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#pragma once
#include "common/types.h"
#include "kernel/spinlock.h"
#include "fs/stat.h"
class FileSystem;
// VFS Inode (Abstract Base Class)
class Inode
{
private:
;
public:
// VFS Common Fields
uint32 dev; // Device number (VirtIO Block ID)
uint32 inum; // Inode number
int ref_cnt; // Memory reference count (number of struct file or processes referencing it)
int valid; // Whether the data is valid (whether metadata has been read from disk)
Mutex lock; // Sleep lock: protects internal Inode data and atomicity of read/write operations
// Metadata Cache (for speeding up getattr)
short type; // T_DIR, T_FILE, T_DEVICE
short major; // Major device number (only for T_DEVICE)
short minor; // Minor device number (only for T_DEVICE)
short nlink; // Number of hard links
uint32 size; // File size
Inode() : ref_cnt(0), valid(0)
{
lock.init("inode");
}
virtual ~Inode() {}
/* Core Operation Interface (Subclass Must Implement) */
// Update metadata
// Sync size, type, links, etc. from memory back to disk
virtual void update() = 0;
// Read content
// Read n bytes from the file at offset into dst
// Returns the actual number of bytes read, returns -1 on error
virtual int read(char *dst, uint32 off, uint32 n, int isUser) = 0;
// 3. Write content
// Write n bytes from src to the file at the given offset
// Need to handle file growth
virtual int write(const char *src, uint32 off, uint32 n, int isUser) = 0;
// Directory Lookup (only valid when type == T_DIR)
// Search for a file named 'name' in the current directory and return its Inode pointer (locked)
// Return nullptr if not found
virtual Inode *lookup(const char *name) = 0;
// Create file/directory (only effective when type == T_DIR)
// Create a new entry in the current directory
virtual Inode *create(const char *name, short type, short major, short minor) = 0;
// Get file status (populate the stat structure)
// Default implementation, subclasses can override to provide more detailed information
virtual void getattr(struct kstat *st);
// Truncate file (set size to 0, release all data blocks)
virtual void truncate() = 0;
};
// File System Abstraction (SuperBlock)
class FileSystem
{
private:
;
public:
virtual void init() = 0;
virtual Inode* root() = 0;
virtual ~FileSystem() {};
};
// Inode Cache Interface (Global Function)
namespace VFS
{
void init();
// Decrease the reference count, and if it reaches 0, free the memory
void iput(Inode *ip);
// Increase reference count
Inode *idup(Inode *ip);
// lock and load data
void ilock(Inode *ip);
// unlock
void iunlock(Inode *ip);
// Mount the root filesystem
void mount_root(Inode *root);
// Get system root node
Inode *get_root();
// Path Analysis
Inode *namei(const char *path);
} // namespace VFS
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