D017 - The C runtime is a first-class section, and it is where positive checks live

decided · 2026-08-19

035-libc checks libSceLibcInternal for behaviour: calloc must return zeroed memory, realloc must preserve contents, qsort must actually sort, snprintf must report the length it would have written.

This was the largest omission in the first pass. A probe was written freestanding and then the guest was assumed to be freestanding too, which is wrong - a title imports more of the C library than of any single vendor subsystem. It went unnoticed because every other library needed research, and this one needed only remembering.

It is also the answer to D007. Everywhere else leans on negative checks because struct layouts are unknown; here the whole interface is ISO C, so every signature is certain and the checks can ask whether the function does the right thing rather than merely whether it rejects nonsense. An implementation that fails everything passes every negative check in the suite and not one of these.

Two details worth keeping:

• memcpy, memset and memmove are excluded. This program defines its own, because the compiler emits calls to them regardless of -ffreestanding. A local definition beats a weak import, so a check would have measured our implementation and passed - a test that passes by testing itself.
• qsort makes the platform call back into guest code. Nothing else in the program exercises that direction, and an emulator has to get it right.

The host build gains real signal from this too: it links a genuine C library, so these are the first checks that can pass there for a non-trivial reason.