commit 0d201ad25ba4ddf83b4f17986ff5fd032c9f209e
author Brad King <brad.king@kitware.com> Thu May 26 11:00:52 2022 -0400
committer Brad King <brad.king@kitware.com> Thu May 26 12:29:41 2022 -0400
tree 49abe450b9e14d12de238562d6033398273d7b9b
parent 512c1f8f75d2536f7db5560fc48d4db8f539c931

zlib: Add initialization to satisfy valgrind

Restore the change from commit cf133ff6b3 (Fix uninitialized variable
access in zlib, 2009-11-18, v2.8.2~705). Their web site claims it does
no harm ( https://www.zlib.net/zlib_faq.html#faq36), but fixing it this
way eliminates the diagnostic.

Utilities/cmzlib/deflate.c

diff --git a/Utilities/cmzlib/deflate.c b/Utilities/cmzlib/deflate.c
index 29ce1f6..5ec8374 100644
--- a/Utilities/cmzlib/deflate.c
+++ b/Utilities/cmzlib/deflate.c
@@ -285,6 +285,13 @@
     s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
 
     s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
+
+    /* The following memset eliminates the valgrind uninitialized warning
+      "swept under the carpet" here:
+      http://www.zlib.net/zlib_faq.html#faq36 */
+
+    memset(s->window, 0, s->w_size*2*sizeof(Byte));
+
     s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
     s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));