libfreemkv 0.31.1

//! Text-extraction helpers used by parsers that scan binary blobs for
//! embedded label strings.
//!
//! Promoted from a byte-scanning helper (`bluray_project.bin`,
//! min_len=4). Single implementation, threshold passed in.
//!
//! `dbp` no longer uses a byte-scanning helper — it iterates
//! `class_reader::CpInfo::Utf8` constant-pool entries directly. Callers
//! that have a more structured parse path (e.g. `class_reader` for
//! `.class`) should prefer that; this helper is for genuinely
//! unstructured input.

/// Walk `data`, emit every maximal run of printable-ASCII bytes
/// (`0x20..=0x7E`) whose length is at least `min_len`.
///
/// Non-printable bytes (including `\t`, `\n`, NUL) terminate the
/// current run. Output strings are guaranteed valid UTF-8 (they're
/// pure 7-bit ASCII). Strings shorter than `min_len` are dropped.
pub fn extract_ascii_strings(data: &[u8], min_len: usize) -> Vec<String> {
    let mut out = Vec::new();
    let mut current = String::new();
    for &b in data {
        if (0x20..=0x7E).contains(&b) {
            current.push(b as char);
        } else if !current.is_empty() && current.len() >= min_len {
            out.push(std::mem::take(&mut current));
        } else {
            current.clear();
        }
    }
    if !current.is_empty() && current.len() >= min_len {
        out.push(current);
    }
    out
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn extracts_simple_runs() {
        let got = extract_ascii_strings(b"hello\0world\0", 3);
        assert_eq!(got, vec!["hello", "world"]);
    }

    #[test]
    fn applies_minimum_length() {
        let got = extract_ascii_strings(b"hi\0ok\0longer\0", 5);
        assert_eq!(got, vec!["longer"]);
    }

    #[test]
    fn treats_tab_and_newline_as_separators() {
        // \t (0x09) and \n (0x0A) are below 0x20, so they break runs.
        let got = extract_ascii_strings(b"alpha\tbeta\ngamma", 3);
        assert_eq!(got, vec!["alpha", "beta", "gamma"]);
    }

    #[test]
    fn handles_trailing_run_without_terminator() {
        // Run at the very end of the buffer should still be emitted.
        let got = extract_ascii_strings(b"prefix\0tail", 3);
        assert_eq!(got, vec!["prefix", "tail"]);
    }

    #[test]
    fn rejects_high_bit_bytes() {
        // 0x80+ is non-printable per this helper's definition.
        let mut buf = b"good".to_vec();
        buf.push(0xC3);
        buf.push(0xA9);
        buf.extend_from_slice(b"more");
        let got = extract_ascii_strings(&buf, 3);
        assert_eq!(got, vec!["good", "more"]);
    }

    #[test]
    fn empty_input_returns_empty() {
        let got = extract_ascii_strings(&[], 1);
        assert!(got.is_empty());
    }

    #[test]
    fn min_len_zero_emits_singletons() {
        // Pathological but well-defined.
        let got = extract_ascii_strings(b"a\0b", 0);
        assert_eq!(got, vec!["a", "b"]);
    }

    #[test]
    fn min_len_zero_skips_empty_runs_on_consecutive_separators() {
        // Consecutive separators must NOT emit empty strings even at
        // min_len=0 — an empty string is not a "run of printable bytes".
        let got = extract_ascii_strings(b"\0\0abc", 0);
        assert_eq!(got, vec!["abc"]);
        let got = extract_ascii_strings(b"ab\0\0\0cd\0\0", 0);
        assert_eq!(got, vec!["ab", "cd"]);
    }
}