fd7c4230b2
part of fixing msdosfs for large sector sizes. One of the fixed bugs was fatal for large sector sizes. 1. The fsinfo block has size 512, but it was misunderstood and declared as having size 1024, with nothing in the second 512 bytes except a signature at the end. The second 512 bytes actually normally (if the file system was created by Windows) consist of a second boot sector which is normally (in WinXP) empty except for a signature -- the normal layout is one boot sector, one fsinfo sector, another boot sector, then these 3 sectors duplicated. However, other layouts are valid. newfs_msdos produces a valid layout with one boot sector, one fsinfo sector, then these 2 sectors duplicated. The signature check for the extra part of the fsinfo was thus normally checking the signature in either the second boot sector or the first boot sector in the copy, and thus accidentally succeeding. The extra signature check would just fail for weirder layouts with 512-byte sectors, and for normal layouts with any other sector size. Remove the extra bytes and the extra signature check. 2. Old versions did i/o to the fsinfo block using size 1024, with the second half only used for the extra signature check on read. This was harmless for sector size 512, and worked accidentally for sector size 1024. The i/o just failed for larger sector sizes. The version being fixed did i/o to the fsinfo block using size fsi_size(pmp) = (1024 << ((pmp)->pm_BlkPerSec >> 2)). This expression makes no sense. It happens to work for sector small sector sizes, but for sector size 32K it gives the preposterous value of 64M and thus causes panics. A sector size of 32768 is necessary for at least some DVD-RW's (where the minimum write size is 32768 although the minimum read size is 2048). Now that the size of the fsinfo block is 512, it always fits in one sector so there is no need for a macro to express it. Just use the sector size where the old code uses 1024. Approved by: re (kensmith) Approved by: nyan (several years ago for a different version of (2))
171 lines
6.3 KiB
C
171 lines
6.3 KiB
C
/* $FreeBSD$ */
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/* $NetBSD: bpb.h,v 1.7 1997/11/17 15:36:24 ws Exp $ */
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/*-
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* Written by Paul Popelka (paulp@uts.amdahl.com)
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*
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* You can do anything you want with this software, just don't say you wrote
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* it, and don't remove this notice.
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*
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* This software is provided "as is".
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*
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* The author supplies this software to be publicly redistributed on the
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* understanding that the author is not responsible for the correct
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* functioning of this software in any circumstances and is not liable for
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* any damages caused by this software.
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*
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* October 1992
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*/
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/*
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* BIOS Parameter Block (BPB) for DOS 3.3
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*/
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struct bpb33 {
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u_int16_t bpbBytesPerSec; /* bytes per sector */
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u_int8_t bpbSecPerClust; /* sectors per cluster */
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u_int16_t bpbResSectors; /* number of reserved sectors */
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u_int8_t bpbFATs; /* number of FATs */
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u_int16_t bpbRootDirEnts; /* number of root directory entries */
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u_int16_t bpbSectors; /* total number of sectors */
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u_int8_t bpbMedia; /* media descriptor */
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u_int16_t bpbFATsecs; /* number of sectors per FAT */
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u_int16_t bpbSecPerTrack; /* sectors per track */
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u_int16_t bpbHeads; /* number of heads */
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u_int16_t bpbHiddenSecs; /* number of hidden sectors */
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};
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/*
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* BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
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* and bpbHugeSectors is not in the 3.3 bpb.
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*/
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struct bpb50 {
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u_int16_t bpbBytesPerSec; /* bytes per sector */
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u_int8_t bpbSecPerClust; /* sectors per cluster */
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u_int16_t bpbResSectors; /* number of reserved sectors */
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u_int8_t bpbFATs; /* number of FATs */
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u_int16_t bpbRootDirEnts; /* number of root directory entries */
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u_int16_t bpbSectors; /* total number of sectors */
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u_int8_t bpbMedia; /* media descriptor */
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u_int16_t bpbFATsecs; /* number of sectors per FAT */
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u_int16_t bpbSecPerTrack; /* sectors per track */
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u_int16_t bpbHeads; /* number of heads */
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u_int32_t bpbHiddenSecs; /* # of hidden sectors */
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u_int32_t bpbHugeSectors; /* # of sectors if bpbSectors == 0 */
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};
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/*
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* BPB for DOS 7.10 (FAT32). This one has a few extensions to bpb50.
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*/
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struct bpb710 {
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u_int16_t bpbBytesPerSec; /* bytes per sector */
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u_int8_t bpbSecPerClust; /* sectors per cluster */
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u_int16_t bpbResSectors; /* number of reserved sectors */
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u_int8_t bpbFATs; /* number of FATs */
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u_int16_t bpbRootDirEnts; /* number of root directory entries */
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u_int16_t bpbSectors; /* total number of sectors */
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u_int8_t bpbMedia; /* media descriptor */
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u_int16_t bpbFATsecs; /* number of sectors per FAT */
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u_int16_t bpbSecPerTrack; /* sectors per track */
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u_int16_t bpbHeads; /* number of heads */
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u_int32_t bpbHiddenSecs; /* # of hidden sectors */
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u_int32_t bpbHugeSectors; /* # of sectors if bpbSectors == 0 */
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u_int32_t bpbBigFATsecs; /* like bpbFATsecs for FAT32 */
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u_int16_t bpbExtFlags; /* extended flags: */
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#define FATNUM 0xf /* mask for numbering active FAT */
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#define FATMIRROR 0x80 /* FAT is mirrored (like it always was) */
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u_int16_t bpbFSVers; /* filesystem version */
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#define FSVERS 0 /* currently only 0 is understood */
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u_int32_t bpbRootClust; /* start cluster for root directory */
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u_int16_t bpbFSInfo; /* filesystem info structure sector */
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u_int16_t bpbBackup; /* backup boot sector */
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/* There is a 12 byte filler here, but we ignore it */
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};
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/*
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* The following structures represent how the bpb's look on disk. shorts
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* and longs are just character arrays of the appropriate length. This is
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* because the compiler forces shorts and longs to align on word or
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* halfword boundaries.
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*/
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#include <sys/endian.h>
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#define getushort(x) le16dec(x)
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#define getulong(x) le32dec(x)
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#define putushort(p, v) le16enc(p, v)
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#define putulong(p, v) le32enc(p, v)
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/*
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* BIOS Parameter Block (BPB) for DOS 3.3
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*/
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struct byte_bpb33 {
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int8_t bpbBytesPerSec[2]; /* bytes per sector */
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int8_t bpbSecPerClust; /* sectors per cluster */
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int8_t bpbResSectors[2]; /* number of reserved sectors */
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int8_t bpbFATs; /* number of FATs */
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int8_t bpbRootDirEnts[2]; /* number of root directory entries */
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int8_t bpbSectors[2]; /* total number of sectors */
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int8_t bpbMedia; /* media descriptor */
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int8_t bpbFATsecs[2]; /* number of sectors per FAT */
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int8_t bpbSecPerTrack[2]; /* sectors per track */
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int8_t bpbHeads[2]; /* number of heads */
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int8_t bpbHiddenSecs[2]; /* number of hidden sectors */
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};
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/*
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* BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
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* and bpbHugeSectors is not in the 3.3 bpb.
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*/
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struct byte_bpb50 {
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int8_t bpbBytesPerSec[2]; /* bytes per sector */
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int8_t bpbSecPerClust; /* sectors per cluster */
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int8_t bpbResSectors[2]; /* number of reserved sectors */
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int8_t bpbFATs; /* number of FATs */
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int8_t bpbRootDirEnts[2]; /* number of root directory entries */
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int8_t bpbSectors[2]; /* total number of sectors */
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int8_t bpbMedia; /* media descriptor */
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int8_t bpbFATsecs[2]; /* number of sectors per FAT */
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int8_t bpbSecPerTrack[2]; /* sectors per track */
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int8_t bpbHeads[2]; /* number of heads */
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int8_t bpbHiddenSecs[4]; /* number of hidden sectors */
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int8_t bpbHugeSectors[4]; /* # of sectors if bpbSectors == 0 */
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};
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/*
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* BPB for DOS 7.10 (FAT32). This one has a few extensions to bpb50.
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*/
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struct byte_bpb710 {
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u_int8_t bpbBytesPerSec[2]; /* bytes per sector */
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u_int8_t bpbSecPerClust; /* sectors per cluster */
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u_int8_t bpbResSectors[2]; /* number of reserved sectors */
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u_int8_t bpbFATs; /* number of FATs */
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u_int8_t bpbRootDirEnts[2]; /* number of root directory entries */
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u_int8_t bpbSectors[2]; /* total number of sectors */
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u_int8_t bpbMedia; /* media descriptor */
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u_int8_t bpbFATsecs[2]; /* number of sectors per FAT */
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u_int8_t bpbSecPerTrack[2]; /* sectors per track */
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u_int8_t bpbHeads[2]; /* number of heads */
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u_int8_t bpbHiddenSecs[4]; /* # of hidden sectors */
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u_int8_t bpbHugeSectors[4]; /* # of sectors if bpbSectors == 0 */
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u_int8_t bpbBigFATsecs[4]; /* like bpbFATsecs for FAT32 */
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u_int8_t bpbExtFlags[2]; /* extended flags: */
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u_int8_t bpbFSVers[2]; /* filesystem version */
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u_int8_t bpbRootClust[4]; /* start cluster for root directory */
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u_int8_t bpbFSInfo[2]; /* filesystem info structure sector */
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u_int8_t bpbBackup[2]; /* backup boot sector */
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/* There is a 12 byte filler here, but we ignore it */
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};
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/*
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* FAT32 FSInfo block.
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*/
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struct fsinfo {
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u_int8_t fsisig1[4];
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u_int8_t fsifill1[480];
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u_int8_t fsisig2[4];
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u_int8_t fsinfree[4];
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u_int8_t fsinxtfree[4];
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u_int8_t fsifill2[12];
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u_int8_t fsisig3[4];
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};
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