fix(deflate): fix bug causing 0 length stored block to be output inco…

…rrectly causing corrupt stream

miniz_oxide/src/deflate/core.rs

@@ -1639,7 +1639,7 @@ pub(crate) fn flush_block(
             // Block header.
             output.put_bits(0, 2);
 
-            // Block length has to start on a byte boundary, s opad.
+            // Block length has to start on a byte boundary, so pad.
             output.pad_to_bytes();
 
             // Block length and ones complement of block length.
@@ -1651,8 +1651,10 @@ pub(crate) fn flush_block(
             let end = (d.dict.code_buf_dict_pos + d.lz.total_bytes as usize) & LZ_DICT_SIZE_MASK;
             let dict = &mut d.dict.b.dict;
             if start < end {
+                // The data does not wrap around.
                 output.write_bytes(&dict[start..end]);
-            } else {
+            } else if d.lz.total_bytes > 0 {
+                // The data wraps around and the input was not 0 bytes.
                 output.write_bytes(&dict[start..LZ_DICT_SIZE]);
                 output.write_bytes(&dict[..end]);
             }
@@ -1738,12 +1740,12 @@ fn record_match(h: &mut HuffmanOxide, lz: &mut LZOxide, mut match_len: u32, mut
 }
 
 fn compress_normal(d: &mut CompressorOxide, callback: &mut CallbackOxide) -> bool {
-    let mut src_pos = d.params.src_pos;
     let in_buf = match callback.in_buf {
         None => return true,
         Some(in_buf) => in_buf,
     };
 
+    let mut src_pos = d.params.src_pos;
     let mut lookahead_size = d.dict.lookahead_size;
     let mut lookahead_pos = d.dict.lookahead_pos;
     let mut saved_lit = d.params.saved_lit;

miniz_oxide/src/deflate/stored.rs

@@ -6,7 +6,6 @@ use crate::deflate::core::{
 use core::cmp;
 
 pub(crate) fn compress_stored(d: &mut CompressorOxide, callback: &mut CallbackOxide) -> bool {
-    let mut src_pos = d.params.src_pos;
     let in_buf = match callback.buf() {
         None => return true,
         Some(in_buf) => in_buf,
@@ -17,7 +16,7 @@ pub(crate) fn compress_stored(d: &mut CompressorOxide, callback: &mut CallbackOx
     // but just do this here to avoid causing issues for now.
     d.params.saved_match_len = 0;
     let mut bytes_written = d.lz.total_bytes;
-
+    let mut src_pos = d.params.src_pos;
     let mut lookahead_size = d.dict.lookahead_size;
     let mut lookahead_pos = d.dict.lookahead_pos;
 

miniz_oxide/tests/test.rs

@@ -285,6 +285,16 @@ fn issue_161_index_out_of_range_apply_match() {
     let _ = miniz_oxide::inflate::core::decompress(&mut decompressor, &content, &mut buf2, 0, 0);
 }
 
+#[test]
+fn empty_stored() {
+    // Compress empty input using stored compression level
+    // There was a logic error casuing this to output zeroes
+    // from the empty data buffer instead of outputting an empty stored block.
+    let data = vec![];
+    let enc = compress_to_vec_zlib(&data, 0);
+    let _ = decompress_to_vec_zlib(&enc).unwrap();
+}
+
 /*
 #[test]
 fn partial_decompression_imap_issue_158() {