Implement NFS Support stub (Phase 11 P0 #3)

NFS Support Features:
- nfs_server.rs: NFSv3 server stub
- nfs_server CLI tool: Port 2049, export directory
- nfsserve crate dependency (v0.11.0)

Implementation Status:
- NfsVfsServer: Placeholder implementation
- NfsConfig: Configuration struct
- CLI: nfs-server command with --port, --root, --share-name

Technical Details:
- nfsserve crate provides NFSFileSystem trait
- NFSFileSystem requires 14 async methods
- Current implementation is stub (pending API study)

Build: ✅ markbase-core + nfs feature
Tests: 495 markbase-core (without nfs feature)

Note: Full NFS server implementation requires studying nfsserve crate API
(expected time: 2-3 days for 500 lines)

Cargo.lock

@@ -3048,6 +3048,7 @@ dependencies = [
  "log",
  "lz4_flex 0.11.6",
  "md5 0.8.0",
+ "nfsserve",
  "nix 0.29.0",
  "once_cell",
  "poly1305 0.8.0",

markbase-core/Cargo.toml

@@ -89,12 +89,16 @@ tracing-subscriber = { version = "0.3", features = ["env-filter", "json"] }
 # === LDAP Authentication (Phase 2) ===
 ldap3 = { version = "0.11", optional = true }  # Async LDAP client (compatible with AD + OpenLDAP)
 
+# === NFS Server (Phase 11) ===
+nfsserve = { version = "0.11", optional = true }  # NFSv3/NFSv4 server implementation
+
 [features]
 default = []                          # 默认不启用可选格式
 optional-formats = ["unrar", "xz2", "sevenz-rust"]  # 争议格式可选启用
 smb-server = ["dep:smb-server"]       # SMB server feature flag
 async-vfs = ["dep:reqwest"]           # Async VfsBackend trait + native async S3
 ldap = ["dep:ldap3"]                  # LDAP authentication provider
+nfs = ["dep:nfsserve"]                # NFSv3/NFSv4 server feature flag
 
 [dev-dependencies]
 # tempfile moved to dependencies (needed for archive extraction)

markbase-core/src/cli/tools/mod.rs

@@ -1,6 +1,8 @@
 pub mod render;
 pub mod smb_server;
 pub mod test;
+#[cfg(feature = "nfs")]
+pub mod nfs_server;
 
 use clap::Subcommand;
 
@@ -12,6 +14,8 @@ pub enum ToolsCommands {
     Test(test::TestCommand),
     #[command(flatten)]
     SmbServer(smb_server::SmbServerCommand),
+    #[cfg(feature = "nfs")]
+    Nfs(nfs_server::NfsServerCommand),
 }
 
 pub async fn handle_tools_command(cmd: ToolsCommands) -> anyhow::Result<()> {
@@ -19,6 +23,8 @@ pub async fn handle_tools_command(cmd: ToolsCommands) -> anyhow::Result<()> {
         ToolsCommands::Render(c) => render::handle_render_command(c)?,
         ToolsCommands::Test(c) => test::handle_test_command(c)?,
         ToolsCommands::SmbServer(c) => smb_server::handle_smb_server_command(c).await?,
+        #[cfg(feature = "nfs")]
+        ToolsCommands::Nfs(c) => nfs_server::run_nfs_server(c).await?,
     }
     Ok(())
 }

markbase-core/src/cli/tools/nfs_server.rs

@@ -0,0 +1,41 @@
+use clap::Args;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+use crate::vfs::{local_fs::LocalFs, nfs_server::{NfsVfsServer, NfsConfig}};
+
+#[derive(Debug, Args)]
+pub struct NfsServerCommand {
+    /// Port to listen on (default: 2049)
+    #[arg(short, long, default_value = "2049")]
+    port: u16,
+    
+    /// Root directory to export
+    #[arg(short, long, default_value = "/tmp/nfs_export")]
+    root: PathBuf,
+    
+    /// Share name (export name)
+    #[arg(short, long, default_value = "export")]
+    share_name: String,
+}
+
+pub async fn run_nfs_server(cmd: NfsServerCommand) -> anyhow::Result<()> {
+    println!("Starting NFS server on port {}", cmd.port);
+    println!("Export directory: {}", cmd.root.display());
+    println!("Share name: {}", cmd.share_name);
+    
+    if !cmd.root.exists() {
+        std::fs::create_dir_all(&cmd.root)?;
+        println!("Created export directory: {}", cmd.root.display());
+    }
+    
+    let vfs = Arc::new(LocalFs::new());
+    let server = NfsVfsServer::new(vfs, cmd.root.clone()).with_port(cmd.port);
+    
+    println!("NFS server starting...");
+    server.start(cmd.port).await?;
+    
+    println!("NFS server stopped");
+    
+    Ok(())
+}

markbase-core/src/vfs/mod.rs

@@ -24,6 +24,8 @@ pub mod async_fs;
 pub mod async_s3_fs;
 #[cfg(feature = "async-vfs")]
 pub mod async_smb_fs;
+#[cfg(feature = "nfs")]
+pub mod nfs_server;
 
 use std::path::{Path, PathBuf};
 use std::time::SystemTime;

markbase-core/src/vfs/nfs_server.rs

@@ -0,0 +1,63 @@
+use crate::vfs::{VfsBackend, VfsError};
+use std::path::PathBuf;
+use std::sync::Arc;
+
+pub struct NfsVfsServer {
+    vfs: Arc<dyn VfsBackend>,
+    root: PathBuf,
+    port: u16,
+}
+
+impl NfsVfsServer {
+    pub fn new(vfs: Arc<dyn VfsBackend>, root: PathBuf) -> Self {
+        Self {
+            vfs,
+            root,
+            port: 2049,
+        }
+    }
+    
+    pub fn with_port(self, port: u16) -> Self {
+        Self { port, ..self }
+    }
+    
+    pub async fn start(&self, port: u16) -> Result<(), VfsError> {
+        #[cfg(feature = "nfs")]
+        {
+            println!("NFS server starting on port {}", port);
+            println!("Export directory: {}", self.root.display());
+            
+            // TODO: Implement actual NFS server using nfsserve crate
+            // Current implementation is a placeholder
+            
+            Err(VfsError::Unsupported("NFS server implementation pending (requires nfsserve crate API study)".to_string()))
+        }
+        
+        #[cfg(not(feature = "nfs"))]
+        {
+            Err(VfsError::Unsupported("NFS server requires 'nfs' feature".to_string()))
+        }
+    }
+}
+
+pub struct NfsConfig {
+    pub port: u16,
+    pub root: PathBuf,
+    pub vfs: Arc<dyn VfsBackend>,
+}
+
+impl Default for NfsConfig {
+    fn default() -> Self {
+        Self {
+            port: 2049,
+            root: PathBuf::from("/"),
+            vfs: Arc::new(crate::vfs::local_fs::LocalFs::new()),
+        }
+    }
+}
+
+impl NfsConfig {
+    pub fn build(&self) -> NfsVfsServer {
+        NfsVfsServer::new(self.vfs.clone(), self.root.clone()).with_port(self.port)
+    }
+}