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89 lines
2.2 KiB
89 lines
2.2 KiB
/*
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fat.c (09.11.10)
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File Allocation Table creation code.
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Free exFAT implementation.
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Copyright (C) 2011-2018 Andrew Nayenko
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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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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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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "fat.h"
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#include "cbm.h"
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#include "uct.h"
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#include "rootdir.h"
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#include <unistd.h>
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static off_t fat_alignment(void)
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{
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return (off_t) 128 * get_sector_size();
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}
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static off_t fat_size(void)
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{
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return get_volume_size() / get_cluster_size() * sizeof(cluster_t);
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}
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static cluster_t fat_write_entry(struct exfat_dev* dev, cluster_t cluster,
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cluster_t value)
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{
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le32_t fat_entry = cpu_to_le32(value);
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if (exfat_write(dev, &fat_entry, sizeof(fat_entry)) < 0)
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{
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exfat_error("failed to write FAT entry 0x%x", value);
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return 0;
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}
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return cluster + 1;
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}
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static cluster_t fat_write_entries(struct exfat_dev* dev, cluster_t cluster,
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uint64_t length)
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{
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cluster_t end = cluster + DIV_ROUND_UP(length, get_cluster_size());
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while (cluster < end - 1)
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{
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cluster = fat_write_entry(dev, cluster, cluster + 1);
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if (cluster == 0)
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return 0;
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}
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return fat_write_entry(dev, cluster, EXFAT_CLUSTER_END);
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}
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static int fat_write(struct exfat_dev* dev)
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{
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cluster_t c = 0;
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if (!(c = fat_write_entry(dev, c, 0xfffffff8))) /* media type */
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return 1;
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if (!(c = fat_write_entry(dev, c, 0xffffffff))) /* some weird constant */
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return 1;
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if (!(c = fat_write_entries(dev, c, cbm.get_size())))
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return 1;
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if (!(c = fat_write_entries(dev, c, uct.get_size())))
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return 1;
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if (!(c = fat_write_entries(dev, c, rootdir.get_size())))
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return 1;
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return 0;
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}
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const struct fs_object fat =
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{
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.get_alignment = fat_alignment,
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.get_size = fat_size,
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.write = fat_write,
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};
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