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[libpng17] Changed user chunk callback API to respect global and per chunk
defaults. Previously a return of 0 from a user chunk callback would result in the chunk being saved (if this was safe, even if the chunk was unsafe-to-copy); this change respects the defaults set by the application, so unknown chunks can be discarded by default and known-safe ones preserved.
This commit is contained in:
John Bowler
Glenn Randers-Pehrson
parent
6152dbd424
commit
ec89aefb44
11
ANNOUNCE
11
ANNOUNCE
@ -1,5 +1,5 @@
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Libpng 1.7.0beta05 - March 2, 2013
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Libpng 1.7.0beta05 - March 3, 2013
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This is not intended to be a public release. It will be replaced
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within a few weeks by a public version or by another test version.
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@ -193,10 +193,13 @@ Version 1.7.0beta04 [February 27, 2013]
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Revised scripts/dfn.awk to work with the buggy MSYS awk that has trouble
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with CRLF line endings.
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Version 1.7.0beta05 [March 2, 2013]
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Version 1.7.0beta05 [March 3, 2013]
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Avoid a possible memory leak in contrib/gregbook/readpng.c
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Fixed bug introduced in libpng-1.6.0beta28 that causes libpng to handle chunks
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even when they have been tagged PNG_HANDLE_CHUNK_NEVER.
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Changed user chunk callback API to respect global and per chunk defaults.
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Previously a return of 0 from a user chunk callback would result in the
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chunk being saved (if this was safe, even if the chunk was unsafe-to-copy);
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this change respects the defaults set by the application, so unknown chunks
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can be discarded by default and known-safe ones preserved.
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Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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(subscription required; visit
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9
CHANGES
9
CHANGES
@ -4480,10 +4480,13 @@ Version 1.7.0beta04 [February 27, 2013]
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Revised scripts/dfn.awk to work with the buggy MSYS awk that has trouble
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with CRLF line endings.
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Version 1.7.0beta05 [March 2, 2013]
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Version 1.7.0beta05 [March 3, 2013]
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Avoid a possible memory leak in contrib/gregbook/readpng.c
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Fixed bug introduced in libpng-1.6.0beta28 that causes libpng to handle chunks
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even when they have been tagged PNG_HANDLE_CHUNK_NEVER.
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Changed user chunk callback API to respect global and per chunk defaults.
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Previously a return of 0 from a user chunk callback would result in the
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chunk being saved (if this was safe, even if the chunk was unsafe-to-copy);
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this change respects the defaults set by the application, so unknown chunks
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can be discarded by default and known-safe ones preserved.
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Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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(subscription required; visit
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@ -1,6 +1,6 @@
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libpng-manual.txt - A description on how to use and modify libpng
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libpng version 1.7.0beta05 - February 27, 2013
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libpng version 1.7.0beta05 - March 3, 2013
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Updated and distributed by Glenn Randers-Pehrson
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<glennrp at users.sourceforge.net>
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Copyright (c) 1998-2013 Glenn Randers-Pehrson
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@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng
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Based on:
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libpng versions 0.97, January 1998, through 1.7.0beta05 - February 27, 2013
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libpng versions 0.97, January 1998, through 1.7.0beta05 - March 3, 2013
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Updated and distributed by Glenn Randers-Pehrson
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Copyright (c) 1998-2013 Glenn Randers-Pehrson
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@ -527,10 +527,15 @@ you can retrieve with
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png_get_user_chunk_ptr(png_ptr);
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If you call the png_set_read_user_chunk_fn() function, then all unknown
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chunks will be saved when read, in case your callback function will need
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one or more of them. This behavior can be changed with the
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png_set_keep_unknown_chunks() function, described below.
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If you call the png_set_read_user_chunk_fn() function, then all unknown chunks
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will be passed to your callback when read. You can cause known chunks to be
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passed in as well by using png_set_keep_unknown_chunks (see below) - this will
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prevent the normal libpng handling of those known chunks.
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If your callback returns 0 the default unknown handling will be used (see
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below). This is new behavior in libpng 1.7, prior to 1.7 it was not possible to
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discard a chunk; PNG_HANDLE_CHUNK_IF_SAFE was forced. Libpng 1.6.0 issues a
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warning when this was done.
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At this point, you can set up a callback function that will be
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called after each row has been read, which you can use to control
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@ -5187,7 +5192,7 @@ Other rules can be inferred by inspecting the libpng source.
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XVII. Y2K Compliance in libpng
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February 27, 2013
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March 3, 2013
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Since the PNG Development group is an ad-hoc body, we can't make
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an official declaration.
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27
libpng.3
27
libpng.3
@ -1,4 +1,4 @@
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.TH LIBPNG 3 "February 27, 2013"
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.TH LIBPNG 3 "March 3, 2013"
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.SH NAME
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libpng \- Portable Network Graphics (PNG) Reference Library 1.7.0beta05
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.SH SYNOPSIS
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@ -494,7 +494,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
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.SH LIBPNG.TXT
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libpng-manual.txt - A description on how to use and modify libpng
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libpng version 1.7.0beta05 - February 27, 2013
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libpng version 1.7.0beta05 - March 3, 2013
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Updated and distributed by Glenn Randers-Pehrson
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<glennrp at users.sourceforge.net>
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Copyright (c) 1998-2013 Glenn Randers-Pehrson
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@ -505,7 +505,7 @@ libpng-manual.txt - A description on how to use and modify libpng
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Based on:
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libpng versions 0.97, January 1998, through 1.7.0beta05 - February 27, 2013
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libpng versions 0.97, January 1998, through 1.7.0beta05 - March 3, 2013
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Updated and distributed by Glenn Randers-Pehrson
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Copyright (c) 1998-2013 Glenn Randers-Pehrson
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@ -1021,10 +1021,15 @@ you can retrieve with
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png_get_user_chunk_ptr(png_ptr);
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If you call the png_set_read_user_chunk_fn() function, then all unknown
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chunks will be saved when read, in case your callback function will need
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one or more of them. This behavior can be changed with the
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png_set_keep_unknown_chunks() function, described below.
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If you call the png_set_read_user_chunk_fn() function, then all unknown chunks
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will be passed to your callback when read. You can cause known chunks to be
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passed in as well by using png_set_keep_unknown_chunks (see below) - this will
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prevent the normal libpng handling of those known chunks.
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If your callback returns 0 the default unknown handling will be used (see
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below). This is new behavior in libpng 1.7, prior to 1.7 it was not possible to
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discard a chunk; PNG_HANDLE_CHUNK_IF_SAFE was forced. Libpng 1.6.0 issues a
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warning when this was done.
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At this point, you can set up a callback function that will be
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called after each row has been read, which you can use to control
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@ -5682,7 +5687,7 @@ Other rules can be inferred by inspecting the libpng source.
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.SH XVII. Y2K Compliance in libpng
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February 27, 2013
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March 3, 2013
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Since the PNG Development group is an ad-hoc body, we can't make
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an official declaration.
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@ -5952,7 +5957,7 @@ possible without all of you.
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Thanks to Frank J. T. Wojcik for helping with the documentation.
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Libpng version 1.7.0beta05 - February 27, 2013:
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Libpng version 1.7.0beta05 - March 3, 2013:
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Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
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Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
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@ -5975,7 +5980,7 @@ this sentence.
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This code is released under the libpng license.
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libpng versions 1.2.6, August 15, 2004, through 1.7.0beta05, February 27, 2013, are
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libpng versions 1.2.6, August 15, 2004, through 1.7.0beta05, March 3, 2013, are
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Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
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distributed according to the same disclaimer and license as libpng-1.2.5
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with the following individual added to the list of Contributing Authors
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@ -6074,7 +6079,7 @@ certification mark of the Open Source Initiative.
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Glenn Randers-Pehrson
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glennrp at users.sourceforge.net
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February 27, 2013
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March 3, 2013
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.\" end of man page
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31
png.h
31
png.h
@ -1,7 +1,7 @@
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/* png.h - header file for PNG reference library
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*
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* libpng version 1.7.0beta05 - March 2, 2013
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* libpng version 1.7.0beta05 - March 3, 2013
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* Copyright (c) 1998-2013 Glenn Randers-Pehrson
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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@ -11,7 +11,7 @@
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* Authors and maintainers:
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* libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
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* libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
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* libpng versions 0.97, January 1998, through 1.7.0beta05 - March 2, 2013: Glenn
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* libpng versions 0.97, January 1998, through 1.7.0beta05 - March 3, 2013: Glenn
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* See also "Contributing Authors", below.
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*
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* Note about libpng version numbers:
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@ -201,7 +201,7 @@
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*
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* This code is released under the libpng license.
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*
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* libpng versions 1.2.6, August 15, 2004, through 1.7.0beta05, March 2, 2013, are
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* libpng versions 1.2.6, August 15, 2004, through 1.7.0beta05, March 3, 2013, are
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* Copyright (c) 2004, 2006-2013 Glenn Randers-Pehrson, and are
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* distributed according to the same disclaimer and license as libpng-1.2.5
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* with the following individual added to the list of Contributing Authors:
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@ -313,7 +313,7 @@
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* Y2K compliance in libpng:
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* =========================
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*
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* March 2, 2013
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* March 3, 2013
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*
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* Since the PNG Development group is an ad-hoc body, we can't make
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* an official declaration.
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@ -381,7 +381,7 @@
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/* Version information for png.h - this should match the version in png.c */
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#define PNG_LIBPNG_VER_STRING "1.7.0beta05"
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#define PNG_HEADER_VERSION_STRING \
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" libpng version 1.7.0beta05 - March 2, 2013\n"
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" libpng version 1.7.0beta05 - March 3, 2013\n"
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#define PNG_LIBPNG_VER_SONUM 17
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#define PNG_LIBPNG_VER_DLLNUM 17
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@ -1838,7 +1838,7 @@ PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
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#endif
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#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
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/* This callback is called only for *unknown* chunks, if
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/* This callback is called only for *unknown* chunks. If
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* PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
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* chunks to be treated as unknown, however in this case the callback must do
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* any processing required by the chunk (e.g. by calling the appropriate
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@ -1850,11 +1850,13 @@ PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
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* The integer return from the callback function is interpreted thus:
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*
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* negative: An error occured, png_chunk_error will be called.
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* zero: The chunk was not handled, the chunk will be discarded unless
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* png_set_keep_unknown_chunks has been used to set a 'keep' behavior
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* for this particular chunk, in which case that will be used. A
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* critical chunk will cause an error at this point unless it is to be
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* saved.
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* zero: The chunk was not handled, the default unknown handling is used
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* (even if this was a chunk that would otherwise be known.)
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* NOTE: prior to libpng 1.7 handling values of
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* PNG_HANDLE_CHUNK_AS_DEFAULT and PNG_HANDLE_CHUNK_NEVER were
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* converted to PNG_HANDLE_CHUNK_IF_SAFE (libpng 1.6.0 warns if this
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* happens) so it was not possible to discard unknown chunk data if a
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* user callback was installed.
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* positive: The chunk was handled, libpng will ignore/discard it.
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*/
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PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
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@ -2369,8 +2371,13 @@ PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
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* NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
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* ignored and the default was used, the per-chunk setting only had an effect on
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* write. If you wish to have chunk-specific handling on read in code that must
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* work on earlier versions you must use a user chunk callback to specify the
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* work on earlier versions you must use a user chunk callback to implement the
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* desired handling (keep or discard.)
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*
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* NOTE: prior to 1.7.0 when a user callback returned '0', indicating that the
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* chunk had not been handled, libpng would preserve it regardless of the
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* default or per-chunk settings. For compatibility with earlier versions
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* simply return '1' (handled) from the callback to discard the chunk.
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*
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* The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below. The
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* parameter is interpreted as follows:
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34
pngrutil.c
34
pngrutil.c
@ -2801,37 +2801,19 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
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if (ret < 0)
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png_chunk_error(png_ptr, "error in user chunk");
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else if (ret == 0)
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{
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/* If the keep value is 'default' or 'never' override it, but
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* still error out on critical chunks unless the keep value is
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* 'always' While this is weird it is the behavior in 1.4.12.
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* A possible improvement would be to obey the value set for the
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* chunk, but this would be an API change that would probably
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* damage some applications.
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*
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* The png_app_warning below catches the case that matters, where
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* the application has not set specific save or ignore for this
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* chunk or global save or ignore.
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*/
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if (keep < PNG_HANDLE_CHUNK_NEVER)
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{
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# ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
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if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
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png_app_warning(png_ptr,
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"forcing save of an unhandled chunk;"
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" please call png_set_keep_unknown_chunks");
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# endif
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keep = PNG_HANDLE_CHUNK_IF_SAFE;
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}
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}
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else /* chunk was handled */
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else if (ret > 0) /* chunk was handled */
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{
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handled = 1;
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/* Critical chunks can be safely discarded at this point. */
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keep = PNG_HANDLE_CHUNK_NEVER;
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}
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/* else: use the default handling.
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* NOTE: this is an API change in 1.7.0, prior to 1.7.0 libpng would
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* force keep to PNG_HANDLE_CHUNK_IF_SAFE at this point, and 1.6.0
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* would issue a warning if this caused a default of discarding the
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* chunk to be changed.
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*/
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}
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else
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