Previously we deleted `PNG_LITERAL_SHARP`.
(See commit 465f654c68b0d8e6ef037028e30f6d003b8b6b6c.)
The remaining `PNG_LITERAL_LEFT_SQUARE_BRACKET` and
`PNG_LITERAL_RIGHT_SQUARE_BRACKET` were next in line to clean up.
The purpose of this feature was to optionally prepend standardized
numbers to error and warning messages. The ERROR_NUMBERS feature was
first drafted in libpng-1.2.0 and further developed in libpng-1.4.0;
and yet, it was always disabled by default, and never completed.
In the light of a recent report concerning the security hazards arising
from enabling this code in custom libpng builds, we think it's best to
simply remove all the code written to support this feature.
Reported-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
Add checks inside the private png*.h header files, in order to reduce
unintentional occurences of application backdoors.
Such backdoors might occur, for example, when we make changes to the
internal data structures that might somehow "leak" from the libpng
code into the user code. The applications that use the libpng API must
pretend not to know that these headers exist at all.
Co-authored-by: John Bowler <jbowler@acm.org>
Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
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 37cc20add8
from branch 'libpng18'.
Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
Fixed point APIs are now supported throughout (no missing APIs).
Internal fixed point arithmetic support exists for all internal floating
point operations.
sCAL validates the floating point strings it is passed.
Safe, albeit rudimentary, Watcom support is provided by PNG_API_RULE==2
Two new APIs exist to get the number of passes without turning on the
PNG_INTERLACE transform and to get the number of rows in the current
pass.
A new test program, pngvalid.c, validates the gamma code.
Errors in the 16 bit gamma correction (overflows) have been corrected.
cHRM chunk testing is done consistently (previously the floating point
API bypassed it, because the test really didn't work on FP, now the test
is performed on the actual values to be stored in the PNG file so it
works in the FP case too.)
Most floating point APIs now simply call the fixed point APIs after
converting the values to the fixed point form used in the PNG file.
The standard headers no longer include zlib.h, which is currently only
required for pngstruct.h and can therefore be internal.
(Patches by John Bowler)
In all prior versions of libpng most configuration options
controlled by compiler #defines had to be repeated by the
application code that used libpng. This patch changes this
so that compilation options that can only be changed at build
time are frozen in the build. Options that are compiler
dependent (and those that are system dependent) are evaluated
each time - pngconf.h holds these. Options that can be changed
per-file in the application are in png.h. Frozen options are
in the new installed header file pnglconf.h
