pngimage.c:
Initialize sig_bits on a NOTREACHED path to avoid warnings about using
uninitialized variables.
pngstest.c:
Enlarge buffers and fix signedness to avoid legitimate warnings about
potential buffer overflows.
pngunknown.c:
pngvalid.c:
Use NULL instead of 0 for pointers and apply other style fixes.
makepng.c:
tarith.c:
Apply various style fixes.
Also remove the "last changed" version info from source comments.
The version control system maintains this information automatically.
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, size_t became a required type. It should be used
consistently. To maintain backwards compatibility, png_size_t
is still maintained in deprecated form.
