Fix bug when level 0 used with Z_HUFFMAN or Z_RLE.

Compression level 0 requests no compression, using only stored
blocks. When Z_HUFFMAN or Z_RLE was used with level 0 (granted,
an odd choice, but permitted), the resulting blocks were mostly
fixed or dynamic. The reason is that deflate_stored() was not
being called in that case. The compressed data was valid, but it
was not what the application requested. This commit assures that
only stored blocks are emitted for compression level 0, regardless
of the strategy selected.

diff --git a/deflate.c b/deflate.c
index 56d073e8e3ed9e815d0512cdd54d0cb8d2cb4e92..ef286450ab60a4bb6fe58fe6c16dcbeb48249e52 100644 (file)
--- a/deflate.c
+++ b/deflate.c
@@ -936,7 +936,8 @@ int ZEXPORT deflate(z_stream *strm, int flush) {
     if (strm->avail_in != 0 || s->lookahead != 0 || (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
         block_state bstate;
 
-        bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
+        bstate = s->level == 0 ? deflate_stored(s, flush) :
+                 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
                  s->strategy == Z_RLE ? deflate_rle(s, flush) :
 #ifdef X86_QUICK_STRATEGY
                  (s->level == 1 && !x86_cpu_has_sse42) ? deflate_fast(s, flush) :