# T11: Virtual Filesystem (VFS) & Sockets

**Track:** T11  
**Status:** IN PROGRESS  
**Date:** 2026-07-12  
**Source:** UniversalisOS 12-Month Roadmap, Month 11

---

## Overview

T11 focuses on enabling a fully functional virtual filesystem and networking endpoints for UniversalisOS. This includes fleshing out the VFS implementation, ensuring proper memory management, and implementing socket operations.

---

## Objectives

1. **Flesh out VFS implementation** — Complete VFS with proper memory management
2. **Implement VFS socket operations** — socket, bind, listen, accept
3. **Ensure munmap correctly frees memory** — Proper resource cleanup
4. **Add socket options** — setsockopt, getsockopt
5. **Add socket I/O** — send, recv, sendto, recvfrom

---

## Tasks

### T11-1: VFS Implementation Completion

**Status:** PENDING

Complete the VFS implementation with proper memory management:

```c
/* VFS operations */
int vfs_open(const char* path, int flags, int mode, uint32_t part_id);
int vfs_close(int fd, uint32_t part_id);
int vfs_read(int fd, void* buf, size_t count, uint32_t part_id);
int vfs_write(int fd, const void* buf, size_t count, uint32_t part_id);
int vfs_lseek(int fd, int offset, int whence, uint32_t part_id);
int vfs_fstat(int fd, void* statbuf, uint32_t part_id);
int vfs_ioctl(int fd, int request, void* arg, uint32_t part_id);
```

**Key Features:**
- File descriptor table per partition
- Path resolution
- File operations (open, close, read, write, lseek)
- File status (fstat)
- I/O control (ioctl)

**TODO:**
- [ ] Implement fd table per partition
- [ ] Implement path resolution
- [ ] Implement file operations
- [ ] Implement fstat
- [ ] Implement ioctl

---

### T11-2: VFS Socket Operations

**Status:** PENDING

Implement VFS socket operations:

```c
/* Socket operations */
int vfs_socket(int domain, int type, int protocol, uint32_t part_id);
int vfs_bind(int sockfd, const void* addr, size_t addrlen, uint32_t part_id);
int vfs_listen(int sockfd, int backlog, uint32_t part_id);
int vfs_accept(int sockfd, void* addr, void* addrlen, uint32_t part_id);
int vfs_connect(int sockfd, const void* addr, size_t addrlen, uint32_t part_id);
```

**Key Features:**
- Socket creation (AF_INET, AF_UNIX, AF_INET6)
- Socket binding
- Connection listening
- Connection acceptance
- Connection establishment

**TODO:**
- [ ] Implement socket creation
- [ ] Implement socket binding
- [ ] Implement listen
- [ ] Implement accept
- [ ] Implement connect

---

### T11-3: Socket I/O Operations

**Status:** PENDING

Implement socket I/O operations:

```c
/* Socket I/O */
ssize_t vfs_send(int sockfd, const void* buf, size_t len, int flags, uint32_t part_id);
ssize_t vfs_recv(int sockfd, void* buf, size_t len, int flags, uint32_t part_id);
ssize_t vfs_sendto(int sockfd, const void* buf, size_t len, int flags, const void* dest_addr, size_t addrlen, uint32_t part_id);
ssize_t vfs_recvfrom(int sockfd, void* buf, size_t len, int flags, void* src_addr, size_t* addrlen, uint32_t part_id);
```

**Key Features:**
- Send data
- Receive data
- Send to specific address
- Receive from specific address

**TODO:**
- [ ] Implement send
- [ ] Implement recv
- [ ] Implement sendto
- [ ] Implement recvfrom

---

### T11-4: Socket Options

**Status:** PENDING

Implement socket options:

```c
/* Socket options */
int vfs_setsockopt(int sockfd, int level, int optname, const void* optval, size_t optlen, uint32_t part_id);
int vfs_getsockopt(int sockfd, int level, int optname, void* optval, size_t* optlen, uint32_t part_id);
```

**Key Features:**
- Set socket options (SO_REUSEADDR, SO_KEEPALIVE, etc.)
- Get socket options

**TODO:**
- [ ] Implement setsockopt
- [ ] Implement getsockopt

---

### T11-5: Memory Management for VFS

**Status:** PENDING

Ensure proper memory management for VFS:

```c
/* Memory management */
int vfs_munmap(void* addr, size_t length, uint32_t part_id);
void* vfs_mmap(void* addr, size_t length, int prot, int flags, int fd, int offset, uint32_t part_id);
```

**Key Features:**
- Proper munmap (free memory resources)
- Memory-mapped files
- Resource cleanup

**TODO:**
- [ ] Implement proper munmap
- [ ] Implement mmap for files
- [ ] Implement resource cleanup

---

## Implementation Files

| File | Purpose |
|------|---------|
| `kernel/src/core/vfs.h` | VFS header |
| `kernel/src/core/vfs.cpp` | VFS implementation |
| `kernel/src/core/abi/uos_posix_abi.cpp` | POSIX ABI dispatch |
| `kernel/src/core/abi/uos_posix_abi.h` | POSIX ABI header |

---

## Verification

- [ ] VFS operations work correctly
- [ ] Socket operations work correctly
- [ ] Socket I/O works correctly
- [ ] Socket options work correctly
- [ ] Memory management works correctly

---

## TODO Summary

### T11-1: VFS Implementation
- [ ] Implement fd table per partition
- [ ] Implement path resolution
- [ ] Implement file operations
- [ ] Implement fstat
- [ ] Implement ioctl

### T11-2: Socket Operations
- [ ] Implement socket creation
- [ ] Implement socket binding
- [ ] Implement listen
- [ ] Implement accept
- [ ] Implement connect

### T11-3: Socket I/O
- [ ] Implement send
- [ ] Implement recv
- [ ] Implement sendto
- [ ] Implement recvfrom

### T11-4: Socket Options
- [ ] Implement setsockopt
- [ ] Implement getsockopt

### T11-5: Memory Management
- [ ] Implement proper munmap
- [ ] Implement mmap for files
- [ ] Implement resource cleanup

---

## References

- `universalisos/docs/UniversalisOS_Stubs_Resolution_Roadmap_12Months.md` — 12-month roadmap
- `universalisos/kernel/src/core/vfs.cpp` — VFS implementation
- `universalisos/kernel/src/core/abi/uos_posix_abi.cpp` — POSIX ABI dispatch