Zireael — libc Policy (Locked)

Zireael’s deterministic core avoids libc features that introduce locale, environment, time, randomness, or process variability.

Enforced by CI

scripts/guardrails.sh enforces a forbidden call list under:

• src/core/
• src/unicode/
• src/util/

Forbidden calls (core/unicode/util)

The following libc families are forbidden in the deterministic core:

• printf family: printf, fprintf, sprintf, snprintf, vprintf, vfprintf, vsprintf, vsnprintf, dprintf, vdprintf
• puts/getchar family: puts, putchar, getchar, fputs, fputc, fgetc
• scanf family: scanf, fscanf, sscanf, vscanf, vfscanf, vsscanf
• Locale / environment: setlocale, getenv, putenv
• Time / clock: time, clock, difftime, mktime, localtime, gmtime, asctime, ctime, strftime
• Randomness: rand, srand
• Process / shell: system, popen, pclose

Allowed patterns

• memcpy/memset/memcmp and small, obvious libc primitives are allowed where they do not violate determinism.
• Platform backends (src/platform/posix, src/platform/win32) may use OS APIs and libc as needed, but must keep the core boundary clean.