111 lines
3.0 KiB
Rust
111 lines
3.0 KiB
Rust
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/// Generic `Iterator` over implementor's of
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/// [`Entry`](trait.Entry.html)'s.
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///
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/// # Examples
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///
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/// #### Iterate over /etc/passwd printing usernames
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///
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/// ```
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/// use std::path::Path;
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/// use pgs_files::passwd::PasswdEntry;
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/// use pgs_files::Entries;
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///
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/// for entry in Entries::<PasswdEntry>::new(&Path::new("/etc/passwd")) {
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/// println!("{}", entry.name);
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/// }
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/// ```
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use std::{
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io::{BufRead,BufReader,Write},
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fs::{OpenOptions,File},
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path::Path,
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marker::PhantomData,
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num::ParseIntError,
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};
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pub struct Entries<T> {
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path: String,
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cursor: BufReader<File>,
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marker: PhantomData<T>,
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}
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impl<T> Entries<T> {
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pub fn new(file_path: &str) -> Entries<T> {
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let file = Path::new(&file_path);
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if ! file.exists() {
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File::create(file).unwrap_or_else(|e|{
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eprintln!("Error file: {}",e);
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std::process::exit(2)
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});
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}
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let reader = BufReader::new(File::open(file).ok().unwrap());
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Entries {
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path: file_path.to_owned(),
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cursor: reader,
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marker: PhantomData,
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}
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}
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pub fn append(&self, entry: String) -> anyhow::Result<()> {
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let file = Path::new(&self.path);
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if ! file.exists() {
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std::fs::write(file,format!("{}\n",entry).as_bytes())?;
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} else {
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let target_file = OpenOptions::new()
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.write(true)
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.append(true) // This is needed to append to file
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.open(&file);
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if let Ok(mut file) = target_file {
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file.write_all( format!("{}\n",entry).as_bytes())?;
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}
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}
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Ok(())
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}
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pub fn write(&self, entries: &Vec<String>) -> anyhow::Result<()> {
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let file = Path::new(&self.path);
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std::fs::write(file,format!("{}\n",entries.clone().join("\n")).as_bytes())?;
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// let target_file = OpenOptions::new()
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// .write(true)
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// .open(&file);
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// if let Ok(mut file) = target_file {
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// file.write_all(entries.clone().join("\n").as_bytes())?;
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// }
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Ok(())
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}
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}
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impl<T: Entry> Iterator for Entries<T> {
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type Item = T;
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fn next(&mut self) -> Option<T> {
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let mut line = String::new();
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loop {
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// We might need to make multiple loops to drain off
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// comment lines. Start with an empty string per loop.
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line.clear();
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match self.cursor.read_line(&mut line){
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Ok(0) => return None,
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Ok(_) => (),
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_ => return None,
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}
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if line.starts_with("#") {
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continue;
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}
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match T::from_line(&line) {
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Ok(entry) => return Some(entry),
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// Parse Error. Just ignore this entry.
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_ => (),
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}
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}
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}
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}
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/// A Trait to represent an entry of data from an
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/// /etc/{`passwd`,`group`,`shadow`} file.
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pub trait Entry: Sized {
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fn from_line(line: &str) -> anyhow::Result<Self, ParseIntError>;
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}
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