fsck_hfs/dfalib/fsck_journal.h

   1 /*
   2  * Copyright (c) 2000-2012 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
  29 #ifndef _FSCK_JOURNAL_H
  30 #define _FSCK_JOURNAL_H
  31
  32 #include <sys/cdefs.h>
  33
  34 #include <sys/types.h>
  35
  36 /*
  37  * The guts of the journal:  a descriptor for which
  38  * block number on the data disk is to be written.
  39  */
  40 typedef struct block_info {
  41         uint64_t        bnum;
  42         uint32_t        bsize;
  43         uint32_t        next;
  44 } __attribute__((__packed__)) block_info;
  45
  46 /*
  47  * A "transaction," for want of a better word.
  48  * This contains a series of block_info, in the
  49  * binfo array, which are used to modify the
  50  * filesystem.
  51  */
  52 typedef struct block_list_header {
  53         uint16_t        max_blocks;
  54         uint16_t        num_blocks;
  55         uint32_t        bytes_used;
  56         uint32_t        checksum;
  57         uint32_t        pad;
  58         block_info      binfo[1];
  59 } __attribute__((__packed__)) block_list_header;
  60
  61 /*
  62  * This is written to block zero of the journal and it
  63  * maintains overall state about the journal.
  64  */
  65 typedef struct journal_header {
  66     int32_t        magic;
  67     int32_t        endian;
  68     off_t        start;         // zero-based byte offset of the start of the first transaction
  69     off_t       end;           // zero-based byte offset of where free space begins
  70     off_t          size;          // size in bytes of the entire journal
  71     int32_t        blhdr_size;    // size in bytes of each block_list_header in the journal
  72     int32_t        checksum;
  73     int32_t        jhdr_size;     // block size (in bytes) of the journal header
  74     uint32_t       sequence_num;  // NEW FIELD: a monotonically increasing value assigned to all txn's
  75 } __attribute__((__packed__)) journal_header;
  76
  77 #define JOURNAL_HEADER_MAGIC    0x4a4e4c78   // 'JNLx'
  78 #define OLD_JOURNAL_HEADER_MAGIC        0x4a484452   // 'JHDR'
  79 #define ENDIAN_MAGIC    0x12345678
  80
  81 //
  82 // we only checksum the original size of the journal_header to remain
  83 // backwards compatible.  the size of the original journal_header is
  84 // everything up to the the sequence_num field, hence we use the
  85 // offsetof macro to calculate the size.
  86 //
  87 #define JOURNAL_HEADER_CKSUM_SIZE  (offsetof(struct journal_header, sequence_num))
  88
  89 #define OLD_JOURNAL_HEADER_MAGIC  0x4a484452   // 'JHDR'
  90
  91 /*
  92  * The function used by fsck_hfs to replay the journal.
  93  * It's modeled on the kernel function.
  94  *
  95  * For the do_write_b block, the offset argument is in bytes --
  96  * the journal replay code will convert from journal block to
  97  * bytes.
  98  */
  99
 100 int     journal_open(int jdev,
 101                      off_t         offset,
 102                      off_t         journal_size,
 103                      size_t        min_fs_block_size,
 104                      uint32_t       flags,
 105                      const char *jdev_name,
 106                      int (^do_write_b)(off_t, void *, size_t));
 107
 108 #endif /* !_FSCK_JOURNAL_H */