fat32.h

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/*
 * PROJECT:     MatanelOS Kernel
 * LICENSE:     NONE
 * PURPOSE:     FAT32 FileSystem Headers.
 */
 
#ifndef X86_KERNEL_FILESYSTEM_FAT32_HEADER
#define X86_KERNEL_FILESYSTEM_FAT32_HEADER
 // Standard headers, required.
#include <stddef.h>
#include <stdbool.h>
#include <stdint.h>
#include "../../drivers/gop/gop.h"
#include "../../mtstatus.h"
 
#define END_OF_DIRECTORY 0x00
#define DELETED_DIR_ENTRY 0xE5
 
 
#define FAT32_FAT_MASK        0x0FFFFFFFU
#define FAT32_FREE_CLUSTER    0x00000000U
#define FAT32_BAD_CLUSTER     0x0FFFFFF7U
#define FAT32_EOC_MIN         0x0FFFFFF8U /* inclusive */
#define FAT32_EOC_MAX         0x0FFFFFFFU /* inclusive */
 
 
 
#ifdef _MSC_VER
#pragma pack(push, 1)
typedef struct _FAT32_BPB {
#else
typedef struct __attribute__((packed)) _FAT32_BPB {
#endif
    uint8_t jump[3];
    uint8_t oem[8];
    uint16_t bytes_per_sector;
    uint8_t sectors_per_cluster;
    uint16_t reserved_sector_count;
    uint8_t num_fats;
    uint16_t root_entry_count;
    uint16_t total_sectors_16;
    uint8_t media;
    uint16_t fat_size_16;
    uint16_t sectors_per_track;
    uint16_t num_heads;
    uint32_t hidden_sectors;
    uint32_t total_sectors_32;
    uint32_t fat_size_32;
    uint16_t ext_flags;
    uint16_t fs_version;
    uint32_t root_cluster;
    uint16_t fs_info_sector;
    uint16_t backup_root_sector;
} FAT32_BPB;
#ifdef _MSC_VER
#pragma pack(pop)
#endif
 
#ifdef _MSC_VER
#pragma pack(push, 1)
typedef struct _FAT32_DIR_ENTRY {
#else
typedef struct __attribute__((packed)) _FAT32_DIR_ENTRY {
#endif
    char name[11];
    uint8_t attr;
    uint8_t nt_res;
    uint8_t crt_time_tenth;
    uint16_t crt_time;
    uint16_t crt_date;
    uint16_t lst_acc_date;
    uint16_t fst_clus_hi;
    uint16_t wrt_time;
    uint16_t wrt_date;
    uint16_t fst_clus_lo;
    uint32_t file_size;
} FAT32_DIR_ENTRY;
#ifdef _MSC_VER
#pragma pack(pop)
#endif
 
#pragma pack(push,1)
typedef struct {
    uint8_t  LDIR_Ord;
    uint16_t LDIR_Name1[5];
    uint8_t  LDIR_Attr;   // always 0x0F
    uint8_t  LDIR_Type;
    uint8_t  LDIR_Chksum;
    uint16_t LDIR_Name2[6];
    uint16_t LDIR_FstClusLO;
    uint16_t LDIR_Name3[2];
} FAT32_LFN_ENTRY;
#pragma pack(pop)
 
typedef struct _FAT32_FSINFO {
    uint32_t first_data_sector;
    uint32_t root_cluster;
    uint32_t sectors_per_fat;
    uint32_t bytes_per_sector;
    uint32_t sectors_per_cluster;
    uint32_t fat_start;
    uint16_t reserved_sector_count;
    uint32_t total_sectors;
    uint32_t total_clusters;
} FAT32_FSINFO;
 
// Initialize a FAT32 FileSystem on a given block device.
MTSTATUS fat32_init(int disk_index);
 
// List files in root dir
void fat32_list_root(void);
 
typedef enum _FAT32_ATTRIBUTES {
    ATTR_READ_ONLY = 0x01,  // File is read-only
    ATTR_HIDDEN = 0x02,  // File is hidden
    ATTR_SYSTEM = 0x04,  // System file
    ATTR_VOLUME_ID = 0x08,  // Volume label
    ATTR_DIRECTORY = 0x10,  // Entry is a directory
    ATTR_ARCHIVE = 0x20,  // File should be archived
    // Special combination values
    ATTR_LONG_NAME = 0x0F,  // Long File Name entry (ATTR_READ_ONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_VOLUME_ID)
} FAT32_ATTRIBUTES;
 
static inline uint16_t fat32_encode_date(uint16_t year, uint8_t month, uint8_t day) {
    // FAT date: YYYYYYYMMMMDDDDD (since 1980)
    return ((year - 1980) << 9) | (month << 5) | (day);
}
 
static inline uint16_t fat32_encode_time(uint8_t hour, uint8_t min, uint8_t sec) {
    // FAT time: HHHHHMMMMMMSSSSS (seconds / 2)
    return (hour << 11) | (min << 5) | (sec / 2);
}
 
static inline void fat32_decode_date(uint16_t date, uint16_t* year, uint8_t* month, uint8_t* day) {
    *year = 1980 + ((date >> 9) & 0x7F); // 7 bits for year
    *month = (date >> 5) & 0x0F;          // 4 bits for month
    *day = date & 0x1F;                 // 5 bits for day
}
 
static inline void fat32_decode_time(uint16_t time, uint8_t* hour, uint8_t* min, uint8_t* sec) {
    *hour = (time >> 11) & 0x1F;          // 5 bits for hours
    *min = (time >> 5) & 0x3F;           // 6 bits for minutes
    *sec = (time & 0x1F) * 2;            // 5 bits for seconds (2-second resolution)
}

MTSTATUS fat32_read_file(const char* filename, uint32_t* file_size_out, void** buffer_out);

MTSTATUS fat32_create_directory(const char* path);

MTSTATUS fat32_write_file(const char* path, const void* data, uint32_t size, uint32_t file_modification_mode);

MTSTATUS fat32_list_directory(const char* path, char* listings, size_t max_len);

MTSTATUS fat32_delete_directory(const char* path);

MTSTATUS fat32_delete_file(const char* path);
bool fat32_directory_is_empty(const char* path);
 
#endif