Hardening & modernization
Replaces old calls to strcat/strcpy/sprintf/malloc/realloc with modern functions that check for string boundaries or integer overflows.
Also quiets a gcc -Wimplicit-fallthrough warning.
Replaces old calls to strcat/strcpy/sprintf/malloc/realloc with modern functions that check for string boundaries or integer overflows.
Also quiets a gcc -Wimplicit-fallthrough warning.