[3621] | 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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