peass-ng/PEASS-ng · error · ArgumentException

The flag value is zero and has no bit position.

Error message

The flag value is zero and has no bit position.

What it means

BitPosition<T> computes the single set bit of a flags value; it throws InvalidEnumArgumentException (with the descriptive text about a zero value having no bit position) when the value is 0, because zero has no bit to locate. The at-fault input is a flags enum value of 0 passed to this extension.

Source

Thrown at winPEAS/winPEASexe/winPEAS/TaskScheduler/EnumUtil.cs:39

            CheckIsEnum<T>();
            if (IsFlags<T>())
            {
                var allFlags = 0L;
                foreach (T flag in Enum.GetValues(typeof(T)))
                    allFlags |= Convert.ToInt64(flag);
                if ((allFlags & Convert.ToInt64(value)) != 0L)
                    return;
            }
            else if (Enum.IsDefined(typeof(T), value))
                return;
            throw new InvalidEnumArgumentException(argName ?? "value", Convert.ToInt32(value), typeof(T));
        }

        public static byte BitPosition<T>(this T flags) where T : struct, IConvertible
        {
            CheckIsEnum<T>(true);
            var flagValue = Convert.ToInt64(flags);
            if (flagValue == 0) throw new ArgumentException("The flag value is zero and has no bit position.");
            var r = Math.Log(flagValue, 2);
            if (r % 1 > 0) throw new ArithmeticException("The flag value has more than a single bit set.");
            return Convert.ToByte(r);
        }

        public static bool IsFlagSet<T>(this T flags, T flag) where T : struct, IConvertible
        {
            CheckIsEnum<T>(true);
            var flagValue = Convert.ToInt64(flag);
            return (Convert.ToInt64(flags) & flagValue) == flagValue;
        }

        public static bool IsValidFlagValue<T>(this T flags) where T : struct, IConvertible
        {
            CheckIsEnum<T>(true);
            var found = 0L;
            foreach (T flag in Enum.GetValues(typeof(T)))
            {

View on GitHub (pinned to 53fb989abc)

Solutions

1. Check the value for 0 before calling BitPosition and handle the 'no bit set' case explicitly.
2. Only call BitPosition on values known to have exactly one bit set.
3. Wrap the call in try/catch for InvalidEnumArgumentException when arbitrary flags values may arrive.

When it happens

Trigger: Thrown at winPEAS/winPEASexe/winPEAS/TaskScheduler/EnumUtil.cs:39 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of peass-ng/PEASS-ng@53fb989abc (2026-09-02). Data as JSON: /api/errors/4f4daa740619e3ab. Report an issue: GitHub.