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