rust-lang / rust-lang/rust-by-example

When learning about filesystem operations, I've encountered some issues with my code.

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Description

use std::fs::{File, OpenOptions};
use std::io;
use std::io::prelude::*;
#[cfg(target_family = "unix")]
use std::os::unix;
#[cfg(target_family = "windows")]
use std::os::windows;
use std::path::Path;

// A simple implementation of `% cat path`
fn cat(path: &Path) -> io::Result<String> {
    let mut f = File::open(path)?;
    let mut s = String::new();
    match f.read_to_string(&mut s) {
        Ok(_) => Ok(s),
        Err(e) => Err(e),
    }
}

// A simple implementation of `% echo s > path`
fn echo(s: &str, path: &Path) -> io::Result<()> {
    let mut f = File::create(path)?;

    f.write_all(s.as_bytes())
}

// A simple implementation of `% touch path` (ignores existing files)
fn touch(path: &Path) -> io::Result<()> {
    match OpenOptions::new().create(true).write(true).open(path) {
        Ok(_) => Ok(()),
        Err(e) => Err(e),
    }
}

fn main() {
    println!("`mkdir a`");
    // Create a directory, returns `io::Result<()>`
    match fs::create_dir("a") {
        Err(why) => println!("! {:?}", why.kind()),
        Ok(_) => {},
    }

    println!("`echo hello > a/b.txt`");
    // The previous match can be simplified using the `unwrap_or_else` method
    echo("hello", &Path::new("a/b.txt")).unwrap_or_else(|why| {
        println!("! {:?}", why.kind());
    });

    println!("`mkdir -p a/c/d`");
    // Recursively create a directory, returns `io::Result<()>`
    fs::create_dir_all("a/c/d").unwrap_or_else(|why| {
        println!("! {:?}", why.kind());
    });

    println!("`touch a/c/e.txt`");
    touch(&Path::new("a/c/e.txt")).unwrap_or_else(|why| {
        println!("! {:?}", why.kind());
    });

    println!("`ln -s ../b.txt a/c/b.txt`");
    // Create a symbolic link, returns `io::Result<()>`
    #[cfg(target_family = "unix")] {
        unix::fs::symlink("../b.txt", "a/c/b.txt").unwrap_or_else(|why| {
            println!("! {:?}", why.kind());
        });
    }
    #[cfg(target_family = "windows")] {
        windows::fs::symlink_file("../b.txt", "a/c/b.txt").unwrap_or_else(|why| {
            println!("! {:?}", why.to_string());
        });
    }

    println!("`cat a/c/b.txt`");
    match cat(&Path::new("a/c/b.txt")) {
        Err(why) => println!("! {:?}", why.kind()),
        Ok(s) => println!("> {}", s),
    }

    println!("`ls a`");
    // Read the contents of a directory, returns `io::Result<Vec<Path>>`
    match fs::read_dir("a") {
        Err(why) => println!("! {:?}", why.kind()),
        Ok(paths) => for path in paths {
            println!("> {:?}", path.unwrap().path());
        },
    }

    println!("`rm a/c/e.txt`");
    // Remove a file, returns `io::Result<()>`
    fs::remove_file("a/c/e.txt").unwrap_or_else(|why| {
        println!("! {:?}", why.kind());
    });

    println!("`rmdir a/c/d`");
    // Remove an empty directory, returns `io::Result<()>`
    fs::remove_dir("a/c/d").unwrap_or_else(|why| {
        println!("! {:?}", why.kind());
    });
}```



```rustc 1.80.0 (051478957 2024-07-21)
机带 RAM	64.0 GB (63.9 GB 可用)
版本	Windows 11 专业版
版本号	23H2
安装日期	‎2022/‎10/‎1
操作系统版本	22631.4037

体验	Windows Feature Experience Pack 1000.22700.1027.0

You're using windows::fs::symlink_file to create a symbolic link for a file on Windows. When you try to open and read the linked file using File::open(path) in Windows, it fails with an InvalidFilename error. However, the same operation succeeds in WSL (Windows Subsystem for Linux). Is this a bug, or is there something wrong with my code?

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  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the filesystem example on Windows with rustc 1.80.0, focusing on windows::fs::symlink_file followed by File::open. Compare that behavior with the successful WSL run; done means determining whether the example or its Windows-specific symlink handling needs correction and documenting the result.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
documentation
Issue type
Bug
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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