0.31.0: hardening and correctness pass across mux, codec, AACS/CSS, UDF/MPLS/CLPI, recovery, drive/SCSI, labels, and I/O

Library-wide review-and-fix pass: tightened AACS keydb/handshake/variant
handling and trailing-partial-unit policy, corrected MPLS mark offset and
added UDF allocation bounds, hardened the mux/codec framing and M2TS paths,
guarded SCSI READ CAPACITY short transfers and unified error mapping, added
overflow guards on untrusted disc input, and made prefetch shutdown
deterministic. Release profile now builds with thin LTO + single codegen unit.

src/labels/text.rs

@@ -1,13 +1,14 @@
 //! Text-extraction helpers used by parsers that scan binary blobs for
 //! embedded label strings.
 //!
-//! Promoted from two near-duplicate implementations:
-//! - `pixelogic::extract_strings` (`bluray_project.bin`, min_len=4)
-//! - `dbp::extract_printable` (`.class` files in jars, min_len=5)
+//! Promoted from a byte-scanning helper (`bluray_project.bin`,
+//! min_len=4). Single implementation, threshold passed in.
 //!
-//! Single implementation, threshold passed in. Callers that have a
-//! more structured parse path (e.g. `class_reader` for .class) should
-//! prefer that — this helper is for genuinely unstructured input.
+//! `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`.
@@ -21,13 +22,13 @@ pub fn extract_ascii_strings(data: &[u8], min_len: usize) -> Vec<String> {
     for &b in data {
         if (0x20..=0x7E).contains(&b) {
             current.push(b as char);
-        } else if current.len() >= min_len {
+        } else if !current.is_empty() && current.len() >= min_len {
             out.push(std::mem::take(&mut current));
         } else {
             current.clear();
         }
     }
-    if current.len() >= min_len {
+    if !current.is_empty() && current.len() >= min_len {
         out.push(current);
     }
     out
@@ -86,4 +87,14 @@ mod tests {
         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"]);
+    }
 }