The Cleanup Ladder

Implement a multi-resource pipeline with the cleanup-goto pattern. The boilerplate declares a tiny fake-resource stack: ``c /* resources must be acquired in order and released in REVERSE order; the tracker records acquire/release for verification */ void tr_reset(void); int tr_acquire(int id); /* 0 ok; -1 if id already held */ void tr_release(int id); /* no-op if not held */ int tr_holds(int id); /* your function: acquire 1, 2, 3; fail if any acquire fails; "work" = return 0; release in reverse order — ALWAYS, on every path */ int pipeline(int fail_at); /* 0 = no failure; 1..3 = fail that acquire */ /* the tracker's record of events, as a string like "a1a2a3r3r2r1" */ const char *tr_log(void); `` pipeline(fail_at) must leave NO resources held — whatever happens.

Difficulty: intermediate