xnu-7195.101.1.tar.gz

[apple/xnu.git] / bsd / kern / kern_subr.c

/*
 * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
 */

#include <machine/atomic.h>

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc_internal.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <vm/pmap.h>
#include <sys/uio_internal.h>
#include <kern/kalloc.h>

#include <kdebug.h>

#include <sys/kdebug.h>
#define DBG_UIO_COPYOUT 16
#define DBG_UIO_COPYIN  17

#if DEBUG
#include <kern/simple_lock.h>

static uint32_t                         uio_t_count = 0;
#endif /* DEBUG */

#define IS_VALID_UIO_SEGFLG(segflg)  \
        ( (segflg) == UIO_USERSPACE || \
          (segflg) == UIO_SYSSPACE || \
          (segflg) == UIO_USERSPACE32 || \
          (segflg) == UIO_USERSPACE64 || \
          (segflg) == UIO_SYSSPACE32 || \
          (segflg) == UIO_USERISPACE || \
          (segflg) == UIO_PHYS_USERSPACE || \
          (segflg) == UIO_PHYS_SYSSPACE || \
          (segflg) == UIO_USERISPACE32 || \
          (segflg) == UIO_PHYS_USERSPACE32 || \
          (segflg) == UIO_USERISPACE64 || \
          (segflg) == UIO_PHYS_USERSPACE64 )

/*
 * Returns:     0                       Success
 *      uiomove64:EFAULT
 *
 * Notes:       The first argument should be a caddr_t, but const poisoning
 *              for typedef'ed types doesn't work in gcc.
 */
int
uiomove(const char * cp, int n, uio_t uio)
{
        return uiomove64((const addr64_t)(uintptr_t)cp, n, uio);
}

/*
 * Returns:     0                       Success
 *              EFAULT
 *      copyout:EFAULT
 *      copyin:EFAULT
 *      copywithin:EFAULT
 *      copypv:EFAULT
 */
int
uiomove64(const addr64_t c_cp, int n, struct uio *uio)
{
        addr64_t cp = c_cp;
        uint64_t acnt;
        int error = 0;

#if DIAGNOSTIC
        if (uio->uio_rw != UIO_READ && uio->uio_rw != UIO_WRITE) {
                panic("uiomove: mode");
        }
#endif

#if LP64_DEBUG
        if (IS_VALID_UIO_SEGFLG(uio->uio_segflg) == 0) {
                panic("%s :%d - invalid uio_segflg\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        while (n > 0 && uio_resid(uio)) {
                uio_update(uio, 0);
                acnt = uio_curriovlen(uio);
                if (acnt == 0) {
                        continue;
                }
                if (n > 0 && acnt > (uint64_t)n) {
                        acnt = n;
                }

                switch ((int) uio->uio_segflg) {
                case UIO_USERSPACE64:
                case UIO_USERISPACE64:
                case UIO_USERSPACE32:
                case UIO_USERISPACE32:
                case UIO_USERSPACE:
                case UIO_USERISPACE:
                        // LP64 - 3rd argument in debug code is 64 bit, expected to be 32 bit
                        if (uio->uio_rw == UIO_READ) {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_START,
                                    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 0, 0);

                                error = copyout( CAST_DOWN(caddr_t, cp), uio->uio_iovs.uiovp->iov_base, (size_t)acnt );

                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_END,
                                    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 0, 0);
                        } else {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_START,
                                    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 0, 0);

                                error = copyin(uio->uio_iovs.uiovp->iov_base, CAST_DOWN(caddr_t, cp), (size_t)acnt);

                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_END,
                                    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 0, 0);
                        }
                        if (error) {
                                return error;
                        }
                        break;

                case UIO_SYSSPACE32:
                case UIO_SYSSPACE:
                        if (uio->uio_rw == UIO_READ) {
                                error = copywithin(CAST_DOWN(caddr_t, cp), CAST_DOWN(caddr_t, uio->uio_iovs.kiovp->iov_base),
                                    (size_t)acnt);
                        } else {
                                error = copywithin(CAST_DOWN(caddr_t, uio->uio_iovs.kiovp->iov_base), CAST_DOWN(caddr_t, cp),
                                    (size_t)acnt);
                        }
                        break;

                case UIO_PHYS_USERSPACE64:
                case UIO_PHYS_USERSPACE32:
                case UIO_PHYS_USERSPACE:
                        acnt = MIN(acnt, UINT_MAX);

                        if (uio->uio_rw == UIO_READ) {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_START,
                                    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 1, 0);

                                error = copypv((addr64_t)cp, uio->uio_iovs.uiovp->iov_base, (unsigned int)acnt, cppvPsrc | cppvNoRefSrc);
                                if (error) {    /* Copy physical to virtual */
                                        error = EFAULT;
                                }

                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_END,
                                    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 1, 0);
                        } else {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_START,
                                    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 1, 0);

                                error = copypv(uio->uio_iovs.uiovp->iov_base, (addr64_t)cp, (unsigned int)acnt, cppvPsnk | cppvNoRefSrc | cppvNoModSnk);
                                if (error) {    /* Copy virtual to physical */
                                        error = EFAULT;
                                }

                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_END,
                                    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 1, 0);
                        }
                        if (error) {
                                return error;
                        }
                        break;

                case UIO_PHYS_SYSSPACE:
                        acnt = MIN(acnt, UINT_MAX);

                        if (uio->uio_rw == UIO_READ) {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_START,
                                    (int)cp, (uintptr_t)uio->uio_iovs.kiovp->iov_base, acnt, 2, 0);

                                error = copypv((addr64_t)cp, uio->uio_iovs.kiovp->iov_base, (unsigned int)acnt, cppvKmap | cppvPsrc | cppvNoRefSrc);
                                if (error) {    /* Copy physical to virtual */
                                        error = EFAULT;
                                }

                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_END,
                                    (int)cp, (uintptr_t)uio->uio_iovs.kiovp->iov_base, acnt, 2, 0);
                        } else {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_START,
                                    (uintptr_t)uio->uio_iovs.kiovp->iov_base, (int)cp, acnt, 2, 0);

                                error = copypv(uio->uio_iovs.kiovp->iov_base, (addr64_t)cp, (unsigned int)acnt, cppvKmap | cppvPsnk | cppvNoRefSrc | cppvNoModSnk);
                                if (error) {    /* Copy virtual to physical */
                                        error = EFAULT;
                                }

                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_END,
                                    (uintptr_t)uio->uio_iovs.kiovp->iov_base, (int)cp, acnt, 2, 0);
                        }
                        if (error) {
                                return error;
                        }
                        break;

                default:
                        break;
                }
                uio_update(uio, (user_size_t)acnt);
                cp += acnt;
                n -= acnt;
        }
        return error;
}

/*
 * Give next character to user as result of read.
 */
int
ureadc(int c, struct uio *uio)
{
        if (uio_resid(uio) <= 0) {
                panic("ureadc: non-positive resid");
        }
        uio_update(uio, 0);
        if (uio->uio_iovcnt == 0) {
                panic("ureadc: non-positive iovcnt");
        }
        if (uio_curriovlen(uio) <= 0) {
                panic("ureadc: non-positive iovlen");
        }

        switch ((int) uio->uio_segflg) {
        case UIO_USERSPACE32:
        case UIO_USERSPACE:
        case UIO_USERISPACE32:
        case UIO_USERISPACE:
        case UIO_USERSPACE64:
        case UIO_USERISPACE64:
                if (subyte((user_addr_t)uio->uio_iovs.uiovp->iov_base, c) < 0) {
                        return EFAULT;
                }
                break;

        case UIO_SYSSPACE32:
        case UIO_SYSSPACE:
                *(CAST_DOWN(caddr_t, uio->uio_iovs.kiovp->iov_base)) = (char)c;
                break;

        default:
                break;
        }
        uio_update(uio, 1);
        return 0;
}

LIST_HEAD(generic_hash_head, generic);

/*
 * General routine to allocate a hash table.
 */
void *
hashinit(int elements, int type __unused, u_long *hashmask)
{
        struct generic_hash_head *hashtbl;
        vm_size_t hashsize;

        if (elements <= 0) {
                panic("hashinit: bad cnt");
        }

        hashsize = 1UL << (fls(elements) - 1);
        hashtbl = kheap_alloc(KHEAP_DEFAULT, hashsize * sizeof(*hashtbl),
            Z_WAITOK | Z_ZERO);
        if (hashtbl != NULL) {
                *hashmask = hashsize - 1;
        }
        return hashtbl;
}

void
hashdestroy(void *hash, int type __unused, u_long hashmask)
{
        struct generic_hash_head *hashtbl = hash;
        assert(powerof2(hashmask + 1));
        kheap_free(KHEAP_DEFAULT, hashtbl, (hashmask + 1) * sizeof(*hashtbl));
}

/*
 * uio_resid - return the residual IO value for the given uio_t
 */
user_ssize_t
uio_resid( uio_t a_uio )
{
#if DEBUG
        if (a_uio == NULL) {
                printf("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
/*      if (IS_VALID_UIO_SEGFLG(a_uio->uio_segflg) == 0) { */
/*              panic("%s :%d - invalid uio_segflg\n", __FILE__, __LINE__);  */
/*      } */
#endif /* DEBUG */

        /* return 0 if there are no active iovecs */
        if (a_uio == NULL) {
                return 0;
        }

        return a_uio->uio_resid_64;
}

/*
 * uio_setresid - set the residual IO value for the given uio_t
 */
void
uio_setresid( uio_t a_uio, user_ssize_t a_value )
{
#if DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
/*      if (IS_VALID_UIO_SEGFLG(a_uio->uio_segflg) == 0) { */
/*              panic("%s :%d - invalid uio_segflg\n", __FILE__, __LINE__);  */
/*      } */
#endif /* DEBUG */

        if (a_uio == NULL) {
                return;
        }

        a_uio->uio_resid_64 = a_value;
        return;
}

/*
 * uio_curriovbase - return the base address of the current iovec associated
 *      with the given uio_t.  May return 0.
 */
user_addr_t
uio_curriovbase( uio_t a_uio )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL || a_uio->uio_iovcnt < 1) {
                return 0;
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                return a_uio->uio_iovs.uiovp->iov_base;
        }
        return (user_addr_t)a_uio->uio_iovs.kiovp->iov_base;
}

/*
 * uio_curriovlen - return the length value of the current iovec associated
 *      with the given uio_t.
 */
user_size_t
uio_curriovlen( uio_t a_uio )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL || a_uio->uio_iovcnt < 1) {
                return 0;
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                return a_uio->uio_iovs.uiovp->iov_len;
        }
        return (user_size_t)a_uio->uio_iovs.kiovp->iov_len;
}

/*
 * uio_setcurriovlen - set the length value of the current iovec associated
 *      with the given uio_t.
 */
__private_extern__ void
uio_setcurriovlen( uio_t a_uio, user_size_t a_value )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL) {
                return;
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                a_uio->uio_iovs.uiovp->iov_len = a_value;
        } else {
#if LP64_DEBUG
                if (a_value > 0xFFFFFFFFull) {
                        panic("%s :%d - invalid a_value\n", __FILE__, __LINE__);
                }
#endif /* LP64_DEBUG */
                a_uio->uio_iovs.kiovp->iov_len = (size_t)a_value;
        }
        return;
}

/*
 * uio_iovcnt - return count of active iovecs for the given uio_t
 */
int
uio_iovcnt( uio_t a_uio )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL) {
                return 0;
        }

        return a_uio->uio_iovcnt;
}

/*
 * uio_offset - return the current offset value for the given uio_t
 */
off_t
uio_offset( uio_t a_uio )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL) {
                return 0;
        }
        return a_uio->uio_offset;
}

/*
 * uio_setoffset - set the current offset value for the given uio_t
 */
void
uio_setoffset( uio_t a_uio, off_t a_offset )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL) {
                return;
        }
        a_uio->uio_offset = a_offset;
        return;
}

/*
 * uio_rw - return the read / write flag for the given uio_t
 */
int
uio_rw( uio_t a_uio )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL) {
                return -1;
        }
        return a_uio->uio_rw;
}

/*
 * uio_setrw - set the read / write flag for the given uio_t
 */
void
uio_setrw( uio_t a_uio, int a_value )
{
        if (a_uio == NULL) {
#if LP64_DEBUG
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
                return;
        }

#if LP64_DEBUG
        if (!(a_value == UIO_READ || a_value == UIO_WRITE)) {
                panic("%s :%d - invalid a_value\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_value == UIO_READ || a_value == UIO_WRITE) {
                a_uio->uio_rw = a_value;
        }
        return;
}

/*
 * uio_isuserspace - return non zero value if the address space
 * flag is for a user address space (could be 32 or 64 bit).
 */
int
uio_isuserspace( uio_t a_uio )
{
        if (a_uio == NULL) {
#if LP64_DEBUG
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
                return 0;
        }

        if (UIO_SEG_IS_USER_SPACE(a_uio->uio_segflg)) {
                return 1;
        }
        return 0;
}


/*
 * uio_create - create an uio_t.
 *      Space is allocated to hold up to a_iovcount number of iovecs.  The uio_t
 *      is not fully initialized until all iovecs are added using uio_addiov calls.
 *      a_iovcount is the maximum number of iovecs you may add.
 */
uio_t
uio_create( int a_iovcount,                     /* number of iovecs */
    off_t a_offset,                                             /* current offset */
    int a_spacetype,                                            /* type of address space */
    int a_iodirection )                                 /* read or write flag */
{
        void *                          my_buf_p;
        size_t                          my_size;
        uio_t                           my_uio;

        my_size = UIO_SIZEOF(a_iovcount);
        my_buf_p = kalloc(my_size);
        my_uio = uio_createwithbuffer( a_iovcount,
            a_offset,
            a_spacetype,
            a_iodirection,
            my_buf_p,
            my_size );
        if (my_uio != 0) {
                /* leave a note that we allocated this uio_t */
                my_uio->uio_flags |= UIO_FLAGS_WE_ALLOCED;
#if DEBUG
                os_atomic_inc(&uio_t_count, relaxed);
#endif
        }

        return my_uio;
}


/*
 * uio_createwithbuffer - create an uio_t.
 *      Create a uio_t using the given buffer.  The uio_t
 *      is not fully initialized until all iovecs are added using uio_addiov calls.
 *      a_iovcount is the maximum number of iovecs you may add.
 *      This call may fail if the given buffer is not large enough.
 */
__private_extern__ uio_t
uio_createwithbuffer( int a_iovcount,                   /* number of iovecs */
    off_t a_offset,                                                             /* current offset */
    int a_spacetype,                                                            /* type of address space */
    int a_iodirection,                                                          /* read or write flag */
    void *a_buf_p,                                                              /* pointer to a uio_t buffer */
    size_t a_buffer_size )                                                      /* size of uio_t buffer */
{
        uio_t                           my_uio = (uio_t) a_buf_p;
        size_t                          my_size;

        assert(a_iovcount >= 0 && a_iovcount <= UIO_MAXIOV);
        if (a_iovcount < 0 || a_iovcount > UIO_MAXIOV) {
                return NULL;
        }

        my_size = UIO_SIZEOF(a_iovcount);
        assert(a_buffer_size >= my_size);
        if (a_buffer_size < my_size) {
                return NULL;
        }
        my_size = a_buffer_size;

        assert(my_size <= INT_MAX);
        if (my_size > INT_MAX) {
                return NULL;
        }

        assert(my_uio != NULL);
        assert(IS_VALID_UIO_SEGFLG(a_spacetype));
        assert(a_iodirection == UIO_READ || a_iodirection == UIO_WRITE);

        bzero(my_uio, my_size);
        my_uio->uio_size = (int)my_size;

        /*
         * we use uio_segflg to indicate if the uio_t is the new format or
         * old (pre LP64 support) legacy format
         * This switch statement should canonicalize incoming space type
         * to one of UIO_USERSPACE32/64, UIO_PHYS_USERSPACE32/64, or
         * UIO_SYSSPACE/UIO_PHYS_SYSSPACE
         */
        switch (a_spacetype) {
        case UIO_USERSPACE:
                my_uio->uio_segflg = UIO_USERSPACE32;
                break;
        case UIO_SYSSPACE32:
                my_uio->uio_segflg = UIO_SYSSPACE;
                break;
        case UIO_PHYS_USERSPACE:
                my_uio->uio_segflg = UIO_PHYS_USERSPACE32;
                break;
        default:
                my_uio->uio_segflg = a_spacetype;
                break;
        }

        if (a_iovcount > 0) {
                my_uio->uio_iovs.uiovp = (struct user_iovec *)
                    (((uint8_t *)my_uio) + sizeof(struct uio));
        } else {
                my_uio->uio_iovs.uiovp = NULL;
        }

        my_uio->uio_max_iovs = a_iovcount;
        my_uio->uio_offset = a_offset;
        my_uio->uio_rw = a_iodirection;
        my_uio->uio_flags = UIO_FLAGS_INITED;

        return my_uio;
}

/*
 * uio_spacetype - return the address space type for the given uio_t
 */
__private_extern__ int
uio_spacetype( uio_t a_uio )
{
        if (a_uio == NULL) {
#if LP64_DEBUG
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
                return -1;
        }

        return a_uio->uio_segflg;
}

/*
 * uio_iovsaddr - get the address of the iovec array for the given uio_t.
 * This returns the location of the iovecs within the uio.
 * NOTE - for compatibility mode we just return the current value in uio_iovs
 * which will increase as the IO is completed and is NOT embedded within the
 * uio, it is a seperate array of one or more iovecs.
 */
__private_extern__ struct user_iovec *
uio_iovsaddr( uio_t a_uio )
{
        struct user_iovec *             my_addr;

        if (a_uio == NULL) {
                return NULL;
        }

        if (UIO_SEG_IS_USER_SPACE(a_uio->uio_segflg)) {
                /* we need this for compatibility mode. */
                my_addr = (struct user_iovec *) a_uio->uio_iovs.uiovp;
        } else {
#if DEBUG
                panic("uio_iovsaddr called for UIO_SYSSPACE request");
#endif
                my_addr = 0;
        }
        return my_addr;
}

/*
 * uio_reset - reset an uio_t.
 *      Reset the given uio_t to initial values.  The uio_t is not fully initialized
 *      until all iovecs are added using uio_addiov calls.
 *      The a_iovcount value passed in the uio_create is the maximum number of
 *      iovecs you may add.
 */
void
uio_reset( uio_t a_uio,
    off_t a_offset,                                             /* current offset */
    int a_spacetype,                                            /* type of address space */
    int a_iodirection )                                         /* read or write flag */
{
        vm_size_t       my_size;
        int                     my_max_iovs;
        u_int32_t       my_old_flags;

#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - could not allocate uio_t\n", __FILE__, __LINE__);
        }
        if (!IS_VALID_UIO_SEGFLG(a_spacetype)) {
                panic("%s :%d - invalid address space type\n", __FILE__, __LINE__);
        }
        if (!(a_iodirection == UIO_READ || a_iodirection == UIO_WRITE)) {
                panic("%s :%d - invalid IO direction flag\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL) {
                return;
        }

        my_size = a_uio->uio_size;
        my_old_flags = a_uio->uio_flags;
        my_max_iovs = a_uio->uio_max_iovs;
        bzero(a_uio, my_size);
        a_uio->uio_size = (int)my_size;

        /*
         * we use uio_segflg to indicate if the uio_t is the new format or
         * old (pre LP64 support) legacy format
         * This switch statement should canonicalize incoming space type
         * to one of UIO_USERSPACE32/64, UIO_PHYS_USERSPACE32/64, or
         * UIO_SYSSPACE/UIO_PHYS_SYSSPACE
         */
        switch (a_spacetype) {
        case UIO_USERSPACE:
                a_uio->uio_segflg = UIO_USERSPACE32;
                break;
        case UIO_SYSSPACE32:
                a_uio->uio_segflg = UIO_SYSSPACE;
                break;
        case UIO_PHYS_USERSPACE:
                a_uio->uio_segflg = UIO_PHYS_USERSPACE32;
                break;
        default:
                a_uio->uio_segflg = a_spacetype;
                break;
        }

        if (my_max_iovs > 0) {
                a_uio->uio_iovs.uiovp = (struct user_iovec *)
                    (((uint8_t *)a_uio) + sizeof(struct uio));
        } else {
                a_uio->uio_iovs.uiovp = NULL;
        }

        a_uio->uio_max_iovs = my_max_iovs;
        a_uio->uio_offset = a_offset;
        a_uio->uio_rw = a_iodirection;
        a_uio->uio_flags = my_old_flags;

        return;
}

/*
 * uio_free - free a uio_t allocated via uio_init.  this also frees all
 *      associated iovecs.
 */
void
uio_free( uio_t a_uio )
{
#if DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - passing NULL uio_t\n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio != NULL && (a_uio->uio_flags & UIO_FLAGS_WE_ALLOCED) != 0) {
#if DEBUG
                if (os_atomic_dec_orig(&uio_t_count, relaxed) == 0) {
                        panic("%s :%d - uio_t_count underflow\n", __FILE__, __LINE__);
                }
#endif
                kfree(a_uio, a_uio->uio_size);
        }
}

/*
 * uio_addiov - add an iovec to the given uio_t.  You may call this up to
 *      the a_iovcount number that was passed to uio_create.  This call will
 *      increment the residual IO count as iovecs are added to the uio_t.
 *      returns 0 if add was successful else non zero.
 */
int
uio_addiov( uio_t a_uio, user_addr_t a_baseaddr, user_size_t a_length )
{
        int i;
        user_size_t resid;

        if (a_uio == NULL) {
#if DEBUG
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif
                return -1;
        }

        if (os_add_overflow(a_length, a_uio->uio_resid_64, &resid)) {
#if DEBUG
                panic("%s :%d - invalid length %lu\n", __FILE__, __LINE__, (unsigned long)a_length);
#endif
                return -1;
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                for (i = 0; i < a_uio->uio_max_iovs; i++) {
                        if (a_uio->uio_iovs.uiovp[i].iov_len == 0 && a_uio->uio_iovs.uiovp[i].iov_base == 0) {
                                a_uio->uio_iovs.uiovp[i].iov_len = a_length;
                                a_uio->uio_iovs.uiovp[i].iov_base = a_baseaddr;
                                a_uio->uio_iovcnt++;
                                a_uio->uio_resid_64 = resid;
                                return 0;
                        }
                }
        } else {
                for (i = 0; i < a_uio->uio_max_iovs; i++) {
                        if (a_uio->uio_iovs.kiovp[i].iov_len == 0 && a_uio->uio_iovs.kiovp[i].iov_base == 0) {
                                a_uio->uio_iovs.kiovp[i].iov_len = (u_int64_t)a_length;
                                a_uio->uio_iovs.kiovp[i].iov_base = (u_int64_t)a_baseaddr;
                                a_uio->uio_iovcnt++;
                                a_uio->uio_resid_64 = resid;
                                return 0;
                        }
                }
        }

        return -1;
}

/*
 * uio_getiov - get iovec data associated with the given uio_t.  Use
 *  a_index to iterate over each iovec (0 to (uio_iovcnt(uio_t) - 1)).
 *  a_baseaddr_p and a_length_p may be NULL.
 *      returns -1 when a_index is >= uio_t.uio_iovcnt or invalid uio_t.
 *      returns 0 when data is returned.
 */
int
uio_getiov( uio_t a_uio,
    int a_index,
    user_addr_t * a_baseaddr_p,
    user_size_t * a_length_p )
{
        if (a_uio == NULL) {
#if DEBUG
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* DEBUG */
                return -1;
        }
        if (a_index < 0 || a_index >= a_uio->uio_iovcnt) {
                return -1;
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                if (a_baseaddr_p != NULL) {
                        *a_baseaddr_p = a_uio->uio_iovs.uiovp[a_index].iov_base;
                }
                if (a_length_p != NULL) {
                        *a_length_p = a_uio->uio_iovs.uiovp[a_index].iov_len;
                }
        } else {
                if (a_baseaddr_p != NULL) {
                        *a_baseaddr_p = (user_addr_t)a_uio->uio_iovs.kiovp[a_index].iov_base;
                }
                if (a_length_p != NULL) {
                        *a_length_p = (user_size_t)a_uio->uio_iovs.kiovp[a_index].iov_len;
                }
        }

        return 0;
}

/*
 * uio_calculateresid - runs through all iovecs associated with this
 *      uio_t and calculates (and sets) the residual IO count.
 */
__private_extern__ int
uio_calculateresid( uio_t a_uio )
{
        int                     i;
        u_int64_t               resid = 0;

        if (a_uio == NULL) {
#if LP64_DEBUG
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
                return EINVAL;
        }

        a_uio->uio_iovcnt = a_uio->uio_max_iovs;
        if (UIO_IS_USER_SPACE(a_uio)) {
                a_uio->uio_resid_64 = 0;
                for (i = 0; i < a_uio->uio_max_iovs; i++) {
                        if (a_uio->uio_iovs.uiovp[i].iov_len != 0 && a_uio->uio_iovs.uiovp[i].iov_base != 0) {
                                if (a_uio->uio_iovs.uiovp[i].iov_len > LONG_MAX) {
                                        return EINVAL;
                                }
                                resid += a_uio->uio_iovs.uiovp[i].iov_len;
                                if (resid > LONG_MAX) {
                                        return EINVAL;
                                }
                        }
                }
                a_uio->uio_resid_64 = (user_size_t)resid;

                /* position to first non zero length iovec (4235922) */
                while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.uiovp->iov_len == 0) {
                        a_uio->uio_iovcnt--;
                        if (a_uio->uio_iovcnt > 0) {
                                a_uio->uio_iovs.uiovp++;
                        }
                }
        } else {
                a_uio->uio_resid_64 = 0;
                for (i = 0; i < a_uio->uio_max_iovs; i++) {
                        if (a_uio->uio_iovs.kiovp[i].iov_len != 0 && a_uio->uio_iovs.kiovp[i].iov_base != 0) {
                                if (a_uio->uio_iovs.kiovp[i].iov_len > LONG_MAX) {
                                        return EINVAL;
                                }
                                resid += a_uio->uio_iovs.kiovp[i].iov_len;
                                if (resid > LONG_MAX) {
                                        return EINVAL;
                                }
                        }
                }
                a_uio->uio_resid_64 = (user_size_t)resid;

                /* position to first non zero length iovec (4235922) */
                while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.kiovp->iov_len == 0) {
                        a_uio->uio_iovcnt--;
                        if (a_uio->uio_iovcnt > 0) {
                                a_uio->uio_iovs.kiovp++;
                        }
                }
        }

        return 0;
}

/*
 * uio_update - update the given uio_t for a_count of completed IO.
 *      This call decrements the current iovec length and residual IO value
 *      and increments the current iovec base address and offset value.
 *      If the current iovec length is 0 then advance to the next
 *      iovec (if any).
 *      If the a_count passed in is 0, than only do the advancement
 *      over any 0 length iovec's.
 */
void
uio_update( uio_t a_uio, user_size_t a_count )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
        if (UIO_IS_32_BIT_SPACE(a_uio) && a_count > 0xFFFFFFFFull) {
                panic("%s :%d - invalid count value \n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL || a_uio->uio_iovcnt < 1) {
                return;
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                /*
                 * if a_count == 0, then we are asking to skip over
                 * any empty iovs
                 */
                if (a_count) {
                        if (a_count > a_uio->uio_iovs.uiovp->iov_len) {
                                a_uio->uio_iovs.uiovp->iov_base += a_uio->uio_iovs.uiovp->iov_len;
                                a_uio->uio_iovs.uiovp->iov_len = 0;
                        } else {
                                a_uio->uio_iovs.uiovp->iov_base += a_count;
                                a_uio->uio_iovs.uiovp->iov_len -= a_count;
                        }
                        if (a_count > (user_size_t)a_uio->uio_resid_64) {
                                a_uio->uio_offset += a_uio->uio_resid_64;
                                a_uio->uio_resid_64 = 0;
                        } else {
                                a_uio->uio_offset += a_count;
                                a_uio->uio_resid_64 -= a_count;
                        }
                }
                /*
                 * advance to next iovec if current one is totally consumed
                 */
                while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.uiovp->iov_len == 0) {
                        a_uio->uio_iovcnt--;
                        if (a_uio->uio_iovcnt > 0) {
                                a_uio->uio_iovs.uiovp++;
                        }
                }
        } else {
                /*
                 * if a_count == 0, then we are asking to skip over
                 * any empty iovs
                 */
                if (a_count) {
                        if (a_count > a_uio->uio_iovs.kiovp->iov_len) {
                                a_uio->uio_iovs.kiovp->iov_base += a_uio->uio_iovs.kiovp->iov_len;
                                a_uio->uio_iovs.kiovp->iov_len = 0;
                        } else {
                                a_uio->uio_iovs.kiovp->iov_base += a_count;
                                a_uio->uio_iovs.kiovp->iov_len -= a_count;
                        }
                        if (a_count > (user_size_t)a_uio->uio_resid_64) {
                                a_uio->uio_offset += a_uio->uio_resid_64;
                                a_uio->uio_resid_64 = 0;
                        } else {
                                a_uio->uio_offset += a_count;
                                a_uio->uio_resid_64 -= a_count;
                        }
                }
                /*
                 * advance to next iovec if current one is totally consumed
                 */
                while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.kiovp->iov_len == 0) {
                        a_uio->uio_iovcnt--;
                        if (a_uio->uio_iovcnt > 0) {
                                a_uio->uio_iovs.kiovp++;
                        }
                }
        }
        return;
}

/*
 * uio_pushback - undo uncommitted I/O by subtracting from the
 * current base address and offset, and incrementing the residiual
 * IO. If the UIO was previously exhausted, this call will panic.
 * New code should not use this functionality.
 */
__private_extern__ void
uio_pushback( uio_t a_uio, user_size_t a_count )
{
#if LP64_DEBUG
        if (a_uio == NULL) {
                panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
        }
        if (UIO_IS_32_BIT_SPACE(a_uio) && a_count > 0xFFFFFFFFull) {
                panic("%s :%d - invalid count value \n", __FILE__, __LINE__);
        }
#endif /* LP64_DEBUG */

        if (a_uio == NULL || a_count == 0) {
                return;
        }

        if (a_uio->uio_iovcnt < 1) {
                panic("Invalid uio for pushback");
        }

        if (UIO_IS_USER_SPACE(a_uio)) {
                a_uio->uio_iovs.uiovp->iov_base -= a_count;
                a_uio->uio_iovs.uiovp->iov_len += a_count;
        } else {
                a_uio->uio_iovs.kiovp->iov_base -= a_count;
                a_uio->uio_iovs.kiovp->iov_len += a_count;
        }

        a_uio->uio_offset -= a_count;
        a_uio->uio_resid_64 += a_count;

        return;
}


/*
 * uio_duplicate - allocate a new uio and make a copy of the given uio_t.
 *      may return NULL.
 */
uio_t
uio_duplicate( uio_t a_uio )
{
        uio_t           my_uio;
        int                     i;

        if (a_uio == NULL) {
                return NULL;
        }

        my_uio = (uio_t) kalloc(a_uio->uio_size);
        if (my_uio == 0) {
                panic("%s :%d - allocation failed\n", __FILE__, __LINE__);
        }

        bcopy((void *)a_uio, (void *)my_uio, a_uio->uio_size);
        /* need to set our iovec pointer to point to first active iovec */
        if (my_uio->uio_max_iovs > 0) {
                my_uio->uio_iovs.uiovp = (struct user_iovec *)
                    (((uint8_t *)my_uio) + sizeof(struct uio));

                /* advance to first nonzero iovec */
                if (my_uio->uio_iovcnt > 0) {
                        for (i = 0; i < my_uio->uio_max_iovs; i++) {
                                if (UIO_IS_USER_SPACE(a_uio)) {
                                        if (my_uio->uio_iovs.uiovp->iov_len != 0) {
                                                break;
                                        }
                                        my_uio->uio_iovs.uiovp++;
                                } else {
                                        if (my_uio->uio_iovs.kiovp->iov_len != 0) {
                                                break;
                                        }
                                        my_uio->uio_iovs.kiovp++;
                                }
                        }
                }
        }

        my_uio->uio_flags = UIO_FLAGS_WE_ALLOCED | UIO_FLAGS_INITED;
#if DEBUG
        os_atomic_inc(&uio_t_count, relaxed);
#endif


        return my_uio;
}

int
copyin_user_iovec_array(user_addr_t uaddr, int spacetype, int count, struct user_iovec *dst)
{
        size_t size_of_iovec = (spacetype == UIO_USERSPACE64 ? sizeof(struct user64_iovec) : sizeof(struct user32_iovec));
        int error;
        int i;

        // copyin to the front of "dst", without regard for putting records in the right places
        error = copyin(uaddr, dst, count * size_of_iovec);
        if (error) {
                return error;
        }

        // now, unpack the entries in reverse order, so we don't overwrite anything
        for (i = count - 1; i >= 0; i--) {
                if (spacetype == UIO_USERSPACE64) {
                        struct user64_iovec iovec = ((struct user64_iovec *)dst)[i];
                        dst[i].iov_base = (user_addr_t)iovec.iov_base;
                        dst[i].iov_len = (user_size_t)iovec.iov_len;
                } else {
                        struct user32_iovec iovec = ((struct user32_iovec *)dst)[i];
                        dst[i].iov_base = iovec.iov_base;
                        dst[i].iov_len = iovec.iov_len;
                }
        }

        return 0;
}