feat(syscall): 添加syscall table的实现 (#1164)

* feat(syscall): 添加syscall table的实现

- 实现syscall table
- 为syscall table适配write/writev、read和readv系统调用

---------

Signed-off-by: longjin <longjin@DragonOS.org>

kernel/src/filesystem/vfs/syscall/sys_read.rs

@@ -0,0 +1,105 @@
+use system_error::SystemError;
+
+use crate::arch::syscall::nr::SYS_READ;
+use crate::process::ProcessManager;
+use crate::syscall::table::FormattedSyscallParam;
+use crate::syscall::table::Syscall;
+use crate::syscall::user_access::UserBufferWriter;
+
+use alloc::string::ToString;
+use alloc::vec::Vec;
+
+/// System call handler for the `read` syscall
+///
+/// This handler implements the `Syscall` trait to provide functionality for reading data from a file descriptor.
+pub struct SysReadHandle;
+
+impl Syscall for SysReadHandle {
+    /// Returns the number of arguments expected by the `read` syscall
+    fn num_args(&self) -> usize {
+        3
+    }
+
+    /// Handles the `read` system call
+    ///
+    /// Reads data from the specified file descriptor into a user buffer.
+    ///
+    /// # Arguments
+    /// * `args` - Array containing:
+    ///   - args[0]: File descriptor (i32)
+    ///   - args[1]: Pointer to user buffer (*mut u8)
+    ///   - args[2]: Length of data to read (usize)
+    /// * `from_user` - Indicates if the call originates from user space
+    ///
+    /// # Returns
+    /// * `Ok(usize)` - Number of bytes successfully read
+    /// * `Err(SystemError)` - Error code if operation fails
+    fn handle(&self, args: &[usize], from_user: bool) -> Result<usize, SystemError> {
+        let fd = Self::fd(args);
+        let buf_vaddr = Self::buf(args);
+        let len = Self::len(args);
+
+        let mut user_buffer_writer = UserBufferWriter::new(buf_vaddr, len, from_user)?;
+
+        let user_buf = user_buffer_writer.buffer(0)?;
+        do_read(fd, user_buf)
+    }
+
+    /// Formats the syscall parameters for display/debug purposes
+    ///
+    /// # Arguments
+    /// * `args` - The raw syscall arguments
+    ///
+    /// # Returns
+    /// Vector of formatted parameters with descriptive names
+    fn entry_format(&self, args: &[usize]) -> Vec<FormattedSyscallParam> {
+        vec![
+            FormattedSyscallParam::new("fd", Self::fd(args).to_string()),
+            FormattedSyscallParam::new("buf", format!("{:#x}", Self::buf(args) as usize)),
+            FormattedSyscallParam::new("len", Self::len(args).to_string()),
+        ]
+    }
+}
+
+impl SysReadHandle {
+    /// Extracts the file descriptor from syscall arguments
+    fn fd(args: &[usize]) -> i32 {
+        args[0] as i32
+    }
+
+    /// Extracts the buffer pointer from syscall arguments
+    fn buf(args: &[usize]) -> *mut u8 {
+        args[1] as *mut u8
+    }
+
+    /// Extracts the buffer length from syscall arguments
+    fn len(args: &[usize]) -> usize {
+        args[2]
+    }
+}
+
+syscall_table_macros::declare_syscall!(SYS_READ, SysReadHandle);
+
+/// Internal implementation of the read operation
+///
+/// # Arguments
+/// * `fd` - File descriptor to read from
+/// * `buf` - Buffer to store read data
+///
+/// # Returns
+/// * `Ok(usize)` - Number of bytes successfully read
+/// * `Err(SystemError)` - Error code if operation fails
+pub(super) fn do_read(fd: i32, buf: &mut [u8]) -> Result<usize, SystemError> {
+    let binding = ProcessManager::current_pcb().fd_table();
+    let fd_table_guard = binding.read();
+
+    let file = fd_table_guard.get_file_by_fd(fd);
+    if file.is_none() {
+        return Err(SystemError::EBADF);
+    }
+    // drop guard 以避免无法调度的问题
+    drop(fd_table_guard);
+    let file = file.unwrap();
+
+    return file.read(buf.len(), buf);
+}