115 lines
3.5 KiB
C
115 lines
3.5 KiB
C
/*
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* cramfs_common - cramfs common code
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*
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* Copyright (c) 2008 Roy Peled, the.roy.peled -at- gmail
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* Copyright (c) 2004-2006 by Juliane Holzt, kju -at- fqdn.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#ifndef __CRAMFS_H
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#define __CRAMFS_H
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#include <stdint.h>
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#define CRAMFS_MAGIC 0x28cd3d45 /* some random number */
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#define CRAMFS_SIGNATURE "Compressed ROMFS"
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/*
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* Width of various bitfields in struct cramfs_inode.
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* Primarily used to generate warnings in mkcramfs.
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*/
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#define CRAMFS_MODE_WIDTH 16
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#define CRAMFS_UID_WIDTH 16
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#define CRAMFS_SIZE_WIDTH 24
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#define CRAMFS_GID_WIDTH 8
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#define CRAMFS_NAMELEN_WIDTH 6
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#define CRAMFS_OFFSET_WIDTH 26
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#ifndef HOST_IS_BIG_ENDIAN
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#ifdef WORDS_BIGENDIAN
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#define HOST_IS_BIG_ENDIAN 1
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#else
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#define HOST_IS_BIG_ENDIAN 0
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#endif
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#endif
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/*
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* Reasonably terse representation of the inode data.
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*/
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struct cramfs_inode {
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uint32_t mode:16, uid:16;
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/* SIZE for device files is i_rdev */
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uint32_t size:24, gid:8;
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/*
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* NAMELEN is the length of the file name, divided by 4 and
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* rounded up. (cramfs doesn't support hard links.)
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*
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* OFFSET: For symlinks and non-empty regular files, this
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* contains the offset (divided by 4) of the file data in
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* compressed form (starting with an array of block pointers;
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* see README). For non-empty directories it is the offset
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* (divided by 4) of the inode of the first file in that
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* directory. For anything else, offset is zero.
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*/
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uint32_t namelen:6, offset:26;
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};
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struct cramfs_info {
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uint32_t crc;
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uint32_t edition;
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uint32_t blocks;
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uint32_t files;
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};
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/*
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* Superblock information at the beginning of the FS.
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*/
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struct cramfs_super {
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uint32_t magic; /* 0x28cd3d45 - random number */
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uint32_t size; /* Not used. mkcramfs currently
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writes a constant 1<<16 here. */
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uint32_t flags; /* 0 */
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uint32_t future; /* 0 */
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uint8_t signature[16]; /* "Compressed ROMFS" */
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struct cramfs_info fsid;/* unique filesystem info */
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uint8_t name[16]; /* user-defined name */
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struct cramfs_inode root; /* Root inode data */
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};
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#define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */
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#define CRAMFS_FLAG_SORTED_DIRS 0x00000002 /* sorted dirs */
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#define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */
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#define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
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#define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */
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/*
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* Valid values in super.flags. Currently we refuse to mount
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* if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be
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* changed to test super.future instead.
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*/
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#define CRAMFS_SUPPORTED_FLAGS (0xff)
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/* Uncompression interfaces to the underlying zlib */
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int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
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int cramfs_uncompress_init(void);
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int cramfs_uncompress_exit(void);
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uint32_t u32_toggle_endianness(int big_endian, uint32_t what);
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void super_toggle_endianness(int from_big_endian, struct cramfs_super *super);
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void inode_to_host(int from_big_endian, struct cramfs_inode *inode_in,
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struct cramfs_inode *inode_out);
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void inode_from_host(int to_big_endian, struct cramfs_inode *inode_in,
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struct cramfs_inode *inode_out);
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#endif
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