This is a regression of commit a8242dd9473a8da4d851623cf0b514a8ee4bee34
"PNGv3 colourspace precedence rules conformance".
Previously, `png_write_iCCP` used the length from the first four bytes
of the profile set by `png_set_iCCP`, rather than the actual data length
recorded by `png_set_iCCP`.
If the profile data were less than 4 bytes long, it would have caused
a read-beyond-end-of-malloc error. This bug was in the libpng code even
before the changes introduced in the above-mentioned commit, but it was
inaccessible. It became accessible when we removed the pre-PNGv3 colour
space checks in `png_set_iCCP`.
Reported-by: Bob Friesenhahn <bobjfriesenhahn@gmail.com>
Reviewed-by: Cosmin Truta <ctruta@gmail.com>
Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
This adds APIs to get/set the two remaining new PNG-v3 colour space
chunks. The mDCV API matches that of cHRM. Both chunks support
floating point APIs (all values in the two chunks are real numbers).
Both chunks have a new encoded type, a four-digit-precision fixed-point
number, which cannot be represented in the existing `png_fixed_point`
type, so a `png_uint_32` is used.
Test examples for cICP, cLLI and mDCV are now in pngtest.png, and a
necessary change to the pngunknown.c test program has been made to
accomodate the additions.
Reviewed-by: Cosmin Truta <ctruta@gmail.com>
Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
Apply the following corrections and improvements:
* Add a validity check in `png_set_cICP`.
* Fix the ordering check in `png_handle_cICP`.
* Add a multiplicity check in `png_handle_cICP`.
* Optimize the implementation of `png_write_cICP`.
* Remove an unnecessary preprocessor guard from pngtest.c.
* Update the dependency declaration in pnglibconf.dfa.
* Fix the indentation where necessary.
This is a cherry-pick of commit c2a02691df1ecf51b7c97142752a7034350cb1f6
from branch 'libpng18'.
This chunk was added in the third edition of the PNG specification and
contains Coding Independent Code Points (related to color space
description). It is fairly simple as it only contains four fields of one
byte each: Colour Primaries, Transfer Function, Matrix Coefficients,
Video Full Range Flag.
The test file originally comes from the related WPT test case:
https://github.com/web-platform-tests/wpt/blob/master/png/support/cicp-display-p3.png
Note that I reencoded the file to make it match libpng's default
encoding parameters (it only modifies the IDAT chunk).
This is a cherry-pick of commit 65925ad4b2cbed934d5d850fe764dc46c4becbcb
from branch 'libpng18'.
Reviewed-by: John Bowler <jbowler@acm.org>
Reviewed-by: Chris Blume <ProgramMax@gmail.com>
Reviewed-by: Cosmin Truta <ctruta@gmail.com>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
Move the definitions of interlace arrays to the top of their respective
translation units, to reduce their repeated copying in various places of
the codebase.
TODO:
As they still exist in three copies, in pngpread.c, in pngrutil.c, and
in pngwutil.c, they should all be further moved to a common place.
This is a cherry-pick of commit 620a2b73b22df66ed099e1faacac2d92f48252b7
from branch 'libpng18'.
The leading blank lines are apparently an artefact of an older source
control system. They are not required and they look like accidents,
because starting a source file with a blank line is not a regular habit
of software developers nowadays.
This is a cherry-pick of commit 37cc20add8fb5b83bb5299a26cd3b41e0f776017
from branch 'libpng18'.
Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
As per the const correctness rules, top-level const-ness of data
in automatic scopes does not propagate outside of these scopes
(unlike const-ness at lower levels, such as pointers to const data).
Previously, const was used liberally, but inconsistently across the
libpng codebase. Using const wherever applicable is not incorrect.
However, _consistent_ use of const is difficult to maintain in such
conditions.
In conclusion, we shall continue to use const only where doing so is
strictly necessary:
1. If a function guarantees that it will not modify an argument
passed by pointer, the corresponding function parameter should be
a pointer-to-const (const T *).
2. Static data should not be modified, therefore it should be const.
Reference:
Google C++ Style Guide
https://google.github.io/styleguide/cppguide.html#Use_of_const
In v1.6.0, compiler support for const became a requirement.
It should be used consistently. To maintain backwards compatibility,
PNG_CONST is still maintained in deprecated form.
In v1.6.0, size_t became a required type. It should be used
consistently. To maintain backwards compatibility, png_size_t
is still maintained in deprecated form.
in pngwrite.c, and made various other fixes to png_write_eXIf().
Eliminated png_ptr->num_exif member from pngstruct.h and added num_exif
to arguments for png_get_eXIf() and png_set_eXIf().
