Addresses a few issues that were noticed when compiling with non-default
warnings enabled. The trimmed-down warnings in the order they are fixed
below are:
* declaration of 'size' shadows a parameter
* '%s' directive output may be truncated writing up to 5 bytes into a
region of size between 1 and 64
* pointer targets in initialization of 'char *' from 'unsigned char *'
differ in signedness