freestanding_check: hosted-RNG check misses rand/srand in headers, macro aliases and function pointers

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
c, shell
Domain
build-system, tooling

Research direction

Start in tools/freestanding_check.sh, where the hosted-RNG stage greps src/.c and extensions/.c for rand( and srand(), and read tools/freestanding_allowlist.txt to see why stage 1 passes. The proposed fix replaces the textual check with an nm -u scan of the hosted objects built by the gate's rows, so the design needs deciding first. Done when the four planted cases (static inline in a header, macro alias, function pointer, untracked file) make make freestanding-check exit nonzero, and src/freestanding/ stays green.

Written by the indexing model from the issue text.

Description

area:gates kind:gate-defect

The hosted-RNG half of tools/freestanding_check.sh (#1818; fail-closed fix in the PR for #2308) searches only tracked src/*.c and extensions/*.c, outside src/freestanding/, for the literal spelling rand( / srand(. The following reach libc rand/srand from hosted runtime code without being seen:

  1. A call inside a static inline function, or a macro body, in a header (src/*.h, extensions/*.h).
  2. A call through a macro alias, e.g. #define RNG rand and then RNG(), or through a function pointer (int (*r)(void) = rand;).
  3. Untracked files. git grep searches the index, so a new file that has not been git added is skipped in a local run. CI only sees committed files, so this matters only locally.

Stage 1 cannot catch any of these, because rand/srand are in tools/freestanding_allowlist.txt.

Possible root fix: check the symbol level instead of the spelling. Every hosted object built by the gate's rows would have no undefined reference to rand/srand (nm -u over the objects that are not freestanding), so headers, macros and pointers are all covered. The textual grep could stay as a fast first pass.

Found while reviewing the hq#58 fix (https://github.com/InauguralSystems/hq/issues/58).

Done when
  • A planted static inline int r(void) { return rand(); } in a header that a runtime .c file includes and calls makes make freestanding-check exit nonzero.
  • A planted #define RNG rand plus RNG() in src/*.c makes it exit nonzero.
  • A planted int (*p)(void) = rand; in src/*.c makes it exit nonzero.
  • src/freestanding/ keeps its own rand implementation, and that case is still green.

Generated by Claude Code

Dominant language
C
Stars
3
Forks
7
Avg merge
6h 32m
Merged PRs (30d)
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