From 5a1ce92c0ccf47b7c9ca37cf7f9a6cfa5c211762 Mon Sep 17 00:00:00 2001
From: John Bowler <jbowler@acm.org>
Date: Sun, 7 Apr 2013 21:37:52 -0500
Subject: [PATCH] [libpng16] Fixed incorrect warning of excess deflate data.
 End condition - the

warning would be produced if the end of the deflate stream wasn't read
in the last row.  The warning is harmless.
---
 ANNOUNCE   |  7 +++++--
 CHANGES    |  5 ++++-
 pngrutil.c | 15 +++++++++------
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/ANNOUNCE b/ANNOUNCE
index 2dc99780a..7aaf171bc 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.7.0beta07 - April 1, 2013
+Libpng 1.7.0beta07 - April 8, 2013
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -236,8 +236,11 @@ Version 1.7.0beta06 [March 13, 2013]
     technically valid, although a reasonable treatment of division would
     show it to be incorrect.
 
-Version 1.7.0beta07 [April 1, 2013]
+Version 1.7.0beta07 [April 8, 2013]
   Updated documentation of 1.5.x to 1.6.x changes in iCCP chunk handling.
+  Fixed incorrect warning of excess deflate data. End condition - the
+    warning would be produced if the end of the deflate stream wasn't read
+    in the last row.  The warning is harmless.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 69e89fc45..6a68ac0ea 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4523,8 +4523,11 @@ Version 1.7.0beta06 [March 13, 2013]
     technically valid, although a reasonable treatment of division would
     show it to be incorrect.
 
-Version 1.7.0beta07 [April 1, 2013]
+Version 1.7.0beta07 [April 8, 2013]
   Updated documentation of 1.5.x to 1.6.x changes in iCCP chunk handling.
+  Fixed incorrect warning of excess deflate data. End condition - the
+    warning would be produced if the end of the deflate stream wasn't read
+    in the last row.  The warning is harmless.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngrutil.c b/pngrutil.c
index 7bbeef273..c74ea5512 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -3962,7 +3962,7 @@ png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
          png_ptr->zstream.avail_out = out;
       }
 
-      else /* check for end */
+      else /* after last row, checking for end */
       {
          png_ptr->zstream.next_out = tmpbuf;
          png_ptr->zstream.avail_out = (sizeof tmpbuf);
@@ -3977,10 +3977,13 @@ png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
        */
       ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
 
-      /* Take the unconsumed output back (so, in the 'check' case this just
-       * counts up).
-       */
-      avail_out += png_ptr->zstream.avail_out;
+      /* Take the unconsumed output back. */
+      if (output != NULL)
+         avail_out += png_ptr->zstream.avail_out;
+
+      else /* avail_out counts the extra bytes */
+         avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
+
       png_ptr->zstream.avail_out = 0;
 
       if (ret == Z_STREAM_END)
@@ -4019,7 +4022,7 @@ png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
       if (output != NULL)
          png_error(png_ptr, "Not enough image data");
 
-      else /* checking */
+      else /* the deflate stream contained extra data */
          png_chunk_benign_error(png_ptr, "Too much image data");
    }
 }