We need more validation for step

[peterqiu07]

cron/parser.go

Line 313 in bc59245

if step == 0 {

There is not enough validation for step
So when we use cron expression like "0/9999 * * * * ?", it still works, but it seems like out of expectation, and more strange
Further more, what do you expect for "0/9999 0/666 * * * ?"

Maybe we need to use the bounds to limit range as well as start and end

[ljluestc]

// cron/parser.go

// Validate step ranges for each cron field
func validateStep(step int, min int, max int) error {
    if step == 0 {
        return fmt.Errorf("step cannot be 0")
    }
    if step < min || step > max {
        return fmt.Errorf("step %d is out of bounds, must be between %d and %d", step, min, max)
    }
    return nil
}

// The cron expression parsing logic
func parseCronExpression(expression string) error {
    // Example for validating minute field with step values
    minuteField := "0/9999"  // Example invalid value
    step := parseStep(minuteField)  // hypothetical function to parse step value from cron expression

    // Step validation for minute field (0 to 59)
    if err := validateStep(step, 0, 59); err != nil {
        return err
    }

    // Example for validating hour field with step values
    hourField := "0/666"  // Example invalid value
    step = parseStep(hourField)  // hypothetical function to parse step value from cron expression

    // Step validation for hour field (0 to 23)
    if err := validateStep(step, 0, 23); err != nil {
        return err
    }

    // Similarly for other fields (day of month, month, day of week), define their valid ranges:
    // - Day of month: 1 to 31
    // - Month: 1 to 12
    // - Day of week: 0 to 6 (Sunday to Saturday)

    return nil
}