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1 | /* $RCSfile: malloc.c,v $$Revision: 4.0.1.3 $$Date: 91/11/05 17:57:40 $ |
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2 | * |
3 | * $Log: malloc.c,v $ |
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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 | * |
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7 | * Revision 4.0.1.2 91/06/07 11:20:45 lwall |
8 | * patch4: many, many itty-bitty portability fixes |
9 | * |
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10 | * Revision 4.0.1.1 91/04/11 17:48:31 lwall |
11 | * patch1: Configure now figures out malloc ptr type |
12 | * |
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13 | * Revision 4.0 91/03/20 01:28:52 lwall |
14 | * 4.0 baseline. |
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15 | * |
16 | */ |
17 | |
18 | #ifndef lint |
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19 | /*SUPPRESS 592*/ |
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20 | static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83"; |
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21 | |
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22 | #ifdef DEBUGGING |
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23 | #define RCHECK |
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24 | #endif |
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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 | |
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37 | #include "EXTERN.h" |
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38 | #include "perl.h" |
39 | |
03a14243 |
40 | static findbucket(), morecore(); |
41 | |
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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 |
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47 | |
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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 */ |
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61 | #endif |
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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 */ |
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77 | #define OLDMAGIC 0x7f /* same after a free() */ |
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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 | |
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117 | #ifdef safemalloc |
118 | static int an = 0; |
119 | #endif |
120 | |
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121 | MALLOCPTRTYPE * |
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122 | malloc(nbytes) |
123 | register unsigned nbytes; |
124 | { |
125 | register union overhead *p; |
126 | register int bucket = 0; |
127 | register unsigned shiftr; |
128 | |
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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 | |
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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); |
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164 | if ((p = (union overhead *)nextf[bucket]) == NULL) { |
165 | #ifdef safemalloc |
166 | fputs("Out of memory!\n", stderr); |
167 | exit(1); |
168 | #else |
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169 | return (NULL); |
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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 | |
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185 | /* remove from linked list */ |
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186 | #ifdef RCHECK |
187 | if (*((int*)p) & (sizeof(union overhead) - 1)) |
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188 | #ifndef I286 |
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189 | fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",*((int*)p),p); |
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190 | #else |
191 | fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n",*((int*)p),p); |
192 | #endif |
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193 | #endif |
194 | nextf[bucket] = p->ov_next; |
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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 |
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210 | return ((MALLOCPTRTYPE *)(p + 1)); |
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211 | } |
212 | |
213 | /* |
214 | * Allocate more memory to the indicated bucket. |
215 | */ |
216 | static |
217 | morecore(bucket) |
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218 | register int bucket; |
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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); |
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233 | #ifndef I286 |
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234 | if ((int)op & 0x3ff) |
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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 |
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241 | /* take 2k unless the block is bigger than that */ |
242 | rnu = (bucket <= 8) ? 11 : bucket + 3; |
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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 |
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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 | */ |
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259 | #ifndef I286 |
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260 | if ((int)op & 7) { |
261 | op = (union overhead *)(((int)op + 8) &~ 7); |
262 | nblks--; |
263 | } |
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264 | #else |
265 | /* Again, this should always be ok on an 80286 */ |
266 | #endif |
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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 |
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280 | free(mp) |
281 | MALLOCPTRTYPE *mp; |
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282 | { |
283 | register int size; |
284 | register union overhead *op; |
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285 | char *cp = (char*)mp; |
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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 |
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305 | if (op->ov_magic != MAGIC) { |
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306 | warn("%s free() ignored", |
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307 | op->ov_magic == OLDMAGIC ? "Duplicate" : "Bad"); |
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308 | return; /* sanity */ |
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309 | } |
310 | op->ov_magic = OLDMAGIC; |
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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 |
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333 | * ``reall_srchlen'' blocks in each list for a match (the variable |
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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 | */ |
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337 | int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ |
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338 | |
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339 | MALLOCPTRTYPE * |
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340 | realloc(mp, nbytes) |
341 | MALLOCPTRTYPE *mp; |
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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; |
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349 | char *cp = (char*)mp; |
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350 | |
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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 | |
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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. |
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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 && |
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389 | (i = findbucket(op, reall_srchlen)) < 0) |
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390 | i = 0; |
391 | } |
392 | onb = (1 << (i + 3)) - sizeof (*op) - RSLOP; |
393 | /* avoid the copy if same size block */ |
394 | if (was_alloced && |
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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 |
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414 | res = cp; |
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415 | } |
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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 */ |