malloc.c revision 776:e09e15b1e474 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include <unistd.h>
30
31#include <errno.h>
32
33#include <string.h>
34
35#include <sys/sysmacros.h>
36
37#include "umem_base.h"
38
39#include "misc.h"
40
41/*
42 * malloc_data_t is an 8-byte structure which is located "before" the pointer
43 * returned from {m,c,re}alloc and memalign.  The first four bytes give
44 * information about the buffer, and the second four bytes are a status byte.
45 *
46 * See umem_impl.h for the various magic numbers used, and the size
47 * encode/decode macros.
48 *
49 * The 'size' of the buffer includes the tags.  That is, we encode the
50 * argument to umem_alloc(), not the argument to malloc().
51 */
52
53typedef struct malloc_data {
54	uint32_t malloc_size;
55	uint32_t malloc_stat; /* = UMEM_MALLOC_ENCODE(state, malloc_size) */
56} malloc_data_t;
57
58void *
59malloc(size_t size_arg)
60{
61#ifdef _LP64
62	uint32_t high_size = 0;
63#endif
64	size_t size;
65
66	malloc_data_t *ret;
67	size = size_arg + sizeof (malloc_data_t);
68
69#ifdef _LP64
70	if (size > UMEM_SECOND_ALIGN) {
71		size += sizeof (malloc_data_t);
72		high_size = (size >> 32);
73	}
74#endif
75	if (size < size_arg) {
76		errno = ENOMEM;			/* overflow */
77		return (NULL);
78	}
79	ret = (malloc_data_t *)_umem_alloc(size, UMEM_DEFAULT);
80	if (ret == NULL) {
81		if (size <= UMEM_MAXBUF)
82			errno = EAGAIN;
83		else
84			errno = ENOMEM;
85		return (NULL);
86#ifdef _LP64
87	} else if (high_size > 0) {
88		uint32_t low_size = (uint32_t)size;
89
90		/*
91		 * uses different magic numbers to make it harder to
92		 * undetectably corrupt
93		 */
94		ret->malloc_size = high_size;
95		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_MAGIC, high_size);
96		ret++;
97
98		ret->malloc_size = low_size;
99		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_OVERSIZE_MAGIC,
100		    low_size);
101		ret++;
102	} else if (size > UMEM_SECOND_ALIGN) {
103		uint32_t low_size = (uint32_t)size;
104
105		ret++; /* leave the first 8 bytes alone */
106
107		ret->malloc_size = low_size;
108		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_SECOND_MAGIC,
109		    low_size);
110		ret++;
111#endif
112	} else {
113		ret->malloc_size = size;
114		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_MAGIC, size);
115		ret++;
116	}
117	return ((void *)ret);
118}
119
120void *
121calloc(size_t nelem, size_t elsize)
122{
123	size_t size = nelem * elsize;
124	void *retval;
125
126	if (nelem > 0 && elsize > 0 && size/nelem != elsize) {
127		errno = ENOMEM;				/* overflow */
128		return (NULL);
129	}
130
131	retval = malloc(size);
132	if (retval == NULL)
133		return (NULL);
134
135	(void) memset(retval, 0, size);
136	return (retval);
137}
138
139/*
140 * memalign uses vmem_xalloc to do its work.
141 *
142 * in 64-bit, the memaligned buffer always has two tags.  This simplifies the
143 * code.
144 */
145
146void *
147memalign(size_t align, size_t size_arg)
148{
149	size_t size;
150	uintptr_t phase;
151
152	void *buf;
153	malloc_data_t *ret;
154
155	size_t overhead;
156
157	if (size_arg == 0 || align == 0 || (align & (align - 1)) != 0) {
158		errno = EINVAL;
159		return (NULL);
160	}
161
162	/*
163	 * if malloc provides the required alignment, use it.
164	 */
165	if (align <= UMEM_ALIGN ||
166	    (align <= UMEM_SECOND_ALIGN && size_arg >= UMEM_SECOND_ALIGN))
167		return (malloc(size_arg));
168
169#ifdef _LP64
170	overhead = 2 * sizeof (malloc_data_t);
171#else
172	overhead = sizeof (malloc_data_t);
173#endif
174
175	ASSERT(overhead <= align);
176
177	size = size_arg + overhead;
178	phase = align - overhead;
179
180	if (umem_memalign_arena == NULL && umem_init() == 0) {
181		errno = ENOMEM;
182		return (NULL);
183	}
184
185	if (size < size_arg) {
186		errno = ENOMEM;			/* overflow */
187		return (NULL);
188	}
189
190	buf = vmem_xalloc(umem_memalign_arena, size, align, phase,
191	    0, NULL, NULL, VM_NOSLEEP);
192
193	if (buf == NULL) {
194		if ((size_arg + align) <= UMEM_MAXBUF)
195			errno = EAGAIN;
196		else
197			errno = ENOMEM;
198
199		return (NULL);
200	}
201
202	ret = (malloc_data_t *)buf;
203	{
204		uint32_t low_size = (uint32_t)size;
205
206#ifdef _LP64
207		uint32_t high_size = (uint32_t)(size >> 32);
208
209		ret->malloc_size = high_size;
210		ret->malloc_stat = UMEM_MALLOC_ENCODE(MEMALIGN_MAGIC,
211		    high_size);
212		ret++;
213#endif
214
215		ret->malloc_size = low_size;
216		ret->malloc_stat = UMEM_MALLOC_ENCODE(MEMALIGN_MAGIC, low_size);
217		ret++;
218	}
219
220	ASSERT(P2PHASE((uintptr_t)ret, align) == 0);
221	ASSERT((void *)((uintptr_t)ret - overhead) == buf);
222
223	return ((void *)ret);
224}
225
226void *
227valloc(size_t size)
228{
229	return (memalign(pagesize, size));
230}
231
232/*
233 * process_free:
234 *
235 * Pulls information out of a buffer pointer, and optionally free it.
236 * This is used by free() and realloc() to process buffers.
237 *
238 * On failure, calls umem_err_recoverable() with an appropriate message
239 * On success, returns the data size through *data_size_arg, if (!is_free).
240 *
241 * Preserves errno, since free()'s semantics require it.
242 */
243
244static int
245process_free(void *buf_arg,
246    int do_free,		/* free the buffer, or just get its size? */
247    size_t *data_size_arg)	/* output: bytes of data in buf_arg */
248{
249	malloc_data_t *buf;
250
251	void *base;
252	size_t size;
253	size_t data_size;
254
255	const char *message;
256	int old_errno = errno;
257
258	buf = (malloc_data_t *)buf_arg;
259
260	buf--;
261	size = buf->malloc_size;
262
263	switch (UMEM_MALLOC_DECODE(buf->malloc_stat, size)) {
264
265	case MALLOC_MAGIC:
266		base = (void *)buf;
267		data_size = size - sizeof (malloc_data_t);
268
269		if (do_free)
270			buf->malloc_stat = UMEM_FREE_PATTERN_32;
271
272		goto process_malloc;
273
274#ifdef _LP64
275	case MALLOC_SECOND_MAGIC:
276		base = (void *)(buf - 1);
277		data_size = size - 2 * sizeof (malloc_data_t);
278
279		if (do_free)
280			buf->malloc_stat = UMEM_FREE_PATTERN_32;
281
282		goto process_malloc;
283
284	case MALLOC_OVERSIZE_MAGIC: {
285		size_t high_size;
286
287		buf--;
288		high_size = buf->malloc_size;
289
290		if (UMEM_MALLOC_DECODE(buf->malloc_stat, high_size) !=
291		    MALLOC_MAGIC) {
292			message = "invalid or corrupted buffer";
293			break;
294		}
295
296		size += high_size << 32;
297
298		base = (void *)buf;
299		data_size = size - 2 * sizeof (malloc_data_t);
300
301		if (do_free) {
302			buf->malloc_stat = UMEM_FREE_PATTERN_32;
303			(buf + 1)->malloc_stat = UMEM_FREE_PATTERN_32;
304		}
305
306		goto process_malloc;
307	}
308#endif
309
310	case MEMALIGN_MAGIC: {
311		size_t overhead = sizeof (malloc_data_t);
312
313#ifdef _LP64
314		size_t high_size;
315
316		overhead += sizeof (malloc_data_t);
317
318		buf--;
319		high_size = buf->malloc_size;
320
321		if (UMEM_MALLOC_DECODE(buf->malloc_stat, high_size) !=
322		    MEMALIGN_MAGIC) {
323			message = "invalid or corrupted buffer";
324			break;
325		}
326		size += high_size << 32;
327
328		/*
329		 * destroy the main tag's malloc_stat
330		 */
331		if (do_free)
332			(buf + 1)->malloc_stat = UMEM_FREE_PATTERN_32;
333#endif
334
335		base = (void *)buf;
336		data_size = size - overhead;
337
338		if (do_free)
339			buf->malloc_stat = UMEM_FREE_PATTERN_32;
340
341		goto process_memalign;
342	}
343	default:
344		if (buf->malloc_stat == UMEM_FREE_PATTERN_32)
345			message = "double-free or invalid buffer";
346		else
347			message = "invalid or corrupted buffer";
348		break;
349	}
350
351	umem_err_recoverable("%s(%p): %s\n",
352	    do_free? "free" : "realloc", buf_arg, message);
353
354	errno = old_errno;
355	return (0);
356
357process_malloc:
358	if (do_free)
359		_umem_free(base, size);
360	else
361		*data_size_arg = data_size;
362
363	errno = old_errno;
364	return (1);
365
366process_memalign:
367	if (do_free)
368		vmem_xfree(umem_memalign_arena, base, size);
369	else
370		*data_size_arg = data_size;
371
372	errno = old_errno;
373	return (1);
374}
375
376void
377free(void *buf)
378{
379	if (buf == NULL)
380		return;
381
382	/*
383	 * Process buf, freeing it if it is not corrupt.
384	 */
385	(void) process_free(buf, 1, NULL);
386}
387
388void *
389realloc(void *buf_arg, size_t newsize)
390{
391	size_t oldsize;
392	void *buf;
393
394	if (buf_arg == NULL)
395		return (malloc(newsize));
396
397	if (newsize == 0) {
398		free(buf_arg);
399		return (NULL);
400	}
401
402	/*
403	 * get the old data size without freeing the buffer
404	 */
405	if (process_free(buf_arg, 0, &oldsize) == 0) {
406		errno = EINVAL;
407		return (NULL);
408	}
409
410	if (newsize == oldsize)		/* size didn't change */
411		return (buf_arg);
412
413	buf = malloc(newsize);
414	if (buf == NULL)
415		return (NULL);
416
417	(void) memcpy(buf, buf_arg, MIN(newsize, oldsize));
418	free(buf_arg);
419	return (buf);
420}
421