From f1b8edadc3c733990f8a8de4d643f968e571ae85 Mon Sep 17 00:00:00 2001

From: Adam Tkac <atkac@redhat.com>

Date: Fri, 17 Aug 2012 15:13:48 +0200

Subject: [PATCH] Rank Z_BLOCK flush below Z_PARTIAL_FLUSH only when last

 flush was Z_BLOCK.

This fixes regression introduced by f1ebdd6a9c495a5db9a22aa80dd7d54ae7db42e9

(Permit stronger flushes after Z_BLOCK flushes.). Now this code is valid

again:

deflate(stream, Z_SYNC_FLUSH);

deflateParams(stream, newLevel, Z_DEFAULT_STRATEGY);

Signed-off-by: Adam Tkac <atkac@redhat.com>

---

 deflate.c | 13 ++++++++++---

 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/deflate.c b/deflate.c

index 9e4c2cb..3422f72 100644

--- a/deflate.c

+++ b/deflate.c

@@ -882,9 +882,16 @@ int ZEXPORT deflate (strm, flush)

      * flushes. For repeated and useless calls with Z_FINISH, we keep

      * returning Z_STREAM_END instead of Z_BUF_ERROR.

      */

-    } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&

-               flush != Z_FINISH) {

-        ERR_RETURN(strm, Z_BUF_ERROR);

+    } else if (strm->avail_in == 0 && flush != Z_FINISH) {

+        char err;

+

+        /* Degrade Z_BLOCK only when last flush was Z_BLOCK */

+        err = (old_flush == Z_BLOCK) ?

+              RANK(flush) <= RANK(old_flush) : flush <= old_flush;

+

+        if (err) {

+            ERR_RETURN(strm, Z_BUF_ERROR);

+        }

     }

     /* User must not provide more input after the first FINISH: */

-- 

1.7.11.4