Fix infinite loop in nextDate() for impossible day-of-month/month combinations - #38
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mrvonkalus wants to merge 1 commit into
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Fix infinite loop in nextDate() for impossible day-of-month/month combinations#38mrvonkalus wants to merge 1 commit into
mrvonkalus wants to merge 1 commit into
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…binations For an unbounded (*) year field, CronosYearsField.nextYear() pushed fromYear unconditionally, with no maxValidYear ceiling (the range/step branch already applies it). When no allowed month can contain any allowed day-of-month (e.g. "0 0 31 4 *" = April 31), _nextMonth() returns null for every year, so _nextYear()'s only exit is never taken and the year counter increments without bound: nextDate() pins a CPU core and never returns. Bound the any-branch by maxValidYear, matching the range/step branch, so the search terminates (scan to year 275759, then null). Adds regression tests: impossible combinations return null quickly; valid controls (May 31, leap-year Feb 29) still resolve. Co-authored-by: Cursor <cursoragent@cursor.com>
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Fixes #37.
What
nextDate()never returns for expressions where no allowed month can contain any allowed day-of-month (0 0 31 4 *= April 31,0 0 30 2 *= February 30, etc.) when the year field is unbounded — the default for every standard 5-field expression. Full analysis and reproduction in #37.Root cause
CronosYearsField.nextYear()pushedfromYearunconditionally for*(any) year fields, with nomaxValidYearceiling — the range/step branch right below already applies it. On an impossible date,_nextYear()'s only exit (nextYear() === null) is therefore never taken, and the year counter increments without bound (observed past year 42,000,000 under instrumentation).Fix
One line: bound the
anybranch by the samemaxValidYearceiling the range/step branch already uses.The search now terminates after the bounded scan (to year 275759) and returns
null.Tests
Five regression tests in
tests/api.test.ts("Impossible day-of-month/month combinations"):0 0 31 4 *,0 0 30 2 *,0 0 31 2,4,6 *→null(each completes in ~0.3–1.1s; without the fix they never complete, so these fail by timeout on unfixed code)0 0 31 4,5 *→ 2029-05-31,0 0 29 2 *→ 2032-02-29 (leap year)Verification
tests/api.test.ts: 18/18 pass, including the 5 new testsmaster(timezone/DST environment-dependent tests intimezone.test.ts; pre-existing, untouched by this change)Disclosure
Found by differential fuzzing against a brute-force reference oracle; analysis, fix and verification produced by AI agents working under my direction, reviewed and run by me before filing. Details in #37.
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