feat(vfs): 增加sys_preadv 增加对readable中对 O_PATH的检查 (#1404)

* 实现preadv系统调用, 增加对对 O_PATH 的可读检查

Signed-off-by: 2448956191@qq.com <2448956191@qq.com>

kernel/src/filesystem/vfs/file.rs

@@ -407,9 +407,10 @@ impl File {
     /// @brief 判断当前文件是否可读
     #[inline]
     pub fn readable(&self) -> Result<(), SystemError> {
+        let mode = *self.mode.read();
         // 暂时认为只要不是write only, 就可读
-        if *self.mode.read() == FileMode::O_WRONLY {
-            return Err(SystemError::EPERM);
+        if mode == FileMode::O_WRONLY || mode.contains(FileMode::O_PATH) {
+            return Err(SystemError::EBADF);
         }
 
         return Ok(());

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

@@ -31,6 +31,7 @@ mod sys_mkdirat;
 pub mod sys_mknodat;
 mod sys_openat;
 mod sys_pread64;
+mod sys_preadv;
 mod sys_pselect6;
 mod sys_pwrite64;
 mod sys_pwritev;

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

@@ -0,0 +1,87 @@
+use alloc::string::ToString;
+use alloc::vec::Vec;
+
+use system_error::SystemError;
+
+use crate::arch::syscall::nr::SYS_PREADV;
+use crate::filesystem::vfs::iov::{IoVec, IoVecs};
+use crate::process::ProcessManager;
+use crate::syscall::table::{FormattedSyscallParam, Syscall};
+
+pub struct SysPreadVHandle;
+
+impl Syscall for SysPreadVHandle {
+    fn num_args(&self) -> usize {
+        4
+    }
+
+    fn handle(
+        &self,
+        args: &[usize],
+        _frame: &mut crate::arch::interrupt::TrapFrame,
+    ) -> Result<usize, SystemError> {
+        let fd = Self::fd(args);
+        let iov = Self::iov(args);
+        let iov_count = Self::iov_count(args);
+        let offset = Self::offset(args);
+
+        // Construct IoVecs from user pointer.
+        // For preadv, we are writing to user buffers, so we need to verify they are writable.
+        // IoVecs::from_user internally uses UserBufferWriter::new which verifies the area.
+        let iovecs = unsafe { IoVecs::from_user(iov, iov_count, true) }?;
+
+        do_preadv(fd, &iovecs, offset)
+    }
+
+    fn entry_format(&self, args: &[usize]) -> Vec<FormattedSyscallParam> {
+        vec![
+            FormattedSyscallParam::new("fd:", Self::fd(args).to_string()),
+            FormattedSyscallParam::new("iov:", format!("{:#x}", Self::iov(args) as usize)),
+            FormattedSyscallParam::new("iov_count:", Self::iov_count(args).to_string()),
+            FormattedSyscallParam::new("offset:", Self::offset(args).to_string()),
+        ]
+    }
+}
+
+impl SysPreadVHandle {
+    fn fd(args: &[usize]) -> i32 {
+        args[0] as i32
+    }
+
+    fn iov(args: &[usize]) -> *const IoVec {
+        args[1] as *const IoVec
+    }
+
+    fn iov_count(args: &[usize]) -> usize {
+        args[2]
+    }
+
+    fn offset(args: &[usize]) -> usize {
+        args[3]
+    }
+}
+
+pub fn do_preadv(fd: i32, iovecs: &IoVecs, offset: usize) -> 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)
+        .ok_or(SystemError::EBADF)?;
+
+    drop(fd_table_guard);
+
+    // Create a kernel buffer to read data into.
+    // TODO: Support scatter-gather I/O directly in FS to avoid this copy.
+    let mut data = vec![0; iovecs.total_len()];
+
+    // Read from file at offset into kernel buffer.
+    let read_len = file.pread(offset, data.len(), &mut data)?;
+
+    // Scatter the read data back to user buffers.
+    iovecs.scatter(&data[..read_len]);
+
+    Ok(read_len)
+}
+
+syscall_table_macros::declare_syscall!(SYS_PREADV, SysPreadVHandle);

user/apps/tests/syscall/gvisor/whitelist.txt

@@ -25,6 +25,7 @@ chdir_test
 fchdir_test
 rename_test
 getdents_test
+preadv_test
 
 # 进程相关测试
 fork_test