = nbytes - 1; | |
182 | p->ov_rmagic = RMAGIC; | |
183 | *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC; | |
184 | #endif | |
2304df62 | 185 | return ((Malloc_t)(p + 1)); |
8d063cd8 LW |
186 | } |
187 | ||
188 | /* | |
189 | * Allocate more memory to the indicated bucket. | |
190 | */ | |
a0d0e21e | 191 | static void |
8d063cd8 | 192 | morecore(bucket) |
a687059c | 193 | register int bucket; |
8d063cd8 LW |
194 | { |
195 | register union overhead *op; | |
196 | register int rnu; /* 2^rnu bytes will be requested */ | |
197 | register int nblks; /* become nblks blocks of the desired size */ | |
ee0007ab | 198 | register MEM_SIZE siz; |
8d063cd8 LW |
199 | |
200 | if (nextf[bucket]) | |
201 | return; | |
202 | /* | |
203 | * Insure memory is allocated | |
204 | * on a page boundary. Should | |
205 | * make getpageize call? | |
206 | */ | |
ee0007ab | 207 | #ifndef atarist /* on the atari we dont have to worry about this */ |
8d063cd8 | 208 | op = (union overhead *)sbrk(0); |
a687059c | 209 | #ifndef I286 |
8d063cd8 | 210 | if ((int)op & 0x3ff) |
a687059c LW |
211 | (void)sbrk(1024 - ((int)op & 0x3ff)); |
212 | #else | |
213 | /* The sbrk(0) call on the I286 always returns the next segment */ | |
214 | #endif | |
ee0007ab | 215 | #endif /* atarist */ |
a687059c | 216 | |
ee0007ab | 217 | #if !(defined(I286) || defined(atarist)) |
8d063cd8 LW |
218 | /* take 2k unless the block is bigger than that */ |
219 | rnu = (bucket <= 8) ? 11 : bucket + 3; | |
a687059c LW |
220 | #else |
221 | /* take 16k unless the block is bigger than that | |
ee0007ab | 222 | (80286s like large segments!), probably good on the atari too */ |
a687059c LW |
223 | rnu = (bucket <= 11) ? 14 : bucket + 3; |
224 | #endif | |
8d063cd8 LW |
225 | nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */ |
226 | if (rnu < bucket) | |
227 | rnu = bucket; | |
ee0007ab | 228 | op = (union overhead *)sbrk(1L << rnu); |
8d063cd8 LW |
229 | /* no more room! */ |
230 | if ((int)op == -1) | |
231 | return; | |
232 | /* | |
233 | * Round up to minimum allocation size boundary | |
234 | * and deduct from block count to reflect. | |
235 | */ | |
a687059c | 236 | #ifndef I286 |
8d063cd8 | 237 | if ((int)op & 7) { |
ee0007ab | 238 | op = (union overhead *)(((MEM_SIZE)op + 8) &~ 7); |
8d063cd8 LW |
239 | nblks--; |
240 | } | |
a687059c LW |
241 | #else |
242 | /* Again, this should always be ok on an 80286 */ | |
243 | #endif | |
8d063cd8 LW |
244 | /* |
245 | * Add new memory allocated to that on | |
246 | * free list for this hash bucket. | |
247 | */ | |
248 | nextf[bucket] = op; | |
249 | siz = 1 << (bucket + 3); | |
250 | while (--nblks > 0) { | |
251 | op->ov_next = (union overhead *)((caddr_t)op + siz); | |
252 | op = (union overhead *)((caddr_t)op + siz); | |
253 | } | |
254 | } | |
255 | ||
94b6baf5 | 256 | Free_t |
352d5a3a | 257 | free(mp) |
2304df62 | 258 | Malloc_t mp; |
8d063cd8 | 259 | { |
ee0007ab | 260 | register MEM_SIZE size; |
8d063cd8 | 261 | register union overhead *op; |
352d5a3a | 262 | char *cp = (char*)mp; |
8d063cd8 | 263 | |
45d8adaa | 264 | #ifdef safemalloc |
a0d0e21e | 265 | DEBUG_m(fprintf(stderr,"0x%lx: (%05d) free\n",(unsigned long)cp,an++)); |
45d8adaa LW |
266 | #endif /* safemalloc */ |
267 | ||
8d063cd8 LW |
268 | if (cp == NULL) |
269 | return; | |
270 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); | |
271 | #ifdef debug | |
272 | ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ | |
273 | #else | |
378cc40b | 274 | if (op->ov_magic != MAGIC) { |
8990e307 | 275 | #ifdef RCHECK |
a687059c | 276 | warn("%s free() ignored", |
8990e307 LW |
277 | op->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad"); |
278 | #else | |
279 | warn("Bad free() ignored"); | |
280 | #endif | |
8d063cd8 | 281 | return; /* sanity */ |
378cc40b | 282 | } |
8d063cd8 LW |
283 | #endif |
284 | #ifdef RCHECK | |
285 | ASSERT(op->ov_rmagic == RMAGIC); | |
286 | if (op->ov_index <= 13) | |
287 | ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC); | |
8990e307 | 288 | op->ov_rmagic = RMAGIC - 1; |
8d063cd8 LW |
289 | #endif |
290 | ASSERT(op->ov_index < NBUCKETS); | |
291 | size = op->ov_index; | |
292 | op->ov_next = nextf[size]; | |
293 | nextf[size] = op; | |
c07a80fd | 294 | #ifdef DEBUGGING_MSTATS |
8d063cd8 LW |
295 | nmalloc[size]--; |
296 | #endif | |
297 | } | |
298 | ||
299 | /* | |
300 | * When a program attempts "storage compaction" as mentioned in the | |
301 | * old malloc man page, it realloc's an already freed block. Usually | |
302 | * this is the last block it freed; occasionally it might be farther | |
303 | * back. We have to search all the free lists for the block in order | |
304 | * to determine its bucket: 1st we make one pass thru the lists | |
305 | * checking only the first block in each; if that fails we search | |
378cc40b | 306 | * ``reall_srchlen'' blocks in each list for a match (the variable |
8d063cd8 LW |
307 | * is extern so the caller can modify it). If that fails we just copy |
308 | * however many bytes was given to realloc() and hope it's not huge. | |
309 | */ | |
378cc40b | 310 | int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ |
8d063cd8 | 311 | |
2304df62 | 312 | Malloc_t |
352d5a3a | 313 | realloc(mp, nbytes) |
2304df62 | 314 | Malloc_t mp; |
ee0007ab | 315 | MEM_SIZE nbytes; |
8d063cd8 | 316 | { |
ee0007ab | 317 | register MEM_SIZE onb; |
8d063cd8 LW |
318 | union overhead *op; |
319 | char *res; | |
320 | register int i; | |
321 | int was_alloced = 0; | |
352d5a3a | 322 | char *cp = (char*)mp; |
8d063cd8 | 323 | |
45d8adaa LW |
324 | #ifdef safemalloc |
325 | #ifdef DEBUGGING | |
ee0007ab | 326 | MEM_SIZE size = nbytes; |
45d8adaa LW |
327 | #endif |
328 | ||
329 | #ifdef MSDOS | |
330 | if (nbytes > 0xffff) { | |
331 | fprintf(stderr, "Reallocation too large: %lx\n", size); | |
79072805 | 332 | my_exit(1); |
45d8adaa LW |
333 | } |
334 | #endif /* MSDOS */ | |
335 | if (!cp) | |
ee0007ab | 336 | return malloc(nbytes); |
45d8adaa LW |
337 | #ifdef DEBUGGING |
338 | if ((long)nbytes < 0) | |
463ee0b2 | 339 | croak("panic: realloc"); |
45d8adaa LW |
340 | #endif |
341 | #endif /* safemalloc */ | |
342 | ||
8d063cd8 LW |
343 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
344 | if (op->ov_magic == MAGIC) { | |
345 | was_alloced++; | |
346 | i = op->ov_index; | |
347 | } else { | |
348 | /* | |
349 | * Already free, doing "compaction". | |
350 | * | |
351 | * Search for the old block of memory on the | |
352 | * free list. First, check the most common | |
353 | * case (last element free'd), then (this failing) | |
378cc40b | 354 | * the last ``reall_srchlen'' items free'd. |
8d063cd8 LW |
355 | * If all lookups fail, then assume the size of |
356 | * the memory block being realloc'd is the | |
357 | * smallest possible. | |
358 | */ | |
359 | if ((i = findbucket(op, 1)) < 0 && | |
378cc40b | 360 | (i = findbucket(op, reall_srchlen)) < 0) |
8d063cd8 LW |
361 | i = 0; |
362 | } | |
ee0007ab | 363 | onb = (1L << (i + 3)) - sizeof (*op) - RSLOP; |
8d063cd8 LW |
364 | /* avoid the copy if same size block */ |
365 | if (was_alloced && | |
a687059c LW |
366 | nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) { |
367 | #ifdef RCHECK | |
368 | /* | |
369 | * Record new allocated size of block and | |
370 | * bound space with magic numbers. | |
371 | */ | |
372 | if (op->ov_index <= 13) { | |
373 | /* | |
374 | * Convert amount of memory requested into | |
375 | * closest block size stored in hash buckets | |
376 | * which satisfies request. Account for | |
377 | * space used per block for accounting. | |
378 | */ | |
379 | nbytes += sizeof (union overhead) + RSLOP; | |
380 | nbytes = (nbytes + 3) &~ 3; | |
381 | op->ov_size = nbytes - 1; | |
382 | *((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC; | |
383 | } | |
384 | #endif | |
45d8adaa | 385 | res = cp; |
a687059c | 386 | } |
45d8adaa LW |
387 | else { |
388 | if ((res = (char*)malloc(nbytes)) == NULL) | |
389 | return (NULL); | |
390 | if (cp != res) /* common optimization */ | |
ee0007ab | 391 | Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char); |
45d8adaa LW |
392 | if (was_alloced) |
393 | free(cp); | |
394 | } | |
395 | ||
396 | #ifdef safemalloc | |
397 | #ifdef DEBUGGING | |
a0d0e21e LW |
398 | if (debug & 128) { |
399 | fprintf(stderr,"0x%lx: (%05d) rfree\n",(unsigned long)res,an++); | |
400 | fprintf(stderr,"0x%lx: (%05d) realloc %ld bytes\n", | |
401 | (unsigned long)res,an++,(long)size); | |
402 | } | |
45d8adaa LW |
403 | #endif |
404 | #endif /* safemalloc */ | |
2304df62 | 405 | return ((Malloc_t)res); |
8d063cd8 LW |
406 | } |
407 | ||
408 | /* | |
409 | * Search ``srchlen'' elements of each free list for a block whose | |
410 | * header starts at ``freep''. If srchlen is -1 search the whole list. | |
411 | * Return bucket number, or -1 if not found. | |
412 | */ | |
ee0007ab | 413 | static int |
8d063cd8 LW |
414 | findbucket(freep, srchlen) |
415 | union overhead *freep; | |
416 | int srchlen; | |
417 | { | |
418 | register union overhead *p; | |
419 | register int i, j; | |
420 | ||
421 | for (i = 0; i < NBUCKETS; i++) { | |
422 | j = 0; | |
423 | for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { | |
424 | if (p == freep) | |
425 | return (i); | |
426 | j++; | |
427 | } | |
428 | } | |
429 | return (-1); | |
430 | } | |
431 | ||
c07a80fd | 432 | #ifdef DEBUGGING_MSTATS |
8d063cd8 LW |
433 | /* |
434 | * mstats - print out statistics about malloc | |
435 | * | |
436 | * Prints two lines of numbers, one showing the length of the free list | |
437 | * for each size category, the second showing the number of mallocs - | |
438 | * frees for each size category. | |
439 | */ | |
ee0007ab | 440 | void |
c07a80fd | 441 | dump_mstats(s) |
8d063cd8 LW |
442 | char *s; |
443 | { | |
444 | register int i, j; | |
445 | register union overhead *p; | |
c07a80fd | 446 | int topbucket=0, totfree=0, totused=0; |
447 | u_int nfree[NBUCKETS]; | |
8d063cd8 | 448 | |
c07a80fd | 449 | for (i=0; i < NBUCKETS; i++) { |
8d063cd8 LW |
450 | for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) |
451 | ; | |
c07a80fd | 452 | nfree[i] = j; |
453 | totfree += nfree[i] * (1 << (i + 3)); | |
8d063cd8 | 454 | totused += nmalloc[i] * (1 << (i + 3)); |
c07a80fd | 455 | if (nfree[i] || nmalloc[i]) |
456 | topbucket = i; | |
457 | } | |
458 | if (s) | |
459 | fprintf(stderr, "Memory allocation statistics %s (buckets 8..%d)\n", | |
460 | s, (1 << (topbucket + 3)) ); | |
461 | fprintf(stderr, " %7d free: ", totfree); | |
462 | for (i=0; i <= topbucket; i++) { | |
463 | fprintf(stderr, (i<5)?" %5d":" %3d", nfree[i]); | |
8d063cd8 | 464 | } |
c07a80fd | 465 | fprintf(stderr, "\n %7d used: ", totused); |
466 | for (i=0; i <= topbucket; i++) { | |
467 | fprintf(stderr, (i<5)?" %5d":" %3d", nmalloc[i]); | |
468 | } | |
469 | fprintf(stderr, "\n"); | |
470 | } | |
471 | #else | |
472 | void | |
473 | dump_mstats(s) | |
474 | char *s; | |
475 | { | |
8d063cd8 LW |
476 | } |
477 | #endif | |
a687059c | 478 | #endif /* lint */ |