root/trunk/malloc.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "@(#)malloc.c   1.5     05/06/08 SMI"

#include "config.h"
#include <unistd.h>

#include <errno.h>

#include <string.h>

#ifdef HAVE_SYS_SYSMACROS_H
#include <sys/sysmacros.h>
#endif

#include "umem_base.h"

#include "misc.h"

/*
 * malloc_data_t is an 8-byte structure which is located "before" the pointer
 * returned from {m,c,re}alloc and memalign.  The first four bytes give
 * information about the buffer, and the second four bytes are a status byte.
 *
 * See umem_impl.h for the various magic numbers used, and the size
 * encode/decode macros.
 *
 * The 'size' of the buffer includes the tags.  That is, we encode the
 * argument to umem_alloc(), not the argument to malloc().
 */

typedef struct malloc_data {
        uint32_t malloc_size;
        uint32_t malloc_stat; /* = UMEM_MALLOC_ENCODE(state, malloc_size) */
} malloc_data_t;

void *
malloc(size_t size_arg)
{
#ifdef _LP64
        uint32_t high_size = 0;
#endif
        size_t size;

        malloc_data_t *ret;
        size = size_arg + sizeof (malloc_data_t);

#ifdef _LP64
        if (size > UMEM_SECOND_ALIGN) {
                size += sizeof (malloc_data_t);
                high_size = (size >> 32);
        }
#endif
        if (size < size_arg) {
                errno = ENOMEM;                 /* overflow */
                return (NULL);
        }
        ret = (malloc_data_t *)_umem_alloc(size, UMEM_DEFAULT);
        if (ret == NULL) {
                if (size <= UMEM_MAXBUF)
                        errno = EAGAIN;
                else
                        errno = ENOMEM;
                return (NULL);
#ifdef _LP64
        } else if (high_size > 0) {
                uint32_t low_size = (uint32_t)size;

                /*
                 * uses different magic numbers to make it harder to
                 * undetectably corrupt
                 */
                ret->malloc_size = high_size;
                ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_MAGIC, high_size);
                ret++;

                ret->malloc_size = low_size;
                ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_OVERSIZE_MAGIC,
                    low_size);
                ret++;
        } else if (size > UMEM_SECOND_ALIGN) {
                uint32_t low_size = (uint32_t)size;

                ret++; /* leave the first 8 bytes alone */

                ret->malloc_size = low_size;
                ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_SECOND_MAGIC,
                    low_size);
                ret++;
#endif
        } else {
                ret->malloc_size = size;
                ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_MAGIC, size);
                ret++;
        }
        return ((void *)ret);
}

void *
calloc(size_t nelem, size_t elsize)
{
        size_t size = nelem * elsize;
        void *retval;

        if (nelem > 0 && elsize > 0 && size/nelem != elsize) {
                errno = ENOMEM;                         /* overflow */
                return (NULL);
        }

        retval = malloc(size);
        if (retval == NULL)
                return (NULL);

        (void) memset(retval, 0, size);
        return (retval);
}

/*
 * memalign uses vmem_xalloc to do its work.
 *
 * in 64-bit, the memaligned buffer always has two tags.  This simplifies the
 * code.
 */

void *
memalign(size_t align, size_t size_arg)
{
        size_t size;
        uintptr_t phase;

        void *buf;
        malloc_data_t *ret;

        size_t overhead;

        if (size_arg == 0 || align == 0 || (align & (align - 1)) != 0) {
                errno = EINVAL;
                return (NULL);
        }

        /*
         * if malloc provides the required alignment, use it.
         */
        if (align <= UMEM_ALIGN ||
            (align <= UMEM_SECOND_ALIGN && size_arg >= UMEM_SECOND_ALIGN))
                return (malloc(size_arg));

#ifdef _LP64
        overhead = 2 * sizeof (malloc_data_t);
#else
        overhead = sizeof (malloc_data_t);
#endif

        ASSERT(overhead <= align);

        size = size_arg + overhead;
        phase = align - overhead;

        if (umem_memalign_arena == NULL && umem_init() == 0) {
                errno = ENOMEM;
                return (NULL);
        }

        if (size < size_arg) {
                errno = ENOMEM;                 /* overflow */
                return (NULL);
        }

        buf = vmem_xalloc(umem_memalign_arena, size, align, phase,
            0, NULL, NULL, VM_NOSLEEP);

        if (buf == NULL) {
                if ((size_arg + align) <= UMEM_MAXBUF)
                        errno = EAGAIN;
                else
                        errno = ENOMEM;

                return (NULL);
        }

        ret = (malloc_data_t *)buf;
        {
                uint32_t low_size = (uint32_t)size;

#ifdef _LP64
                uint32_t high_size = (uint32_t)(size >> 32);

                ret->malloc_size = high_size;
                ret->malloc_stat = UMEM_MALLOC_ENCODE(MEMALIGN_MAGIC,
                    high_size);
                ret++;
#endif

                ret->malloc_size = low_size;
                ret->malloc_stat = UMEM_MALLOC_ENCODE(MEMALIGN_MAGIC, low_size);
                ret++;
        }

        ASSERT(P2PHASE((uintptr_t)ret, align) == 0);
        ASSERT((void *)((uintptr_t)ret - overhead) == buf);

        return ((void *)ret);
}

int
posix_memalign(void **memptr, size_t alignment, size_t size)
{
        *memptr = memalign(alignment, size);
        if (*memptr) {
                return 0;
        }
        return errno;
}

void *
valloc(size_t size)
{
        return (memalign(pagesize, size));
}

/*
 * process_free:
 *
 * Pulls information out of a buffer pointer, and optionally free it.
 * This is used by free() and realloc() to process buffers.
 *
 * On failure, calls umem_err_recoverable() with an appropriate message
 * On success, returns the data size through *data_size_arg, if (!is_free).
 *
 * Preserves errno, since free()'s semantics require it.
 */

static int
process_free(void *buf_arg,
    int do_free,                /* free the buffer, or just get its size? */
    size_t *data_size_arg)      /* output: bytes of data in buf_arg */
{
        malloc_data_t *buf;

        void *base;
        size_t size;
        size_t data_size;

        const char *message;
        int old_errno = errno;

        buf = (malloc_data_t *)buf_arg;

        buf--;
        size = buf->malloc_size;

        switch (UMEM_MALLOC_DECODE(buf->malloc_stat, size)) {

        case MALLOC_MAGIC:
                base = (void *)buf;
                data_size = size - sizeof (malloc_data_t);

                if (do_free)
                        buf->malloc_stat = UMEM_FREE_PATTERN_32;

                goto process_malloc;

#ifdef _LP64
        case MALLOC_SECOND_MAGIC:
                base = (void *)(buf - 1);
                data_size = size - 2 * sizeof (malloc_data_t);

                if (do_free)
                        buf->malloc_stat = UMEM_FREE_PATTERN_32;

                goto process_malloc;

        case MALLOC_OVERSIZE_MAGIC: {
                size_t high_size;

                buf--;
                high_size = buf->malloc_size;

                if (UMEM_MALLOC_DECODE(buf->malloc_stat, high_size) !=
                    MALLOC_MAGIC) {
                        message = "invalid or corrupted buffer";
                        break;
                }

                size += high_size << 32;

                base = (void *)buf;
                data_size = size - 2 * sizeof (malloc_data_t);

                if (do_free) {
                        buf->malloc_stat = UMEM_FREE_PATTERN_32;
                        (buf + 1)->malloc_stat = UMEM_FREE_PATTERN_32;
                }

                goto process_malloc;
        }
#endif

        case MEMALIGN_MAGIC: {
                size_t overhead = sizeof (malloc_data_t);

#ifdef _LP64
                size_t high_size;

                overhead += sizeof (malloc_data_t);

                buf--;
                high_size = buf->malloc_size;

                if (UMEM_MALLOC_DECODE(buf->malloc_stat, high_size) !=
                    MEMALIGN_MAGIC) {
                        message = "invalid or corrupted buffer";
                        break;
                }
                size += high_size << 32;

                /*
                 * destroy the main tag's malloc_stat
                 */
                if (do_free)
                        (buf + 1)->malloc_stat = UMEM_FREE_PATTERN_32;
#endif

                base = (void *)buf;
                data_size = size - overhead;

                if (do_free)
                        buf->malloc_stat = UMEM_FREE_PATTERN_32;

                goto process_memalign;
        }
        default:
                if (buf->malloc_stat == UMEM_FREE_PATTERN_32)
                        message = "double-free or invalid buffer";
                else
                        message = "invalid or corrupted buffer";
                break;
        }

        umem_err_recoverable("%s(%p): %s\n",
            do_free? "free" : "realloc", buf_arg, message);

        errno = old_errno;
        return (0);

process_malloc:
        if (do_free)
                _umem_free(base, size);
        else
                *data_size_arg = data_size;

        errno = old_errno;
        return (1);

process_memalign:
        if (do_free)
                vmem_xfree(umem_memalign_arena, base, size);
        else
                *data_size_arg = data_size;

        errno = old_errno;
        return (1);
}

void
free(void *buf)
{
        if (buf == NULL)
                return;

        /*
         * Process buf, freeing it if it is not corrupt.
         */
        (void) process_free(buf, 1, NULL);
}

void *
realloc(void *buf_arg, size_t newsize)
{
        size_t oldsize;
        void *buf;

        if (buf_arg == NULL)
                return (malloc(newsize));

        if (newsize == 0) {
                free(buf_arg);
                return (NULL);
        }

        /*
         * get the old data size without freeing the buffer
         */
        if (process_free(buf_arg, 0, &oldsize) == 0) {
                errno = EINVAL;
                return (NULL);
        }

        if (newsize == oldsize)         /* size didn't change */
                return (buf_arg);

        buf = malloc(newsize);
        if (buf == NULL)
                return (NULL);

        (void) memcpy(buf, buf_arg, MIN(newsize, oldsize));
        free(buf_arg);
        return (buf);
}