refactor(vfs/syscall): 重构部分vfs下的系统调用

kernel/src/filesystem/vfs/syscall/dup2.rs

@@ -0,0 +1,55 @@
+use system_error::SystemError;
+
+use crate::{
+    filesystem::vfs::file::{FileDescriptorVec, FileMode},
+    libs::rwlock::RwLockWriteGuard,
+};
+
+pub fn do_dup2(
+    oldfd: i32,
+    newfd: i32,
+    fd_table_guard: &mut RwLockWriteGuard<'_, FileDescriptorVec>,
+) -> Result<usize, SystemError> {
+    do_dup3(oldfd, newfd, FileMode::empty(), fd_table_guard)
+}
+
+pub fn do_dup3(
+    oldfd: i32,
+    newfd: i32,
+    flags: FileMode,
+    fd_table_guard: &mut RwLockWriteGuard<'_, FileDescriptorVec>,
+) -> Result<usize, SystemError> {
+    // 确认oldfd, newid是否有效
+    if !(FileDescriptorVec::validate_fd(oldfd) && FileDescriptorVec::validate_fd(newfd)) {
+        return Err(SystemError::EBADF);
+    }
+
+    if oldfd == newfd {
+        // 若oldfd与newfd相等
+        return Ok(newfd as usize);
+    }
+    let new_exists = fd_table_guard.get_file_by_fd(newfd).is_some();
+    if new_exists {
+        // close newfd
+        if fd_table_guard.drop_fd(newfd).is_err() {
+            // An I/O error occurred while attempting to close fildes2.
+            return Err(SystemError::EIO);
+        }
+    }
+
+    let old_file = fd_table_guard
+        .get_file_by_fd(oldfd)
+        .ok_or(SystemError::EBADF)?;
+    let new_file = old_file.try_clone().ok_or(SystemError::EBADF)?;
+
+    if flags.contains(FileMode::O_CLOEXEC) {
+        new_file.set_close_on_exec(true);
+    } else {
+        new_file.set_close_on_exec(false);
+    }
+    // 申请文件描述符，并把文件对象存入其中
+    let res = fd_table_guard
+        .alloc_fd(new_file, Some(newfd))
+        .map(|x| x as usize);
+    return res;
+}

kernel/src/filesystem/vfs/syscall/faccessat2.rs

@@ -0,0 +1,17 @@
+use system_error::SystemError;
+
+use crate::filesystem::vfs::{open::do_faccessat, syscall::ModeType};
+
+pub fn do_faccessat2(
+    dirfd: i32,
+    pathname: *const u8,
+    mode: u32,
+    flags: u32,
+) -> Result<usize, SystemError> {
+    return do_faccessat(
+        dirfd,
+        pathname,
+        ModeType::from_bits(mode).ok_or(SystemError::EINVAL)?,
+        flags,
+    );
+}

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

@@ -0,0 +1,72 @@
+use crate::filesystem::vfs::syscall::AtFlags;
+use crate::filesystem::vfs::utils::rsplit_path;
+use crate::filesystem::vfs::utils::user_path_at;
+use crate::filesystem::vfs::FileType;
+use crate::filesystem::vfs::IndexNode;
+use crate::filesystem::vfs::SystemError;
+use crate::filesystem::vfs::VFS_MAX_FOLLOW_SYMLINK_TIMES;
+use crate::process::ProcessManager;
+use alloc::sync::Arc;
+/// **创建硬连接的系统调用**
+///    
+/// ## 参数
+///
+/// - 'oldfd': 用于解析源文件路径的文件描述符
+/// - 'old': 源文件路径
+/// - 'newfd': 用于解析新文件路径的文件描述符
+/// - 'new': 新文件将创建的路径
+/// - 'flags': 标志位，仅以位或方式包含AT_EMPTY_PATH和AT_SYMLINK_FOLLOW
+///
+///
+pub fn do_linkat(
+    oldfd: i32,
+    old: &str,
+    newfd: i32,
+    new: &str,
+    flags: AtFlags,
+) -> Result<usize, SystemError> {
+    // flag包含其他未规定值时返回EINVAL
+    if !(AtFlags::AT_EMPTY_PATH | AtFlags::AT_SYMLINK_FOLLOW).contains(flags) {
+        return Err(SystemError::EINVAL);
+    }
+    // TODO AT_EMPTY_PATH标志启用时，进行调用者CAP_DAC_READ_SEARCH或相似的检查
+    let symlink_times = if flags.contains(AtFlags::AT_SYMLINK_FOLLOW) {
+        0_usize
+    } else {
+        VFS_MAX_FOLLOW_SYMLINK_TIMES
+    };
+    let pcb = ProcessManager::current_pcb();
+
+    // 得到源路径的inode
+    let old_inode: Arc<dyn IndexNode> = if old.is_empty() {
+        if flags.contains(AtFlags::AT_EMPTY_PATH) {
+            // 在AT_EMPTY_PATH启用时，old可以为空，old_inode实际为oldfd所指文件，但该文件不能为目录。
+            let binding = pcb.fd_table();
+            let fd_table_guard = binding.read();
+            let file = fd_table_guard
+                .get_file_by_fd(oldfd)
+                .ok_or(SystemError::EBADF)?;
+            let old_inode = file.inode();
+            old_inode
+        } else {
+            return Err(SystemError::ENONET);
+        }
+    } else {
+        let (old_begin_inode, old_remain_path) = user_path_at(&pcb, oldfd, old)?;
+        old_begin_inode.lookup_follow_symlink(&old_remain_path, symlink_times)?
+    };
+
+    // old_inode为目录时返回EPERM
+    if old_inode.metadata().unwrap().file_type == FileType::Dir {
+        return Err(SystemError::EPERM);
+    }
+
+    // 得到新创建节点的父节点
+    let (new_begin_inode, new_remain_path) = user_path_at(&pcb, newfd, new)?;
+    let (new_name, new_parent_path) = rsplit_path(&new_remain_path);
+    let new_parent =
+        new_begin_inode.lookup_follow_symlink(new_parent_path.unwrap_or("/"), symlink_times)?;
+
+    // 被调用者利用downcast_ref判断两inode是否为同一文件系统
+    return new_parent.link(new_name, &old_inode).map(|_| 0);
+}