Code reviewHardcr-g174

Subject Uninitialized memoryLevel Senior–Staff~35 minCommon in Code quality & review interviewsIndustries Software development

Question

Review this Rust function that pre-sizes a buffer before reading into it.

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Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix — specific and kind.

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Code to reviewrust

1use std::io::Read;2 3fn read_n(mut r: impl Read, n: usize) -> std::io::Result<Vec<u8>> {4    let mut buf: Vec<u8> = Vec::with_capacity(n);5    unsafe { buf.set_len(n); }6    let got = r.read(&mut buf)?;7    buf.truncate(got);8    Ok(buf)9}

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