bsd/hfs/hfs_endian.h

   1 /*
   2  * Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 #ifndef __HFS_ENDIAN_H__
  31 #define __HFS_ENDIAN_H__
  32
  33 #include <sys/appleapiopts.h>
  34
  35 #ifdef KERNEL
  36 #ifdef __APPLE_API_PRIVATE
  37 /*
  38  * hfs_endian.h
  39  *
  40  * This file prototypes endian swapping routines for the HFS/HFS Plus
  41  * volume format.
  42  */
  43 #include "hfs.h"
  44 #include "hfscommon/headers/BTreesInternal.h"
  45 #include <architecture/byte_order.h>
  46
  47 /*********************/
  48 /* BIG ENDIAN Macros */
  49 /*********************/
  50 #if BYTE_ORDER == BIG_ENDIAN
  51
  52     /* HFS is always big endian, make swaps into no-ops */
  53     #define SWAP_BE16(__a) (__a)
  54     #define SWAP_BE32(__a) (__a)
  55     #define SWAP_BE64(__a) (__a)
  56
  57     /* HFS is always big endian, no swapping needed */
  58     #define SWAP_HFS_PLUS_FORK_DATA(__a)
  59
  60 /************************/
  61 /* LITTLE ENDIAN Macros */
  62 /************************/
  63 #elif BYTE_ORDER == LITTLE_ENDIAN
  64
  65     /* HFS is always big endian, make swaps actually swap */
  66     #define SWAP_BE16(__a)                                                      NXSwapBigShortToHost (__a)
  67     #define SWAP_BE32(__a)                                                      NXSwapBigLongToHost (__a)
  68     #define SWAP_BE64(__a)                                                      NXSwapBigLongLongToHost (__a)
  69
  70     #define SWAP_HFS_PLUS_FORK_DATA(__a)                        hfs_swap_HFSPlusForkData ((__a))
  71
  72 #else
  73 #warning Unknown byte order
  74 #error
  75 #endif
  76
  77 #ifdef __cplusplus
  78 extern "C" {
  79 #endif
  80
  81 /*
  82  * Constants for the "unswap" argument to hfs_swap_BTNode:
  83  */
  84 enum HFSBTSwapDirection {
  85         kSwapBTNodeBigToHost            =       0,
  86         kSwapBTNodeHostToBig            =       1,
  87
  88         /*
  89          * kSwapBTNodeHeaderRecordOnly is used to swap just the header record
  90          * of a header node from big endian (on disk) to host endian (in memory).
  91          * It does not swap the node descriptor (forward/backward links, record
  92          * count, etc.).  It assumes the header record is at offset 0x000E.
  93          *
  94          * Since HFS Plus doesn't have fixed B-tree node sizes, we have to read
  95          * the header record to determine the actual node size for that tree
  96          * before we can set up the B-tree control block.  We read it initially
  97          * as 512 bytes, then re-read it once we know the correct node size.  Since
  98          * we may not have read the entire header node the first time, we can't
  99          * swap the record offsets, other records, or do most sanity checks.
 100          */
 101         kSwapBTNodeHeaderRecordOnly     =       3
 102 };
 103
 104 int  hfs_swap_BTNode (BlockDescriptor *src, vnode_t vp, enum HFSBTSwapDirection direction);
 105
 106 #ifdef __cplusplus
 107 }
 108 #endif
 109
 110 #endif /* __APPLE_API_PRIVATE */
 111 #endif /* KERNEL */
 112 #endif /* __HFS_FORMAT__ */