core/hfs_endian.h

   1 /*
   2  * Copyright (c) 2000, 2002-2003, 2005-2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_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 License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 #ifndef __HFS_ENDIAN_H__
  29 #define __HFS_ENDIAN_H__
  30
  31 #include <sys/appleapiopts.h>
  32
  33 #ifdef KERNEL
  34 #ifdef __APPLE_API_PRIVATE
  35 /*
  36  * hfs_endian.h
  37  *
  38  * This file prototypes endian swapping routines for the HFS/HFS Plus
  39  * volume format.
  40  */
  41 #include "hfs.h"
  42 #include "BTreesInternal.h"
  43 #include <libkern/OSByteOrder.h>
  44
  45 /*********************/
  46 /* BIG ENDIAN Macros */
  47 /*********************/
  48 #define SWAP_BE16(__a)                                                  OSSwapBigToHostInt16 (__a)
  49 #define SWAP_BE32(__a)                                                  OSSwapBigToHostInt32 (__a)
  50 #define SWAP_BE64(__a)                                                  OSSwapBigToHostInt64 (__a)
  51
  52 #if BYTE_ORDER == BIG_ENDIAN
  53
  54     /* HFS is always big endian, no swapping needed */
  55     #define SWAP_HFS_PLUS_FORK_DATA(__a)
  56
  57 /************************/
  58 /* LITTLE ENDIAN Macros */
  59 /************************/
  60 #elif BYTE_ORDER == LITTLE_ENDIAN
  61
  62     #define SWAP_HFS_PLUS_FORK_DATA(__a)                        hfs_swap_HFSPlusForkData ((__a))
  63
  64 #else
  65 #warning Unknown byte order
  66 #error
  67 #endif
  68
  69 #ifdef __cplusplus
  70 extern "C" {
  71 #endif
  72
  73 /*
  74  * Constants for the "unswap" argument to hfs_swap_BTNode:
  75  */
  76 enum HFSBTSwapDirection {
  77         kSwapBTNodeBigToHost            =       0,
  78         kSwapBTNodeHostToBig            =       1,
  79
  80         /*
  81          * kSwapBTNodeHeaderRecordOnly is used to swap just the header record
  82          * of a header node from big endian (on disk) to host endian (in memory).
  83          * It does not swap the node descriptor (forward/backward links, record
  84          * count, etc.).  It assumes the header record is at offset 0x000E.
  85          *
  86          * Since HFS Plus doesn't have fixed B-tree node sizes, we have to read
  87          * the header record to determine the actual node size for that tree
  88          * before we can set up the B-tree control block.  We read it initially
  89          * as 512 bytes, then re-read it once we know the correct node size.  Since
  90          * we may not have read the entire header node the first time, we can't
  91          * swap the record offsets, other records, or do most sanity checks.
  92          */
  93         kSwapBTNodeHeaderRecordOnly     =       3
  94 };
  95
  96 int  hfs_swap_BTNode (BlockDescriptor *src, vnode_t vp, enum HFSBTSwapDirection direction,
  97         u_int8_t allow_empty_node);
  98
  99 #ifdef __cplusplus
 100 }
 101 #endif
 102
 103 #endif /* __APPLE_API_PRIVATE */
 104 #endif /* KERNEL */
 105 #endif /* __HFS_FORMAT__ */