libm & rtld: Ansify some remaining functions.
[dragonfly.git] / libexec / rtld-elf / malloc.c
CommitLineData
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1/*-
2 * Copyright (c) 1983 Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
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34/*
35 * malloc.c (Caltech) 2/21/82
36 * Chris Kingsley, kingsley@cit-20.
37 *
38 * This is a very fast storage allocator. It allocates blocks of a small
39 * number of different sizes, and keeps free lists of each size. Blocks that
40 * don't exactly fit are passed up to the next larger size. In this
41 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long.
42 * This is designed for use in a virtual memory environment.
43 */
44
45#include <sys/types.h>
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46#include <paths.h>
47#include <stdarg.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <string.h>
51#include <unistd.h>
52#include <sys/param.h>
53#include <sys/mman.h>
abfcd5b1 54#include "rtld_printf.h"
984263bc 55
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56static void morecore();
57static int findbucket();
58
59/*
60 * Pre-allocate mmap'ed pages
61 */
62#define NPOOLPAGES (32*1024/pagesz)
63static caddr_t pagepool_start, pagepool_end;
64static int morepages();
65
66/*
67 * The overhead on a block is at least 4 bytes. When free, this space
68 * contains a pointer to the next free block, and the bottom two bits must
69 * be zero. When in use, the first byte is set to MAGIC, and the second
70 * byte is the size index. The remaining bytes are for alignment.
71 * If range checking is enabled then a second word holds the size of the
72 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
73 * The order of elements is critical: ov_magic must overlay the low order
74 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
75 */
76union overhead {
77 union overhead *ov_next; /* when free */
78 struct {
79 u_char ovu_magic; /* magic number */
80 u_char ovu_index; /* bucket # */
81#ifdef RCHECK
82 u_short ovu_rmagic; /* range magic number */
83 u_int ovu_size; /* actual block size */
84#endif
85 } ovu;
86#define ov_magic ovu.ovu_magic
87#define ov_index ovu.ovu_index
88#define ov_rmagic ovu.ovu_rmagic
89#define ov_size ovu.ovu_size
90};
91
92#define MAGIC 0xef /* magic # on accounting info */
93#define RMAGIC 0x5555 /* magic # on range info */
94
95#ifdef RCHECK
96#define RSLOP sizeof (u_short)
97#else
98#define RSLOP 0
99#endif
100
101/*
102 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
103 * smallest allocatable block is 8 bytes. The overhead information
104 * precedes the data area returned to the user.
105 */
106#define NBUCKETS 30
107static union overhead *nextf[NBUCKETS];
108
109static int pagesz; /* page size */
110static int pagebucket; /* page size bucket */
111
112#ifdef MSTATS
113/*
114 * nmalloc[i] is the difference between the number of mallocs and frees
115 * for a given block size.
116 */
117static u_int nmalloc[NBUCKETS];
118#include <stdio.h>
119#endif
120
121#if defined(MALLOC_DEBUG) || defined(RCHECK)
122#define ASSERT(p) if (!(p)) botch("p")
123#include <stdio.h>
124static void
472de6d1 125botch(char *s)
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126{
127 fprintf(stderr, "\r\nassertion botched: %s\r\n", s);
128 (void) fflush(stderr); /* just in case user buffered it */
129 abort();
130}
131#else
132#define ASSERT(p)
133#endif
134
135/* Debugging stuff */
abfcd5b1 136#define TRACE() rtld_printf("TRACE %s:%d\n", __FILE__, __LINE__)
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137
138void *
472de6d1 139malloc(size_t nbytes)
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140{
141 register union overhead *op;
142 register int bucket;
143 register long n;
144 register unsigned amt;
145
146 /*
147 * First time malloc is called, setup page size and
148 * align break pointer so all data will be page aligned.
149 */
150 if (pagesz == 0) {
151 pagesz = n = getpagesize();
152 if (morepages(NPOOLPAGES) == 0)
153 return NULL;
154 op = (union overhead *)(pagepool_start);
155 n = n - sizeof (*op) - ((long)op & (n - 1));
156 if (n < 0)
157 n += pagesz;
158 if (n) {
159 pagepool_start += n;
160 }
161 bucket = 0;
162 amt = 8;
fcf53d9b 163 while ((unsigned)pagesz > amt) {
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164 amt <<= 1;
165 bucket++;
166 }
167 pagebucket = bucket;
168 }
169 /*
170 * Convert amount of memory requested into closest block size
171 * stored in hash buckets which satisfies request.
172 * Account for space used per block for accounting.
173 */
fcf53d9b 174 if (nbytes <= (unsigned long)(n = pagesz - sizeof (*op) - RSLOP)) {
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175#ifndef RCHECK
176 amt = 8; /* size of first bucket */
177 bucket = 0;
178#else
179 amt = 16; /* size of first bucket */
180 bucket = 1;
181#endif
182 n = -(sizeof (*op) + RSLOP);
183 } else {
184 amt = pagesz;
185 bucket = pagebucket;
186 }
187 while (nbytes > amt + n) {
188 amt <<= 1;
189 if (amt == 0)
190 return (NULL);
191 bucket++;
192 }
193 /*
194 * If nothing in hash bucket right now,
195 * request more memory from the system.
196 */
197 if ((op = nextf[bucket]) == NULL) {
198 morecore(bucket);
199 if ((op = nextf[bucket]) == NULL)
200 return (NULL);
201 }
202 /* remove from linked list */
203 nextf[bucket] = op->ov_next;
204 op->ov_magic = MAGIC;
205 op->ov_index = bucket;
206#ifdef MSTATS
207 nmalloc[bucket]++;
208#endif
209#ifdef RCHECK
210 /*
211 * Record allocated size of block and
212 * bound space with magic numbers.
213 */
214 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
215 op->ov_rmagic = RMAGIC;
216 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
217#endif
218 return ((char *)(op + 1));
219}
220
221/*
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222 * Used by rtld.c, if we don't override it here the calloc from
223 * libc may try to pull in the malloc/realloc/free from libc too.
224 */
225void *
226calloc(size_t num, size_t size)
227{
228 void *p;
229
230 size *= num;
231 if ((p = malloc(size)) != NULL)
232 bzero(p, size);
233 return(p);
234}
235
236/*
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237 * Allocate more memory to the indicated bucket.
238 */
239static void
472de6d1 240morecore(int bucket)
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241{
242 register union overhead *op;
243 register int sz; /* size of desired block */
244 int amt; /* amount to allocate */
245 int nblks; /* how many blocks we get */
246
247 /*
248 * sbrk_size <= 0 only for big, FLUFFY, requests (about
249 * 2^30 bytes on a VAX, I think) or for a negative arg.
250 */
251 sz = 1 << (bucket + 3);
252#ifdef MALLOC_DEBUG
253 ASSERT(sz > 0);
254#else
255 if (sz <= 0)
256 return;
257#endif
258 if (sz < pagesz) {
259 amt = pagesz;
260 nblks = amt / sz;
261 } else {
262 amt = sz + pagesz;
263 nblks = 1;
264 }
265 if (amt > pagepool_end - pagepool_start)
266 if (morepages(amt/pagesz + NPOOLPAGES) == 0)
267 return;
268 op = (union overhead *)pagepool_start;
269 pagepool_start += amt;
270
271 /*
272 * Add new memory allocated to that on
273 * free list for this hash bucket.
274 */
275 nextf[bucket] = op;
276 while (--nblks > 0) {
277 op->ov_next = (union overhead *)((caddr_t)op + sz);
278 op = (union overhead *)((caddr_t)op + sz);
279 }
280}
281
282void
472de6d1 283free(void *cp)
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284{
285 register int size;
286 register union overhead *op;
287
288 if (cp == NULL)
289 return;
290 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
291#ifdef MALLOC_DEBUG
292 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
293#else
294 if (op->ov_magic != MAGIC)
295 return; /* sanity */
296#endif
297#ifdef RCHECK
298 ASSERT(op->ov_rmagic == RMAGIC);
299 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
300#endif
301 size = op->ov_index;
302 ASSERT(size < NBUCKETS);
303 op->ov_next = nextf[size]; /* also clobbers ov_magic */
304 nextf[size] = op;
305#ifdef MSTATS
306 nmalloc[size]--;
307#endif
308}
309
310/*
311 * When a program attempts "storage compaction" as mentioned in the
312 * old malloc man page, it realloc's an already freed block. Usually
313 * this is the last block it freed; occasionally it might be farther
314 * back. We have to search all the free lists for the block in order
315 * to determine its bucket: 1st we make one pass thru the lists
316 * checking only the first block in each; if that fails we search
317 * ``realloc_srchlen'' blocks in each list for a match (the variable
318 * is extern so the caller can modify it). If that fails we just copy
319 * however many bytes was given to realloc() and hope it's not huge.
320 */
321int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
322
323void *
472de6d1 324realloc(void *cp, size_t nbytes)
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325{
326 register u_int onb;
327 register int i;
328 union overhead *op;
329 char *res;
330 int was_alloced = 0;
331
332 if (cp == NULL)
333 return (malloc(nbytes));
334 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
335 if (op->ov_magic == MAGIC) {
336 was_alloced++;
337 i = op->ov_index;
338 } else {
339 /*
340 * Already free, doing "compaction".
341 *
342 * Search for the old block of memory on the
343 * free list. First, check the most common
344 * case (last element free'd), then (this failing)
345 * the last ``realloc_srchlen'' items free'd.
346 * If all lookups fail, then assume the size of
347 * the memory block being realloc'd is the
348 * largest possible (so that all "nbytes" of new
349 * memory are copied into). Note that this could cause
350 * a memory fault if the old area was tiny, and the moon
351 * is gibbous. However, that is very unlikely.
352 */
353 if ((i = findbucket(op, 1)) < 0 &&
354 (i = findbucket(op, realloc_srchlen)) < 0)
355 i = NBUCKETS;
356 }
357 onb = 1 << (i + 3);
fcf53d9b 358 if (onb < (u_int)pagesz)
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359 onb -= sizeof (*op) + RSLOP;
360 else
361 onb += pagesz - sizeof (*op) - RSLOP;
362 /* avoid the copy if same size block */
363 if (was_alloced) {
364 if (i) {
365 i = 1 << (i + 2);
366 if (i < pagesz)
367 i -= sizeof (*op) + RSLOP;
368 else
369 i += pagesz - sizeof (*op) - RSLOP;
370 }
fcf53d9b 371 if (nbytes <= onb && nbytes > (size_t)i) {
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372#ifdef RCHECK
373 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
374 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
375#endif
376 return(cp);
377 } else
378 free(cp);
379 }
380 if ((res = malloc(nbytes)) == NULL)
381 return (NULL);
382 if (cp != res) /* common optimization if "compacting" */
383 bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
384 return (res);
385}
386
387/*
388 * Search ``srchlen'' elements of each free list for a block whose
389 * header starts at ``freep''. If srchlen is -1 search the whole list.
390 * Return bucket number, or -1 if not found.
391 */
392static int
472de6d1 393findbucket(union overhead *freep, int srchlen)
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394{
395 register union overhead *p;
396 register int i, j;
397
398 for (i = 0; i < NBUCKETS; i++) {
399 j = 0;
400 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
401 if (p == freep)
402 return (i);
403 j++;
404 }
405 }
406 return (-1);
407}
408
409#ifdef MSTATS
410/*
411 * mstats - print out statistics about malloc
412 *
413 * Prints two lines of numbers, one showing the length of the free list
414 * for each size category, the second showing the number of mallocs -
415 * frees for each size category.
416 */
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417void
418mstats(char *s)
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419{
420 register int i, j;
421 register union overhead *p;
422 int totfree = 0,
423 totused = 0;
424
425 fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
426 for (i = 0; i < NBUCKETS; i++) {
427 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
428 ;
429 fprintf(stderr, " %d", j);
430 totfree += j * (1 << (i + 3));
431 }
432 fprintf(stderr, "\nused:\t");
433 for (i = 0; i < NBUCKETS; i++) {
434 fprintf(stderr, " %d", nmalloc[i]);
435 totused += nmalloc[i] * (1 << (i + 3));
436 }
437 fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
438 totused, totfree);
439}
440#endif
441
442
443static int
472de6d1 444morepages(int n)
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445{
446 int fd = -1;
447 int offset;
448
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449 if (pagepool_end - pagepool_start > pagesz) {
450 caddr_t addr = (caddr_t)
451 (((long)pagepool_start + pagesz - 1) & ~(pagesz - 1));
452 if (munmap(addr, pagepool_end - addr) != 0)
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453 rtld_fdprintf(STDERR_FILENO, "morepages: munmap %p",
454 addr);
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455 }
456
457 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1));
458
459 if ((pagepool_start = mmap(0, n * pagesz,
460 PROT_READ|PROT_WRITE,
461 MAP_ANON|MAP_COPY, fd, 0)) == (caddr_t)-1) {
abfcd5b1 462 rtld_printf("Cannot map anonymous memory\n");
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463 return 0;
464 }
465 pagepool_end = pagepool_start + n * pagesz;
466 pagepool_start += offset;
467
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468 return n;
469}