Intermediate changes

commit_hash:f15cd769f87762d4807f0d4ae628b5dfb830bef5

10 files changed, 1647 insertions, 375 deletions

diff --git a/contrib/libs/libpng/.yandex_meta/__init__.py b/contrib/libs/libpng/.yandex_meta/__init__.py
index 47a1b39885..0e0556b959 100644
--- a/contrib/libs/libpng/.yandex_meta/__init__.py
+++ b/contrib/libs/libpng/.yandex_meta/__init__.py
@@ -7,6 +7,9 @@ from devtools.yamaker.project import GNUMakeNixProject
 
 def post_install(self):
     with self.yamakes["."] as libpng:
+        # libpng generates export script, but we are going to link statically
+        os.remove(f"{self.dstdir}/libpng.vers")
+
         # libpng generates config.h but does not use any of its defines.
         os.remove(f"{self.dstdir}/config.h")
         libpng.CFLAGS.remove("-DHAVE_CONFIG_H")
diff --git a/contrib/libs/libpng/.yandex_meta/devtools.copyrights.report b/contrib/libs/libpng/.yandex_meta/devtools.copyrights.report
index 0383d68e36..943f1a9a9d 100644
--- a/contrib/libs/libpng/.yandex_meta/devtools.copyrights.report
+++ b/contrib/libs/libpng/.yandex_meta/devtools.copyrights.report
@@ -151,30 +151,6 @@ BELONGS ya.make
         powerpc/filter_vsx_intrinsics.c [3:5]
         powerpc/powerpc_init.c [4:6]
 
-KEEP     COPYRIGHT_SERVICE_LABEL 45a151e61f5d9f2924b225327a93f376
-BELONGS ya.make
-    License text:
-        Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2023 Max Stepin,
-        and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
-        surrounding them in the modified libpng source files.
-    Scancode info:
-        Original SPDX id: COPYRIGHT_SERVICE_LABEL
-        Score           : 100.00
-        Match type      : COPYRIGHT
-    Files with this license:
-        LICENSE [6:8]
-        png.h [29:31]
-
-KEEP     COPYRIGHT_SERVICE_LABEL 4644b73a371ed2c05c5ac0b3899bd563
-BELONGS ya.make
-    Note: matched license text is too long. Read it in the source files.
-    Scancode info:
-        Original SPDX id: COPYRIGHT_SERVICE_LABEL
-        Score           : 100.00
-        Match type      : COPYRIGHT
-    Files with this license:
-        png.c [819:827]
-
 KEEP     COPYRIGHT_SERVICE_LABEL 4ab05cc7c9d27c8a3fbcc6350cf56230
 BELONGS ya.make
     License text:
@@ -212,7 +188,7 @@ BELONGS ya.make
     Files with this license:
         LICENSE [13:17]
         png.c [4:7]
-        png.c [819:827]
+        png.c [819:825]
         png.h [6:9]
         png.h [36:40]
         pngget.c [4:7]
@@ -238,7 +214,7 @@ BELONGS ya.make
 KEEP     COPYRIGHT_SERVICE_LABEL 5fc45730df09b1e4ad9f9d6a2d097232
 BELONGS ya.make
     License text:
-        Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2023 Max Stepin,
+        Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
         and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
         surrounding them in the modified libpng source files.
     Scancode info:
@@ -260,7 +236,7 @@ BELONGS ya.make
         LICENSE [13:17]
         LICENSE [87:91]
         png.c [4:7]
-        png.c [819:827]
+        png.c [819:825]
         png.h [6:9]
         png.h [36:40]
         png.h [110:114]
@@ -293,7 +269,7 @@ BELONGS ya.make
         Match type      : COPYRIGHT
     Files with this license:
         png.c [4:7]
-        png.c [819:827]
+        png.c [819:825]
         png.h [6:9]
         pngget.c [4:7]
         pnglibconf.h [5:6]
@@ -307,6 +283,20 @@ BELONGS ya.make
         pngwrite.c [4:7]
         pngwutil.c [4:7]
 
+KEEP     COPYRIGHT_SERVICE_LABEL 9524c4c0aaaea5b1ba2ffbc048713d9e
+BELONGS ya.make
+    License text:
+        Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
+        and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
+        surrounding them in the modified libpng source files.
+    Scancode info:
+        Original SPDX id: COPYRIGHT_SERVICE_LABEL
+        Score           : 100.00
+        Match type      : COPYRIGHT
+    Files with this license:
+        LICENSE [6:8]
+        png.h [29:31]
+
 KEEP     COPYRIGHT_SERVICE_LABEL a590c93284482861546eac4b62974abf
 BELONGS ya.make
     License text:
@@ -331,7 +321,7 @@ BELONGS ya.make
         LICENSE [13:17]
         LICENSE [103:104]
         png.c [4:7]
-        png.c [819:827]
+        png.c [819:825]
         png.h [6:9]
         png.h [36:40]
         png.h [126:127]
@@ -381,16 +371,6 @@ BELONGS ya.make
     Files with this license:
         pngset.c [4:7]
 
-KEEP     COPYRIGHT_SERVICE_LABEL ba5441522ec42a475b4efc4c19d96da2
-BELONGS ya.make
-    Note: matched license text is too long. Read it in the source files.
-    Scancode info:
-        Original SPDX id: COPYRIGHT_SERVICE_LABEL
-        Score           : 100.00
-        Match type      : COPYRIGHT
-    Files with this license:
-        png.c [819:827]
-
 KEEP     COPYRIGHT_SERVICE_LABEL c486f222c872d0101647b08aaad5c74c
 BELONGS ya.make
     Note: matched license text is too long. Read it in the source files.
diff --git a/contrib/libs/libpng/.yandex_meta/devtools.licenses.report b/contrib/libs/libpng/.yandex_meta/devtools.licenses.report
index ffa339d7d3..90b3c5d0b6 100644
--- a/contrib/libs/libpng/.yandex_meta/devtools.licenses.report
+++ b/contrib/libs/libpng/.yandex_meta/devtools.licenses.report
@@ -218,18 +218,6 @@ BELONGS ya.make
     Files with this license:
         CHANGES [2692:2692]
 
-KEEP     libpng-2.0           70f7ac29617c1f96c3c72a8706953d6f
-BELONGS ya.make
-FILE_INCLUDE LICENSE found in files: LICENSE at line 1
-    Note: matched license text is too long. Read it in the source files.
-    Scancode info:
-        Original SPDX id: libpng-2.0
-        Score           : 95.76
-        Match type      : TEXT
-        Links           : http://www.libpng.org/pub/png/src/libpng-LICENSE.txt, https://spdx.org/licenses/libpng-2.0
-    Files with this license:
-        LICENSE [1:42]
-
 SKIP     LicenseRef-scancode-free-unknown 7223032bb9df755f6ce7298a13e95cee
 BELONGS ya.make
     # we have no contrib in libpng directory
@@ -422,6 +410,18 @@ BELONGS ya.make
     Files with this license:
         png.h [73:94]
 
+KEEP     libpng-2.0           d964429a132bf678731f5df030520bfb
+BELONGS ya.make
+FILE_INCLUDE LICENSE found in files: LICENSE at line 1
+    Note: matched license text is too long. Read it in the source files.
+    Scancode info:
+        Original SPDX id: libpng-2.0
+        Score           : 95.76
+        Match type      : TEXT
+        Links           : http://www.libpng.org/pub/png/src/libpng-LICENSE.txt, https://spdx.org/licenses/libpng-2.0
+    Files with this license:
+        LICENSE [1:42]
+
 KEEP     Libpng               e9bb4f8fbab91484ba62ccb1611b70bb
 BELONGS ya.make
     License text:
diff --git a/contrib/libs/libpng/.yandex_meta/licenses.list.txt b/contrib/libs/libpng/.yandex_meta/licenses.list.txt
index 40d116cc42..80ff5f75ee 100644
--- a/contrib/libs/libpng/.yandex_meta/licenses.list.txt
+++ b/contrib/libs/libpng/.yandex_meta/licenses.list.txt
@@ -1,16 +1,4 @@
 ====================COPYRIGHT====================
-      "Copyright (c) 2018-2023 Cosmin Truta" PNG_STRING_NEWLINE \
-      "Copyright (c) 1998-2002,2004,2006-2018 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 \
-      "Portions Copyright (c) 2006-2007 Andrew Smith" PNG_STRING_NEWLINE \
-      "Portions Copyright (c) 2008-2023 Max Stepin" PNG_STRING_NEWLINE ;
-#endif
-
-
-====================COPYRIGHT====================
  * Copyright (c) 1995-2023 The PNG Reference Library Authors.
  * Copyright (c) 2018-2023 Cosmin Truta.
  * Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson.
@@ -118,7 +106,7 @@
 
 
 ====================COPYRIGHT====================
-Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2023 Max Stepin,
+Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
 and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
 surrounding them in the modified libpng source files.
 
@@ -611,7 +599,7 @@ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
 
 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) 2008-2023 Max Stepin,
+Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
 and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
 surrounding them in the modified libpng source files.
 
@@ -1065,7 +1053,7 @@ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
 
 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) 2008-2023 Max Stepin,
+Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
 and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
 surrounding them in the modified libpng source files.
 
diff --git a/contrib/libs/libpng/.yandex_meta/override.nix b/contrib/libs/libpng/.yandex_meta/override.nix
index 61a324e710..23f741e884 100644
--- a/contrib/libs/libpng/.yandex_meta/override.nix
+++ b/contrib/libs/libpng/.yandex_meta/override.nix
@@ -8,17 +8,12 @@ pkgs: attrs: with pkgs; rec {
     hash = "sha256-Rad7Y5Z9PUCipBTQcB7LEP8fIVTG3JsnMeknUkZ/rRg=";
   };
 
-  # nixpkgs use a patch from libpng-apng project for getting A(nimated) PNG support.
-  # While libpng-apng project patch is functionally equivalent to apng one,
-  # the latter seems to provide somewhat better code.
-  #
-  # The sha256 checksum of the patch has to be updated upon libpng version update.
-  patch_src = fetchurl {
-    url = "mirror://sourceforge/apng/libpng-${version}-apng.patch.gz";
-    hash = "sha256-esYjxN5hBg8Uue6AOAowulcB22U7rnQz2TjLM0+w+0w=";
-  };
+  # nixpkgs applies apng patch from sourceforge.net, which changes for every libpng version.
+  # We apply a sligthly modified version of this patch via patches/apng.patch
+  patches = [];
+  postPatch = "";
 
-  postPatch = ''
-    gunzip < ${patch_src} | patch -Np0
-  '';
+  configureFlags = [
+    "--build=x86_64-pc-linux-gnu"
+  ];
 }
diff --git a/contrib/libs/libpng/LICENSE b/contrib/libs/libpng/LICENSE
index 8e4d6a4436..10033488bd 100644
--- a/contrib/libs/libpng/LICENSE
+++ b/contrib/libs/libpng/LICENSE
@@ -3,7 +3,7 @@ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
 
 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) 2008-2023 Max Stepin,
+Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
 and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
 surrounding them in the modified libpng source files.
 
diff --git a/contrib/libs/libpng/libpng.vers b/contrib/libs/libpng/libpng.vers
deleted file mode 100644
index 5762bcee46..0000000000
--- a/contrib/libs/libpng/libpng.vers
+++ /dev/null
@@ -1,268 +0,0 @@
-PNG16_0 {global:
- png_access_version_number;
- png_set_sig_bytes;
- png_sig_cmp;
- png_create_read_struct;
- png_create_write_struct;
- png_get_compression_buffer_size;
- png_set_compression_buffer_size;
- png_set_longjmp_fn;
- png_longjmp;
- png_reset_zstream;
- png_create_read_struct_2;
- png_create_write_struct_2;
- png_write_sig;
- png_write_chunk;
- png_write_chunk_start;
- png_write_chunk_data;
- png_write_chunk_end;
- png_create_info_struct;
- png_info_init_3;
- png_write_info_before_PLTE;
- png_write_info;
- png_read_info;
- png_convert_to_rfc1123;
- png_convert_to_rfc1123_buffer;
- png_convert_from_struct_tm;
- png_convert_from_time_t;
- png_set_expand;
- png_set_expand_gray_1_2_4_to_8;
- png_set_palette_to_rgb;
- png_set_tRNS_to_alpha;
- png_set_expand_16;
- png_set_bgr;
- png_set_gray_to_rgb;
- png_set_rgb_to_gray;
- png_set_rgb_to_gray_fixed;
- png_get_rgb_to_gray_status;
- png_build_grayscale_palette;
- png_set_alpha_mode;
- png_set_alpha_mode_fixed;
- png_set_strip_alpha;
- png_set_swap_alpha;
- png_set_invert_alpha;
- png_set_filler;
- png_set_add_alpha;
- png_set_swap;
- png_set_packing;
- png_set_packswap;
- png_set_shift;
- png_set_interlace_handling;
- png_set_invert_mono;
- png_set_background;
- png_set_background_fixed;
- png_set_scale_16;
- png_set_strip_16;
- png_set_quantize;
- png_set_gamma;
- png_set_gamma_fixed;
- png_set_flush;
- png_write_flush;
- png_start_read_image;
- png_read_update_info;
- png_read_rows;
- png_read_row;
- png_read_image;
- png_write_row;
- png_write_rows;
- png_write_image;
- png_write_end;
- png_read_end;
- png_destroy_info_struct;
- png_destroy_read_struct;
- png_destroy_write_struct;
- png_set_crc_action;
- png_set_filter;
- png_set_filter_heuristics;
- png_set_filter_heuristics_fixed;
- png_set_compression_level;
- png_set_compression_mem_level;
- png_set_compression_strategy;
- png_set_compression_window_bits;
- png_set_compression_method;
- png_set_text_compression_level;
- png_set_text_compression_mem_level;
- png_set_text_compression_strategy;
- png_set_text_compression_window_bits;
- png_set_text_compression_method;
- png_init_io;
- png_set_error_fn;
- png_get_error_ptr;
- png_set_write_fn;
- png_set_read_fn;
- png_get_io_ptr;
- png_set_read_status_fn;
- png_set_write_status_fn;
- png_set_mem_fn;
- png_get_mem_ptr;
- png_set_read_user_transform_fn;
- png_set_write_user_transform_fn;
- png_set_user_transform_info;
- png_get_user_transform_ptr;
- png_get_current_row_number;
- png_get_current_pass_number;
- png_set_read_user_chunk_fn;
- png_get_user_chunk_ptr;
- png_set_progressive_read_fn;
- png_get_progressive_ptr;
- png_process_data;
- png_process_data_pause;
- png_process_data_skip;
- png_progressive_combine_row;
- png_malloc;
- png_calloc;
- png_malloc_warn;
- png_free;
- png_free_data;
- png_data_freer;
- png_malloc_default;
- png_free_default;
- png_error;
- png_chunk_error;
- png_warning;
- png_chunk_warning;
- png_benign_error;
- png_chunk_benign_error;
- png_set_benign_errors;
- png_get_valid;
- png_get_rowbytes;
- png_get_rows;
- png_set_rows;
- png_get_channels;
- png_get_image_width;
- png_get_image_height;
- png_get_bit_depth;
- png_get_color_type;
- png_get_filter_type;
- png_get_interlace_type;
- png_get_compression_type;
- png_get_pixels_per_meter;
- png_get_x_pixels_per_meter;
- png_get_y_pixels_per_meter;
- png_get_pixel_aspect_ratio;
- png_get_pixel_aspect_ratio_fixed;
- png_get_x_offset_pixels;
- png_get_y_offset_pixels;
- png_get_x_offset_microns;
- png_get_y_offset_microns;
- png_get_signature;
- png_get_bKGD;
- png_set_bKGD;
- png_get_cHRM;
- png_get_cHRM_XYZ;
- png_get_cHRM_fixed;
- png_get_cHRM_XYZ_fixed;
- png_set_cHRM;
- png_set_cHRM_XYZ;
- png_set_cHRM_fixed;
- png_set_cHRM_XYZ_fixed;
- png_get_eXIf;
- png_set_eXIf;
- png_get_eXIf_1;
- png_set_eXIf_1;
- png_get_gAMA;
- png_get_gAMA_fixed;
- png_set_gAMA;
- png_set_gAMA_fixed;
- png_get_hIST;
- png_set_hIST;
- png_get_IHDR;
- png_set_IHDR;
- png_get_oFFs;
- png_set_oFFs;
- png_get_pCAL;
- png_set_pCAL;
- png_get_pHYs;
- png_set_pHYs;
- png_get_PLTE;
- png_set_PLTE;
- png_get_sBIT;
- png_set_sBIT;
- png_get_sRGB;
- png_set_sRGB;
- png_set_sRGB_gAMA_and_cHRM;
- png_get_iCCP;
- png_set_iCCP;
- png_get_sPLT;
- png_set_sPLT;
- png_get_text;
- png_set_text;
- png_get_tIME;
- png_set_tIME;
- png_get_tRNS;
- png_set_tRNS;
- png_get_sCAL;
- png_get_sCAL_fixed;
- png_get_sCAL_s;
- png_set_sCAL;
- png_set_sCAL_fixed;
- png_set_sCAL_s;
- png_set_keep_unknown_chunks;
- png_handle_as_unknown;
- png_set_unknown_chunks;
- png_set_unknown_chunk_location;
- png_get_unknown_chunks;
- png_set_invalid;
- png_read_png;
- png_write_png;
- png_get_copyright;
- png_get_header_ver;
- png_get_header_version;
- png_get_libpng_ver;
- png_permit_mng_features;
- png_set_user_limits;
- png_get_user_width_max;
- png_get_user_height_max;
- png_set_chunk_cache_max;
- png_get_chunk_cache_max;
- png_set_chunk_malloc_max;
- png_get_chunk_malloc_max;
- png_get_pixels_per_inch;
- png_get_x_pixels_per_inch;
- png_get_y_pixels_per_inch;
- png_get_x_offset_inches;
- png_get_x_offset_inches_fixed;
- png_get_y_offset_inches;
- png_get_y_offset_inches_fixed;
- png_get_pHYs_dpi;
- png_get_io_state;
- png_get_io_chunk_type;
- png_get_uint_32;
- png_get_uint_16;
- png_get_int_32;
- png_get_uint_31;
- png_save_uint_32;
- png_save_int_32;
- png_save_uint_16;
- png_set_check_for_invalid_index;
- png_get_palette_max;
- png_image_begin_read_from_file;
- png_image_begin_read_from_stdio;
- png_image_begin_read_from_memory;
- png_image_finish_read;
- png_image_free;
- png_image_write_to_file;
- png_image_write_to_stdio;
- png_image_write_to_memory;
- png_set_option;
- png_get_acTL;
- png_set_acTL;
- png_get_num_frames;
- png_get_num_plays;
- png_get_next_frame_fcTL;
- png_set_next_frame_fcTL;
- png_get_next_frame_width;
- png_get_next_frame_height;
- png_get_next_frame_x_offset;
- png_get_next_frame_y_offset;
- png_get_next_frame_delay_num;
- png_get_next_frame_delay_den;
- png_get_next_frame_dispose_op;
- png_get_next_frame_blend_op;
- png_get_first_frame_is_hidden;
- png_set_first_frame_is_hidden;
- png_read_frame_head;
- png_set_progressive_frame_fn;
- png_write_frame_head;
- png_write_frame_tail;
-local: *; };
diff --git a/contrib/libs/libpng/patches/apng.patch b/contrib/libs/libpng/patches/apng.patch
new file mode 100644
index 0000000000..0f7fcdc07b
--- /dev/null
+++ b/contrib/libs/libpng/patches/apng.patch
@@ -0,0 +1,1577 @@
+Index: LICENSE
+===================================================================
+--- a/LICENSE
++++ b/LICENSE
+@@ -1,6 +1,12 @@
+ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
+ =========================================
+ 
++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) 2008-2024 Max Stepin,
++and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
++surrounding them in the modified libpng source files.
++
+ PNG Reference Library License version 2
+ ---------------------------------------
+ 
+Index: pngread.c
+===================================================================
+--- a/pngread.c
++++ b/pngread.c
+@@ -161,6 +161,9 @@
+ 
+       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;
+       }
+@@ -255,6 +258,17 @@
+          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);
+@@ -262,6 +276,72 @@
+ }
+ #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
+===================================================================
+--- a/pngget.c
++++ b/pngget.c
+@@ -1264,4 +1264,166 @@
+ #  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.h
+===================================================================
+--- a/png.h
++++ b/png.h
+@@ -24,6 +24,12 @@
+  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
+  * =========================================
+  *
++ * 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) 2008-2024 Max Stepin,
++ * and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
++ * surrounding them in the modified libpng source files.
++ *
+  * PNG Reference Library License version 2
+  * ---------------------------------------
+  *
+@@ -329,6 +336,10 @@
+ #   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"
+@@ -424,6 +435,17 @@
+  * 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.
+  */
+@@ -745,6 +767,10 @@
+ #define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
+ #define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
+ #define PNG_INFO_eXIf 0x10000U /* GR-P, 1.6.31 */
++#ifdef PNG_APNG_SUPPORTED
++#define PNG_INFO_acTL 0x20000U
++#define PNG_INFO_fcTL 0x40000U
++#endif
+ 
+ /* This is used for the transformation routines, as some of them
+  * change these values for the row.  It also should enable using
+@@ -782,6 +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
+@@ -3230,6 +3260,75 @@
+  *  END OF HARDWARE AND SOFTWARE OPTIONS
+  ******************************************************************************/
+ 
++#ifdef PNG_APNG_SUPPORTED
++PNG_EXPORT(250, 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(251, 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(252, png_uint_32, png_get_num_frames, (png_structp png_ptr,
++   png_infop info_ptr));
++
++PNG_EXPORT(253, png_uint_32, png_get_num_plays, (png_structp png_ptr,
++   png_infop info_ptr));
++
++PNG_EXPORT(254, 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(255, 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(256, png_uint_32, png_get_next_frame_width,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(257, png_uint_32, png_get_next_frame_height,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(258, png_uint_32, png_get_next_frame_x_offset,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(259, png_uint_32, png_get_next_frame_y_offset,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(260, png_uint_16, png_get_next_frame_delay_num,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(261, png_uint_16, png_get_next_frame_delay_den,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(262, png_byte, png_get_next_frame_dispose_op,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(263, png_byte, png_get_next_frame_blend_op,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(264, png_byte, png_get_first_frame_is_hidden,
++   (png_structp png_ptr, png_infop info_ptr));
++PNG_EXPORT(265, 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(266, void, png_read_frame_head, (png_structp png_ptr,
++   png_infop info_ptr));
++#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
++PNG_EXPORT(267, 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(268, 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(269, 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.
+  */
+@@ -3238,7 +3337,11 @@
+  * one to use is one more than this.)
+  */
+ #ifdef PNG_EXPORT_LAST_ORDINAL
++#ifdef PNG_APNG_SUPPORTED
++  PNG_EXPORT_LAST_ORDINAL(269);
++#else
+   PNG_EXPORT_LAST_ORDINAL(249);
++#endif /* APNG */
+ #endif
+ 
+ #ifdef __cplusplus
+Index: pngpriv.h
+===================================================================
+--- a/pngpriv.h
++++ b/pngpriv.h
+@@ -621,6 +621,10 @@
+ #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
+ #define PNG_WROTE_eXIf            0x4000U
+ #define PNG_IS_READ_STRUCT        0x8000U /* Else is a write struct */
++#ifdef PNG_APNG_SUPPORTED
++#define PNG_HAVE_acTL            0x10000U
++#define PNG_HAVE_fcTL            0x20000U
++#endif
+ 
+ /* Flags for the transformations the PNG library does on the image data */
+ #define PNG_BGR                 0x0001U
+@@ -857,6 +861,16 @@
+ #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       0x0001U
++#define PNG_APNG_APP                 0x0002U
++#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.
+  */
+@@ -1642,6 +1656,49 @@
+ 
+ #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, 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
+===================================================================
+--- a/pnginfo.h
++++ b/pnginfo.h
+@@ -263,5 +263,18 @@
+    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
+===================================================================
+--- a/pngstruct.h
++++ b/pngstruct.h
+@@ -399,6 +399,27 @@
+    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
+===================================================================
+--- a/pngwrite.c
++++ b/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 &&
+@@ -368,7 +372,12 @@
+    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");
+ #endif
+@@ -2415,4 +2424,42 @@
+ }
+ #endif /* SIMPLIFIED_WRITE_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
+===================================================================
+--- a/pngpread.c
++++ b/pngpread.c
+@@ -195,6 +195,89 @@
+ 
+    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)
+@@ -261,6 +344,9 @@
+ 
+    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);
+@@ -415,6 +501,20 @@
+    }
+ #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
+@@ -547,7 +647,11 @@
+       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);
+@@ -555,17 +659,60 @@
+       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)
+@@ -639,6 +786,16 @@
+    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.
+@@ -1093,6 +1250,18 @@
+    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
+===================================================================
+--- a/pngset.c
++++ b/pngset.c
+@@ -280,6 +280,11 @@
+    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
+@@ -1151,6 +1156,146 @@
+ }
+ #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 == 0 || width > PNG_UINT_31_MAX)
++        png_error(png_ptr, "invalid width in fcTL (0 or > 2^31-1)");
++    if (height == 0 || height > PNG_UINT_31_MAX)
++        png_error(png_ptr, "invalid height in fcTL (0 or > 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
+===================================================================
+--- a/pngrutil.c
++++ b/pngrutil.c
+@@ -863,6 +863,11 @@
+    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;
+@@ -2857,6 +2862,180 @@
+ }
+ #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
+@@ -3162,7 +3341,11 @@
+    if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+       limit = PNG_USER_CHUNK_MALLOC_MAX;
+ # endif
++#ifdef PNG_READ_APNG_SUPPORTED
++   if (png_ptr->chunk_name == png_IDAT || png_ptr->chunk_name == png_fdAT)
++#else
+    if (png_ptr->chunk_name == png_IDAT)
++#endif
+    {
+       png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
+       size_t row_factor =
+@@ -4166,6 +4349,38 @@
+          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);
+@@ -4177,6 +4392,7 @@
+             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;
+ 
+@@ -4240,6 +4456,9 @@
+ 
+          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");
+@@ -4677,4 +4896,80 @@
+ 
+    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 const png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
++
++    /* Offset to next interlace block */
++    static const png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
++
++    /* Start of interlace block in the y direction */
++    static const png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
++
++    /* Offset to next interlace block in the y direction */
++    static 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
+===================================================================
+--- a/pngwutil.c
++++ b/pngwutil.c
+@@ -821,6 +821,11 @@
+    /* Write the chunk */
+    png_write_complete_chunk(png_ptr, png_IHDR, buf, 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 ||
+@@ -1003,7 +1008,17 @@
+ #endif
+ 
+          if (size > 0)
++#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;
+@@ -1050,7 +1065,17 @@
+ #endif
+ 
+          if (size > 0)
++#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;
+@@ -1885,6 +1910,82 @@
+ }
+ #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, 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, 26);
++
++    png_ptr->next_seq_num++;
++}
++
++void /* PRIVATE */
++png_write_fdAT(png_structp png_ptr,
++    png_const_bytep data, 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)
+@@ -2778,4 +2879,39 @@
+    }
+ #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 */
+ 
diff --git a/contrib/libs/libpng/png.c b/contrib/libs/libpng/png.c
index 56800d8aec..d6471b06cc 100644
--- a/contrib/libs/libpng/png.c
+++ b/contrib/libs/libpng/png.c
@@ -815,15 +815,13 @@ png_get_copyright(png_const_structrp png_ptr)
    return PNG_STRING_COPYRIGHT
 #else
    return PNG_STRING_NEWLINE \
-      "libpng version 1.6.40+apng" PNG_STRING_NEWLINE \
+      "libpng version 1.6.40" PNG_STRING_NEWLINE \
       "Copyright (c) 2018-2023 Cosmin Truta" PNG_STRING_NEWLINE \
       "Copyright (c) 1998-2002,2004,2006-2018 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 \
-      "Portions Copyright (c) 2006-2007 Andrew Smith" PNG_STRING_NEWLINE \
-      "Portions Copyright (c) 2008-2023 Max Stepin" PNG_STRING_NEWLINE ;
+      PNG_STRING_NEWLINE;
 #endif
 }
 
diff --git a/contrib/libs/libpng/png.h b/contrib/libs/libpng/png.h
index 0b26e307ec..7a9848eb12 100644
--- a/contrib/libs/libpng/png.h
+++ b/contrib/libs/libpng/png.h
@@ -26,7 +26,7 @@
  *
  * 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) 2008-2023 Max Stepin,
+ * Copyright (c) 2006-2007 Andrew Smith, Copyright (c) 2008-2024 Max Stepin,
  * and are delimited by "#ifdef PNG_APNG_SUPPORTED / #endif" directives
  * surrounding them in the modified libpng source files.
  *
@@ -284,9 +284,8 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.40+apng"
-#define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.40+apng - June 21, 2023\n"
+#define PNG_LIBPNG_VER_STRING "1.6.40"
+#define PNG_HEADER_VERSION_STRING " libpng version 1.6.40 - June 21, 2023\n"
 
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -3258,70 +3257,70 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
  ******************************************************************************/
 
 #ifdef PNG_APNG_SUPPORTED
-PNG_EXPORT(248, png_uint_32, png_get_acTL, (png_structp png_ptr,
+PNG_EXPORT(250, 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(249, png_uint_32, png_set_acTL, (png_structp png_ptr,
+PNG_EXPORT(251, 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(250, png_uint_32, png_get_num_frames, (png_structp png_ptr,
+PNG_EXPORT(252, png_uint_32, png_get_num_frames, (png_structp png_ptr,
    png_infop info_ptr));
 
-PNG_EXPORT(251, png_uint_32, png_get_num_plays, (png_structp png_ptr,
+PNG_EXPORT(253, png_uint_32, png_get_num_plays, (png_structp png_ptr,
    png_infop info_ptr));
 
-PNG_EXPORT(252, png_uint_32, png_get_next_frame_fcTL,
+PNG_EXPORT(254, 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(253, png_uint_32, png_set_next_frame_fcTL,
+PNG_EXPORT(255, 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(254, png_uint_32, png_get_next_frame_width,
+PNG_EXPORT(256, png_uint_32, png_get_next_frame_width,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(255, png_uint_32, png_get_next_frame_height,
+PNG_EXPORT(257, png_uint_32, png_get_next_frame_height,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(256, png_uint_32, png_get_next_frame_x_offset,
+PNG_EXPORT(258, png_uint_32, png_get_next_frame_x_offset,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(257, png_uint_32, png_get_next_frame_y_offset,
+PNG_EXPORT(259, png_uint_32, png_get_next_frame_y_offset,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(258, png_uint_16, png_get_next_frame_delay_num,
+PNG_EXPORT(260, png_uint_16, png_get_next_frame_delay_num,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(259, png_uint_16, png_get_next_frame_delay_den,
+PNG_EXPORT(261, png_uint_16, png_get_next_frame_delay_den,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(260, png_byte, png_get_next_frame_dispose_op,
+PNG_EXPORT(262, png_byte, png_get_next_frame_dispose_op,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(261, png_byte, png_get_next_frame_blend_op,
+PNG_EXPORT(263, png_byte, png_get_next_frame_blend_op,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(262, png_byte, png_get_first_frame_is_hidden,
+PNG_EXPORT(264, png_byte, png_get_first_frame_is_hidden,
    (png_structp png_ptr, png_infop info_ptr));
-PNG_EXPORT(263, png_uint_32, png_set_first_frame_is_hidden,
+PNG_EXPORT(265, 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(264, void, png_read_frame_head, (png_structp png_ptr,
+PNG_EXPORT(266, void, png_read_frame_head, (png_structp png_ptr,
    png_infop info_ptr));
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
-PNG_EXPORT(265, void, png_set_progressive_frame_fn, (png_structp png_ptr,
+PNG_EXPORT(267, 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(266, void, png_write_frame_head, (png_structp png_ptr,
+PNG_EXPORT(268, 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(267, void, png_write_frame_tail, (png_structp png_ptr,
+PNG_EXPORT(269, void, png_write_frame_tail, (png_structp png_ptr,
    png_infop info_ptr));
 #endif /* WRITE_APNG */
 #endif /* APNG */