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Diffstat (limited to 'lume-legacy/include/fs/fat32.h')
| -rw-r--r-- | lume-legacy/include/fs/fat32.h | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/lume-legacy/include/fs/fat32.h b/lume-legacy/include/fs/fat32.h new file mode 100644 index 0000000..63d62ae --- /dev/null +++ b/lume-legacy/include/fs/fat32.h @@ -0,0 +1,122 @@ +// 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();
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