46 lines
1.2 KiB
Rust
46 lines
1.2 KiB
Rust
// SPDX-License-Identifier: MPL-2.0
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use super::SyscallReturn;
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use crate::{
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fs,
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fs::file_table::{FileDesc, get_file_fast},
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prelude::*,
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};
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pub fn sys_read(
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fd: FileDesc,
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user_buf_addr: Vaddr,
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buf_len: usize,
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ctx: &Context,
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) -> Result<SyscallReturn> {
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debug!(
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"fd = {}, user_buf_ptr = 0x{:x}, buf_len = 0x{:x}",
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fd, user_buf_addr, buf_len
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);
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let mut file_table = ctx.thread_local.borrow_file_table_mut();
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let file = get_file_fast!(&mut file_table, fd);
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// According to <https://man7.org/linux/man-pages/man2/read.2.html>, if
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// the user specified an empty buffer, we should detect errors by checking
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// the file descriptor. If no errors detected, return 0 successfully.
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let read_len = {
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if buf_len != 0 {
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let user_space = ctx.user_space();
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let mut writer = user_space.writer(user_buf_addr, buf_len)?;
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file.read(&mut writer)
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} else {
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file.read_bytes(&mut [])
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}
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}
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.map_err(|err| match err.error() {
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Errno::EINTR => Error::new(Errno::ERESTARTSYS),
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_ => err,
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})?;
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if read_len > 0 {
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fs::notify::on_access(&file);
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}
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Ok(SyscallReturn::Return(read_len as _))
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}
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