Fix Overlapping src and dest for strcpy in Client Code #639
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Recently, when playing with OpenArena assets, I noticed some visual glitches (lightning gun beam and a part of a machine gun are missing). Luckily, another user pinpointed the exact issue, which is a glibc commit:
https://forum.manjaro.org/t/openarena-lightning-gun-beam-not-visible-with-glibc-2-37-x86-64-bug/135312/8
https://sourceware.org/git?p=glibc.git;a=commit;h=642933158e7cf072d873231b1a9bb03291f2b989
An issue on another project concerning the glibc commit (https://sourceware.org/bugzilla/show_bug.cgi?id=30112) shows that this is due to invalidating str*cpy invariant that src and destination cannot overlap.
Indeed, upon inspection with AddressSanitizer, you can see src and dest arguments of strncpy overlap in cl_cgame.c and cl_ui.c
This PR adds a safe reimplementation of Strncpy, that is safe against overlapping src and dest and fixes the visual glitches on OpenArena.