ports/opt (3.1): [notify] libpng: updated to 1.6.20. Reissued fix for CVE-2015-8126

3 Dec 2015

commit 262e9331b17317cb3780ec32cbd35dca44af77b9
Author: Fredrik Rinnestam <fredrik@crux.nu>
Date:   Thu Dec 3 19:15:01 2015 +0100

    [notify] libpng: updated to 1.6.20. Reissued fix for CVE-2015-8126

diff --git a/libpng/.footprint b/libpng/.footprint
index f642b36..150fcd9 100644
--- a/libpng/.footprint
+++ b/libpng/.footprint
@@ -18,9 +18,9 @@ lrwxrwxrwx	root/root	usr/lib/libpng.la -> libpng16.la
 lrwxrwxrwx	root/root	usr/lib/libpng.so -> libpng16.so
 -rw-r--r--	root/root	usr/lib/libpng16.a
 -rwxr-xr-x	root/root	usr/lib/libpng16.la
-lrwxrwxrwx	root/root	usr/lib/libpng16.so -> libpng16.so.16.19.0
-lrwxrwxrwx	root/root	usr/lib/libpng16.so.16 -> libpng16.so.16.19.0
--rwxr-xr-x	root/root	usr/lib/libpng16.so.16.19.0
+lrwxrwxrwx	root/root	usr/lib/libpng16.so -> libpng16.so.16.20.0
+lrwxrwxrwx	root/root	usr/lib/libpng16.so.16 -> libpng16.so.16.20.0
+-rwxr-xr-x	root/root	usr/lib/libpng16.so.16.20.0
 drwxr-xr-x	root/root	usr/lib/pkgconfig/
 lrwxrwxrwx	root/root	usr/lib/pkgconfig/libpng.pc -> libpng16.pc
 -rw-r--r--	root/root	usr/lib/pkgconfig/libpng16.pc
diff --git a/libpng/.md5sum b/libpng/.md5sum
index 83d9f03..7ea5896 100644
--- a/libpng/.md5sum
+++ b/libpng/.md5sum
@@ -1,2 +1,2 @@
-4991e8e3a79d9aaefc4106b4a3c7e13e  libpng-1.6.19-apng.patch
-1e6a458429e850fc93c1f3b6dc00a48f  libpng-1.6.19.tar.xz
+935fa62557ba6f547ccad74d261d11c4  libpng-1.6.20-apng.patch
+3968acb7c66ef81a9dab867f35d0eb4b  libpng-1.6.20.tar.xz
diff --git a/libpng/Pkgfile b/libpng/Pkgfile
index d0e7e45..2acfec1 100644
--- a/libpng/Pkgfile
+++ b/libpng/Pkgfile
@@ -4,14 +4,14 @@
 # Depends on:  zlib
 
 name=libpng
-version=1.6.19
+version=1.6.20
 release=1
 source=(http://download.sourceforge.net/$name/$name-$version.tar.xz \
         $name-$version-apng.patch)
 
 build() {
     cd $name-$version
-    patch -p1 -i $SRC/$name-$version-apng.patch
+    patch -p0 -i $SRC/$name-$version-apng.patch
     ./configure --prefix=/usr --mandir=/usr/man
 
     make
diff --git a/libpng/libpng-1.6.19-apng.patch b/libpng/libpng-1.6.19-apng.patch
deleted file mode 100644
index 811d1e3..0000000
--- a/libpng/libpng-1.6.19-apng.patch
+++ /dev/null
@@ -1,1699 +0,0 @@
-diff -Nru libpng-1.6.19-orig/pngget.c libpng-1.6.19/pngget.c
---- libpng-1.6.19-orig/pngget.c	2015-11-13 21:37:46.357671356 +0100
-+++ libpng-1.6.19/pngget.c	2015-11-13 21:38:46.566768235 +0100
-@@ -1216,4 +1216,166 @@
- #  endif
- #endif
- 
-+#ifdef PNG_APNG_SUPPORTED
-+png_uint_32 PNGAPI
-+png_get_acTL(png_structp png_ptr, png_infop info_ptr,
-+             png_uint_32 *num_frames, png_uint_32 *num_plays)
-+{
-+    png_debug1(1, "in %s retrieval function", "acTL");
-+
-+    if (png_ptr != NULL && info_ptr != NULL &&
-+        (info_ptr->valid & PNG_INFO_acTL) &&
-+        num_frames != NULL && num_plays != NULL)
-+    {
-+        *num_frames = info_ptr->num_frames;
-+        *num_plays = info_ptr->num_plays;
-+        return (1);
-+    }
-+
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_num_frames(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_num_frames()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->num_frames);
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_num_plays(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_num_plays()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->num_plays);
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_next_frame_fcTL(png_structp png_ptr, png_infop info_ptr,
-+             png_uint_32 *width, png_uint_32 *height,
-+             png_uint_32 *x_offset, png_uint_32 *y_offset,
-+             png_uint_16 *delay_num, png_uint_16 *delay_den,
-+             png_byte *dispose_op, png_byte *blend_op)
-+{
-+    png_debug1(1, "in %s retrieval function", "fcTL");
-+
-+    if (png_ptr != NULL && info_ptr != NULL &&
-+        (info_ptr->valid & PNG_INFO_fcTL) &&
-+        width != NULL && height != NULL &&
-+        x_offset != NULL && y_offset != NULL &&
-+        delay_num != NULL && delay_den != NULL &&
-+        dispose_op != NULL && blend_op != NULL)
-+    {
-+        *width = info_ptr->next_frame_width;
-+        *height = info_ptr->next_frame_height;
-+        *x_offset = info_ptr->next_frame_x_offset;
-+        *y_offset = info_ptr->next_frame_y_offset;
-+        *delay_num = info_ptr->next_frame_delay_num;
-+        *delay_den = info_ptr->next_frame_delay_den;
-+        *dispose_op = info_ptr->next_frame_dispose_op;
-+        *blend_op = info_ptr->next_frame_blend_op;
-+        return (1);
-+    }
-+
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_next_frame_width(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_width()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_width);
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_next_frame_height(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_height()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_height);
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_next_frame_x_offset(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_x_offset()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_x_offset);
-+    return (0);
-+}
-+
-+png_uint_32 PNGAPI
-+png_get_next_frame_y_offset(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_y_offset()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_y_offset);
-+    return (0);
-+}
-+
-+png_uint_16 PNGAPI
-+png_get_next_frame_delay_num(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_delay_num()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_delay_num);
-+    return (0);
-+}
-+
-+png_uint_16 PNGAPI
-+png_get_next_frame_delay_den(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_delay_den()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_delay_den);
-+    return (0);
-+}
-+
-+png_byte PNGAPI
-+png_get_next_frame_dispose_op(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_dispose_op()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_dispose_op);
-+    return (0);
-+}
-+
-+png_byte PNGAPI
-+png_get_next_frame_blend_op(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_get_next_frame_blend_op()");
-+
-+    if (png_ptr != NULL && info_ptr != NULL)
-+        return (info_ptr->next_frame_blend_op);
-+    return (0);
-+}
-+
-+png_byte PNGAPI
-+png_get_first_frame_is_hidden(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_first_frame_is_hidden()");
-+
-+    if (png_ptr != NULL)
-+       return (png_byte)(png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN);
-+
-+    PNG_UNUSED(info_ptr)
-+
-+    return 0;
-+}
-+#endif /* PNG_APNG_SUPPORTED */
- #endif /* READ || WRITE */
-diff -Nru libpng-1.6.19-orig/png.h libpng-1.6.19/png.h
---- libpng-1.6.19-orig/png.h	2015-11-13 21:37:46.323670172 +0100
-+++ libpng-1.6.19/png.h	2015-11-13 21:41:07.687687990 +0100
-@@ -334,6 +334,10 @@
- #   include "pnglibconf.h"
- #endif
- 
-+#define PNG_APNG_SUPPORTED
-+#define PNG_READ_APNG_SUPPORTED
-+#define PNG_WRITE_APNG_SUPPORTED
-+
- #ifndef PNG_VERSION_INFO_ONLY
-    /* Machine specific configuration. */
- #  include "pngconf.h"
-@@ -429,6 +433,17 @@
-  * See pngconf.h for base types that vary by machine/system
-  */
- 
-+#ifdef PNG_APNG_SUPPORTED
-+/* dispose_op flags from inside fcTL */
-+#define PNG_DISPOSE_OP_NONE        0x00
-+#define PNG_DISPOSE_OP_BACKGROUND  0x01
-+#define PNG_DISPOSE_OP_PREVIOUS    0x02
-+
-+/* blend_op flags from inside fcTL */
-+#define PNG_BLEND_OP_SOURCE        0x00
-+#define PNG_BLEND_OP_OVER          0x01
-+#endif /* PNG_APNG_SUPPORTED */
-+
- /* This triggers a compiler error in png.c, if png.c and png.h
-  * do not agree upon the version number.
-  */
-@@ -750,6 +765,11 @@
- #define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
- #if INT_MAX >= 0x8000 /* else this might break */
- #define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */
-+#ifdef PNG_APNG_SUPPORTED
-+#define PNG_INFO_acTL 0x10000
-+#define PNG_INFO_fcTL 0x20000
-+#endif
-+
- #endif
- 
- /* This is used for the transformation routines, as some of them
-@@ -788,6 +808,10 @@
- #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
- typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
- typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
-+#ifdef PNG_APNG_SUPPORTED
-+typedef PNG_CALLBACK(void, *png_progressive_frame_ptr, (png_structp,
-+    png_uint_32));
-+#endif
- 
- /* The following callback receives png_uint_32 row_number, int pass for the
-  * png_bytep data of the row.  When transforming an interlaced image the
-@@ -3108,6 +3132,74 @@
- /*******************************************************************************
-  *  END OF HARDWARE AND SOFTWARE OPTIONS
-  ******************************************************************************/
-+#ifdef PNG_APNG_SUPPORTED
-+PNG_EXPORT(245, png_uint_32, png_get_acTL, (png_structp png_ptr,
-+   png_infop info_ptr, png_uint_32 *num_frames, png_uint_32 *num_plays));
-+
-+PNG_EXPORT(246, png_uint_32, png_set_acTL, (png_structp png_ptr,
-+   png_infop info_ptr, png_uint_32 num_frames, png_uint_32 num_plays));
-+
-+PNG_EXPORT(247, png_uint_32, png_get_num_frames, (png_structp png_ptr,
-+   png_infop info_ptr));
-+
-+PNG_EXPORT(248, png_uint_32, png_get_num_plays, (png_structp png_ptr,
-+   png_infop info_ptr));
-+
-+PNG_EXPORT(249, png_uint_32, png_get_next_frame_fcTL,
-+   (png_structp png_ptr, png_infop info_ptr, png_uint_32 *width,
-+   png_uint_32 *height, png_uint_32 *x_offset, png_uint_32 *y_offset,
-+   png_uint_16 *delay_num, png_uint_16 *delay_den, png_byte *dispose_op,
-+   png_byte *blend_op));
-+
-+PNG_EXPORT(250, png_uint_32, png_set_next_frame_fcTL,
-+   (png_structp png_ptr, png_infop info_ptr, png_uint_32 width,
-+   png_uint_32 height, png_uint_32 x_offset, png_uint_32 y_offset,
-+   png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
-+   png_byte blend_op));
-+
-+PNG_EXPORT(251, png_uint_32, png_get_next_frame_width,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(252, png_uint_32, png_get_next_frame_height,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(253, png_uint_32, png_get_next_frame_x_offset,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(254, png_uint_32, png_get_next_frame_y_offset,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(255, png_uint_16, png_get_next_frame_delay_num,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(256, png_uint_16, png_get_next_frame_delay_den,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(257, png_byte, png_get_next_frame_dispose_op,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(258, png_byte, png_get_next_frame_blend_op,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(259, png_byte, png_get_first_frame_is_hidden,
-+   (png_structp png_ptr, png_infop info_ptr));
-+PNG_EXPORT(260, png_uint_32, png_set_first_frame_is_hidden,
-+   (png_structp png_ptr, png_infop info_ptr, png_byte is_hidden));
-+
-+#ifdef PNG_READ_APNG_SUPPORTED
-+PNG_EXPORT(261, void, png_read_frame_head, (png_structp png_ptr,
-+   png_infop info_ptr));
-+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-+PNG_EXPORT(262, void, png_set_progressive_frame_fn, (png_structp png_ptr,
-+   png_progressive_frame_ptr frame_info_fn,
-+   png_progressive_frame_ptr frame_end_fn));
-+#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
-+#endif /* PNG_READ_APNG_SUPPORTED */
-+
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+PNG_EXPORT(263, void, png_write_frame_head, (png_structp png_ptr,
-+   png_infop info_ptr, png_bytepp row_pointers,
-+   png_uint_32 width, png_uint_32 height,
-+   png_uint_32 x_offset, png_uint_32 y_offset,
-+   png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
-+   png_byte blend_op));
-+
-+PNG_EXPORT(264, void, png_write_frame_tail, (png_structp png_ptr,
-+   png_infop info_ptr));
-+#endif /* PNG_WRITE_APNG_SUPPORTED */
-+#endif /* PNG_APNG_SUPPORTED */
- 
- /* Maintainer: Put new public prototypes here ^, in libpng.3, in project
-  * defs, and in scripts/symbols.def.
-@@ -3117,7 +3209,11 @@
-  * one to use is one more than this.)
-  */
- #ifdef PNG_EXPORT_LAST_ORDINAL
-+#ifdef PNG_APNG_SUPPORTED
-+  PNG_EXPORT_LAST_ORDINAL(264);
-+#else
-   PNG_EXPORT_LAST_ORDINAL(244);
-+#endif /* PNG_APNG_SUPPORTED */
- #endif
- 
- #ifdef __cplusplus
-diff -Nru libpng-1.6.19-orig/pnginfo.h libpng-1.6.19/pnginfo.h
---- libpng-1.6.19-orig/pnginfo.h	2015-11-13 21:37:46.348671042 +0100
-+++ libpng-1.6.19/pnginfo.h	2015-11-13 21:38:46.567768270 +0100
-@@ -255,5 +255,18 @@
-    png_bytepp row_pointers;        /* the image bits */
- #endif
- 
-+#ifdef PNG_APNG_SUPPORTED
-+   png_uint_32 num_frames; /* including default image */
-+   png_uint_32 num_plays;
-+   png_uint_32 next_frame_width;
-+   png_uint_32 next_frame_height;
-+   png_uint_32 next_frame_x_offset;
-+   png_uint_32 next_frame_y_offset;
-+   png_uint_16 next_frame_delay_num;
-+   png_uint_16 next_frame_delay_den;
-+   png_byte next_frame_dispose_op;
-+   png_byte next_frame_blend_op;
-+#endif
-+
- };
- #endif /* PNGINFO_H */
-diff -Nru libpng-1.6.19-orig/pngpread.c libpng-1.6.19/pngpread.c
---- libpng-1.6.19-orig/pngpread.c	2015-11-13 21:37:46.359671425 +0100
-+++ libpng-1.6.19/pngpread.c	2015-11-13 21:38:46.567768270 +0100
-@@ -194,6 +194,106 @@
- 
-    chunk_name = png_ptr->chunk_name;
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+   if (png_ptr->num_frames_read > 0 &&
-+       png_ptr->num_frames_read < info_ptr->num_frames)
-+   {
-+      if (chunk_name == png_IDAT)
-+      {
-+         /* Discard trailing IDATs for the first frame */
-+         if (png_ptr->mode & PNG_HAVE_fcTL || png_ptr->num_frames_read > 1)
-+            png_error(png_ptr, "out of place IDAT");
-+
-+         if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+         {
-+            png_push_save_buffer(png_ptr);
-+            return;
-+         }
-+
-+         png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
-+         return;
-+      }
-+      else if (chunk_name == png_fdAT)
-+      {
-+         if (png_ptr->buffer_size < 4)
-+         {
-+            png_push_save_buffer(png_ptr);
-+            return;
-+         }
-+
-+         png_ensure_sequence_number(png_ptr, 4);
-+
-+         if (!(png_ptr->mode & PNG_HAVE_fcTL))
-+         {
-+            /* Discard trailing fdATs for frames other than the first */
-+            if (png_ptr->num_frames_read < 2)
-+               png_error(png_ptr, "out of place fdAT");
-+
-+            if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+            {
-+               png_push_save_buffer(png_ptr);
-+               return;
-+            }
-+
-+            png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
-+            return;
-+         }
-+
-+         else
-+         {
-+            /* frame data follows */
-+            png_ptr->idat_size = png_ptr->push_length - 4;
-+            png_ptr->mode |= PNG_HAVE_IDAT;
-+            png_ptr->process_mode = PNG_READ_IDAT_MODE;
-+
-+            return;
-+         }
-+      }
-+
-+      else if (chunk_name == png_fcTL)
-+      {
-+         if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+         {
-+            png_push_save_buffer(png_ptr);
-+            return;
-+         }
-+
-+         png_read_reset(png_ptr);
-+         png_ptr->mode &= ~PNG_HAVE_fcTL;
-+
-+         png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
-+
-+         if (!(png_ptr->mode & PNG_HAVE_fcTL))
-+            png_error(png_ptr, "missing required fcTL chunk");
-+
-+         png_read_reinit(png_ptr, info_ptr);
-+         png_progressive_read_reset(png_ptr);
-+
-+         if (png_ptr->frame_info_fn != NULL)
-+            (*(png_ptr->frame_info_fn))(png_ptr, png_ptr->num_frames_read);
-+
-+         png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
-+
-+         return;
-+      }
-+
-+      else
-+      {
-+         if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+         {
-+            png_push_save_buffer(png_ptr);
-+            return;
-+         }
-+         png_warning(png_ptr, "Skipped (ignored) a chunk "
-+                              "between APNG chunks");
-+         png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
-+         return;
-+      }
-+
-+      return;
-+   }
-+#endif /* PNG_READ_APNG_SUPPORTED */
-+
-    if (chunk_name == png_IDAT)
-    {
-       if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
-@@ -258,6 +358,9 @@
- 
-    else if (chunk_name == png_IDAT)
-    {
-+#ifdef PNG_READ_APNG_SUPPORTED
-+      png_have_info(png_ptr, info_ptr);
-+#endif
-       png_ptr->idat_size = png_ptr->push_length;
-       png_ptr->process_mode = PNG_READ_IDAT_MODE;
-       png_push_have_info(png_ptr, info_ptr);
-@@ -403,6 +506,30 @@
-       png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
-    }
- #endif
-+#ifdef PNG_READ_APNG_SUPPORTED
-+   else if (chunk_name == png_acTL)
-+   {
-+      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+      {
-+         png_push_save_buffer(png_ptr);
-+         return;
-+      }
-+
-+      png_handle_acTL(png_ptr, info_ptr, png_ptr->push_length);
-+   }
-+
-+   else if (chunk_name == png_fcTL)
-+   {
-+      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+      {
-+         png_push_save_buffer(png_ptr);
-+         return;
-+      }
-+
-+      png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
-+   }
-+
-+#endif /* PNG_READ_APNG_SUPPORTED */
- 
-    else
-    {
-@@ -533,7 +660,11 @@
-       png_byte chunk_tag[4];
- 
-       /* TODO: this code can be commoned up with the same code in push_read */
-+#ifdef PNG_READ_APNG_SUPPORTED
-+      PNG_PUSH_SAVE_BUFFER_IF_LT(12)
-+#else
-       PNG_PUSH_SAVE_BUFFER_IF_LT(8)
-+#endif
-       png_push_fill_buffer(png_ptr, chunk_length, 4);
-       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
-       png_reset_crc(png_ptr);
-@@ -541,17 +672,64 @@
-       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
-       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+      if (png_ptr->chunk_name != png_fdAT && png_ptr->num_frames_read > 0)
-+      {
-+          if (png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)
-+          {
-+              png_ptr->process_mode = PNG_READ_CHUNK_MODE;
-+              if (png_ptr->frame_end_fn != NULL)
-+                 (*(png_ptr->frame_end_fn))(png_ptr, png_ptr->num_frames_read);
-+              png_ptr->num_frames_read++;
-+              return;
-+          }
-+          else
-+          {
-+              if (png_ptr->chunk_name == png_IEND)
-+                  png_error(png_ptr, "Not enough image data");
-+              if (png_ptr->push_length + 4 > png_ptr->buffer_size)
-+              {
-+                 png_push_save_buffer(png_ptr);
-+                 return;
-+              }
-+              png_warning(png_ptr, "Skipping (ignoring) a chunk between "
-+                                   "APNG chunks");
-+              png_crc_finish(png_ptr, png_ptr->push_length);
-+              png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
-+              return;
-+          }
-+      }
-+      else
-+#endif
-+#ifdef PNG_READ_APNG_SUPPORTED
-+      if (png_ptr->chunk_name != png_IDAT && png_ptr->num_frames_read == 0)
-+#else
-       if (png_ptr->chunk_name != png_IDAT)
-+#endif
-       {
-          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
- 
-          if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
-             png_error(png_ptr, "Not enough compressed data");
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+         if (png_ptr->frame_end_fn != NULL)
-+            (*(png_ptr->frame_end_fn))(png_ptr, png_ptr->num_frames_read);
-+         png_ptr->num_frames_read++;
-+#endif
-+
-          return;
-       }
- 
-       png_ptr->idat_size = png_ptr->push_length;
-+
-+#ifdef PNG_READ_APNG_SUPPORTED
-+      if (png_ptr->num_frames_read > 0)
-+      {
-+         png_ensure_sequence_number(png_ptr, 4);
-+         png_ptr->idat_size -= 4;
-+      }
-+#endif
-    }
- 
-    if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
-@@ -625,6 +803,15 @@
-    if (!(buffer_length > 0) || buffer == NULL)
-       png_error(png_ptr, "No IDAT data (internal error)");
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+   /* If the app is not APNG-aware, decode only the first frame */
-+   if (!(png_ptr->apng_flags & PNG_APNG_APP) && png_ptr->num_frames_read > 0)
-+   {
-+     png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
-+     return;
-+   }
-+#endif
-+
-    /* This routine must process all the data it has been given
-     * before returning, calling the row callback as required to
-     * handle the uncompressed results.
-@@ -1074,6 +1261,18 @@
-    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
- }
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+void PNGAPI
-+png_set_progressive_frame_fn(png_structp png_ptr,
-+   png_progressive_frame_ptr frame_info_fn,
-+   png_progressive_frame_ptr frame_end_fn)
-+{
-+   png_ptr->frame_info_fn = frame_info_fn;
-+   png_ptr->frame_end_fn = frame_end_fn;
-+   png_ptr->apng_flags |= PNG_APNG_APP;
-+}
-+#endif
-+
- png_voidp PNGAPI
- png_get_progressive_ptr(png_const_structrp png_ptr)
- {
-diff -Nru libpng-1.6.19-orig/pngpriv.h libpng-1.6.19/pngpriv.h
---- libpng-1.6.19-orig/pngpriv.h	2015-11-13 21:37:46.359671425 +0100
-+++ libpng-1.6.19/pngpriv.h	2015-11-13 21:38:46.567768270 +0100
-@@ -537,6 +537,10 @@
- #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
-                    /*             0x4000 (unused) */
- #define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */
-+#ifdef PNG_APNG_SUPPORTED
-+#define PNG_HAVE_acTL            0x10000
-+#define PNG_HAVE_fcTL            0x20000
-+#endif
- 
- /* Flags for the transformations the PNG library does on the image data */
- #define PNG_BGR                 0x0001
-@@ -754,6 +758,16 @@
- #define png_tRNS PNG_U32(116,  82,  78,  83)
- #define png_zTXt PNG_U32(122,  84,  88, 116)
- 
-+#ifdef PNG_APNG_SUPPORTED
-+#define png_acTL PNG_U32( 97,  99,  84,  76)
-+#define png_fcTL PNG_U32(102,  99,  84,  76)
-+#define png_fdAT PNG_U32(102, 100,  65,  84)
-+
-+/* For png_struct.apng_flags: */
-+#define PNG_FIRST_FRAME_HIDDEN       0x0001
-+#define PNG_APNG_APP                 0x0002
-+#endif
-+
- /* The following will work on (signed char*) strings, whereas the get_uint_32
-  * macro will fail on top-bit-set values because of the sign extension.
-  */
-@@ -1453,6 +1467,47 @@
-      */
- #endif
- 
-+#ifdef PNG_APNG_SUPPORTED
-+PNG_INTERNAL_FUNCTION(void,png_ensure_fcTL_is_valid,(png_structp png_ptr,
-+   png_uint_32 width, png_uint_32 height,
-+   png_uint_32 x_offset, png_uint_32 y_offset,
-+   png_uint_16 delay_num, png_uint_16 delay_den,
-+   png_byte dispose_op, png_byte blend_op), PNG_EMPTY);
-+
-+#ifdef PNG_READ_APNG_SUPPORTED
-+PNG_INTERNAL_FUNCTION(void,png_handle_acTL,(png_structp png_ptr, png_infop info_ptr,
-+   png_uint_32 length),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_handle_fcTL,(png_structp png_ptr, png_infop info_ptr,
-+   png_uint_32 length),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_handle_fdAT,(png_structp png_ptr, png_infop info_ptr,
-+   png_uint_32 length),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_have_info,(png_structp png_ptr, png_infop info_ptr),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_ensure_sequence_number,(png_structp png_ptr,
-+   png_uint_32 length),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_reset,(png_structp png_ptr),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_read_reinit,(png_structp png_ptr,
-+   png_infop info_ptr),PNG_EMPTY);
-+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-+PNG_INTERNAL_FUNCTION(void,png_progressive_read_reset,(png_structp png_ptr),PNG_EMPTY);
-+#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
-+#endif /* PNG_READ_APNG_SUPPORTED */
-+
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+PNG_INTERNAL_FUNCTION(void,png_write_acTL,(png_structp png_ptr,
-+   png_uint_32 num_frames, png_uint_32 num_plays),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_write_fcTL,(png_structp png_ptr,
-+   png_uint_32 width, png_uint_32 height,
-+   png_uint_32 x_offset, png_uint_32 y_offset,
-+   png_uint_16 delay_num, png_uint_16 delay_den,
-+   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_write_fdAT,(png_structp png_ptr,
-+   png_const_bytep data, png_size_t length),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_write_reset,(png_structp png_ptr),PNG_EMPTY);
-+PNG_INTERNAL_FUNCTION(void,png_write_reinit,(png_structp png_ptr,
-+   png_infop info_ptr, png_uint_32 width, png_uint_32 height),PNG_EMPTY);
-+#endif /* PNG_WRITE_APNG_SUPPORTED */
-+#endif /* PNG_APNG_SUPPORTED */
-+
- /* Added at libpng version 1.4.0 */
- #ifdef PNG_COLORSPACE_SUPPORTED
- /* These internal functions are for maintaining the colorspace structure within
-diff -Nru libpng-1.6.19-orig/pngread.c libpng-1.6.19/pngread.c
---- libpng-1.6.19-orig/pngread.c	2015-11-13 21:37:46.324670207 +0100
-+++ libpng-1.6.19/pngread.c	2015-11-13 21:38:46.568768304 +0100
-@@ -158,6 +158,9 @@
- 
-       else if (chunk_name == png_IDAT)
-       {
-+#ifdef PNG_READ_APNG_SUPPORTED
-+         png_have_info(png_ptr, info_ptr);
-+#endif
-          png_ptr->idat_size = length;
-          break;
-       }
-@@ -247,6 +250,17 @@
-          png_handle_iTXt(png_ptr, info_ptr, length);
- #endif
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+      else if (chunk_name == png_acTL)
-+         png_handle_acTL(png_ptr, info_ptr, length);
-+
-+      else if (chunk_name == png_fcTL)
-+         png_handle_fcTL(png_ptr, info_ptr, length);
-+
-+      else if (chunk_name == png_fdAT)
-+         png_handle_fdAT(png_ptr, info_ptr, length);
-+#endif
-+
-       else
-          png_handle_unknown(png_ptr, info_ptr, length,
-             PNG_HANDLE_CHUNK_AS_DEFAULT);
-@@ -254,6 +268,72 @@
- }
- #endif /* SEQUENTIAL_READ */
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+void PNGAPI
-+png_read_frame_head(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */
-+
-+    png_debug(0, "Reading frame head");
-+
-+    if (!(png_ptr->mode & PNG_HAVE_acTL))
-+        png_error(png_ptr, "attempt to png_read_frame_head() but "
-+                           "no acTL present");
-+
-+    /* do nothing for the main IDAT */
-+    if (png_ptr->num_frames_read == 0)
-+        return;
-+
-+    png_read_reset(png_ptr);
-+    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
-+    png_ptr->mode &= ~PNG_HAVE_fcTL;
-+
-+    have_chunk_after_DAT = 0;
-+    for (;;)
-+    {
-+        png_uint_32 length = png_read_chunk_header(png_ptr);
-+
-+        if (png_ptr->chunk_name == png_IDAT)
-+        {
-+            /* discard trailing IDATs for the first frame */
-+            if (have_chunk_after_DAT || png_ptr->num_frames_read > 1)
-+                png_error(png_ptr, "png_read_frame_head(): out of place IDAT");
-+            png_crc_finish(png_ptr, length);
-+        }
-+
-+        else if (png_ptr->chunk_name == png_fcTL)
-+        {
-+            png_handle_fcTL(png_ptr, info_ptr, length);
-+            have_chunk_after_DAT = 1;
-+        }
-+
-+        else if (png_ptr->chunk_name == png_fdAT)
-+        {
-+            png_ensure_sequence_number(png_ptr, length);
-+
-+            /* discard trailing fdATs for frames other than the first */
-+            if (!have_chunk_after_DAT && png_ptr->num_frames_read > 1)
-+                png_crc_finish(png_ptr, length - 4);
-+            else if(png_ptr->mode & PNG_HAVE_fcTL)
-+            {
-+                png_ptr->idat_size = length - 4;
-+                png_ptr->mode |= PNG_HAVE_IDAT;
-+
-+                break;
-+            }
-+            else
-+                png_error(png_ptr, "png_read_frame_head(): out of place fdAT");
-+        }
-+        else
-+        {
-+            png_warning(png_ptr, "Skipped (ignored) a chunk "
-+                                 "between APNG chunks");
-+            png_crc_finish(png_ptr, length);
-+        }
-+    }
-+}
-+#endif /* PNG_READ_APNG_SUPPORTED */
-+
- /* Optional call to update the users info_ptr structure */
- void PNGAPI
- png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
-diff -Nru libpng-1.6.19-orig/pngrutil.c libpng-1.6.19/pngrutil.c
---- libpng-1.6.19-orig/pngrutil.c	2015-11-13 21:37:46.327670311 +0100
-+++ libpng-1.6.19/pngrutil.c	2015-11-13 21:38:46.568768304 +0100
-@@ -824,6 +824,11 @@
-    filter_type = buf[11];
-    interlace_type = buf[12];
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+   png_ptr->first_frame_width = width;
-+   png_ptr->first_frame_height = height;
-+#endif
-+
-    /* Set internal variables */
-    png_ptr->width = width;
-    png_ptr->height = height;
-@@ -2724,6 +2729,179 @@
- }
- #endif
- 
-+#ifdef PNG_READ_APNG_SUPPORTED
-+void /* PRIVATE */
-+png_handle_acTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-+{
-+    png_byte data[8];
-+    png_uint_32 num_frames;
-+    png_uint_32 num_plays;
-+    png_uint_32 didSet;
-+
-+    png_debug(1, "in png_handle_acTL");
-+
-+    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-+    {
-+        png_error(png_ptr, "Missing IHDR before acTL");
-+    }
-+    else if (png_ptr->mode & PNG_HAVE_IDAT)
-+    {
-+        png_warning(png_ptr, "Invalid acTL after IDAT skipped");
-+        png_crc_finish(png_ptr, length);
-+        return;
-+    }
-+    else if (png_ptr->mode & PNG_HAVE_acTL)
-+    {
-+        png_warning(png_ptr, "Duplicate acTL skipped");
-+        png_crc_finish(png_ptr, length);
-+        return;
-+    }
-+    else if (length != 8)
-+    {
-+        png_warning(png_ptr, "acTL with invalid length skipped");
-+        png_crc_finish(png_ptr, length);
-+        return;
-+    }
-+
-+    png_crc_read(png_ptr, data, 8);
-+    png_crc_finish(png_ptr, 0);
-+
-+    num_frames = png_get_uint_31(png_ptr, data);
-+    num_plays = png_get_uint_31(png_ptr, data + 4);
-+
-+    /* the set function will do error checking on num_frames */
-+    didSet = png_set_acTL(png_ptr, info_ptr, num_frames, num_plays);
-+    if(didSet)
-+        png_ptr->mode |= PNG_HAVE_acTL;
-+}
-+
-+void /* PRIVATE */
-+png_handle_fcTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-+{
-+    png_byte data[22];
-+    png_uint_32 width;
-+    png_uint_32 height;
-+    png_uint_32 x_offset;
-+    png_uint_32 y_offset;
-+    png_uint_16 delay_num;
-+    png_uint_16 delay_den;
-+    png_byte dispose_op;
-+    png_byte blend_op;
-+
-+    png_debug(1, "in png_handle_fcTL");
-+
-+    png_ensure_sequence_number(png_ptr, length);
-+
-+    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-+    {
-+        png_error(png_ptr, "Missing IHDR before fcTL");
-+    }
-+    else if (png_ptr->mode & PNG_HAVE_IDAT)
-+    {
-+        /* for any frames other then the first this message may be misleading,
-+        * but correct. PNG_HAVE_IDAT is unset before the frame head is read
-+        * i can't think of a better message */
-+        png_warning(png_ptr, "Invalid fcTL after IDAT skipped");
-+        png_crc_finish(png_ptr, length-4);
-+        return;
-+    }
-+    else if (png_ptr->mode & PNG_HAVE_fcTL)
-+    {
-+        png_warning(png_ptr, "Duplicate fcTL within one frame skipped");
-+        png_crc_finish(png_ptr, length-4);
-+        return;
-+    }
-+    else if (length != 26)
-+    {
-+        png_warning(png_ptr, "fcTL with invalid length skipped");
-+        png_crc_finish(png_ptr, length-4);
-+        return;
-+    }
-+
-+    png_crc_read(png_ptr, data, 22);
-+    png_crc_finish(png_ptr, 0);
-+
-+    width = png_get_uint_31(png_ptr, data);
-+    height = png_get_uint_31(png_ptr, data + 4);
-+    x_offset = png_get_uint_31(png_ptr, data + 8);
-+    y_offset = png_get_uint_31(png_ptr, data + 12);
-+    delay_num = png_get_uint_16(data + 16);
-+    delay_den = png_get_uint_16(data + 18);
-+    dispose_op = data[20];
-+    blend_op = data[21];
-+
-+    if (png_ptr->num_frames_read == 0 && (x_offset != 0 || y_offset != 0))
-+    {
-+        png_warning(png_ptr, "fcTL for the first frame must have zero offset");
-+        return;
-+    }
-+
-+    if (info_ptr != NULL)
-+    {
-+        if (png_ptr->num_frames_read == 0 &&
-+            (width != info_ptr->width || height != info_ptr->height))
-+        {
-+            png_warning(png_ptr, "size in first frame's fcTL must match "
-+                               "the size in IHDR");
-+            return;
-+        }
-+
-+        /* The set function will do more error checking */
-+        png_set_next_frame_fcTL(png_ptr, info_ptr, width, height,
-+                                x_offset, y_offset, delay_num, delay_den,
-+                                dispose_op, blend_op);
-+
-+        png_read_reinit(png_ptr, info_ptr);
-+
-+        png_ptr->mode |= PNG_HAVE_fcTL;
-+    }
-+}
-+
-+void /* PRIVATE */
-+png_have_info(png_structp png_ptr, png_infop info_ptr)
-+{
-+    if((info_ptr->valid & PNG_INFO_acTL) && !(info_ptr->valid & PNG_INFO_fcTL))
-+    {
-+        png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN;
-+        info_ptr->num_frames++;
-+    }
-+}
-+
-+void /* PRIVATE */
-+png_handle_fdAT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-+{
-+    png_ensure_sequence_number(png_ptr, length);
-+
-+    /* This function is only called from png_read_end(), png_read_info(),
-+    * and png_push_read_chunk() which means that:
-+    * - the user doesn't want to read this frame
-+    * - or this is an out-of-place fdAT
-+    * in either case it is safe to ignore the chunk with a warning */
-+    png_warning(png_ptr, "ignoring fdAT chunk");
-+    png_crc_finish(png_ptr, length - 4);
-+    PNG_UNUSED(info_ptr)
-+}
-+
-+void /* PRIVATE */
-+png_ensure_sequence_number(png_structp png_ptr, png_uint_32 length)
-+{
-+    png_byte data[4];
-+    png_uint_32 sequence_number;
-+
-+    if (length < 4)
-+        png_error(png_ptr, "invalid fcTL or fdAT chunk found");
-+
-+    png_crc_read(png_ptr, data, 4);
-+    sequence_number = png_get_uint_31(png_ptr, data);
-+
-+    if (sequence_number != png_ptr->next_seq_num)
-+        png_error(png_ptr, "fcTL or fdAT chunk with out-of-order sequence "
-+                           "number found");
-+
-+    png_ptr->next_seq_num++;
-+}
-+#endif /* PNG_READ_APNG_SUPPORTED */
-+
- #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
- /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
- static int
-@@ -3982,7 +4160,38 @@
-       {
-          uInt avail_in;
-          png_bytep buffer;
-+#ifdef PNG_READ_APNG_SUPPORTED
-+         png_uint_32 bytes_to_skip = 0;
-+
-+         while (png_ptr->idat_size == 0 || bytes_to_skip != 0)
-+         {
-+            png_crc_finish(png_ptr, bytes_to_skip);
-+            bytes_to_skip = 0;
-+
-+            png_ptr->idat_size = png_read_chunk_header(png_ptr);
-+            if (png_ptr->num_frames_read == 0)
-+            {
-+               if (png_ptr->chunk_name != png_IDAT)
-+                  png_error(png_ptr, "Not enough image data");
-+            }
-+            else
-+            {
-+               if (png_ptr->chunk_name == png_IEND)
-+                  png_error(png_ptr, "Not enough image data");
-+               if (png_ptr->chunk_name != png_fdAT)
-+               {
-+                  png_warning(png_ptr, "Skipped (ignored) a chunk "
-+                                       "between APNG chunks");
-+                  bytes_to_skip = png_ptr->idat_size;
-+                  continue;
-+               }
- 
-+               png_ensure_sequence_number(png_ptr, png_ptr->idat_size);
-+
-+               png_ptr->idat_size -= 4;
-+            }
-+         }
-+#else
-          while (png_ptr->idat_size == 0)
-          {
-             png_crc_finish(png_ptr, 0);
-@@ -3994,7 +4203,7 @@
-             if (png_ptr->chunk_name != png_IDAT)
-                png_error(png_ptr, "Not enough image data");
-          }
--
-+#endif /* PNG_READ_APNG_SUPPORTED */
-          avail_in = png_ptr->IDAT_read_size;
- 
-          if (avail_in > png_ptr->idat_size)
-@@ -4057,6 +4266,9 @@
- 
-          png_ptr->mode |= PNG_AFTER_IDAT;
-          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
-+#ifdef PNG_READ_APNG_SUPPORTED
-+         png_ptr->num_frames_read++;
-+#endif
- 
-          if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
-             png_chunk_benign_error(png_ptr, "Extra compressed data");
-@@ -4495,4 +4707,80 @@
- 
-    png_ptr->flags |= PNG_FLAG_ROW_INIT;
- }
-+
-+#ifdef PNG_READ_APNG_SUPPORTED
-+/* This function is to be called after the main IDAT set has been read and
-+ * before a new IDAT is read. It resets some parts of png_ptr
-+ * to make them usable by the read functions again */
-+void /* PRIVATE */
-+png_read_reset(png_structp png_ptr)
-+{
-+    png_ptr->mode &= ~PNG_HAVE_IDAT;
-+    png_ptr->mode &= ~PNG_AFTER_IDAT;
-+    png_ptr->row_number = 0;
-+    png_ptr->pass = 0;
-+}
-+
-+void /* PRIVATE */
-+png_read_reinit(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_ptr->width = info_ptr->next_frame_width;
-+    png_ptr->height = info_ptr->next_frame_height;
-+    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->width);
-+    png_ptr->info_rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth,
-+        png_ptr->width);
-+    if (png_ptr->prev_row)
-+        memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
-+}
-+
-+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-+/* same as png_read_reset() but for the progressive reader */
-+void /* PRIVATE */
-+png_progressive_read_reset(png_structp png_ptr)
-+{
-+#ifdef PNG_READ_INTERLACING_SUPPORTED
-+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-+
-+   /* Start of interlace block */
-+    const int png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
-+
-+    /* Offset to next interlace block */
-+    const int png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
-+
-+    /* Start of interlace block in the y direction */
-+    const int png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
-+
-+    /* Offset to next interlace block in the y direction */
-+    const int png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
-+
-+    if (png_ptr->interlaced)
-+    {
-+        if (!(png_ptr->transformations & PNG_INTERLACE))
-+            png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
-+                                png_pass_ystart[0]) / png_pass_yinc[0];
-+        else
-+            png_ptr->num_rows = png_ptr->height;
-+
-+        png_ptr->iwidth = (png_ptr->width +
-+                           png_pass_inc[png_ptr->pass] - 1 -
-+                           png_pass_start[png_ptr->pass]) /
-+                           png_pass_inc[png_ptr->pass];
-+    }
-+    else
-+#endif /* PNG_READ_INTERLACING_SUPPORTED */
-+    {
-+        png_ptr->num_rows = png_ptr->height;
-+        png_ptr->iwidth = png_ptr->width;
-+    }
-+    png_ptr->flags &= ~PNG_FLAG_ZSTREAM_ENDED;
-+    if (inflateReset(&(png_ptr->zstream)) != Z_OK)
-+        png_error(png_ptr, "inflateReset failed");
-+    png_ptr->zstream.avail_in = 0;
-+    png_ptr->zstream.next_in = 0;
-+    png_ptr->zstream.next_out = png_ptr->row_buf;
-+    png_ptr->zstream.avail_out = (uInt)PNG_ROWBYTES(png_ptr->pixel_depth,
-+        png_ptr->iwidth) + 1;
-+}
-+#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
-+#endif /* PNG_READ_APNG_SUPPORTED */
- #endif /* READ */
-diff -Nru libpng-1.6.19-orig/pngset.c libpng-1.6.19/pngset.c
---- libpng-1.6.19-orig/pngset.c	2015-11-13 21:37:46.329670381 +0100
-+++ libpng-1.6.19/pngset.c	2015-11-13 21:38:46.569768339 +0100
-@@ -241,6 +241,11 @@
-    info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);
- 
-    info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, width);
-+
-+#ifdef PNG_APNG_SUPPORTED
-+   /* for non-animated png. this may be overwritten from an acTL chunk later */
-+   info_ptr->num_frames = 1;
-+#endif
- }
- 
- #ifdef PNG_oFFs_SUPPORTED
-@@ -1094,6 +1099,147 @@
- }
- #endif /* sPLT */
- 
-+#ifdef PNG_APNG_SUPPORTED
-+png_uint_32 PNGAPI
-+png_set_acTL(png_structp png_ptr, png_infop info_ptr,
-+    png_uint_32 num_frames, png_uint_32 num_plays)
-+{
-+    png_debug1(1, "in %s storage function", "acTL");
-+
-+    if (png_ptr == NULL || info_ptr == NULL)
-+    {
-+        png_warning(png_ptr,
-+                    "Call to png_set_acTL() with NULL png_ptr "
-+                    "or info_ptr ignored");
-+        return (0);
-+    }
-+    if (num_frames == 0)
-+    {
-+        png_warning(png_ptr,
-+                    "Ignoring attempt to set acTL with num_frames zero");
-+        return (0);
-+    }
-+    if (num_frames > PNG_UINT_31_MAX)
-+    {
-+        png_warning(png_ptr,
-+                    "Ignoring attempt to set acTL with num_frames > 2^31-1");
-+        return (0);
-+    }
-+    if (num_plays > PNG_UINT_31_MAX)
-+    {
-+        png_warning(png_ptr,
-+                    "Ignoring attempt to set acTL with num_plays "
-+                    "> 2^31-1");
-+        return (0);
-+    }
-+
-+    info_ptr->num_frames = num_frames;
-+    info_ptr->num_plays = num_plays;
-+
-+    info_ptr->valid |= PNG_INFO_acTL;
-+
-+    return (1);
-+}
-+
-+/* delay_num and delay_den can hold any 16-bit values including zero */
-+png_uint_32 PNGAPI
-+png_set_next_frame_fcTL(png_structp png_ptr, png_infop info_ptr,
-+    png_uint_32 width, png_uint_32 height,
-+    png_uint_32 x_offset, png_uint_32 y_offset,
-+    png_uint_16 delay_num, png_uint_16 delay_den,
-+    png_byte dispose_op, png_byte blend_op)
-+{
-+    png_debug1(1, "in %s storage function", "fcTL");
-+
-+    if (png_ptr == NULL || info_ptr == NULL)
-+    {
-+        png_warning(png_ptr,
-+                    "Call to png_set_fcTL() with NULL png_ptr or info_ptr "
-+                    "ignored");
-+        return (0);
-+    }
-+
-+    png_ensure_fcTL_is_valid(png_ptr, width, height, x_offset, y_offset,
-+                             delay_num, delay_den, dispose_op, blend_op);
-+
-+    if (blend_op == PNG_BLEND_OP_OVER)
-+    {
-+        if (!(png_ptr->color_type & PNG_COLOR_MASK_ALPHA) &&
-+            !(png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
-+        {
-+          png_warning(png_ptr, "PNG_BLEND_OP_OVER is meaningless "
-+                               "and wasteful for opaque images, ignored");
-+          blend_op = PNG_BLEND_OP_SOURCE;
-+        }
-+    }
-+
-+    info_ptr->next_frame_width = width;
-+    info_ptr->next_frame_height = height;
-+    info_ptr->next_frame_x_offset = x_offset;
-+    info_ptr->next_frame_y_offset = y_offset;
-+    info_ptr->next_frame_delay_num = delay_num;
-+    info_ptr->next_frame_delay_den = delay_den;
-+    info_ptr->next_frame_dispose_op = dispose_op;
-+    info_ptr->next_frame_blend_op = blend_op;
-+
-+    info_ptr->valid |= PNG_INFO_fcTL;
-+
-+    return (1);
-+}
-+
-+void /* PRIVATE */
-+png_ensure_fcTL_is_valid(png_structp png_ptr,
-+    png_uint_32 width, png_uint_32 height,
-+    png_uint_32 x_offset, png_uint_32 y_offset,
-+    png_uint_16 delay_num, png_uint_16 delay_den,
-+    png_byte dispose_op, png_byte blend_op)
-+{
-+    if (width > PNG_UINT_31_MAX)
-+        png_error(png_ptr, "invalid width in fcTL (> 2^31-1)");
-+    if (height > PNG_UINT_31_MAX)
-+        png_error(png_ptr, "invalid height in fcTL (> 2^31-1)");
-+    if (x_offset > PNG_UINT_31_MAX)
-+        png_error(png_ptr, "invalid x_offset in fcTL (> 2^31-1)");
-+    if (y_offset > PNG_UINT_31_MAX)
-+        png_error(png_ptr, "invalid y_offset in fcTL (> 2^31-1)");
-+    if (width + x_offset > png_ptr->first_frame_width ||
-+        height + y_offset > png_ptr->first_frame_height)
-+        png_error(png_ptr, "dimensions of a frame are greater than"
-+                           "the ones in IHDR");
-+
-+    if (dispose_op != PNG_DISPOSE_OP_NONE &&
-+        dispose_op != PNG_DISPOSE_OP_BACKGROUND &&
-+        dispose_op != PNG_DISPOSE_OP_PREVIOUS)
-+        png_error(png_ptr, "invalid dispose_op in fcTL");
-+
-+    if (blend_op != PNG_BLEND_OP_SOURCE &&
-+        blend_op != PNG_BLEND_OP_OVER)
-+        png_error(png_ptr, "invalid blend_op in fcTL");
-+
-+    PNG_UNUSED(delay_num)
-+    PNG_UNUSED(delay_den)
-+}
-+
-+png_uint_32 PNGAPI
-+png_set_first_frame_is_hidden(png_structp png_ptr, png_infop info_ptr,
-+                              png_byte is_hidden)
-+{
-+    png_debug(1, "in png_first_frame_is_hidden()");
-+
-+    if (png_ptr == NULL)
-+        return 0;
-+
-+    if (is_hidden)
-+        png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN;
-+    else
-+        png_ptr->apng_flags &= ~PNG_FIRST_FRAME_HIDDEN;
-+
-+    PNG_UNUSED(info_ptr)
-+
-+    return 1;
-+}
-+#endif /* PNG_APNG_SUPPORTED */
-+
- #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
- static png_byte
- check_location(png_const_structrp png_ptr, int location)
-diff -Nru libpng-1.6.19-orig/pngstruct.h libpng-1.6.19/pngstruct.h
---- libpng-1.6.19-orig/pngstruct.h	2015-11-13 21:37:46.356671321 +0100
-+++ libpng-1.6.19/pngstruct.h	2015-11-13 21:38:46.569768339 +0100
-@@ -400,6 +400,27 @@
-    png_byte filter_type;
- #endif
- 
-+#ifdef PNG_APNG_SUPPORTED
-+   png_uint_32 apng_flags;
-+   png_uint_32 next_seq_num;         /* next fcTL/fdAT chunk sequence number */
-+   png_uint_32 first_frame_width;
-+   png_uint_32 first_frame_height;
-+
-+#ifdef PNG_READ_APNG_SUPPORTED
-+   png_uint_32 num_frames_read;      /* incremented after all image data of */
-+                                     /* a frame is read */
-+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-+   png_progressive_frame_ptr frame_info_fn; /* frame info read callback */
-+   png_progressive_frame_ptr frame_end_fn;  /* frame data read callback */
-+#endif
-+#endif
-+
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+   png_uint_32 num_frames_to_write;
-+   png_uint_32 num_frames_written;
-+#endif
-+#endif /* PNG_APNG_SUPPORTED */
-+
- /* New members added in libpng-1.2.0 */
- 
- /* New members added in libpng-1.0.2 but first enabled by default in 1.2.0 */
-diff -Nru libpng-1.6.19-orig/pngtest.c libpng-1.6.19/pngtest.c
---- libpng-1.6.19-orig/pngtest.c	2015-11-13 21:37:46.319670033 +0100
-+++ libpng-1.6.19/pngtest.c	2015-11-13 21:48:03.778227241 +0100
-@@ -850,6 +850,10 @@
-    png_uint_32 width, height;
-    int num_pass = 1, pass;
-    int bit_depth, color_type;
-+#ifdef PNG_APNG_SUPPORTED
-+   png_uint_32 num_frames;
-+   png_uint_32 num_plays;
-+#endif
- 
-    row_buf = NULL;
-    error_parameters.file_name = inname;
-@@ -1406,6 +1410,89 @@
-    t_misc += (t_stop - t_start);
-    t_start = t_stop;
- #endif
-+#ifdef PNG_APNG_SUPPORTED
-+   if (png_get_valid(read_ptr, read_info_ptr, PNG_INFO_acTL))
-+   {
-+      png_uint_32 frame;
-+      for (frame = 0; frame < num_frames; frame++)
-+      {
-+         png_uint_32 frame_width;
-+         png_uint_32 frame_height;
-+         png_uint_32 x_offset;
-+         png_uint_32 y_offset;
-+         png_uint_16 delay_num;
-+         png_uint_16 delay_den;
-+         png_byte dispose_op;
-+         png_byte blend_op;
-+         png_read_frame_head(read_ptr, read_info_ptr);
-+         if (png_get_valid(read_ptr, read_info_ptr, PNG_INFO_fcTL))
-+         {
-+            png_get_next_frame_fcTL(read_ptr, read_info_ptr,
-+                                    &frame_width, &frame_height,
-+                                    &x_offset, &y_offset,
-+                                    &delay_num, &delay_den,
-+                                    &dispose_op, &blend_op);
-+         }
-+         else
-+         {
-+            frame_width = width;
-+            frame_height = height;
-+            x_offset = 0;
-+            y_offset = 0;
-+            delay_num = 1;
-+            delay_den = 1;
-+            dispose_op = PNG_DISPOSE_OP_NONE;
-+            blend_op = PNG_BLEND_OP_SOURCE;
-+         }
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+         png_write_frame_head(write_ptr, write_info_ptr, (png_bytepp)&row_buf,
-+                              frame_width, frame_height,
-+                              x_offset, y_offset,
-+                              delay_num, delay_den,
-+                              dispose_op, blend_op);
-+#endif
-+         for (pass = 0; pass < num_pass; pass++)
-+         {
-+            pngtest_debug1("Writing row data for pass %d", pass);
-+            for (y = 0; y < frame_height; y++)
-+            {
-+#ifndef SINGLE_ROWBUF_ALLOC
-+               pngtest_debug2("Allocating row buffer (pass %d, y = %ld)...", pass, y);
-+               row_buf = (png_bytep)png_malloc(read_ptr,
-+                  png_get_rowbytes(read_ptr, read_info_ptr));
-+               pngtest_debug2("0x%08lx (%ld bytes)", (unsigned long)row_buf,
-+                  png_get_rowbytes(read_ptr, read_info_ptr));
-+#endif /* !SINGLE_ROWBUF_ALLOC */
-+               png_read_rows(read_ptr, (png_bytepp)&row_buf, NULL, 1);
-+
-+#ifdef PNG_WRITE_SUPPORTED
-+#ifdef PNGTEST_TIMING
-+               t_stop = (float)clock();
-+               t_decode += (t_stop - t_start);
-+               t_start = t_stop;
-+#endif
-+               png_write_rows(write_ptr, (png_bytepp)&row_buf, 1);
-+#ifdef PNGTEST_TIMING
-+               t_stop = (float)clock();
-+               t_encode += (t_stop - t_start);
-+               t_start = t_stop;
-+#endif
-+#endif /* PNG_WRITE_SUPPORTED */
-+
-+#ifndef SINGLE_ROWBUF_ALLOC
-+               pngtest_debug2("Freeing row buffer (pass %d, y = %ld)", pass, y);
-+               png_free(read_ptr, row_buf);
-+               row_buf = NULL;
-+#endif /* !SINGLE_ROWBUF_ALLOC */
-+            }
-+         }
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+         png_write_frame_tail(write_ptr, write_info_ptr);
-+#endif
-+      }
-+   }
-+   else
-+#endif
-    for (pass = 0; pass < num_pass; pass++)
-    {
-       pngtest_debug1("Writing row data for pass %d", pass);
-@@ -1506,6 +1593,20 @@
-       }
-    }
- #endif
-+#ifdef PNG_APNG_SUPPORTED
-+   if (png_get_valid(read_ptr, read_info_ptr, PNG_INFO_acTL))
-+   {
-+      if (png_get_acTL(read_ptr, read_info_ptr, &num_frames, &num_plays))
-+      {
-+         png_byte is_hidden;
-+         pngtest_debug2("Handling acTL chunks (frames %ld, plays %ld)",
-+                    num_frames, num_plays);
-+         png_set_acTL(write_ptr, write_info_ptr, num_frames, num_plays);
-+         is_hidden = png_get_first_frame_is_hidden(read_ptr, read_info_ptr);
-+         png_set_first_frame_is_hidden(write_ptr, write_info_ptr, is_hidden);
-+      }
-+   }
-+#endif
- #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
-    {
-       png_unknown_chunkp unknowns;
-diff -Nru libpng-1.6.19-orig/pngwrite.c libpng-1.6.19/pngwrite.c
---- libpng-1.6.19-orig/pngwrite.c	2015-11-13 21:37:46.348671042 +0100
-+++ libpng-1.6.19/pngwrite.c	2015-11-13 21:38:46.570768374 +0100
-@@ -128,6 +128,10 @@
-        * the application continues writing the PNG.  So check the 'invalid'
-        * flag here too.
-        */
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+      if (info_ptr->valid & PNG_INFO_acTL)
-+         png_write_acTL(png_ptr, info_ptr->num_frames, info_ptr->num_plays);
-+#endif
- #ifdef PNG_GAMMA_SUPPORTED
- #  ifdef PNG_WRITE_gAMA_SUPPORTED
-       if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
-@@ -365,6 +369,11 @@
-       png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
- #endif
- 
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+   if (png_ptr->num_frames_written != png_ptr->num_frames_to_write)
-+      png_error(png_ptr, "Not enough frames written");
-+#endif
-+
-    /* See if user wants us to write information chunks */
-    if (info_ptr != NULL)
-    {
-@@ -1450,6 +1459,43 @@
- }
- #endif
- 
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+void PNGAPI
-+png_write_frame_head(png_structp png_ptr, png_infop info_ptr,
-+    png_bytepp row_pointers, png_uint_32 width, png_uint_32 height,
-+    png_uint_32 x_offset, png_uint_32 y_offset,
-+    png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
-+    png_byte blend_op)
-+{
-+    png_debug(1, "in png_write_frame_head");
-+
-+    /* there is a chance this has been set after png_write_info was called,
-+    * so it would be set but not written. is there a way to be sure? */
-+    if (!(info_ptr->valid & PNG_INFO_acTL))
-+        png_error(png_ptr, "png_write_frame_head(): acTL not set");
-+
-+    png_write_reset(png_ptr);
-+
-+    png_write_reinit(png_ptr, info_ptr, width, height);
-+
-+    if ( !(png_ptr->num_frames_written == 0 &&
-+           (png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN) ) )
-+        png_write_fcTL(png_ptr, width, height, x_offset, y_offset,
-+                       delay_num, delay_den, dispose_op, blend_op);
-+
-+    PNG_UNUSED(row_pointers)
-+}
-+
-+void PNGAPI
-+png_write_frame_tail(png_structp png_ptr, png_infop info_ptr)
-+{
-+    png_debug(1, "in png_write_frame_tail");
-+
-+    png_ptr->num_frames_written++;
-+
-+    PNG_UNUSED(info_ptr)
-+}
-+#endif /* PNG_WRITE_APNG_SUPPORTED */
- 
- #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
- # ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
-diff -Nru libpng-1.6.19-orig/pngwutil.c libpng-1.6.19/pngwutil.c
---- libpng-1.6.19-orig/pngwutil.c	2015-11-13 21:37:46.349671077 +0100
-+++ libpng-1.6.19/pngwutil.c	2015-11-13 21:38:46.570768374 +0100
-@@ -901,6 +901,11 @@
-    /* Write the chunk */
-    png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
- 
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+   png_ptr->first_frame_width = width;
-+   png_ptr->first_frame_height = height;
-+#endif
-+
-    if ((png_ptr->do_filter) == PNG_NO_FILTERS)
-    {
-       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
-@@ -1082,7 +1087,14 @@
-                optimize_cmf(data, png_image_size(png_ptr));
- #endif
- 
-+#        ifdef PNG_WRITE_APNG_SUPPORTED
-+            if (png_ptr->num_frames_written == 0)
-+#        endif
-          png_write_complete_chunk(png_ptr, png_IDAT, data, size);
-+#        ifdef PNG_WRITE_APNG_SUPPORTED
-+            else
-+               png_write_fdAT(png_ptr, data, size);
-+#        endif /* PNG_WRITE_APNG_SUPPORTED */
-          png_ptr->mode |= PNG_HAVE_IDAT;
- 
-          png_ptr->zstream.next_out = data;
-@@ -1128,7 +1140,15 @@
-             optimize_cmf(data, png_image_size(png_ptr));
- #endif
- 
-+#        ifdef PNG_WRITE_APNG_SUPPORTED
-+            if (png_ptr->num_frames_written == 0)
-+#        endif
-          png_write_complete_chunk(png_ptr, png_IDAT, data, size);
-+#        ifdef PNG_WRITE_APNG_SUPPORTED
-+            else
-+               png_write_fdAT(png_ptr, data, size);
-+#        endif /* PNG_WRITE_APNG_SUPPORTED */
-+
-          png_ptr->zstream.avail_out = 0;
-          png_ptr->zstream.next_out = NULL;
-          png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
-@@ -1941,6 +1961,82 @@
- }
- #endif
- 
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+void /* PRIVATE */
-+png_write_acTL(png_structp png_ptr,
-+    png_uint_32 num_frames, png_uint_32 num_plays)
-+{
-+    png_byte buf[8];
-+
-+    png_debug(1, "in png_write_acTL");
-+
-+    png_ptr->num_frames_to_write = num_frames;
-+
-+    if (png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN)
-+        num_frames--;
-+
-+    png_save_uint_32(buf, num_frames);
-+    png_save_uint_32(buf + 4, num_plays);
-+
-+    png_write_complete_chunk(png_ptr, png_acTL, buf, (png_size_t)8);
-+}
-+
-+void /* PRIVATE */
-+png_write_fcTL(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
-+    png_uint_32 x_offset, png_uint_32 y_offset,
-+    png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
-+    png_byte blend_op)
-+{
-+    png_byte buf[26];
-+
-+    png_debug(1, "in png_write_fcTL");
-+
-+    if (png_ptr->num_frames_written == 0 && (x_offset != 0 || y_offset != 0))
-+        png_error(png_ptr, "x and/or y offset for the first frame aren't 0");
-+    if (png_ptr->num_frames_written == 0 &&
-+        (width != png_ptr->first_frame_width ||
-+         height != png_ptr->first_frame_height))
-+        png_error(png_ptr, "width and/or height in the first frame's fcTL "
-+                           "don't match the ones in IHDR");
-+
-+    /* more error checking */
-+    png_ensure_fcTL_is_valid(png_ptr, width, height, x_offset, y_offset,
-+                             delay_num, delay_den, dispose_op, blend_op);
-+
-+    png_save_uint_32(buf, png_ptr->next_seq_num);
-+    png_save_uint_32(buf + 4, width);
-+    png_save_uint_32(buf + 8, height);
-+    png_save_uint_32(buf + 12, x_offset);
-+    png_save_uint_32(buf + 16, y_offset);
-+    png_save_uint_16(buf + 20, delay_num);
-+    png_save_uint_16(buf + 22, delay_den);
-+    buf[24] = dispose_op;
-+    buf[25] = blend_op;
-+
-+    png_write_complete_chunk(png_ptr, png_fcTL, buf, (png_size_t)26);
-+
-+    png_ptr->next_seq_num++;
-+}
-+
-+void /* PRIVATE */
-+png_write_fdAT(png_structp png_ptr,
-+    png_const_bytep data, png_size_t length)
-+{
-+    png_byte buf[4];
-+
-+    png_write_chunk_header(png_ptr, png_fdAT, (png_uint_32)(4 + length));
-+
-+    png_save_uint_32(buf, png_ptr->next_seq_num);
-+    png_write_chunk_data(png_ptr, buf, 4);
-+
-+    png_write_chunk_data(png_ptr, data, length);
-+
-+    png_write_chunk_end(png_ptr);
-+
-+    png_ptr->next_seq_num++;
-+}
-+#endif /* PNG_WRITE_APNG_SUPPORTED */
-+
- /* Initializes the row writing capability of libpng */
- void /* PRIVATE */
- png_write_start_row(png_structrp png_ptr)
-@@ -2706,4 +2802,39 @@
-    }
- #endif /* WRITE_FLUSH */
- }
-+
-+#ifdef PNG_WRITE_APNG_SUPPORTED
-+void /* PRIVATE */
-+png_write_reset(png_structp png_ptr)
-+{
-+    png_ptr->row_number = 0;
-+    png_ptr->pass = 0;
-+    png_ptr->mode &= ~PNG_HAVE_IDAT;
-+}
-+
-+void /* PRIVATE */
-+png_write_reinit(png_structp png_ptr, png_infop info_ptr,
-+                 png_uint_32 width, png_uint_32 height)
-+{
-+    if (png_ptr->num_frames_written == 0 &&
-+        (width != png_ptr->first_frame_width ||
-+         height != png_ptr->first_frame_height))
-+        png_error(png_ptr, "width and/or height in the first frame's fcTL "
-+                           "don't match the ones in IHDR");
-+    if (width > png_ptr->first_frame_width ||
-+        height > png_ptr->first_frame_height)
-+        png_error(png_ptr, "width and/or height for a frame greater than"
-+                           "the ones in IHDR");
-+
-+    png_set_IHDR(png_ptr, info_ptr, width, height,
-+                 info_ptr->bit_depth, info_ptr->color_type,
-+                 info_ptr->interlace_type, info_ptr->compression_type,
-+                 info_ptr->filter_type);
-+
-+    png_ptr->width = width;
-+    png_ptr->height = height;
-+    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
-+    png_ptr->usr_width = png_ptr->width;
-+}
-+#endif /* PNG_WRITE_APNG_SUPPORTED */
- #endif /* WRITE */
-diff -Nru libpng-1.6.19-orig/scripts/symbols.def libpng-1.6.19/scripts/symbols.def
---- libpng-1.6.19-orig/scripts/symbols.def	2015-11-13 21:37:46.354671251 +0100
-+++ libpng-1.6.19/scripts/symbols.def	2015-11-13 21:38:46.570768374 +0100
-@@ -249,3 +249,23 @@
-  png_set_check_for_invalid_index @242
-  png_get_palette_max @243
-  png_set_option @244
-+ png_get_acTL @245
-+ png_set_acTL @246
-+ png_get_num_frames @247
-+ png_get_num_plays @248
-+ png_get_next_frame_fcTL @249
-+ png_set_next_frame_fcTL @250
-+ png_get_next_frame_width @251
-+ png_get_next_frame_height @252
-+ png_get_next_frame_x_offset @253
-+ png_get_next_frame_y_offset @254
-+ png_get_next_frame_delay_num @255
-+ png_get_next_frame_delay_den @256
-+ png_get_next_frame_dispose_op @257
-+ png_get_next_frame_blend_op @258
-+ png_get_first_frame_is_hidden @259
-+ png_set_first_frame_is_hidden @260
-+ png_read_frame_head @261
-+ png_set_progressive_frame_fn @262
-+ png_write_frame_head @263
-+ png_write_frame_tail @264
diff --git a/libpng/libpng-1.6.20-apng.patch b/libpng/libpng-1.6.20-apng.patch
new file mode 100644
index 0000000..c9fd552
--- /dev/null
+++ b/libpng/libpng-1.6.20-apng.patch
@@ -0,0 +1,1628 @@
+Index: LICENSE
+===================================================================
+--- LICENSE
++++ LICENSE
+@@ -8,6 +8,12 @@
+ If you modify libpng you may insert additional notices immediately following
+ this sentence.
+ 
++This modified version of libpng code adds animated PNG support and is
++released under the libpng license described below. The modifications are
++Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2015 Max Stepin,
++and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
++surrounding them in the modified libpng source files.
++
+ This code is released under the libpng license.
+ 
+ libpng versions 1.0.7, July 1, 2000, through 1.6.20, December 3, 2015, are
+Index: pngread.c
+===================================================================
+--- pngread.c
++++ pngread.c
+@@ -158,6 +158,9 @@
+ 
+       else if (chunk_name == png_IDAT)
+       {
++#ifdef PNG_READ_APNG_SUPPORTED
++         png_have_info(png_ptr, info_ptr);
++#endif
+          png_ptr->idat_size = length;
+          break;
+       }
+@@ -247,6 +250,17 @@
+          png_handle_iTXt(png_ptr, info_ptr, length);
+ #endif
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++      else if (chunk_name == png_acTL)
++         png_handle_acTL(png_ptr, info_ptr, length);
++
++      else if (chunk_name == png_fcTL)
++         png_handle_fcTL(png_ptr, info_ptr, length);
++
++      else if (chunk_name == png_fdAT)
++         png_handle_fdAT(png_ptr, info_ptr, length);
++#endif
++
+       else
+          png_handle_unknown(png_ptr, info_ptr, length,
+             PNG_HANDLE_CHUNK_AS_DEFAULT);
+@@ -254,6 +268,72 @@
+ }
+ #endif /* SEQUENTIAL_READ */
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++void PNGAPI
++png_read_frame_head(png_structp png_ptr, png_infop info_ptr)
++{
++    png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */
++
++    png_debug(0, "Reading frame head");
++
++    if ((png_ptr->mode & PNG_HAVE_acTL) == 0)
++        png_error(png_ptr, "attempt to png_read_frame_head() but "
++                           "no acTL present");
++
++    /* do nothing for the main IDAT */
++    if (png_ptr->num_frames_read == 0)
++        return;
++
++    png_read_reset(png_ptr);
++    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
++    png_ptr->mode &= ~PNG_HAVE_fcTL;
++
++    have_chunk_after_DAT = 0;
++    for (;;)
++    {
++        png_uint_32 length = png_read_chunk_header(png_ptr);
++
++        if (png_ptr->chunk_name == png_IDAT)
++        {
++            /* discard trailing IDATs for the first frame */
++            if (have_chunk_after_DAT != 0 || png_ptr->num_frames_read > 1)
++                png_error(png_ptr, "png_read_frame_head(): out of place IDAT");
++            png_crc_finish(png_ptr, length);
++        }
++
++        else if (png_ptr->chunk_name == png_fcTL)
++        {
++            png_handle_fcTL(png_ptr, info_ptr, length);
++            have_chunk_after_DAT = 1;
++        }
++
++        else if (png_ptr->chunk_name == png_fdAT)
++        {
++            png_ensure_sequence_number(png_ptr, length);
++
++            /* discard trailing fdATs for frames other than the first */
++            if (have_chunk_after_DAT == 0 && png_ptr->num_frames_read > 1)
++                png_crc_finish(png_ptr, length - 4);
++            else if(png_ptr->mode & PNG_HAVE_fcTL)
++            {
++                png_ptr->idat_size = length - 4;
++                png_ptr->mode |= PNG_HAVE_IDAT;
++
++                break;
++            }
++            else
++                png_error(png_ptr, "png_read_frame_head(): out of place fdAT");
++        }
++        else
++        {
++            png_warning(png_ptr, "Skipped (ignored) a chunk "
++                                 "between APNG chunks");
++            png_crc_finish(png_ptr, length);
++        }
++    }
++}
++#endif /* READ_APNG */
++
+ /* Optional call to update the users info_ptr structure */
+ void PNGAPI
+ png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
+Index: pngget.c
+===================================================================
+--- pngget.c
++++ pngget.c
+@@ -1216,4 +1216,166 @@
+ #  endif
+ #endif
+ 
++#ifdef PNG_APNG_SUPPORTED
++png_uint_32 PNGAPI
++png_get_acTL(png_structp png_ptr, png_infop info_ptr,
++             png_uint_32 *num_frames, png_uint_32 *num_plays)
++{
++    png_debug1(1, "in %s retrieval function", "acTL");
++
++    if (png_ptr != NULL && info_ptr != NULL &&
++        (info_ptr->valid & PNG_INFO_acTL) != 0 &&
++        num_frames != NULL && num_plays != NULL)
++    {
++        *num_frames = info_ptr->num_frames;
++        *num_plays = info_ptr->num_plays;
++        return (1);
++    }
++
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_num_frames(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_num_frames()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->num_frames);
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_num_plays(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_num_plays()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->num_plays);
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_next_frame_fcTL(png_structp png_ptr, png_infop info_ptr,
++             png_uint_32 *width, png_uint_32 *height,
++             png_uint_32 *x_offset, png_uint_32 *y_offset,
++             png_uint_16 *delay_num, png_uint_16 *delay_den,
++             png_byte *dispose_op, png_byte *blend_op)
++{
++    png_debug1(1, "in %s retrieval function", "fcTL");
++
++    if (png_ptr != NULL && info_ptr != NULL &&
++        (info_ptr->valid & PNG_INFO_fcTL) != 0 &&
++        width != NULL && height != NULL &&
++        x_offset != NULL && y_offset != NULL &&
++        delay_num != NULL && delay_den != NULL &&
++        dispose_op != NULL && blend_op != NULL)
++    {
++        *width = info_ptr->next_frame_width;
++        *height = info_ptr->next_frame_height;
++        *x_offset = info_ptr->next_frame_x_offset;
++        *y_offset = info_ptr->next_frame_y_offset;
++        *delay_num = info_ptr->next_frame_delay_num;
++        *delay_den = info_ptr->next_frame_delay_den;
++        *dispose_op = info_ptr->next_frame_dispose_op;
++        *blend_op = info_ptr->next_frame_blend_op;
++        return (1);
++    }
++
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_next_frame_width(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_width()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_width);
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_next_frame_height(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_height()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_height);
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_next_frame_x_offset(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_x_offset()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_x_offset);
++    return (0);
++}
++
++png_uint_32 PNGAPI
++png_get_next_frame_y_offset(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_y_offset()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_y_offset);
++    return (0);
++}
++
++png_uint_16 PNGAPI
++png_get_next_frame_delay_num(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_delay_num()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_delay_num);
++    return (0);
++}
++
++png_uint_16 PNGAPI
++png_get_next_frame_delay_den(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_delay_den()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_delay_den);
++    return (0);
++}
++
++png_byte PNGAPI
++png_get_next_frame_dispose_op(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_dispose_op()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_dispose_op);
++    return (0);
++}
++
++png_byte PNGAPI
++png_get_next_frame_blend_op(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_get_next_frame_blend_op()");
++
++    if (png_ptr != NULL && info_ptr != NULL)
++        return (info_ptr->next_frame_blend_op);
++    return (0);
++}
++
++png_byte PNGAPI
++png_get_first_frame_is_hidden(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_first_frame_is_hidden()");
++
++    if (png_ptr != NULL)
++       return (png_byte)(png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN);
++
++    PNG_UNUSED(info_ptr)
++
++    return 0;
++}
++#endif /* APNG */
+ #endif /* READ || WRITE */
+Index: png.c
+===================================================================
+--- png.c
++++ png.c
+@@ -775,16 +775,20 @@
+ #else
+ #  ifdef __STDC__
+    return PNG_STRING_NEWLINE \
+-      "libpng version 1.6.20 - December 3, 2015" PNG_STRING_NEWLINE \
++      "libpng version 1.6.20+apng - December 3, 2015" PNG_STRING_NEWLINE \
+       "Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
+       "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
+       "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
+-      PNG_STRING_NEWLINE;
++      PNG_STRING_NEWLINE \
++      "Portions Copyright (c) 2006-2007 Andrew Smith" PNG_STRING_NEWLINE \
++      "Portions Copyright (c) 2008-2015 Max Stepin" PNG_STRING_NEWLINE ;
+ #  else
+-   return "libpng version 1.6.20 - December 3, 2015\
++   return "libpng version 1.6.20+apng - December 3, 2015\
+       Copyright (c) 1998-2015 Glenn Randers-Pehrson\
+       Copyright (c) 1996-1997 Andreas Dilger\
+-      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
++      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\
++      Portions Copyright (c) 2006-2007 Andrew Smith\
++      Portions Copyright (c) 2008-2015 Max Stepin";
+ #  endif
+ #endif
+ }
+Index: png.h
+===================================================================
+--- png.h
++++ png.h
+@@ -23,6 +23,12 @@
+  * If you modify libpng you may insert additional notices immediately following
+  * this sentence.
+  *
++ * This modified version of libpng code adds animated PNG support and is
++ * released under the libpng license described below. The modifications are
++ * Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2015 Max Stepin,
++ * and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
++ * surrounding them in the modified libpng source files.
++ *
+  * This code is released under the libpng license.
+  *
+  * libpng versions 1.0.7, July 1, 2000, through 1.6.20, December 3, 2015, are
+@@ -282,9 +288,9 @@
+  */
+ 
+ /* Version information for png.h - this should match the version in png.c */
+-#define PNG_LIBPNG_VER_STRING "1.6.20"
++#define PNG_LIBPNG_VER_STRING "1.6.20+apng"
+ #define PNG_HEADER_VERSION_STRING \
+-     " libpng version 1.6.20 - December 3, 2015\n"
++     " libpng version 1.6.20+apng - December 3, 2015\n"
+ 
+ #define PNG_LIBPNG_VER_SONUM   16
+ #define PNG_LIBPNG_VER_DLLNUM  16
+@@ -335,6 +341,10 @@
+ #   include "pnglibconf.h"
+ #endif
+ 
++#define PNG_APNG_SUPPORTED
++#define PNG_READ_APNG_SUPPORTED
++#define PNG_WRITE_APNG_SUPPORTED
++
+ #ifndef PNG_VERSION_INFO_ONLY
+    /* Machine specific configuration. */
+ #  include "pngconf.h"
+@@ -430,6 +440,17 @@
+  * See pngconf.h for base types that vary by machine/system
+  */
+ 
++#ifdef PNG_APNG_SUPPORTED
++/* dispose_op flags from inside fcTL */
++#define PNG_DISPOSE_OP_NONE        0x00
++#define PNG_DISPOSE_OP_BACKGROUND  0x01
++#define PNG_DISPOSE_OP_PREVIOUS    0x02
++
++/* blend_op flags from inside fcTL */
++#define PNG_BLEND_OP_SOURCE        0x00
++#define PNG_BLEND_OP_OVER          0x01
++#endif /* APNG */
++
+ /* This triggers a compiler error in png.c, if png.c and png.h
+  * do not agree upon the version number.
+  */
+@@ -752,6 +773,10 @@
+ #if INT_MAX >= 0x8000 /* else this might break */
+ #define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */
+ #endif
++#ifdef PNG_APNG_SUPPORTED
++#define PNG_INFO_acTL 0x10000
++#define PNG_INFO_fcTL 0x20000
++#endif
+ 
+ /* This is used for the transformation routines, as some of them
+  * change these values for the row.  It also should enable using
+@@ -789,6 +814,10 @@
+ #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+ typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
+ typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
++#ifdef PNG_APNG_SUPPORTED
++typedef PNG_CALLBACK(void, *png_progressive_frame_ptr, (png_structp,
++    png_uint_32));
++#endif
+ 
+ /* The following callback receives png_uint_32 row_number, int pass for the
+  * png_bytep data of the row.  When transforming an interlaced image the
+@@ -3110,6 +3139,75 @@
+  *  END OF HARDWARE AND SOFTWARE OPTIONS
+  ******************************************************************************/
+ 
++#ifdef PNG_APNG_SUPPORTED
++PNG_EXPORT(245, png_uint_32, png_get_acTL, (png_structp png_ptr,
++   png_infop info_ptr, png_uint_32 *num_frames, png_uint_32 *num_plays));
++
++PNG_EXPORT(246, png_uint_32, png_set_acTL, (png_structp png_ptr,
++   png_infop info_ptr, png_uint_32 num_frames, png_uint_32 num_plays));
++
++PNG_EXPORT(247, png_uint_32, png_get_num_frames, (png_structp png_ptr,
++   png_infop info_ptr));
++
++PNG_EXPORT(248, png_uint_32, png_get_num_plays, (png_structp png_ptr,
++   png_infop info_ptr));
++
++PNG_EXPORT(249, png_uint_32, png_get_next_frame_fcTL,
++   (png_structp png_ptr, png_infop info_ptr, png_uint_32 *width,
++   png_uint_32 *height, png_uint_32 *x_offset, png_uint_32 *y_offset,
++   png_uint_16 *delay_num, png_uint_16 *delay_den, png_byte *dispose_op,
++   png_byte *blend_op));
++
++PNG_EXPORT(250, png_uint_32, png_set_next_frame_fcTL,
++   (png_structp png_ptr, png_infop info_ptr, png_uint_32 width,
++   png_uint_32 height, png_uint_32 x_offset, png_uint_32 y_offset,
++   png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
++   png_byte blend_op));
++
++PNG_EXPORT(251, png_uint_32, png_get_next_frame_width,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(252, png_uint_32, png_get_next_frame_height,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(253, png_uint_32, png_get_next_frame_x_offset,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(254, png_uint_32, png_get_next_frame_y_offset,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(255, png_uint_16, png_get_next_frame_delay_num,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(256, png_uint_16, png_get_next_frame_delay_den,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(257, png_byte, png_get_next_frame_dispose_op,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(258, png_byte, png_get_next_frame_blend_op,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(259, png_byte, png_get_first_frame_is_hidden,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(260, png_uint_32, png_set_first_frame_is_hidden,
++   (png_structp png_ptr, png_infop info_ptr, png_byte is_hidden));
++
++#ifdef PNG_READ_APNG_SUPPORTED
++PNG_EXPORT(261, void, png_read_frame_head, (png_structp png_ptr,
++   png_infop info_ptr));
++#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
++PNG_EXPORT(262, void, png_set_progressive_frame_fn, (png_structp png_ptr,
++   png_progressive_frame_ptr frame_info_fn,
++   png_progressive_frame_ptr frame_end_fn));
++#endif /* PROGRESSIVE_READ */
++#endif /* READ_APNG */
++
++#ifdef PNG_WRITE_APNG_SUPPORTED
++PNG_EXPORT(263, void, png_write_frame_head, (png_structp png_ptr,
++   png_infop info_ptr, png_bytepp row_pointers,
++   png_uint_32 width, png_uint_32 height,
++   png_uint_32 x_offset, png_uint_32 y_offset,
++   png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
++   png_byte blend_op));
++
++PNG_EXPORT(264, void, png_write_frame_tail, (png_structp png_ptr,
++   png_infop info_ptr));
++#endif /* WRITE_APNG */
++#endif /* APNG */
++
+ /* Maintainer: Put new public prototypes here ^, in libpng.3, in project
+  * defs, and in scripts/symbols.def.
+  */
+@@ -3118,7 +3216,11 @@
+  * one to use is one more than this.)
+  */
+ #ifdef PNG_EXPORT_LAST_ORDINAL
++#ifdef PNG_APNG_SUPPORTED
++  PNG_EXPORT_LAST_ORDINAL(264);
++#else
+   PNG_EXPORT_LAST_ORDINAL(244);
++#endif /* APNG */
+ #endif
+ 
+ #ifdef __cplusplus
+Index: pngpriv.h
+===================================================================
+--- pngpriv.h
++++ pngpriv.h
+@@ -537,6 +537,10 @@
+ #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
+                    /*             0x4000 (unused) */
+ #define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */
++#ifdef PNG_APNG_SUPPORTED
++#define PNG_HAVE_acTL            0x10000
++#define PNG_HAVE_fcTL            0x20000
++#endif
+ 
+ /* Flags for the transformations the PNG library does on the image data */
+ #define PNG_BGR                 0x0001
+@@ -754,6 +758,16 @@
+ #define png_tRNS PNG_U32(116,  82,  78,  83)
+ #define png_zTXt PNG_U32(122,  84,  88, 116)
+ 
++#ifdef PNG_APNG_SUPPORTED
++#define png_acTL PNG_U32( 97,  99,  84,  76)
++#define png_fcTL PNG_U32(102,  99,  84,  76)
++#define png_fdAT PNG_U32(102, 100,  65,  84)
++
++/* For png_struct.apng_flags: */
++#define PNG_FIRST_FRAME_HIDDEN       0x0001
++#define PNG_APNG_APP                 0x0002
++#endif
++
+ /* The following will work on (signed char*) strings, whereas the get_uint_32
+  * macro will fail on top-bit-set values because of the sign extension.
+  */
+@@ -1441,6 +1455,49 @@
+ 
+ #endif /* PROGRESSIVE_READ */
+ 
++#ifdef PNG_APNG_SUPPORTED
++PNG_INTERNAL_FUNCTION(void,png_ensure_fcTL_is_valid,(png_structp png_ptr,
++   png_uint_32 width, png_uint_32 height,
++   png_uint_32 x_offset, png_uint_32 y_offset,
++   png_uint_16 delay_num, png_uint_16 delay_den,
++   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);
++
++#ifdef PNG_READ_APNG_SUPPORTED
++PNG_INTERNAL_FUNCTION(void,png_handle_acTL,(png_structp png_ptr,
++   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_handle_fcTL,(png_structp png_ptr,
++   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_handle_fdAT,(png_structp png_ptr,
++   png_infop info_ptr, png_uint_32 length),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_have_info,(png_structp png_ptr,
++   png_infop info_ptr),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_ensure_sequence_number,(png_structp png_ptr,
++   png_uint_32 length),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_read_reset,(png_structp png_ptr),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_read_reinit,(png_structp png_ptr,
++   png_infop info_ptr),PNG_EMPTY);
++#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
++PNG_INTERNAL_FUNCTION(void,png_progressive_read_reset,(png_structp png_ptr),
++   PNG_EMPTY);
++#endif /* PROGRESSIVE_READ */
++#endif /* READ_APNG */
++
++#ifdef PNG_WRITE_APNG_SUPPORTED
++PNG_INTERNAL_FUNCTION(void,png_write_acTL,(png_structp png_ptr,
++   png_uint_32 num_frames, png_uint_32 num_plays),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_write_fcTL,(png_structp png_ptr,
++   png_uint_32 width, png_uint_32 height,
++   png_uint_32 x_offset, png_uint_32 y_offset,
++   png_uint_16 delay_num, png_uint_16 delay_den,
++   png_byte dispose_op, png_byte blend_op),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_write_fdAT,(png_structp png_ptr,
++   png_const_bytep data, png_size_t length),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_write_reset,(png_structp png_ptr),PNG_EMPTY);
++PNG_INTERNAL_FUNCTION(void,png_write_reinit,(png_structp png_ptr,
++   png_infop info_ptr, png_uint_32 width, png_uint_32 height),PNG_EMPTY);
++#endif /* WRITE_APNG */
++#endif /* APNG */
++
+ /* Added at libpng version 1.6.0 */
+ #ifdef PNG_GAMMA_SUPPORTED
+ PNG_INTERNAL_FUNCTION(void,png_colorspace_set_gamma,(png_const_structrp png_ptr,
+Index: pnginfo.h
+===================================================================
+--- pnginfo.h
++++ pnginfo.h
+@@ -255,5 +255,18 @@
+    png_bytepp row_pointers;        /* the image bits */
+ #endif
+ 
++#ifdef PNG_APNG_SUPPORTED
++   png_uint_32 num_frames; /* including default image */
++   png_uint_32 num_plays;
++   png_uint_32 next_frame_width;
++   png_uint_32 next_frame_height;
++   png_uint_32 next_frame_x_offset;
++   png_uint_32 next_frame_y_offset;
++   png_uint_16 next_frame_delay_num;
++   png_uint_16 next_frame_delay_den;
++   png_byte next_frame_dispose_op;
++   png_byte next_frame_blend_op;
++#endif
++
+ };
+ #endif /* PNGINFO_H */
+Index: pngstruct.h
+===================================================================
+--- pngstruct.h
++++ pngstruct.h
+@@ -403,6 +403,27 @@
+    png_byte filter_type;
+ #endif
+ 
++#ifdef PNG_APNG_SUPPORTED
++   png_uint_32 apng_flags;
++   png_uint_32 next_seq_num;         /* next fcTL/fdAT chunk sequence number */
++   png_uint_32 first_frame_width;
++   png_uint_32 first_frame_height;
++
++#ifdef PNG_READ_APNG_SUPPORTED
++   png_uint_32 num_frames_read;      /* incremented after all image data of */
++                                     /* a frame is read */
++#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
++   png_progressive_frame_ptr frame_info_fn; /* frame info read callback */
++   png_progressive_frame_ptr frame_end_fn;  /* frame data read callback */
++#endif
++#endif
++
++#ifdef PNG_WRITE_APNG_SUPPORTED
++   png_uint_32 num_frames_to_write;
++   png_uint_32 num_frames_written;
++#endif
++#endif /* APNG */
++
+ /* New members added in libpng-1.2.0 */
+ 
+ /* New members added in libpng-1.0.2 but first enabled by default in 1.2.0 */
+Index: pngwrite.c
+===================================================================
+--- pngwrite.c
++++ pngwrite.c
+@@ -128,6 +128,10 @@
+        * the application continues writing the PNG.  So check the 'invalid'
+        * flag here too.
+        */
++#ifdef PNG_WRITE_APNG_SUPPORTED
++   if ((info_ptr->valid & PNG_INFO_acTL) != 0)
++      png_write_acTL(png_ptr, info_ptr->num_frames, info_ptr->num_plays);
++#endif
+ #ifdef PNG_GAMMA_SUPPORTED
+ #  ifdef PNG_WRITE_gAMA_SUPPORTED
+       if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+@@ -360,6 +364,11 @@
+    if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
+       png_error(png_ptr, "No IDATs written into file");
+ 
++#ifdef PNG_WRITE_APNG_SUPPORTED
++   if (png_ptr->num_frames_written != png_ptr->num_frames_to_write)
++      png_error(png_ptr, "Not enough frames written");
++#endif
++
+ #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
+    if (png_ptr->num_palette_max > png_ptr->num_palette)
+       png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
+@@ -2227,4 +2236,42 @@
+ }
+ # endif /* STDIO */
+ #endif /* SIMPLIFIED_WRITE */
++
++#ifdef PNG_WRITE_APNG_SUPPORTED
++void PNGAPI
++png_write_frame_head(png_structp png_ptr, png_infop info_ptr,
++    png_bytepp row_pointers, png_uint_32 width, png_uint_32 height,
++    png_uint_32 x_offset, png_uint_32 y_offset,
++    png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
++    png_byte blend_op)
++{
++    png_debug(1, "in png_write_frame_head");
++
++    /* there is a chance this has been set after png_write_info was called,
++    * so it would be set but not written. is there a way to be sure? */
++    if ((info_ptr->valid & PNG_INFO_acTL) == 0)
++        png_error(png_ptr, "png_write_frame_head(): acTL not set");
++
++    png_write_reset(png_ptr);
++
++    png_write_reinit(png_ptr, info_ptr, width, height);
++
++    if ((png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN) == 0 ||
++        png_ptr->num_frames_written != 0)
++        png_write_fcTL(png_ptr, width, height, x_offset, y_offset,
++                       delay_num, delay_den, dispose_op, blend_op);
++
++    PNG_UNUSED(row_pointers)
++}
++
++void PNGAPI
++png_write_frame_tail(png_structp png_ptr, png_infop info_ptr)
++{
++    png_debug(1, "in png_write_frame_tail");
++
++    png_ptr->num_frames_written++;
++
++    PNG_UNUSED(info_ptr)
++}
++#endif /* WRITE_APNG */
+ #endif /* WRITE */
+Index: pngpread.c
+===================================================================
+--- pngpread.c
++++ pngpread.c
+@@ -194,6 +194,89 @@
+ 
+    chunk_name = png_ptr->chunk_name;
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++   if (png_ptr->num_frames_read > 0 &&
++       png_ptr->num_frames_read < info_ptr->num_frames)
++   {
++      if (chunk_name == png_IDAT)
++      {
++         /* Discard trailing IDATs for the first frame */
++         if ((png_ptr->mode & PNG_HAVE_fcTL) != 0 ||
++             png_ptr->num_frames_read > 1)
++            png_error(png_ptr, "out of place IDAT");
++
++         PNG_PUSH_SAVE_BUFFER_IF_FULL
++         png_crc_finish(png_ptr, png_ptr->push_length);
++         png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
++      }
++
++      else if (chunk_name == png_fdAT)
++      {
++         PNG_PUSH_SAVE_BUFFER_IF_LT(4)
++         png_ensure_sequence_number(png_ptr, 4);
++
++         if ((png_ptr->mode & PNG_HAVE_fcTL) == 0)
++         {
++            /* Discard trailing fdATs for frames other than the first */
++            if (png_ptr->num_frames_read < 2)
++               png_error(png_ptr, "out of place fdAT");
++
++            PNG_PUSH_SAVE_BUFFER_IF_FULL
++            png_crc_finish(png_ptr, png_ptr->push_length);
++            png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
++         }
++
++         else
++         {
++            /* frame data follows */
++            png_ptr->idat_size = png_ptr->push_length - 4;
++            png_ptr->mode |= PNG_HAVE_IDAT;
++            png_ptr->process_mode = PNG_READ_IDAT_MODE;
++         }
++      }
++
++      else if (chunk_name == png_fcTL)
++      {
++         PNG_PUSH_SAVE_BUFFER_IF_FULL
++         png_read_reset(png_ptr);
++         png_ptr->mode &= ~PNG_HAVE_fcTL;
++
++         png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
++
++         if ((png_ptr->mode & PNG_HAVE_fcTL) == 0)
++            png_error(png_ptr, "missing required fcTL chunk");
++
++         png_read_reinit(png_ptr, info_ptr);
++         png_progressive_read_reset(png_ptr);
++
++         if (png_ptr->frame_info_fn != NULL)
++            (*(png_ptr->frame_info_fn))(png_ptr, png_ptr->num_frames_read);
++
++         png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
++      }
++
++      else if (chunk_name == png_IEND)
++      {
++         PNG_PUSH_SAVE_BUFFER_IF_FULL
++         png_warning(png_ptr, "Number of actual frames fewer than expected");
++         png_crc_finish(png_ptr, png_ptr->push_length);
++         png_ptr->process_mode = PNG_READ_DONE_MODE;
++         png_push_have_end(png_ptr, info_ptr);
++      }
++
++      else
++      {
++         PNG_PUSH_SAVE_BUFFER_IF_FULL
++         png_warning(png_ptr, "Skipped (ignored) a chunk "
++                              "between APNG chunks");
++         png_crc_finish(png_ptr, png_ptr->push_length);
++         png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
++      }
++
++      return;
++   }
++#endif /* READ_APNG */
++
+    if (chunk_name == png_IDAT)
+    {
+       if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
+@@ -258,6 +341,9 @@
+ 
+    else if (chunk_name == png_IDAT)
+    {
++#ifdef PNG_READ_APNG_SUPPORTED
++      png_have_info(png_ptr, info_ptr);
++#endif
+       png_ptr->idat_size = png_ptr->push_length;
+       png_ptr->process_mode = PNG_READ_IDAT_MODE;
+       png_push_have_info(png_ptr, info_ptr);
+@@ -404,6 +490,20 @@
+    }
+ #endif
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++   else if (chunk_name == png_acTL)
++   {
++      PNG_PUSH_SAVE_BUFFER_IF_FULL
++      png_handle_acTL(png_ptr, info_ptr, png_ptr->push_length);
++   }
++
++   else if (chunk_name == png_fcTL)
++   {
++      PNG_PUSH_SAVE_BUFFER_IF_FULL
++      png_handle_fcTL(png_ptr, info_ptr, png_ptr->push_length);
++   }
++
++#endif /* READ_APNG */
+    else
+    {
+       PNG_PUSH_SAVE_BUFFER_IF_FULL
+@@ -533,7 +633,11 @@
+       png_byte chunk_tag[4];
+ 
+       /* TODO: this code can be commoned up with the same code in push_read */
++#ifdef PNG_READ_APNG_SUPPORTED
++      PNG_PUSH_SAVE_BUFFER_IF_LT(12)
++#else
+       PNG_PUSH_SAVE_BUFFER_IF_LT(8)
++#endif
+       png_push_fill_buffer(png_ptr, chunk_length, 4);
+       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
+       png_reset_crc(png_ptr);
+@@ -541,17 +645,60 @@
+       png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
+       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++      if (png_ptr->chunk_name != png_fdAT && png_ptr->num_frames_read > 0)
++      {
++          if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) != 0)
++          {
++              png_ptr->process_mode = PNG_READ_CHUNK_MODE;
++              if (png_ptr->frame_end_fn != NULL)
++                 (*(png_ptr->frame_end_fn))(png_ptr, png_ptr->num_frames_read);
++              png_ptr->num_frames_read++;
++              return;
++          }
++          else
++          {
++              if (png_ptr->chunk_name == png_IEND)
++                  png_error(png_ptr, "Not enough image data");
++              PNG_PUSH_SAVE_BUFFER_IF_FULL
++              png_warning(png_ptr, "Skipping (ignoring) a chunk between "
++                                   "APNG chunks");
++              png_crc_finish(png_ptr, png_ptr->push_length);
++              png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
++              return;
++          }
++      }
++      else
++#endif
++#ifdef PNG_READ_APNG_SUPPORTED
++      if (png_ptr->chunk_name != png_IDAT && png_ptr->num_frames_read == 0)
++#else
+       if (png_ptr->chunk_name != png_IDAT)
++#endif
+       {
+          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
+ 
+          if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
+             png_error(png_ptr, "Not enough compressed data");
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++         if (png_ptr->frame_end_fn != NULL)
++            (*(png_ptr->frame_end_fn))(png_ptr, png_ptr->num_frames_read);
++         png_ptr->num_frames_read++;
++#endif
++
+          return;
+       }
+ 
+       png_ptr->idat_size = png_ptr->push_length;
++
++#ifdef PNG_READ_APNG_SUPPORTED
++      if (png_ptr->num_frames_read > 0)
++      {
++         png_ensure_sequence_number(png_ptr, 4);
++         png_ptr->idat_size -= 4;
++      }
++#endif
+    }
+ 
+    if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
+@@ -625,6 +772,16 @@
+    if (!(buffer_length > 0) || buffer == NULL)
+       png_error(png_ptr, "No IDAT data (internal error)");
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++   /* If the app is not APNG-aware, decode only the first frame */
++   if ((png_ptr->apng_flags & PNG_APNG_APP) == 0 &&
++      png_ptr->num_frames_read > 0)
++   {
++      png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
++      return;
++   }
++#endif
++
+    /* This routine must process all the data it has been given
+     * before returning, calling the row callback as required to
+     * handle the uncompressed results.
+@@ -1074,6 +1231,18 @@
+    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
+ }
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++void PNGAPI
++png_set_progressive_frame_fn(png_structp png_ptr,
++   png_progressive_frame_ptr frame_info_fn,
++   png_progressive_frame_ptr frame_end_fn)
++{
++   png_ptr->frame_info_fn = frame_info_fn;
++   png_ptr->frame_end_fn = frame_end_fn;
++   png_ptr->apng_flags |= PNG_APNG_APP;
++}
++#endif
++
+ png_voidp PNGAPI
+ png_get_progressive_ptr(png_const_structrp png_ptr)
+ {
+Index: pngset.c
+===================================================================
+--- pngset.c
++++ pngset.c
+@@ -241,6 +241,11 @@
+    info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);
+ 
+    info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, width);
++
++#ifdef PNG_APNG_SUPPORTED
++   /* for non-animated png. this may be overwritten from an acTL chunk later */
++   info_ptr->num_frames = 1;
++#endif
+ }
+ 
+ #ifdef PNG_oFFs_SUPPORTED
+@@ -1094,6 +1099,146 @@
+ }
+ #endif /* sPLT */
+ 
++#ifdef PNG_APNG_SUPPORTED
++png_uint_32 PNGAPI
++png_set_acTL(png_structp png_ptr, png_infop info_ptr,
++    png_uint_32 num_frames, png_uint_32 num_plays)
++{
++    png_debug1(1, "in %s storage function", "acTL");
++
++    if (png_ptr == NULL || info_ptr == NULL)
++    {
++        png_warning(png_ptr,
++                    "Call to png_set_acTL() with NULL png_ptr "
++                    "or info_ptr ignored");
++        return (0);
++    }
++    if (num_frames == 0)
++    {
++        png_warning(png_ptr,
++                    "Ignoring attempt to set acTL with num_frames zero");
++        return (0);
++    }
++    if (num_frames > PNG_UINT_31_MAX)
++    {
++        png_warning(png_ptr,
++                    "Ignoring attempt to set acTL with num_frames > 2^31-1");
++        return (0);
++    }
++    if (num_plays > PNG_UINT_31_MAX)
++    {
++        png_warning(png_ptr,
++                    "Ignoring attempt to set acTL with num_plays > 2^31-1");
++        return (0);
++    }
++
++    info_ptr->num_frames = num_frames;
++    info_ptr->num_plays = num_plays;
++
++    info_ptr->valid |= PNG_INFO_acTL;
++
++    return (1);
++}
++
++/* delay_num and delay_den can hold any 16-bit values including zero */
++png_uint_32 PNGAPI
++png_set_next_frame_fcTL(png_structp png_ptr, png_infop info_ptr,
++    png_uint_32 width, png_uint_32 height,
++    png_uint_32 x_offset, png_uint_32 y_offset,
++    png_uint_16 delay_num, png_uint_16 delay_den,
++    png_byte dispose_op, png_byte blend_op)
++{
++    png_debug1(1, "in %s storage function", "fcTL");
++
++    if (png_ptr == NULL || info_ptr == NULL)
++    {
++        png_warning(png_ptr,
++                    "Call to png_set_fcTL() with NULL png_ptr or info_ptr "
++                    "ignored");
++        return (0);
++    }
++
++    png_ensure_fcTL_is_valid(png_ptr, width, height, x_offset, y_offset,
++                             delay_num, delay_den, dispose_op, blend_op);
++
++    if (blend_op == PNG_BLEND_OP_OVER)
++    {
++        if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0 &&
++            png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) == 0)
++        {
++          png_warning(png_ptr, "PNG_BLEND_OP_OVER is meaningless "
++                               "and wasteful for opaque images, ignored");
++          blend_op = PNG_BLEND_OP_SOURCE;
++        }
++    }
++
++    info_ptr->next_frame_width = width;
++    info_ptr->next_frame_height = height;
++    info_ptr->next_frame_x_offset = x_offset;
++    info_ptr->next_frame_y_offset = y_offset;
++    info_ptr->next_frame_delay_num = delay_num;
++    info_ptr->next_frame_delay_den = delay_den;
++    info_ptr->next_frame_dispose_op = dispose_op;
++    info_ptr->next_frame_blend_op = blend_op;
++
++    info_ptr->valid |= PNG_INFO_fcTL;
++
++    return (1);
++}
++
++void /* PRIVATE */
++png_ensure_fcTL_is_valid(png_structp png_ptr,
++    png_uint_32 width, png_uint_32 height,
++    png_uint_32 x_offset, png_uint_32 y_offset,
++    png_uint_16 delay_num, png_uint_16 delay_den,
++    png_byte dispose_op, png_byte blend_op)
++{
++    if (width > PNG_UINT_31_MAX)
++        png_error(png_ptr, "invalid width in fcTL (> 2^31-1)");
++    if (height > PNG_UINT_31_MAX)
++        png_error(png_ptr, "invalid height in fcTL (> 2^31-1)");
++    if (x_offset > PNG_UINT_31_MAX)
++        png_error(png_ptr, "invalid x_offset in fcTL (> 2^31-1)");
++    if (y_offset > PNG_UINT_31_MAX)
++        png_error(png_ptr, "invalid y_offset in fcTL (> 2^31-1)");
++    if (width + x_offset > png_ptr->first_frame_width ||
++        height + y_offset > png_ptr->first_frame_height)
++        png_error(png_ptr, "dimensions of a frame are greater than "
++                           "the ones in IHDR");
++
++    if (dispose_op != PNG_DISPOSE_OP_NONE &&
++        dispose_op != PNG_DISPOSE_OP_BACKGROUND &&
++        dispose_op != PNG_DISPOSE_OP_PREVIOUS)
++        png_error(png_ptr, "invalid dispose_op in fcTL");
++
++    if (blend_op != PNG_BLEND_OP_SOURCE &&
++        blend_op != PNG_BLEND_OP_OVER)
++        png_error(png_ptr, "invalid blend_op in fcTL");
++
++    PNG_UNUSED(delay_num)
++    PNG_UNUSED(delay_den)
++}
++
++png_uint_32 PNGAPI
++png_set_first_frame_is_hidden(png_structp png_ptr, png_infop info_ptr,
++                              png_byte is_hidden)
++{
++    png_debug(1, "in png_first_frame_is_hidden()");
++
++    if (png_ptr == NULL)
++        return 0;
++
++    if (is_hidden != 0)
++        png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN;
++    else
++        png_ptr->apng_flags &= ~PNG_FIRST_FRAME_HIDDEN;
++
++    PNG_UNUSED(info_ptr)
++
++    return 1;
++}
++#endif /* APNG */
++
+ #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+ static png_byte
+ check_location(png_const_structrp png_ptr, int location)
+Index: pngrutil.c
+===================================================================
+--- pngrutil.c
++++ pngrutil.c
+@@ -855,6 +855,11 @@
+    filter_type = buf[11];
+    interlace_type = buf[12];
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++   png_ptr->first_frame_width = width;
++   png_ptr->first_frame_height = height;
++#endif
++
+    /* Set internal variables */
+    png_ptr->width = width;
+    png_ptr->height = height;
+@@ -2755,6 +2760,180 @@
+ }
+ #endif
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++void /* PRIVATE */
++png_handle_acTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
++{
++    png_byte data[8];
++    png_uint_32 num_frames;
++    png_uint_32 num_plays;
++    png_uint_32 didSet;
++
++    png_debug(1, "in png_handle_acTL");
++
++    if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
++    {
++        png_error(png_ptr, "Missing IHDR before acTL");
++    }
++    else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
++    {
++        png_warning(png_ptr, "Invalid acTL after IDAT skipped");
++        png_crc_finish(png_ptr, length);
++        return;
++    }
++    else if ((png_ptr->mode & PNG_HAVE_acTL) != 0)
++    {
++        png_warning(png_ptr, "Duplicate acTL skipped");
++        png_crc_finish(png_ptr, length);
++        return;
++    }
++    else if (length != 8)
++    {
++        png_warning(png_ptr, "acTL with invalid length skipped");
++        png_crc_finish(png_ptr, length);
++        return;
++    }
++
++    png_crc_read(png_ptr, data, 8);
++    png_crc_finish(png_ptr, 0);
++
++    num_frames = png_get_uint_31(png_ptr, data);
++    num_plays = png_get_uint_31(png_ptr, data + 4);
++
++    /* the set function will do error checking on num_frames */
++    didSet = png_set_acTL(png_ptr, info_ptr, num_frames, num_plays);
++    if (didSet != 0)
++        png_ptr->mode |= PNG_HAVE_acTL;
++}
++
++void /* PRIVATE */
++png_handle_fcTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
++{
++    png_byte data[22];
++    png_uint_32 width;
++    png_uint_32 height;
++    png_uint_32 x_offset;
++    png_uint_32 y_offset;
++    png_uint_16 delay_num;
++    png_uint_16 delay_den;
++    png_byte dispose_op;
++    png_byte blend_op;
++
++    png_debug(1, "in png_handle_fcTL");
++
++    png_ensure_sequence_number(png_ptr, length);
++
++    if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
++    {
++        png_error(png_ptr, "Missing IHDR before fcTL");
++    }
++    else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
++    {
++        /* for any frames other then the first this message may be misleading,
++        * but correct. PNG_HAVE_IDAT is unset before the frame head is read
++        * i can't think of a better message */
++        png_warning(png_ptr, "Invalid fcTL after IDAT skipped");
++        png_crc_finish(png_ptr, length-4);
++        return;
++    }
++    else if ((png_ptr->mode & PNG_HAVE_fcTL) != 0)
++    {
++        png_warning(png_ptr, "Duplicate fcTL within one frame skipped");
++        png_crc_finish(png_ptr, length-4);
++        return;
++    }
++    else if (length != 26)
++    {
++        png_warning(png_ptr, "fcTL with invalid length skipped");
++        png_crc_finish(png_ptr, length-4);
++        return;
++    }
++
++    png_crc_read(png_ptr, data, 22);
++    png_crc_finish(png_ptr, 0);
++
++    width = png_get_uint_31(png_ptr, data);
++    height = png_get_uint_31(png_ptr, data + 4);
++    x_offset = png_get_uint_31(png_ptr, data + 8);
++    y_offset = png_get_uint_31(png_ptr, data + 12);
++    delay_num = png_get_uint_16(data + 16);
++    delay_den = png_get_uint_16(data + 18);
++    dispose_op = data[20];
++    blend_op = data[21];
++
++    if (png_ptr->num_frames_read == 0 && (x_offset != 0 || y_offset != 0))
++    {
++        png_warning(png_ptr, "fcTL for the first frame must have zero offset");
++        return;
++    }
++
++    if (info_ptr != NULL)
++    {
++        if (png_ptr->num_frames_read == 0 &&
++            (width != info_ptr->width || height != info_ptr->height))
++        {
++            png_warning(png_ptr, "size in first frame's fcTL must match "
++                               "the size in IHDR");
++            return;
++        }
++
++        /* The set function will do more error checking */
++        png_set_next_frame_fcTL(png_ptr, info_ptr, width, height,
++                                x_offset, y_offset, delay_num, delay_den,
++                                dispose_op, blend_op);
++
++        png_read_reinit(png_ptr, info_ptr);
++
++        png_ptr->mode |= PNG_HAVE_fcTL;
++    }
++}
++
++void /* PRIVATE */
++png_have_info(png_structp png_ptr, png_infop info_ptr)
++{
++    if ((info_ptr->valid & PNG_INFO_acTL) != 0 &&
++        (info_ptr->valid & PNG_INFO_fcTL) == 0)
++    {
++        png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN;
++        info_ptr->num_frames++;
++    }
++}
++
++void /* PRIVATE */
++png_handle_fdAT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
++{
++    png_ensure_sequence_number(png_ptr, length);
++
++    /* This function is only called from png_read_end(), png_read_info(),
++    * and png_push_read_chunk() which means that:
++    * - the user doesn't want to read this frame
++    * - or this is an out-of-place fdAT
++    * in either case it is safe to ignore the chunk with a warning */
++    png_warning(png_ptr, "ignoring fdAT chunk");
++    png_crc_finish(png_ptr, length - 4);
++    PNG_UNUSED(info_ptr)
++}
++
++void /* PRIVATE */
++png_ensure_sequence_number(png_structp png_ptr, png_uint_32 length)
++{
++    png_byte data[4];
++    png_uint_32 sequence_number;
++
++    if (length < 4)
++        png_error(png_ptr, "invalid fcTL or fdAT chunk found");
++
++    png_crc_read(png_ptr, data, 4);
++    sequence_number = png_get_uint_31(png_ptr, data);
++
++    if (sequence_number != png_ptr->next_seq_num)
++        png_error(png_ptr, "fcTL or fdAT chunk with out-of-order sequence "
++                           "number found");
++
++    png_ptr->next_seq_num++;
++}
++#endif /* READ_APNG */
++
+ #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+ /* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
+ static int
+@@ -4014,6 +4193,38 @@
+          uInt avail_in;
+          png_bytep buffer;
+ 
++#ifdef PNG_READ_APNG_SUPPORTED
++         png_uint_32 bytes_to_skip = 0;
++
++         while (png_ptr->idat_size == 0 || bytes_to_skip != 0)
++         {
++            png_crc_finish(png_ptr, bytes_to_skip);
++            bytes_to_skip = 0;
++
++            png_ptr->idat_size = png_read_chunk_header(png_ptr);
++            if (png_ptr->num_frames_read == 0)
++            {
++               if (png_ptr->chunk_name != png_IDAT)
++                  png_error(png_ptr, "Not enough image data");
++            }
++            else
++            {
++               if (png_ptr->chunk_name == png_IEND)
++                  png_error(png_ptr, "Not enough image data");
++               if (png_ptr->chunk_name != png_fdAT)
++               {
++                  png_warning(png_ptr, "Skipped (ignored) a chunk "
++                                       "between APNG chunks");
++                  bytes_to_skip = png_ptr->idat_size;
++                  continue;
++               }
++
++               png_ensure_sequence_number(png_ptr, png_ptr->idat_size);
++
++               png_ptr->idat_size -= 4;
++            }
++         }
++#else
+          while (png_ptr->idat_size == 0)
+          {
+             png_crc_finish(png_ptr, 0);
+@@ -4025,6 +4236,7 @@
+             if (png_ptr->chunk_name != png_IDAT)
+                png_error(png_ptr, "Not enough image data");
+          }
++#endif /* READ_APNG */
+ 
+          avail_in = png_ptr->IDAT_read_size;
+ 
+@@ -4088,6 +4300,9 @@
+ 
+          png_ptr->mode |= PNG_AFTER_IDAT;
+          png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
++#ifdef PNG_READ_APNG_SUPPORTED
++         png_ptr->num_frames_read++;
++#endif
+ 
+          if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
+             png_chunk_benign_error(png_ptr, "Extra compressed data");
+@@ -4526,4 +4741,80 @@
+ 
+    png_ptr->flags |= PNG_FLAG_ROW_INIT;
+ }
++
++#ifdef PNG_READ_APNG_SUPPORTED
++/* This function is to be called after the main IDAT set has been read and
++ * before a new IDAT is read. It resets some parts of png_ptr
++ * to make them usable by the read functions again */
++void /* PRIVATE */
++png_read_reset(png_structp png_ptr)
++{
++    png_ptr->mode &= ~PNG_HAVE_IDAT;
++    png_ptr->mode &= ~PNG_AFTER_IDAT;
++    png_ptr->row_number = 0;
++    png_ptr->pass = 0;
++}
++
++void /* PRIVATE */
++png_read_reinit(png_structp png_ptr, png_infop info_ptr)
++{
++    png_ptr->width = info_ptr->next_frame_width;
++    png_ptr->height = info_ptr->next_frame_height;
++    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->width);
++    png_ptr->info_rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth,
++        png_ptr->width);
++    if (png_ptr->prev_row != NULL)
++        memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
++}
++
++#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
++/* same as png_read_reset() but for the progressive reader */
++void /* PRIVATE */
++png_progressive_read_reset(png_structp png_ptr)
++{
++#ifdef PNG_READ_INTERLACING_SUPPORTED
++    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
++
++    /* Start of interlace block */
++    static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
++
++    /* Offset to next interlace block */
++    static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
++
++    /* Start of interlace block in the y direction */
++    static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
++
++    /* Offset to next interlace block in the y direction */
++    static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
++
++    if (png_ptr->interlaced != 0)
++    {
++        if ((png_ptr->transformations & PNG_INTERLACE) == 0)
++            png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
++                                png_pass_ystart[0]) / png_pass_yinc[0];
++        else
++            png_ptr->num_rows = png_ptr->height;
++
++        png_ptr->iwidth = (png_ptr->width +
++                           png_pass_inc[png_ptr->pass] - 1 -
++                           png_pass_start[png_ptr->pass]) /
++                           png_pass_inc[png_ptr->pass];
++    }
++    else
++#endif /* READ_INTERLACING */
++    {
++        png_ptr->num_rows = png_ptr->height;
++        png_ptr->iwidth = png_ptr->width;
++    }
++    png_ptr->flags &= ~PNG_FLAG_ZSTREAM_ENDED;
++    if (inflateReset(&(png_ptr->zstream)) != Z_OK)
++        png_error(png_ptr, "inflateReset failed");
++    png_ptr->zstream.avail_in = 0;
++    png_ptr->zstream.next_in = 0;
++    png_ptr->zstream.next_out = png_ptr->row_buf;
++    png_ptr->zstream.avail_out = (uInt)PNG_ROWBYTES(png_ptr->pixel_depth,
++        png_ptr->iwidth) + 1;
++}
++#endif /* PROGRESSIVE_READ */
++#endif /* READ_APNG */
+ #endif /* READ */
+Index: pngwutil.c
+===================================================================
+--- pngwutil.c
++++ pngwutil.c
+@@ -901,6 +901,11 @@
+    /* Write the chunk */
+    png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
+ 
++#ifdef PNG_WRITE_APNG_SUPPORTED
++   png_ptr->first_frame_width = width;
++   png_ptr->first_frame_height = height;
++#endif
++
+    if ((png_ptr->do_filter) == PNG_NO_FILTERS)
+    {
+       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
+@@ -1082,7 +1087,15 @@
+                optimize_cmf(data, png_image_size(png_ptr));
+ #endif
+ 
++#ifdef PNG_WRITE_APNG_SUPPORTED
++         if (png_ptr->num_frames_written == 0)
++#endif
+          png_write_complete_chunk(png_ptr, png_IDAT, data, size);
++#ifdef PNG_WRITE_APNG_SUPPORTED
++         else
++            png_write_fdAT(png_ptr, data, size);
++#endif /* WRITE_APNG */
++
+          png_ptr->mode |= PNG_HAVE_IDAT;
+ 
+          png_ptr->zstream.next_out = data;
+@@ -1128,7 +1141,15 @@
+             optimize_cmf(data, png_image_size(png_ptr));
+ #endif
+ 
++#ifdef PNG_WRITE_APNG_SUPPORTED
++         if (png_ptr->num_frames_written == 0)
++#endif
+          png_write_complete_chunk(png_ptr, png_IDAT, data, size);
++#ifdef PNG_WRITE_APNG_SUPPORTED
++         else
++            png_write_fdAT(png_ptr, data, size);
++#endif /* WRITE_APNG */
++
+          png_ptr->zstream.avail_out = 0;
+          png_ptr->zstream.next_out = NULL;
+          png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
+@@ -1941,6 +1962,82 @@
+ }
+ #endif
+ 
++#ifdef PNG_WRITE_APNG_SUPPORTED
++void /* PRIVATE */
++png_write_acTL(png_structp png_ptr,
++    png_uint_32 num_frames, png_uint_32 num_plays)
++{
++    png_byte buf[8];
++
++    png_debug(1, "in png_write_acTL");
++
++    png_ptr->num_frames_to_write = num_frames;
++
++    if ((png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN) != 0)
++        num_frames--;
++
++    png_save_uint_32(buf, num_frames);
++    png_save_uint_32(buf + 4, num_plays);
++
++    png_write_complete_chunk(png_ptr, png_acTL, buf, (png_size_t)8);
++}
++
++void /* PRIVATE */
++png_write_fcTL(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
++    png_uint_32 x_offset, png_uint_32 y_offset,
++    png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
++    png_byte blend_op)
++{
++    png_byte buf[26];
++
++    png_debug(1, "in png_write_fcTL");
++
++    if (png_ptr->num_frames_written == 0 && (x_offset != 0 || y_offset != 0))
++        png_error(png_ptr, "x and/or y offset for the first frame aren't 0");
++    if (png_ptr->num_frames_written == 0 &&
++        (width != png_ptr->first_frame_width ||
++         height != png_ptr->first_frame_height))
++        png_error(png_ptr, "width and/or height in the first frame's fcTL "
++                           "don't match the ones in IHDR");
++
++    /* more error checking */
++    png_ensure_fcTL_is_valid(png_ptr, width, height, x_offset, y_offset,
++                             delay_num, delay_den, dispose_op, blend_op);
++
++    png_save_uint_32(buf, png_ptr->next_seq_num);
++    png_save_uint_32(buf + 4, width);
++    png_save_uint_32(buf + 8, height);
++    png_save_uint_32(buf + 12, x_offset);
++    png_save_uint_32(buf + 16, y_offset);
++    png_save_uint_16(buf + 20, delay_num);
++    png_save_uint_16(buf + 22, delay_den);
++    buf[24] = dispose_op;
++    buf[25] = blend_op;
++
++    png_write_complete_chunk(png_ptr, png_fcTL, buf, (png_size_t)26);
++
++    png_ptr->next_seq_num++;
++}
++
++void /* PRIVATE */
++png_write_fdAT(png_structp png_ptr,
++    png_const_bytep data, png_size_t length)
++{
++    png_byte buf[4];
++
++    png_write_chunk_header(png_ptr, png_fdAT, (png_uint_32)(4 + length));
++
++    png_save_uint_32(buf, png_ptr->next_seq_num);
++    png_write_chunk_data(png_ptr, buf, 4);
++
++    png_write_chunk_data(png_ptr, data, length);
++
++    png_write_chunk_end(png_ptr);
++
++    png_ptr->next_seq_num++;
++}
++#endif /* WRITE_APNG */
++
+ /* Initializes the row writing capability of libpng */
+ void /* PRIVATE */
+ png_write_start_row(png_structrp png_ptr)
+@@ -2706,4 +2803,39 @@
+    }
+ #endif /* WRITE_FLUSH */
+ }
++
++#ifdef PNG_WRITE_APNG_SUPPORTED
++void /* PRIVATE */
++png_write_reset(png_structp png_ptr)
++{
++    png_ptr->row_number = 0;
++    png_ptr->pass = 0;
++    png_ptr->mode &= ~PNG_HAVE_IDAT;
++}
++
++void /* PRIVATE */
++png_write_reinit(png_structp png_ptr, png_infop info_ptr,
++                 png_uint_32 width, png_uint_32 height)
++{
++    if (png_ptr->num_frames_written == 0 &&
++        (width != png_ptr->first_frame_width ||
++         height != png_ptr->first_frame_height))
++        png_error(png_ptr, "width and/or height in the first frame's fcTL "
++                           "don't match the ones in IHDR");
++    if (width > png_ptr->first_frame_width ||
++        height > png_ptr->first_frame_height)
++        png_error(png_ptr, "width and/or height for a frame greater than "
++                           "the ones in IHDR");
++
++    png_set_IHDR(png_ptr, info_ptr, width, height,
++                 info_ptr->bit_depth, info_ptr->color_type,
++                 info_ptr->interlace_type, info_ptr->compression_type,
++                 info_ptr->filter_type);
++
++    png_ptr->width = width;
++    png_ptr->height = height;
++    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
++    png_ptr->usr_width = png_ptr->width;
++}
++#endif /* WRITE_APNG */
+ #endif /* WRITE */
+Index: scripts/symbols.def
+===================================================================
+--- scripts/symbols.def
++++ scripts/symbols.def
+@@ -249,3 +249,23 @@
+  png_set_check_for_invalid_index @242
+  png_get_palette_max @243
+  png_set_option @244
++ png_get_acTL @245
++ png_set_acTL @246
++ png_get_num_frames @247
++ png_get_num_plays @248
++ png_get_next_frame_fcTL @249
++ png_set_next_frame_fcTL @250
++ png_get_next_frame_width @251
++ png_get_next_frame_height @252
++ png_get_next_frame_x_offset @253
++ png_get_next_frame_y_offset @254
++ png_get_next_frame_delay_num @255
++ png_get_next_frame_delay_den @256
++ png_get_next_frame_dispose_op @257
++ png_get_next_frame_blend_op @258
++ png_get_first_frame_is_hidden @259
++ png_set_first_frame_is_hidden @260
++ png_read_frame_head @261
++ png_set_progressive_frame_fn @262
++ png_write_frame_head @263
++ png_write_frame_tail @264

    

ports/opt (3.1): [notify] libpng: updated to 1.6.20. Reissued fix for CVE-2015-8126

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