mirror of
https://github.com/nitraiolo/CfgUSBLoader.git
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156 lines
3.5 KiB
C
156 lines
3.5 KiB
C
/*
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* ext_attr.c --- extended attribute blocks
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*
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* Copyright (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
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*
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* Copyright (C) 2002 Theodore Ts'o.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Library
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* General Public License, version 2.
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* %End-Header%
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*/
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#include <stdio.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <string.h>
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#include <time.h>
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#include "ext2_fs.h"
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#include "ext2_ext_attr.h"
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#include "ext2fs.h"
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#define NAME_HASH_SHIFT 5
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#define VALUE_HASH_SHIFT 16
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/*
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* ext2_xattr_hash_entry()
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*
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* Compute the hash of an extended attribute.
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*/
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__u32 ext2fs_ext_attr_hash_entry(struct ext2_ext_attr_entry *entry, void *data)
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{
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__u32 hash = 0;
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char *name = ((char *) entry) + sizeof(struct ext2_ext_attr_entry);
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int n;
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for (n = 0; n < entry->e_name_len; n++) {
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hash = (hash << NAME_HASH_SHIFT) ^
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(hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
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*name++;
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}
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/* The hash needs to be calculated on the data in little-endian. */
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if (entry->e_value_block == 0 && entry->e_value_size != 0) {
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__u32 *value = (__u32 *)data;
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for (n = (entry->e_value_size + EXT2_EXT_ATTR_ROUND) >>
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EXT2_EXT_ATTR_PAD_BITS; n; n--) {
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hash = (hash << VALUE_HASH_SHIFT) ^
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(hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
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ext2fs_le32_to_cpu(*value++);
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}
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}
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return hash;
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}
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#undef NAME_HASH_SHIFT
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#undef VALUE_HASH_SHIFT
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errcode_t ext2fs_read_ext_attr2(ext2_filsys fs, blk64_t block, void *buf)
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{
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errcode_t retval;
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retval = io_channel_read_blk64(fs->io, block, 1, buf);
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if (retval)
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return retval;
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#ifdef WORDS_BIGENDIAN
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ext2fs_swap_ext_attr(buf, buf, fs->blocksize, 1);
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#endif
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return 0;
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}
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errcode_t ext2fs_read_ext_attr(ext2_filsys fs, blk_t block, void *buf)
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{
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return ext2fs_read_ext_attr2(fs, block, buf);
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}
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errcode_t ext2fs_write_ext_attr2(ext2_filsys fs, blk64_t block, void *inbuf)
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{
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errcode_t retval;
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char *write_buf;
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char *buf = NULL;
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#ifdef WORDS_BIGENDIAN
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retval = ext2fs_get_mem(fs->blocksize, &buf);
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if (retval)
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return retval;
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write_buf = buf;
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ext2fs_swap_ext_attr(buf, inbuf, fs->blocksize, 1);
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#else
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write_buf = (char *) inbuf;
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#endif
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retval = io_channel_write_blk64(fs->io, block, 1, write_buf);
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if (buf)
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ext2fs_free_mem(&buf);
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if (!retval)
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ext2fs_mark_changed(fs);
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return retval;
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}
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errcode_t ext2fs_write_ext_attr(ext2_filsys fs, blk_t block, void *inbuf)
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{
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return ext2fs_write_ext_attr2(fs, block, inbuf);
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}
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/*
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* This function adjusts the reference count of the EA block.
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*/
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errcode_t ext2fs_adjust_ea_refcount2(ext2_filsys fs, blk64_t blk,
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char *block_buf, int adjust,
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__u32 *newcount)
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{
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errcode_t retval;
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struct ext2_ext_attr_header *header;
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char *buf = 0;
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if ((blk >= ext2fs_blocks_count(fs->super)) ||
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(blk < fs->super->s_first_data_block))
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return EXT2_ET_BAD_EA_BLOCK_NUM;
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if (!block_buf) {
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retval = ext2fs_get_mem(fs->blocksize, &buf);
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if (retval)
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return retval;
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block_buf = buf;
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}
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retval = ext2fs_read_ext_attr2(fs, blk, block_buf);
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if (retval)
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goto errout;
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header = (struct ext2_ext_attr_header *) block_buf;
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header->h_refcount += adjust;
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if (newcount)
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*newcount = header->h_refcount;
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retval = ext2fs_write_ext_attr2(fs, blk, block_buf);
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if (retval)
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goto errout;
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errout:
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if (buf)
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ext2fs_free_mem(&buf);
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return retval;
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}
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errcode_t ext2fs_adjust_ea_refcount(ext2_filsys fs, blk_t blk,
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char *block_buf, int adjust,
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__u32 *newcount)
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{
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return ext2fs_adjust_ea_refcount(fs, blk, block_buf, adjust, newcount);
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}
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