Remove the shim kernel crate

kernel/src/syscall/preadv.rs

@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::SyscallReturn;
+use crate::{
+    fs::file_table::FileDesc,
+    prelude::*,
+    util::{copy_iovs_from_user, IoVec},
+};
+
+pub fn sys_readv(
+    fd: FileDesc,
+    io_vec_ptr: Vaddr,
+    io_vec_count: usize,
+    ctx: &Context,
+) -> Result<SyscallReturn> {
+    let res = do_sys_readv(fd, io_vec_ptr, io_vec_count, ctx)?;
+    Ok(SyscallReturn::Return(res as _))
+}
+
+pub fn sys_preadv(
+    fd: FileDesc,
+    io_vec_ptr: Vaddr,
+    io_vec_count: usize,
+    offset: i64,
+    ctx: &Context,
+) -> Result<SyscallReturn> {
+    let res = do_sys_preadv(fd, io_vec_ptr, io_vec_count, offset, RWFFlag::empty(), ctx)?;
+    Ok(SyscallReturn::Return(res as _))
+}
+
+pub fn sys_preadv2(
+    fd: FileDesc,
+    io_vec_ptr: Vaddr,
+    io_vec_count: usize,
+    offset: i64,
+    flags: u32,
+    ctx: &Context,
+) -> Result<SyscallReturn> {
+    let flags = match RWFFlag::from_bits(flags) {
+        Some(flags) => flags,
+        None => return_errno_with_message!(Errno::EINVAL, "invalid flags"),
+    };
+    let res = if offset == -1 {
+        do_sys_readv(fd, io_vec_ptr, io_vec_count, ctx)?
+    } else {
+        do_sys_preadv(fd, io_vec_ptr, io_vec_count, offset, flags, ctx)?
+    };
+    Ok(SyscallReturn::Return(res as _))
+}
+
+fn do_sys_preadv(
+    fd: FileDesc,
+    io_vec_ptr: Vaddr,
+    io_vec_count: usize,
+    offset: i64,
+    _flags: RWFFlag,
+    ctx: &Context,
+) -> Result<usize> {
+    debug!(
+        "preadv: fd = {}, io_vec_ptr = 0x{:x}, io_vec_counter = 0x{:x}, offset = 0x{:x}",
+        fd, io_vec_ptr, io_vec_count, offset
+    );
+
+    if offset < 0 {
+        return_errno_with_message!(Errno::EINVAL, "offset cannot be negative");
+    }
+
+    let file = {
+        let filetable = ctx.process.file_table().lock();
+        filetable.get_file(fd)?.clone()
+    };
+
+    if io_vec_count == 0 {
+        return Ok(0);
+    }
+
+    // Calculate the total buffer length and check for overflow
+    let total_len = io_vec_count
+        .checked_mul(core::mem::size_of::<IoVec>())
+        .and_then(|val| val.checked_add(offset as usize));
+    if total_len.is_none() {
+        return_errno_with_message!(Errno::EINVAL, "offset + io_vec_count overflow");
+    }
+
+    let mut total_len: usize = 0;
+    let mut cur_offset = offset as usize;
+
+    let io_vecs = copy_iovs_from_user(io_vec_ptr, io_vec_count)?;
+    for io_vec in io_vecs.as_ref() {
+        if io_vec.is_empty() {
+            continue;
+        }
+        if total_len.checked_add(io_vec.len()).is_none()
+            || total_len
+                .checked_add(io_vec.len())
+                .and_then(|sum| sum.checked_add(cur_offset))
+                .is_none()
+            || total_len
+                .checked_add(io_vec.len())
+                .and_then(|sum| sum.checked_add(cur_offset))
+                .map(|sum| sum > isize::MAX as usize)
+                .unwrap_or(false)
+        {
+            return_errno_with_message!(Errno::EINVAL, "Total length overflow");
+        }
+
+        let mut buffer = vec![0u8; io_vec.len()];
+
+        // TODO: According to the man page
+        // at <https://man7.org/linux/man-pages/man2/readv.2.html>,
+        // readv must be atomic,
+        // but the current implementation does not ensure atomicity.
+        // A suitable fix would be to add a `readv` method for the `FileLike` trait,
+        // allowing each subsystem to implement atomicity.
+        let read_len = file.read_bytes_at(cur_offset, &mut buffer)?;
+        io_vec.write_exact_to_user(&buffer)?;
+        total_len += read_len;
+        cur_offset += read_len;
+        if read_len == 0 || read_len < buffer.len() {
+            // End of file reached or no more data to read
+            break;
+        }
+    }
+
+    Ok(total_len)
+}
+
+fn do_sys_readv(
+    fd: FileDesc,
+    io_vec_ptr: Vaddr,
+    io_vec_count: usize,
+    ctx: &Context,
+) -> Result<usize> {
+    debug!(
+        "fd = {}, io_vec_ptr = 0x{:x}, io_vec_counter = 0x{:x}",
+        fd, io_vec_ptr, io_vec_count
+    );
+
+    let file = {
+        let filetable = ctx.process.file_table().lock();
+        filetable.get_file(fd)?.clone()
+    };
+
+    if io_vec_count == 0 {
+        return Ok(0);
+    }
+
+    let mut total_len = 0;
+
+    let io_vecs = copy_iovs_from_user(io_vec_ptr, io_vec_count)?;
+    for io_vec in io_vecs.as_ref() {
+        if io_vec.is_empty() {
+            continue;
+        }
+
+        let mut buffer = vec![0u8; io_vec.len()];
+        // TODO: According to the man page
+        // at <https://man7.org/linux/man-pages/man2/readv.2.html>,
+        // readv must be atomic,
+        // but the current implementation does not ensure atomicity.
+        // A suitable fix would be to add a `readv` method for the `FileLike` trait,
+        // allowing each subsystem to implement atomicity.
+        let read_len = file.read_bytes(&mut buffer)?;
+        io_vec.write_exact_to_user(&buffer)?;
+        total_len += read_len;
+        if read_len == 0 || read_len < buffer.len() {
+            // End of file reached or no more data to read
+            break;
+        }
+    }
+
+    Ok(total_len)
+}
+
+bitflags! {
+    struct RWFFlag: u32 {
+        const RWF_DSYNC = 0x00000001;
+        const RWF_HIPRI = 0x00000002;
+        const RWF_SYNC = 0x00000004;
+        const RWF_NOWAIT = 0x00000008;
+    }
+}