rustLogic errorMedium

Unexpected file descriptor leak in Rust application

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BugFind the bug and fix the code

What it should do

Reads a file and returns its contents as a String. Example: process_file_descriptor("data.txt") -> "file contents"

What happens instead

Resource temporarily unavailable: Too many open files

use std::fs::File;
use std::io::Read;

pub fn process_file_descriptor(filename: &str) -> String {
    let mut file = File::open(filename).expect("Failed to open file");
    let mut contents = String::new();
    file.read_to_string(&mut contents).expect("Failed to read file");
    std::mem::forget(file);
    contents
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

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Hints

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Hint 2

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Hint 3

Unlocks after Hint 2

This bug belongs to the logic errors pattern

The wrong operator, an inverted condition, a formula the right way round but backwards.

Learn the logic errors pattern Step through your own code

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use std::fs::File; use std::io::Read; pub fn process_file_descriptor(filename: &str) -> String { let mut file = File::open(filename).expect("Failed to open file"); let mut contents = String::new(); file.read_to_string(&mut contents).expect("Failed to read file"); std::mem::forget(file); contents }

Unexpected file descriptor leak in Rust application

What it should do

What happens instead

More logic errors to practise

Unexpected file descriptor leak in Rust application

What it should do

What happens instead

More logic errors to practise