`head --bytes=0K` outputs up to 1 KiB instead of zero bytes

[SichangHe]

Doing

printf 0123456789 | cargo r -- head --bytes=0K

gives

0123456789

But it should instead print nothing.

It seems the code passes 0K through the function below, removes every initial 0, turning 0K into bare K.

coreutils/src/uucore/src/lib/features/parser/parse_signed_num.rs

Lines 77 to 95 in 0c8a3c7

	pub fn parse_signed_num_max(src: &str) -> Result<SignedNum, ParseSizeError> {
	let (sign, size_string) = strip_sign_prefix(src);
	// Empty string after stripping sign is an error
	if size_string.is_empty() {
	return Err(ParseSizeError::ParseFailure(src.to_string()));
	}
	// Remove leading zeros so size is interpreted as decimal, not octal
	let trimmed = size_string.trim_start_matches('0');
	let value = if trimmed.is_empty() {
	// All zeros (e.g., "000" or "0")
	0
	} else {
	parse_size_u64_max(trimmed)?
	};
	Ok(SignedNum { value, sign })
	}

Then, the bare K is interpreted as 1K.

The fix can simply be to check if any zeros were removed before interpreting K to 1K.