feat(fs): Complete full FAT32 storage filesystem driver, auto-mount at /mnt/fat32, and add df & mkfs.vfat tools

include/fs/fat32.h

@@ -5,8 +5,22 @@
 #include <stddef.h>
 #include <stdbool.h>
 #include <fs/vfs.h>
+#include <block/block.h>
 
-/* FAT32 Extended BIOS Parameter Block */
+#define FAT_ATTR_READ_ONLY 0x01
+#define FAT_ATTR_HIDDEN    0x02
+#define FAT_ATTR_SYSTEM    0x04
+#define FAT_ATTR_VOLUME_ID 0x08
+#define FAT_ATTR_DIRECTORY 0x10
+#define FAT_ATTR_ARCHIVE   0x20
+#define FAT_ATTR_LFN       0x0F
+
+#define FAT32_EOC_MIN      0x0FFFFFF8
+#define FAT32_EOC_MAX      0x0FFFFFFF
+#define FAT32_BAD_CLUSTER  0x0FFFFFF7
+#define FAT32_FREE_CLUSTER 0x00000000
+
+/* FAT32 Extended BIOS Parameter Block (BPB) */
 typedef struct {
     uint8_t  jmp[3];
     char     oem[8];
@@ -23,7 +37,7 @@ typedef struct {
     uint32_t hidden_sectors;
     uint32_t total_sectors_32;
 
-    // FAT32 Extended
+    // FAT32 Extended Fields
     uint32_t table_size_32;
     uint16_t extended_flags;
     uint16_t fat_version;
@@ -39,6 +53,7 @@ typedef struct {
     char     fat_type_label[8];
 } __attribute__((packed)) fat32_bpb_t;
 
+/* Standard 32-byte FAT Directory Entry */
 typedef struct {
     char     name[11];
     uint8_t  attr;
@@ -54,7 +69,23 @@ typedef struct {
     uint32_t file_size;
 } __attribute__((packed)) fat32_dirent_t;
 
+/* In-Memory Mounted FAT32 Filesystem Descriptor */
+typedef struct {
+    block_device_t* dev;
+    fat32_bpb_t     bpb;
+    uint32_t        fat_begin_lba;
+    uint32_t        cluster_begin_lba;
+    uint32_t        sectors_per_cluster;
+    uint32_t        root_cluster;
+    uint32_t        total_clusters;
+    uint32_t        free_clusters;
+    char            mountpoint[64];
+    bool            mounted;
+} fat32_fs_t;
+
 void fat32_init(void);
-vfs_node_t* fat32_mount(const char* block_device_name);
+vfs_node_t* fat32_mount(const char* block_device_name, const char* mountpoint);
+int fat32_format(const char* block_device_name, const char* volume_label);
+const fat32_fs_t* fat32_get_fs_info(void);
 
 #endif // _FS_FAT32_H