From: Mark Adler <madler@alumni.caltech.edu>
Date: Fri, 24 Aug 2012 22:02:28 +0000 (-0700)
Subject: Fix unintialized value bug in gzputc() introduced by const patches.
X-Git-Tag: v1.2.7.1~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa566e86c46d2264bf623e51f5840bde642548ad;p=thirdparty%2Fzlib-ng.git

Fix unintialized value bug in gzputc() introduced by const patches.

Avoid the use of an uninitialized value when the write buffers have
not been initialized.  A recent change to avoid the use of strm->
next_in in order to resolve some const conflicts added the use of
state->in in its place.  This patch avoids the use of state->in
when it is not initialized.  Nothing bad would actually happen,
since two variables set to the same unintialized value are
subtracted.  However valgrind was rightly complaining.  So this
fixes that.
---

diff --git a/gzwrite.c b/gzwrite.c
index bf5791354..f53aace49 100644
--- a/gzwrite.c
+++ b/gzwrite.c
@@ -270,14 +270,16 @@ int ZEXPORT gzputc(file, c)
 
     /* try writing to input buffer for speed (state->size == 0 if buffer not
        initialized) */
-    if (strm->avail_in == 0)
-        strm->next_in = state->in;
-    have = strm->next_in + strm->avail_in - state->in;
-    if (have < state->size) {
-        state->in[have] = c;
-        strm->avail_in++;
-        state->x.pos++;
-        return c & 0xff;
+    if (state->size) {
+        if (strm->avail_in == 0)
+            strm->next_in = state->in;
+        have = strm->next_in + strm->avail_in - state->in;
+        if (have < state->size) {
+            state->in[have] = c;
+            strm->avail_in++;
+            state->x.pos++;
+            return c & 0xff;
+        }
     }
 
     /* no room in buffer or not initialized, use gz_write() */