blob: 63d62ae1b50d8f511e12ce8588680b3ec6d83bde (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2026 Richard QIn
*/
#pragma once
#include "fs/fs.h"
#include "kernel/buf.h"
// Disk Layout Structures (On-Disk)
// FAT32 Boot Sector (BPB)
struct FAT32_BPB
{
uint8 jmpBoot[3];
char oemName[8];
uint16 bytesPerSector;
uint8 secPerClus;
uint16 reservedSecCnt;
uint8 numFATs;
uint16 rootEntCnt;
uint16 totSec16;
uint8 media;
uint16 FATSz16;
uint16 secPerTrk;
uint16 numHeads;
uint32 hiddSec;
uint32 totSec32;
uint32 FATSz32;
uint16 extFlags;
uint16 FSVer;
uint32 rootClus;
uint16 FSInfo;
uint16 bkBootSec;
uint8 reserved[12];
uint8 drvNum;
uint8 reserved1;
uint8 bootSig;
uint32 volID;
char volLab[11];
char filSysType[8];
} __attribute__((packed));
// FAT32 Directory Entry (32 bytes)
struct FAT32_DirEnt
{
char name[11]; // 8.3 filename
uint8 attr; // File attributes
uint8 ntRes;
uint8 crtTimeTenth;
uint16 crtTime;
uint16 crtDate;
uint16 lstAccDate;
uint16 fstClusHI; // High 16 bits of first cluster
uint16 wrtTime;
uint16 wrtDate;
uint16 fstClusLO; // Low 16 bits of first cluster
uint32 fileSize;
} __attribute__((packed));
#define ATTR_READ_ONLY 0x01
#define ATTR_HIDDEN 0x02
#define ATTR_SYSTEM 0x04
#define ATTR_VOLUME_ID 0x08
#define ATTR_DIRECTORY 0x10
#define ATTR_ARCHIVE 0x20
#define ATTR_LONG_NAME 0x0F
// In-Memory Classes
class FAT32FileSystem;
class FAT32Inode : public Inode
{
public:
FAT32FileSystem *fs;
// FAT32 Private Data
uint32 first_clus; // The starting cluster number of the file
uint32 parent_clus; // Starting cluster number of the parent directory
uint32 dir_offset; // The byte offset of this directory entry in the parent directory
uint32 ent_sec; // Sector number of the directory entry
uint32 ent_off; // Offset of the directory entry within the sector
FAT32Inode() : fs(nullptr), first_clus(0) {}
// Implement VFS Interface
void update() override;
int read(char *dst, uint32 off, uint32 n, int isUser) override;
int write(const char *src, uint32 off, uint32 n, int isUser) override;
Inode *lookup(const char *name) override;
Inode *create(const char *name, short type, short major, short minor) override;
void truncate() override;
int unlink(const char *name) override;
};
class FAT32FileSystem : public FileSystem
{
public:
uint32 fat_start_sector;
uint32 data_start_sector;
uint32 root_cluster;
uint32 sectors_per_cluster;
uint32 bytes_per_cluster;
uint32 fat_sz; // Size of the FAT table (number of sectors)
void init() override;
Inode* root() override;
// Helper functions
uint32 next_cluster(uint32 cluster); // Check the FAT table for the next cluster
uint32 alloc_cluster(); // Assign a new cluster
uint32 cluster_to_sector(uint32 cluster);
// directory entry parsing
void read_dir_ent(struct FAT32_DirEnt *de, char *filename);
// Release the entire cluster chain starting from the cluster
void free_cluster_chain(uint32 cluster);
};
extern FAT32FileSystem fat32_fs;
void fat32_test();
|
