Function count_parent_prefix

hail-fuzz/src/utils.rs:217–246

Returns a count of the number of bytes within each stream shared with the parent input.

(
    fuzzer: &Fuzzer,
    input_id: usize,
    extension_only: bool,
)

/// Returns a count of the number of bytes within each stream shared with the parent input.
pub fn count_parent_prefix(
    fuzzer: &Fuzzer,
    input_id: usize,
    extension_only: bool,
) -> HashMap<u64, usize> {
    let input = &fuzzer.corpus[input_id];

    if !input.metadata.stage.is_extension() && extension_only {
        return HashMap::new();
    }
    let Some(parent) = input.metadata.parent_id
    else {
        return HashMap::new();
    };
    let parent_data = &fuzzer.corpus[parent].data;

    let mut extensions = HashMap::new();
    for (addr, stream) in &input.data.streams {
        let Some(parent_stream) = parent_data.streams.get(addr)
        else {
            continue;
        };

        let shared_prefix =
            stream.bytes.iter().zip(&parent_stream.bytes).take_while(|(a, b)| a == b).count();
        extensions.insert(*addr, shared_prefix);
    }

    extensions
}

#[cfg(test)]
mod tests {