Semi-experienced C user here, I believe the anonymous block is perfectly adequate here. No idea why they are wrapping it in a single instance do loop, unless they’re unaware of block scoping or I’m unaware of some UB here.

do {} while(0) is a common idiom for macros in C, because it consumes the trailing semicolon, which a bare {} block doesn't do.

    if(x) MACRO();
    else something();

expands to

    if(x) { ... }; // Error!
    else something();