1 /* $NetBSD: xmalloc.c,v 1.12 2013/01/24 17:57:29 christos Exp $ */
2
3 /*
4 * Copyright 1996 John D. Polstra.
5 * Copyright 1996 Matt Thomas <matt@3am-software.com>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by John Polstra.
19 * 4. The name of the author may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 /*
35 * Copyright (c) 1983 Regents of the University of California.
36 * All rights reserved.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. Neither the name of the University nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60 * SUCH DAMAGE.
61 */
62
63 #if defined(LIBC_SCCS) && !defined(lint)
64 /*static char *sccsid = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/
65 #endif /* LIBC_SCCS and not lint */
66
67 /*
68 * malloc.c (Caltech) 2/21/82
69 * Chris Kingsley, kingsley@cit-20.
70 *
71 * This is a very fast storage allocator. It allocates blocks of a small
72 * number of different sizes, and keeps free lists of each size. Blocks that
73 * don't exactly fit are passed up to the next larger size. In this
74 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long.
75 * This is designed for use in a virtual memory environment.
76 */
77
78 #include <sys/cdefs.h>
79 #ifndef lint
80 __RCSID("$NetBSD: xmalloc.c,v 1.12 2013/01/24 17:57:29 christos Exp $");
81 #endif /* not lint */
82
83 #include <stdlib.h>
84 #include <string.h>
85 #include <unistd.h>
86 #include <errno.h>
87
88 #include <sys/types.h>
89 #include <sys/param.h>
90 #include <sys/mman.h>
91 #include <sys/stat.h>
92
93 #include "rtld.h"
94
95 /*
96 * Pre-allocate mmap'ed pages
97 */
98 #define NPOOLPAGES (32*1024/pagesz)
99 static char *pagepool_start, *pagepool_end;
100 static int morepages(int);
101 #define PAGEPOOL_SIZE (size_t)(pagepool_end - pagepool_start)
102
103 /*
104 * The overhead on a block is at least 4 bytes. When free, this space
105 * contains a pointer to the next free block, and the bottom two bits must
106 * be zero. When in use, the first byte is set to MAGIC, and the second
107 * byte is the size index. The remaining bytes are for alignment.
108 * If range checking is enabled then a second word holds the size of the
109 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
110 * The order of elements is critical: ov_magic must overlay the low order
111 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
112 */
113 union overhead {
114 union overhead *ov_next; /* when free */
115 struct {
116 u_char ovu_magic; /* magic number */
117 u_char ovu_index; /* bucket # */
118 #ifdef RCHECK
119 u_short ovu_rmagic; /* range magic number */
120 u_int ovu_size; /* actual block size */
121 #endif
122 } ovu;
123 #define ov_magic ovu.ovu_magic
124 #define ov_index ovu.ovu_index
125 #define ov_rmagic ovu.ovu_rmagic
126 #define ov_size ovu.ovu_size
127 };
128
129 static void morecore(size_t);
130 static void *imalloc(size_t);
131
132 #define MAGIC 0xef /* magic # on accounting info */
133 #define RMAGIC 0x5555 /* magic # on range info */
134
135 #ifdef RCHECK
136 #define RSLOP (sizeof (u_short))
137 #else
138 #define RSLOP 0
139 #endif
140
141 /*
142 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
143 * smallest allocatable block is 8 bytes. The overhead information
144 * precedes the data area returned to the user.
145 */
146 #define NBUCKETS 30
147 static union overhead *nextf[NBUCKETS];
148
149 static size_t pagesz; /* page size */
150 static size_t pagebucket; /* page size bucket */
151 static size_t pageshift; /* page size shift */
152
153 #ifdef MSTATS
154 /*
155 * nmalloc[i] is the difference between the number of mallocs and frees
156 * for a given block size.
157 */
158 static u_int nmalloc[NBUCKETS];
159 #endif
160
161 #if defined(MALLOC_DEBUG) || defined(RCHECK)
162 #define ASSERT(p) if (!(p)) botch("p")
163 static void
botch(const char * s)164 botch(const char *s)
165 {
166 xwarnx("\r\nassertion botched: %s\r\n", s);
167 abort();
168 }
169 #else
170 #define ASSERT(p)
171 #endif
172
173 #define TRACE() xprintf("TRACE %s:%d\n", __FILE__, __LINE__)
174
175 static void *
imalloc(size_t nbytes)176 imalloc(size_t nbytes)
177 {
178 union overhead *op;
179 size_t bucket;
180 size_t n, m;
181 unsigned amt;
182
183 /*
184 * First time malloc is called, setup page size and
185 * align break pointer so all data will be page aligned.
186 */
187 if (pagesz == 0) {
188 pagesz = n = _rtld_pagesz;
189 if (morepages(NPOOLPAGES) == 0)
190 return NULL;
191 op = (union overhead *)(pagepool_start);
192 m = sizeof (*op) - (((char *)op - (char *)NULL) & (n - 1));
193 if (n < m)
194 n += pagesz - m;
195 else
196 n -= m;
197 if (n) {
198 pagepool_start += n;
199 }
200 bucket = 0;
201 amt = sizeof(union overhead);
202 while (pagesz > amt) {
203 amt <<= 1;
204 bucket++;
205 }
206 pagebucket = bucket;
207 pageshift = ffs(pagesz) - 1;
208 }
209 /*
210 * Convert amount of memory requested into closest block size
211 * stored in hash buckets which satisfies request.
212 * Account for space used per block for accounting.
213 */
214 if (nbytes <= (n = pagesz - sizeof (*op) - RSLOP)) {
215 if (sizeof(union overhead) & (sizeof(union overhead) - 1)) {
216 amt = sizeof(union overhead) * 2;
217 bucket = 1;
218 } else {
219 amt = sizeof(union overhead); /* size of first bucket */
220 bucket = 0;
221 }
222 n = -(sizeof (*op) + RSLOP);
223 } else {
224 amt = pagesz;
225 bucket = pagebucket;
226 }
227 while (nbytes > amt + n) {
228 amt <<= 1;
229 if (amt == 0)
230 return (NULL);
231 bucket++;
232 }
233 /*
234 * If nothing in hash bucket right now,
235 * request more memory from the system.
236 */
237 if ((op = nextf[bucket]) == NULL) {
238 morecore(bucket);
239 if ((op = nextf[bucket]) == NULL)
240 return (NULL);
241 }
242 /* remove from linked list */
243 nextf[bucket] = op->ov_next;
244 op->ov_magic = MAGIC;
245 op->ov_index = bucket;
246 #ifdef MSTATS
247 nmalloc[bucket]++;
248 #endif
249 #ifdef RCHECK
250 /*
251 * Record allocated size of block and
252 * bound space with magic numbers.
253 */
254 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
255 op->ov_rmagic = RMAGIC;
256 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
257 #endif
258 return ((char *)(op + 1));
259 }
260
261 /*
262 * Allocate more memory to the indicated bucket.
263 */
264 static void
morecore(size_t bucket)265 morecore(size_t bucket)
266 {
267 union overhead *op;
268 size_t sz; /* size of desired block */
269 size_t amt; /* amount to allocate */
270 size_t nblks; /* how many blocks we get */
271
272 /*
273 * sbrk_size <= 0 only for big, FLUFFY, requests (about
274 * 2^30 bytes on a VAX, I think) or for a negative arg.
275 */
276 sz = 1 << (bucket + 3);
277 #ifdef MALLOC_DEBUG
278 ASSERT(sz > 0);
279 #endif
280 if (sz < pagesz) {
281 amt = pagesz;
282 nblks = amt >> (bucket + 3);
283 } else {
284 amt = sz + pagesz;
285 nblks = 1;
286 }
287 if (amt > PAGEPOOL_SIZE)
288 if (morepages((amt >> pageshift) + NPOOLPAGES) == 0)
289 return;
290 op = (union overhead *)pagepool_start;
291 pagepool_start += amt;
292
293 /*
294 * Add new memory allocated to that on
295 * free list for this hash bucket.
296 */
297 nextf[bucket] = op;
298 while (--nblks > 0) {
299 op->ov_next = (union overhead *)((caddr_t)op + sz);
300 op = (union overhead *)((caddr_t)op + sz);
301 }
302 }
303
304 void
xfree(void * cp)305 xfree(void *cp)
306 {
307 int size;
308 union overhead *op;
309
310 if (cp == NULL)
311 return;
312 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
313 #ifdef MALLOC_DEBUG
314 ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
315 #else
316 if (op->ov_magic != MAGIC)
317 return; /* sanity */
318 #endif
319 #ifdef RCHECK
320 ASSERT(op->ov_rmagic == RMAGIC);
321 ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
322 #endif
323 size = op->ov_index;
324 ASSERT(size < NBUCKETS);
325 op->ov_next = nextf[size]; /* also clobbers ov_magic */
326 nextf[size] = op;
327 #ifdef MSTATS
328 nmalloc[size]--;
329 #endif
330 }
331
332 static void *
irealloc(void * cp,size_t nbytes)333 irealloc(void *cp, size_t nbytes)
334 {
335 size_t onb;
336 size_t i;
337 union overhead *op;
338 char *res;
339
340 if (cp == NULL)
341 return (imalloc(nbytes));
342 op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
343 if (op->ov_magic != MAGIC) {
344 static const char *err_str =
345 "memory corruption or double free in realloc\n";
346 extern char *__progname;
347 write(STDERR_FILENO, __progname, strlen(__progname));
348 write(STDERR_FILENO, err_str, strlen(err_str));
349 abort();
350 }
351
352 i = op->ov_index;
353 onb = 1 << (i + 3);
354 if (onb < pagesz)
355 onb -= sizeof (*op) + RSLOP;
356 else
357 onb += pagesz - sizeof (*op) - RSLOP;
358 /* avoid the copy if same size block */
359 if (i) {
360 i = 1 << (i + 2);
361 if (i < pagesz)
362 i -= sizeof (*op) + RSLOP;
363 else
364 i += pagesz - sizeof (*op) - RSLOP;
365 }
366 if (nbytes <= onb && nbytes > i) {
367 #ifdef RCHECK
368 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
369 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
370 #endif
371 return(cp);
372 }
373 if ((res = imalloc(nbytes)) == NULL)
374 return (NULL);
375 if (cp != res) { /* common optimization if "compacting" */
376 memcpy(res, cp, (nbytes < onb) ? nbytes : onb);
377 xfree(cp);
378 }
379 return (res);
380 }
381
382 #ifdef MSTATS
383 /*
384 * mstats - print out statistics about malloc
385 *
386 * Prints two lines of numbers, one showing the length of the free list
387 * for each size category, the second showing the number of mallocs -
388 * frees for each size category.
389 */
390 void
mstats(char * s)391 mstats(char *s)
392 {
393 int i, j;
394 union overhead *p;
395 int totfree = 0,
396 totused = 0;
397
398 xprintf("Memory allocation statistics %s\nfree:\t", s);
399 for (i = 0; i < NBUCKETS; i++) {
400 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
401 ;
402 xprintf(" %d", j);
403 totfree += j * (1 << (i + 3));
404 }
405 xprintf("\nused:\t");
406 for (i = 0; i < NBUCKETS; i++) {
407 xprintf(" %d", nmalloc[i]);
408 totused += nmalloc[i] * (1 << (i + 3));
409 }
410 xprintf("\n\tTotal in use: %d, total free: %d\n",
411 totused, totfree);
412 }
413 #endif
414
415
416 static int
morepages(int n)417 morepages(int n)
418 {
419 int fd = -1;
420 int offset;
421
422 #ifdef NEED_DEV_ZERO
423 fd = open("/dev/zero", O_RDWR, 0);
424 if (fd == -1)
425 xerr(1, "/dev/zero");
426 #endif
427
428 if (PAGEPOOL_SIZE > pagesz) {
429 caddr_t addr = (caddr_t)
430 (((long)pagepool_start + pagesz - 1) & ~(pagesz - 1));
431 if (munmap(addr, pagepool_end - addr) != 0)
432 xwarn("morepages: munmap %p", addr);
433 }
434
435 offset = (long)pagepool_start - ((long)pagepool_start & ~(pagesz - 1));
436
437 if ((pagepool_start = mmap(0, n * pagesz,
438 PROT_READ|PROT_WRITE,
439 MAP_ANON|MAP_PRIVATE, fd, 0)) == (caddr_t)-1) {
440 xprintf("Cannot map anonymous memory");
441 return 0;
442 }
443 pagepool_end = pagepool_start + n * pagesz;
444 pagepool_start += offset;
445
446 #ifdef NEED_DEV_ZERO
447 close(fd);
448 #endif
449 return n;
450 }
451
452 void *
xcalloc(size_t size)453 xcalloc(size_t size)
454 {
455
456 return memset(xmalloc(size), 0, size);
457 }
458
459 void *
xmalloc(size_t size)460 xmalloc(size_t size)
461 {
462 void *p = imalloc(size);
463
464 if (p == NULL)
465 xerr(1, "%s", xstrerror(errno));
466 return p;
467 }
468
469 void *
xrealloc(void * p,size_t size)470 xrealloc(void *p, size_t size)
471 {
472 p = irealloc(p, size);
473
474 if (p == NULL)
475 xerr(1, "%s", xstrerror(errno));
476 return p;
477 }
478
479 char *
xstrdup(const char * str)480 xstrdup(const char *str)
481 {
482 size_t len;
483 char *copy;
484
485 len = strlen(str) + 1;
486 copy = xmalloc(len);
487 memcpy(copy, str, len);
488 return (copy);
489 }
490