Commit | Line | Data |
a0d0e21e |
1 | /* malloc.c |
8d063cd8 |
2 | * |
8d063cd8 |
3 | */ |
4 | |
5 | #ifndef lint |
a687059c |
6 | #ifdef DEBUGGING |
8d063cd8 |
7 | #define RCHECK |
a687059c |
8 | #endif |
8d063cd8 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
107 | { |
108 | register union overhead *p; |
109 | register int bucket = 0; |
ee0007ab |
110 | register MEM_SIZE shiftr; |
8d063cd8 |
111 | |
45d8adaa |
112 | #ifdef safemalloc |
113 | #ifdef DEBUGGING |
ee0007ab |
114 | MEM_SIZE size = nbytes; |
45d8adaa |
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 |
121 | } |
122 | #endif /* MSDOS */ |
123 | #ifdef DEBUGGING |
124 | if ((long)nbytes < 0) |
463ee0b2 |
125 | croak("panic: malloc"); |
45d8adaa |
126 | #endif |
127 | #endif /* safemalloc */ |
128 | |
11343788 |
129 | MUTEX_LOCK(&malloc_mutex); |
8d063cd8 |
130 | /* |
131 | * Convert amount of memory requested into |
132 | * closest block size stored in hash buckets |
133 | * which satisfies request. Account for |
134 | * space used per block for accounting. |
135 | */ |
136 | nbytes += sizeof (union overhead) + RSLOP; |
137 | nbytes = (nbytes + 3) &~ 3; |
138 | shiftr = (nbytes - 1) >> 2; |
139 | /* apart from this loop, this is O(1) */ |
140 | while (shiftr >>= 1) |
141 | bucket++; |
142 | /* |
143 | * If nothing in hash bucket right now, |
144 | * request more memory from the system. |
145 | */ |
146 | if (nextf[bucket] == NULL) |
147 | morecore(bucket); |
45d8adaa |
148 | if ((p = (union overhead *)nextf[bucket]) == NULL) { |
11343788 |
149 | MUTEX_UNLOCK(&malloc_mutex); |
45d8adaa |
150 | #ifdef safemalloc |
ee0007ab |
151 | if (!nomemok) { |
152 | fputs("Out of memory!\n", stderr); |
79072805 |
153 | my_exit(1); |
ee0007ab |
154 | } |
45d8adaa |
155 | #else |
8d063cd8 |
156 | return (NULL); |
45d8adaa |
157 | #endif |
158 | } |
159 | |
160 | #ifdef safemalloc |
a0d0e21e |
161 | DEBUG_m(fprintf(stderr,"0x%lx: (%05d) malloc %ld bytes\n", |
162 | (unsigned long)(p+1),an++,(long)size)); |
45d8adaa |
163 | #endif /* safemalloc */ |
164 | |
8d063cd8 |
165 | /* remove from linked list */ |
bf38876a |
166 | #ifdef RCHECK |
167 | if (*((int*)p) & (sizeof(union overhead) - 1)) |
a0d0e21e |
168 | fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n", |
169 | (unsigned long)*((int*)p),(unsigned long)p); |
bf38876a |
170 | #endif |
171 | nextf[bucket] = p->ov_next; |
8d063cd8 |
172 | p->ov_magic = MAGIC; |
173 | p->ov_index= bucket; |
c07a80fd |
174 | #ifdef DEBUGGING_MSTATS |
8d063cd8 |
175 | nmalloc[bucket]++; |
176 | #endif |
177 | #ifdef RCHECK |
178 | /* |
179 | * Record allocated size of block and |
180 | * bound space with magic numbers. |
181 | */ |
182 | if (nbytes <= 0x10000) |
183 | p->ov_size = nbytes - 1; |
184 | p->ov_rmagic = RMAGIC; |
185 | *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC; |
186 | #endif |
11343788 |
187 | MUTEX_UNLOCK(&malloc_mutex); |
2304df62 |
188 | return ((Malloc_t)(p + 1)); |
8d063cd8 |
189 | } |
190 | |
191 | /* |
192 | * Allocate more memory to the indicated bucket. |
193 | */ |
a0d0e21e |
194 | static void |
8d063cd8 |
195 | morecore(bucket) |
a687059c |
196 | register int bucket; |
8d063cd8 |
197 | { |
198 | register union overhead *op; |
199 | register int rnu; /* 2^rnu bytes will be requested */ |
200 | register int nblks; /* become nblks blocks of the desired size */ |
ee0007ab |
201 | register MEM_SIZE siz; |
8d063cd8 |
202 | |
203 | if (nextf[bucket]) |
204 | return; |
205 | /* |
206 | * Insure memory is allocated |
207 | * on a page boundary. Should |
208 | * make getpageize call? |
209 | */ |
ee0007ab |
210 | #ifndef atarist /* on the atari we dont have to worry about this */ |
8d063cd8 |
211 | op = (union overhead *)sbrk(0); |
a687059c |
212 | #ifndef I286 |
8d063cd8 |
213 | if ((int)op & 0x3ff) |
a687059c |
214 | (void)sbrk(1024 - ((int)op & 0x3ff)); |
215 | #else |
216 | /* The sbrk(0) call on the I286 always returns the next segment */ |
217 | #endif |
ee0007ab |
218 | #endif /* atarist */ |
a687059c |
219 | |
ee0007ab |
220 | #if !(defined(I286) || defined(atarist)) |
8d063cd8 |
221 | /* take 2k unless the block is bigger than that */ |
222 | rnu = (bucket <= 8) ? 11 : bucket + 3; |
a687059c |
223 | #else |
224 | /* take 16k unless the block is bigger than that |
ee0007ab |
225 | (80286s like large segments!), probably good on the atari too */ |
a687059c |
226 | rnu = (bucket <= 11) ? 14 : bucket + 3; |
227 | #endif |
8d063cd8 |
228 | nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */ |
229 | if (rnu < bucket) |
230 | rnu = bucket; |
ee0007ab |
231 | op = (union overhead *)sbrk(1L << rnu); |
8d063cd8 |
232 | /* no more room! */ |
233 | if ((int)op == -1) |
234 | return; |
235 | /* |
236 | * Round up to minimum allocation size boundary |
237 | * and deduct from block count to reflect. |
238 | */ |
a687059c |
239 | #ifndef I286 |
8d063cd8 |
240 | if ((int)op & 7) { |
ee0007ab |
241 | op = (union overhead *)(((MEM_SIZE)op + 8) &~ 7); |
8d063cd8 |
242 | nblks--; |
243 | } |
a687059c |
244 | #else |
245 | /* Again, this should always be ok on an 80286 */ |
246 | #endif |
8d063cd8 |
247 | /* |
248 | * Add new memory allocated to that on |
249 | * free list for this hash bucket. |
250 | */ |
251 | nextf[bucket] = op; |
252 | siz = 1 << (bucket + 3); |
253 | while (--nblks > 0) { |
254 | op->ov_next = (union overhead *)((caddr_t)op + siz); |
255 | op = (union overhead *)((caddr_t)op + siz); |
256 | } |
257 | } |
258 | |
94b6baf5 |
259 | Free_t |
352d5a3a |
260 | free(mp) |
2304df62 |
261 | Malloc_t mp; |
8d063cd8 |
262 | { |
ee0007ab |
263 | register MEM_SIZE size; |
8d063cd8 |
264 | register union overhead *op; |
352d5a3a |
265 | char *cp = (char*)mp; |
8d063cd8 |
266 | |
45d8adaa |
267 | #ifdef safemalloc |
a0d0e21e |
268 | DEBUG_m(fprintf(stderr,"0x%lx: (%05d) free\n",(unsigned long)cp,an++)); |
45d8adaa |
269 | #endif /* safemalloc */ |
270 | |
8d063cd8 |
271 | if (cp == NULL) |
272 | return; |
273 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
274 | #ifdef debug |
275 | ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ |
276 | #else |
378cc40b |
277 | if (op->ov_magic != MAGIC) { |
8990e307 |
278 | #ifdef RCHECK |
a687059c |
279 | warn("%s free() ignored", |
8990e307 |
280 | op->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad"); |
281 | #else |
282 | warn("Bad free() ignored"); |
283 | #endif |
8d063cd8 |
284 | return; /* sanity */ |
378cc40b |
285 | } |
8d063cd8 |
286 | #endif |
11343788 |
287 | MUTEX_LOCK(&malloc_mutex); |
8d063cd8 |
288 | #ifdef RCHECK |
289 | ASSERT(op->ov_rmagic == RMAGIC); |
290 | if (op->ov_index <= 13) |
291 | ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC); |
8990e307 |
292 | op->ov_rmagic = RMAGIC - 1; |
8d063cd8 |
293 | #endif |
294 | ASSERT(op->ov_index < NBUCKETS); |
295 | size = op->ov_index; |
296 | op->ov_next = nextf[size]; |
297 | nextf[size] = op; |
c07a80fd |
298 | #ifdef DEBUGGING_MSTATS |
8d063cd8 |
299 | nmalloc[size]--; |
300 | #endif |
11343788 |
301 | MUTEX_UNLOCK(&malloc_mutex); |
8d063cd8 |
302 | } |
303 | |
304 | /* |
305 | * When a program attempts "storage compaction" as mentioned in the |
306 | * old malloc man page, it realloc's an already freed block. Usually |
307 | * this is the last block it freed; occasionally it might be farther |
308 | * back. We have to search all the free lists for the block in order |
309 | * to determine its bucket: 1st we make one pass thru the lists |
310 | * checking only the first block in each; if that fails we search |
378cc40b |
311 | * ``reall_srchlen'' blocks in each list for a match (the variable |
8d063cd8 |
312 | * is extern so the caller can modify it). If that fails we just copy |
313 | * however many bytes was given to realloc() and hope it's not huge. |
314 | */ |
378cc40b |
315 | int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ |
8d063cd8 |
316 | |
2304df62 |
317 | Malloc_t |
352d5a3a |
318 | realloc(mp, nbytes) |
2304df62 |
319 | Malloc_t mp; |
ee0007ab |
320 | MEM_SIZE nbytes; |
8d063cd8 |
321 | { |
ee0007ab |
322 | register MEM_SIZE onb; |
8d063cd8 |
323 | union overhead *op; |
324 | char *res; |
325 | register int i; |
326 | int was_alloced = 0; |
352d5a3a |
327 | char *cp = (char*)mp; |
8d063cd8 |
328 | |
45d8adaa |
329 | #ifdef safemalloc |
330 | #ifdef DEBUGGING |
ee0007ab |
331 | MEM_SIZE size = nbytes; |
45d8adaa |
332 | #endif |
333 | |
334 | #ifdef MSDOS |
335 | if (nbytes > 0xffff) { |
336 | fprintf(stderr, "Reallocation too large: %lx\n", size); |
79072805 |
337 | my_exit(1); |
45d8adaa |
338 | } |
339 | #endif /* MSDOS */ |
340 | if (!cp) |
ee0007ab |
341 | return malloc(nbytes); |
45d8adaa |
342 | #ifdef DEBUGGING |
343 | if ((long)nbytes < 0) |
463ee0b2 |
344 | croak("panic: realloc"); |
45d8adaa |
345 | #endif |
346 | #endif /* safemalloc */ |
347 | |
11343788 |
348 | MUTEX_LOCK(&malloc_mutex); |
8d063cd8 |
349 | op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); |
350 | if (op->ov_magic == MAGIC) { |
351 | was_alloced++; |
352 | i = op->ov_index; |
353 | } else { |
354 | /* |
355 | * Already free, doing "compaction". |
356 | * |
357 | * Search for the old block of memory on the |
358 | * free list. First, check the most common |
359 | * case (last element free'd), then (this failing) |
378cc40b |
360 | * the last ``reall_srchlen'' items free'd. |
8d063cd8 |
361 | * If all lookups fail, then assume the size of |
362 | * the memory block being realloc'd is the |
363 | * smallest possible. |
364 | */ |
365 | if ((i = findbucket(op, 1)) < 0 && |
378cc40b |
366 | (i = findbucket(op, reall_srchlen)) < 0) |
8d063cd8 |
367 | i = 0; |
368 | } |
ee0007ab |
369 | onb = (1L << (i + 3)) - sizeof (*op) - RSLOP; |
8d063cd8 |
370 | /* avoid the copy if same size block */ |
371 | if (was_alloced && |
a687059c |
372 | nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) { |
373 | #ifdef RCHECK |
374 | /* |
375 | * Record new allocated size of block and |
376 | * bound space with magic numbers. |
377 | */ |
378 | if (op->ov_index <= 13) { |
379 | /* |
380 | * Convert amount of memory requested into |
381 | * closest block size stored in hash buckets |
382 | * which satisfies request. Account for |
383 | * space used per block for accounting. |
384 | */ |
385 | nbytes += sizeof (union overhead) + RSLOP; |
386 | nbytes = (nbytes + 3) &~ 3; |
387 | op->ov_size = nbytes - 1; |
388 | *((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC; |
389 | } |
390 | #endif |
45d8adaa |
391 | res = cp; |
11343788 |
392 | MUTEX_UNLOCK(&malloc_mutex); |
a687059c |
393 | } |
45d8adaa |
394 | else { |
11343788 |
395 | MUTEX_UNLOCK(&malloc_mutex); |
45d8adaa |
396 | if ((res = (char*)malloc(nbytes)) == NULL) |
397 | return (NULL); |
398 | if (cp != res) /* common optimization */ |
ee0007ab |
399 | Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char); |
45d8adaa |
400 | if (was_alloced) |
401 | free(cp); |
402 | } |
403 | |
404 | #ifdef safemalloc |
405 | #ifdef DEBUGGING |
a0d0e21e |
406 | if (debug & 128) { |
407 | fprintf(stderr,"0x%lx: (%05d) rfree\n",(unsigned long)res,an++); |
408 | fprintf(stderr,"0x%lx: (%05d) realloc %ld bytes\n", |
409 | (unsigned long)res,an++,(long)size); |
410 | } |
45d8adaa |
411 | #endif |
412 | #endif /* safemalloc */ |
2304df62 |
413 | return ((Malloc_t)res); |
8d063cd8 |
414 | } |
415 | |
416 | /* |
417 | * Search ``srchlen'' elements of each free list for a block whose |
418 | * header starts at ``freep''. If srchlen is -1 search the whole list. |
419 | * Return bucket number, or -1 if not found. |
420 | */ |
ee0007ab |
421 | static int |
8d063cd8 |
422 | findbucket(freep, srchlen) |
423 | union overhead *freep; |
424 | int srchlen; |
425 | { |
426 | register union overhead *p; |
427 | register int i, j; |
428 | |
429 | for (i = 0; i < NBUCKETS; i++) { |
430 | j = 0; |
431 | for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { |
432 | if (p == freep) |
433 | return (i); |
434 | j++; |
435 | } |
436 | } |
437 | return (-1); |
438 | } |
439 | |
c07a80fd |
440 | #ifdef DEBUGGING_MSTATS |
8d063cd8 |
441 | /* |
442 | * mstats - print out statistics about malloc |
443 | * |
444 | * Prints two lines of numbers, one showing the length of the free list |
445 | * for each size category, the second showing the number of mallocs - |
446 | * frees for each size category. |
447 | */ |
ee0007ab |
448 | void |
c07a80fd |
449 | dump_mstats(s) |
8d063cd8 |
450 | char *s; |
451 | { |
452 | register int i, j; |
453 | register union overhead *p; |
c07a80fd |
454 | int topbucket=0, totfree=0, totused=0; |
455 | u_int nfree[NBUCKETS]; |
8d063cd8 |
456 | |
c07a80fd |
457 | for (i=0; i < NBUCKETS; i++) { |
8d063cd8 |
458 | for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) |
459 | ; |
c07a80fd |
460 | nfree[i] = j; |
461 | totfree += nfree[i] * (1 << (i + 3)); |
8d063cd8 |
462 | totused += nmalloc[i] * (1 << (i + 3)); |
c07a80fd |
463 | if (nfree[i] || nmalloc[i]) |
464 | topbucket = i; |
465 | } |
466 | if (s) |
467 | fprintf(stderr, "Memory allocation statistics %s (buckets 8..%d)\n", |
468 | s, (1 << (topbucket + 3)) ); |
469 | fprintf(stderr, " %7d free: ", totfree); |
470 | for (i=0; i <= topbucket; i++) { |
471 | fprintf(stderr, (i<5)?" %5d":" %3d", nfree[i]); |
8d063cd8 |
472 | } |
c07a80fd |
473 | fprintf(stderr, "\n %7d used: ", totused); |
474 | for (i=0; i <= topbucket; i++) { |
475 | fprintf(stderr, (i<5)?" %5d":" %3d", nmalloc[i]); |
476 | } |
477 | fprintf(stderr, "\n"); |
478 | } |
479 | #else |
480 | void |
481 | dump_mstats(s) |
482 | char *s; |
483 | { |
8d063cd8 |
484 | } |
485 | #endif |
a687059c |
486 | #endif /* lint */ |