Bug fix: allow invalid compressed files, but verify length if decompression succeeds

fuzz/fuzz_targets/fuzz_read.rs

@@ -2,13 +2,19 @@
 use libfuzzer_sys::fuzz_target;
 use std::io::Read;
 
+const MAX_BYTES_TO_READ: u64 = 1 << 24;
+
 fn decompress_all(data: &[u8]) -> Result<(), Box<dyn std::error::Error>> {
     let reader = std::io::Cursor::new(data);
     let mut zip = zip_next::ZipArchive::new(reader)?;
 
     for i in 0..zip.len() {
         let file = zip.by_index(i)?;
-        std::io::copy(&mut file.take(1 << 24), &mut std::io::sink())?;
+        let expected_bytes = file.size().max(MAX_BYTES_TO_READ);
+        let result = std::io::copy(&mut file.take(MAX_BYTES_TO_READ), &mut std::io::sink());
+        if let Ok(bytes) = result {
+            assert_eq!(expected_bytes, bytes)
+        }
     }
 
     Ok(())