| bigbiff bigbiff | 9c75405 | 2013-01-09 09:09:08 -0500 | [diff] [blame] | 1 | /* |
| 2 | fat.c (09.11.10) |
| 3 | File Allocation Table creation code. |
| 4 | |
| 5 | Copyright (C) 2011, 2012 Andrew Nayenko |
| 6 | |
| 7 | This program is free software: you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation, either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 19 | */ |
| 20 | |
| 21 | #include <unistd.h> |
| 22 | #include "fat.h" |
| 23 | #include "cbm.h" |
| 24 | #include "uct.h" |
| 25 | #include "rootdir.h" |
| 26 | |
| 27 | static off64_t fat_alignment(void) |
| 28 | { |
| 29 | return (off64_t) 128 * get_sector_size(); |
| 30 | } |
| 31 | |
| 32 | static off64_t fat_size(void) |
| 33 | { |
| 34 | return get_volume_size() / get_cluster_size() * sizeof(cluster_t); |
| 35 | } |
| 36 | |
| 37 | static cluster_t fat_write_entry(struct exfat_dev* dev, cluster_t cluster, |
| 38 | cluster_t value) |
| 39 | { |
| 40 | le32_t fat_entry = cpu_to_le32(value); |
| 41 | if (exfat_write(dev, &fat_entry, sizeof(fat_entry)) < 0) |
| 42 | { |
| 43 | exfat_error("failed to write FAT entry 0x%x", value); |
| 44 | return 0; |
| 45 | } |
| 46 | return cluster + 1; |
| 47 | } |
| 48 | |
| 49 | static cluster_t fat_write_entries(struct exfat_dev* dev, cluster_t cluster, |
| 50 | uint64_t length) |
| 51 | { |
| 52 | cluster_t end = cluster + DIV_ROUND_UP(length, get_cluster_size()); |
| 53 | |
| 54 | while (cluster < end - 1) |
| 55 | { |
| 56 | cluster = fat_write_entry(dev, cluster, cluster + 1); |
| 57 | if (cluster == 0) |
| 58 | return 0; |
| 59 | } |
| 60 | return fat_write_entry(dev, cluster, EXFAT_CLUSTER_END); |
| 61 | } |
| 62 | |
| 63 | static int fat_write(struct exfat_dev* dev) |
| 64 | { |
| 65 | cluster_t c = 0; |
| 66 | |
| 67 | if (!(c = fat_write_entry(dev, c, 0xfffffff8))) /* media type */ |
| 68 | return 1; |
| 69 | if (!(c = fat_write_entry(dev, c, 0xffffffff))) /* some weird constant */ |
| 70 | return 1; |
| 71 | if (!(c = fat_write_entries(dev, c, cbm.get_size()))) |
| 72 | return 1; |
| 73 | if (!(c = fat_write_entries(dev, c, uct.get_size()))) |
| 74 | return 1; |
| 75 | if (!(c = fat_write_entries(dev, c, rootdir.get_size()))) |
| 76 | return 1; |
| 77 | |
| 78 | return 0; |
| 79 | } |
| 80 | |
| 81 | const struct fs_object fat = |
| 82 | { |
| 83 | .get_alignment = fat_alignment, |
| 84 | .get_size = fat_size, |
| 85 | .write = fat_write, |
| 86 | }; |