113 lines
3.4 KiB
C
113 lines
3.4 KiB
C
/*
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* Copyright (c) 2023 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* fat.c
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* File Allocation Table filesystem.
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*/
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#include <stdbool.h>
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#include <stddef.h>
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#include <string.h>
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#include <mount/blockdevice.h>
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#include <mount/fat.h>
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#include <mount/filesystem.h>
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#include <mount/partition.h>
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#include <mount/uuid.h>
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#include "util.h"
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static size_t fat_probe_amount(struct blockdevice* bdev)
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{
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(void) bdev;
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return 512;
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}
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static bool fat_probe(struct blockdevice* bdev,
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const unsigned char* leading,
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size_t amount)
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{
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(void) leading;
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(void) amount;
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// TODO: Relax restriction that this must be a partition? At least for non-EFI.
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struct partition* p = bdev->p;
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if ( !p )
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return false;
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// TODO: Test for a space padded FAT32 at 0x52 + 8 bytes.
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if ( p->table_type == PARTITION_TABLE_TYPE_GPT )
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{
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unsigned char bdp_uuid[16];
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uuid_from_string(bdp_uuid, BDP_GPT_TYPE_UUID);
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unsigned char esp_uuid[16];
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uuid_from_string(esp_uuid, ESP_GPT_TYPE_UUID);
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// TODO: Additional probing is needed to detect FAT vs NTFS.
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return memcmp(p->gpt_type_guid, bdp_uuid, 16) == 0 ||
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memcmp(p->gpt_type_guid, esp_uuid, 16) == 0;
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}
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if ( p->table_type == PARTITION_TABLE_TYPE_MBR )
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return p->mbr_system_id == 0x01 ||
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p->mbr_system_id == 0x04 ||
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p->mbr_system_id == 0x06 ||
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p->mbr_system_id == 0x04 ||
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p->mbr_system_id == 0x0C ||
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p->mbr_system_id == 0x0E ||
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p->mbr_system_id == 0xEF;
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return false;
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}
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static void fat_release(struct filesystem* fs)
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{
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if ( !fs )
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return;
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free(fs);
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}
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static enum filesystem_error fat_inspect(struct filesystem** fs_ptr,
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struct blockdevice* bdev)
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{
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*fs_ptr = NULL;
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struct filesystem* fs = CALLOC_TYPE(struct filesystem);
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if ( !fs )
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return FILESYSTEM_ERROR_ERRNO;
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fs->bdev = bdev;
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fs->handler = &fat_handler;
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fs->handler_private = NULL;
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unsigned char vbr[512];
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if ( blockdevice_preadall(bdev, vbr, sizeof(vbr), 0) != sizeof(vbr) )
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return fat_release(fs), FILESYSTEM_ERROR_ERRNO;
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// TODO: Report efi instead if ESP.
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fs->fstype_name = "fat";
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// TODO: Port a fat fsck.
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fs->driver = "fatfs";
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fs->flags |= FILESYSTEM_FLAG_UUID;
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// Use the serial number + label as the UUID.
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// TODO: The location varies between FAT12/16 and FAT32. This is the wrong
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// way to detect the FAT type.
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if ( vbr[82 + 3] == '3' && vbr[82 + 4] == '2' )
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memcpy(fs->uuid, vbr + 67, 4 + 11);
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else
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memcpy(fs->uuid, vbr + 39, 4 + 11);
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return *fs_ptr = fs, FILESYSTEM_ERROR_NONE;
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}
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const struct filesystem_handler fat_handler =
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{
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.handler_name = "fat",
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.probe_amount = fat_probe_amount,
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.probe = fat_probe,
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.inspect = fat_inspect,
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.release = fat_release,
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};
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