jD91mZM2
98 lines
2.4 KiB
Rust
98 lines
2.4 KiB
Rust
use alloc::vec::Vec;
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use platform::types::*;
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use platform::{Pal, Sys};
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use header::unistd::{lseek, SEEK_SET};
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/// Implements an `Iterator` which returns on either newline or EOF.
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#[derive(Clone)]
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pub struct RawLineBuffer {
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pub fd: c_int,
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buf: Vec<u8>,
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newline: Option<usize>,
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read: usize,
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}
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#[derive(PartialEq)]
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pub enum Line<'a> {
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Error,
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EOF,
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Some(&'a [u8]),
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}
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impl RawLineBuffer {
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pub const fn new(fd: c_int) -> Self {
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Self {
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fd: fd,
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buf: Vec::new(),
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newline: None,
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read: 0,
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}
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}
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// Can't use iterators because we want to return a reference.
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// See https://stackoverflow.com/a/30422716/5069285
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pub fn next(&mut self) -> Line {
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// Remove last line
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if let Some(newline) = self.newline {
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self.buf.drain(..newline + 1);
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}
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loop {
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// Exit if newline was read already
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self.newline = self.buf.iter().position(|b| *b == b'\n');
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if self.newline.is_some() {
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break;
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}
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let len = self.buf.len();
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if len >= self.buf.capacity() {
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self.buf.reserve(1024);
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}
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// Create buffer of what's left in the vector, uninitialized memory
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unsafe {
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let capacity = self.buf.capacity();
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self.buf.set_len(capacity);
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}
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let read = Sys::read(self.fd, &mut self.buf[len..]);
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let read_usize = read.max(0) as usize;
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// Remove all uninitialized memory that wasn't read
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unsafe {
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self.buf.set_len(len + read_usize);
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}
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self.read += read_usize;
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if read == 0 {
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return Line::EOF;
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}
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if read < 0 {
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return Line::Error;
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}
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}
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let newline = self.newline.unwrap(); // safe because it doesn't break the loop otherwise
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Line::Some(&self.buf[..newline])
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}
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/// Return the byte position of the start of the line
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pub fn line_pos(&self) -> usize {
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self.read - self.buf.len()
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}
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/// Seek to a byte position in the file
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pub fn seek(&mut self, pos: usize) -> off_t {
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let ret = lseek(self.fd, pos as i64, SEEK_SET);
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if ret != !0 {
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self.read = pos;
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}
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ret
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}
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}
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