Fix problems detected by CodeQL static analysis

Fix problems detected by CodeQL static analysis

3 types of issues were found:
* Incorrect format specifiers
* Not providing required format specifies
* Using alloca in a loop

There are multiple instances of alloca in loops, but to fix them would
require significant refactoring. This commit includes 1 move of alloca inside
a for loop to the outside, but this is because the logic was redoing work
in a for loop that could have been done once at the start of the function.