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[libpng17 Updated the documentation about CRC and ADLER32 handling.

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Glenn Randers-Pehrson 2016-09-26 11:16:08 -05:00
parent 1757736115
commit 2127ecd0fa
4 changed files with 14 additions and 4 deletions
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1
ANNOUNCE
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@ -1409,6 +1409,7 @@ Version 1.7.0beta84 [September 26, 2016]
Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
Version 1.7.0beta85 [September 26, 2016]
Updated the documentation about CRC and ADLER32 handling.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

1
CHANGES
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@ -5709,6 +5709,7 @@ Version 1.7.0beta84 [September 26, 2016]
Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
Version 1.7.0beta85 [September 26, 2016]
Updated the documentation about CRC and ADLER32 handling.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

8
libpng-manual.txt
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@ -471,8 +471,9 @@ the default, use
The values for png_set_crc_action() say how libpng is to handle CRC errors in
ancillary and critical chunks, and whether to use the data contained
therein. Note that it is impossible to "discard" data in a critical
chunk.
therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
is handled while reading the IDAT chunk. Note that it is impossible to
"discard" data in a critical chunk.
Choices for (int) crit_action are
PNG_CRC_DEFAULT 0 error/quit
@ -489,6 +490,9 @@ Choices for (int) ancil_action are
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
checksums are not only ignored, but they are not evaluated.
Setting up callback code
You can set up a callback function to handle any unknown chunks in the

8
libpng.3
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@ -971,8 +971,9 @@ the default, use
The values for png_set_crc_action() say how libpng is to handle CRC errors in
ancillary and critical chunks, and whether to use the data contained
therein. Note that it is impossible to "discard" data in a critical
chunk.
therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
is handled while reading the IDAT chunk. Note that it is impossible to
"discard" data in a critical chunk.
Choices for (int) crit_action are
PNG_CRC_DEFAULT 0 error/quit
@ -989,6 +990,9 @@ Choices for (int) ancil_action are
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
checksums are not only ignored, but they are not evaluated.
.SS Setting up callback code
You can set up a callback function to handle any unknown chunks in the