106 lines
2.4 KiB
Rust
106 lines
2.4 KiB
Rust
use anyhow::{Context as _, Result, bail};
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use std::{
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fs,
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io::{Read as _, Write as _},
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};
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fn main() -> Result<()> {
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let app = App::try_new()?;
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app.run()
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}
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struct App {
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filenames: Vec<String>,
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is_terminal: bool,
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}
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impl App {
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fn try_new() -> Result<Self> {
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use std::io::IsTerminal as _;
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let is_terminal = std::io::stdout().is_terminal();
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let mut args = std::env::args();
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let _exe_name = args.next().context("How do we not have an exe name?")?;
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let mut filenames = vec![];
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for arg in args {
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filenames.push(arg);
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}
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Ok(App {
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filenames,
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is_terminal,
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})
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}
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fn run(&self) -> Result<()> {
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if self.filenames.is_empty() {
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return self.ls(".");
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}
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for filename in &self.filenames {
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let metadata = fs::metadata(filename)?;
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if metadata.is_dir() {
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self.ls(filename)?;
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} else {
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self.cat(filename)?;
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}
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}
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Ok(())
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}
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fn cat(&self, filename: &str) -> Result<()> {
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let mut cat = Cat::try_new(filename)?;
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while let Some(buf) = cat.poll()? {
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std::io::stdout().write_all(buf)?;
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}
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Ok(())
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}
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fn ls(&self, filename: &str) -> Result<()> {
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// Use `/usr/bin` just in case for some weird reason we're symlinked as ls,
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// we don't want to recurse into ourselves
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let mut command = std::process::Command::new("/usr/bin/ls");
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if self.is_terminal {
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command.arg("--color=always");
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}
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let status = command.arg(filename).status()?;
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if !status.success() {
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bail!("subprocess `ls` failed");
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}
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Ok(())
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}
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}
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struct Cat {
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f: fs::File,
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buf: Vec<u8>,
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}
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impl Cat {
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fn try_new(filename: &str) -> Result<Self> {
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let f = fs::File::open(filename)?;
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let buf = vec![0u8; 4_096];
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Ok(Self { f, buf })
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}
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fn poll(&mut self) -> Result<Option<&[u8]>> {
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let bytes_read = self.f.read(&mut self.buf)?;
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let buf = &self.buf[0..bytes_read];
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if bytes_read == 0 {
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return Ok(None);
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}
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Ok(Some(buf))
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test() -> Result<()> {
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let dir = tempfile::tempdir()?;
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Ok(())
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}
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}
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