1 | /*
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2 | * volume_id - reads filesystem label and uuid
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3 | *
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4 | * Copyright (C) 2012 S-G Bergh <sgb@systemasis.org>
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5 | *
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6 | * Licensed under GPLv2, see file LICENSE in this source tree.
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7 | */
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8 |
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9 | //kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_SQUASHFS) += squashfs.o
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10 |
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11 | //config:
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12 | //config:config FEATURE_VOLUMEID_SQUASHFS
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13 | //config: bool "SquashFS filesystem"
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14 | //config: default y
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15 | //config: depends on VOLUMEID && FEATURE_BLKID_TYPE
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16 | //config: help
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17 | //config: Squashfs is a compressed read-only filesystem for Linux. Squashfs is
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18 | //config: intended for general read-only filesystem use and in constrained block
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19 | //config: device/memory systems (e.g. embedded systems) where low overhead is
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20 | //config: needed.
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21 | //config:
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22 |
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23 | #include "volume_id_internal.h"
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24 |
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25 | struct squashfs_superblock {
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26 | uint32_t magic;
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27 | /*
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28 | uint32_t dummy[6];
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29 | uint16_t major;
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30 | uint16_t minor;
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31 | */
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32 | } PACKED;
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33 |
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34 | int FAST_FUNC volume_id_probe_squashfs(struct volume_id *id /*,uint64_t off*/)
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35 | {
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36 | #define off ((uint64_t)0)
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37 | struct squashfs_superblock *sb;
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38 |
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39 | dbg("SquashFS: probing at offset 0x%llx", (unsigned long long) off);
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40 | sb = volume_id_get_buffer(id, off, 0x200);
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41 | if (!sb)
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42 | return -1;
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43 |
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44 | // Old SquashFS (pre 4.0) can be both big and little endian, so test for both.
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45 | // Likewise, it is commonly used in firwmare with some non-standard signatures.
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46 | #define pack(a,b,c,d) ( (uint32_t)((a * 256 + b) * 256 + c) * 256 + d )
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47 | #define SIG1 pack('s','q','s','h')
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48 | #define SIG2 pack('h','s','q','s')
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49 | #define SIG3 pack('s','h','s','q')
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50 | #define SIG4 pack('q','s','h','s')
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51 | if (sb->magic == SIG1
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52 | || sb->magic == SIG2
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53 | || sb->magic == SIG3
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54 | || sb->magic == SIG4
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55 | ) {
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56 | IF_FEATURE_BLKID_TYPE(id->type = "squashfs";)
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57 | return 0;
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58 | }
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59 |
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60 | return -1;
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61 | }
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