fix: Limit the max output of printf

[howjmay]

Closes #1879

[sylvestre]

Clippy is not happy

[jfinkels]

I'm not sure this is solving the right problem. The linked issue is requesting the following behavior:

$ /usr/bin/printf '%.*d\n' 2147483648 0
/usr/bin/printf: invalid precision: ‘2147483648’

First, this pull request does not produce that error message. Second, it would need to fill a vector with a very long string just to get to that point. This would probably be more effectively implemented by just checking at the time of parsing the command-line arguments whether the number is 2^31 or greater. Also, it would benefit from a unit test in the tests/by-util/test_printf.rs file.

[howjmay]

I'm not sure this is solving the right problem. The linked issue is requesting the following behavior:

$ /usr/bin/printf '%.*d\n' 2147483648 0
/usr/bin/printf: invalid precision: ‘2147483648’

First, this pull request does not produce that error message. Second, it would need to fill a vector with a very long string just to get to that point. This would probably be more effectively implemented by just checking at the time of parsing the command-line arguments whether the number is 2^31 or greater. Also, it would benefit from a unit test in the tests/by-util/test_printf.rs file.

So I should find if %.*d exist in the format patter? I am implementing in this way, since I found it quite hard to find escape character and corresponding parameter

[tertsdiepraam]

This would probably be more effectively implemented by just checking at the time of parsing the command-line arguments whether the number is 2^31 or greater

Indeed, the goal here is that this number is so large that it's probably a user error and just writes a nonsensical amount of data. So we don't gain much if we still try to write it to a vec, which might also make printf run out of memory.

I am implementing in this way, since I found it quite hard to find escape character and corresponding parameter

Yeah that is quite difficult. I suppose it should be a check somewhere inside Memo, which already does most of the parsing.

[sylvestre]

Clippy complains about:
ERROR: cargo clippy: this comparison involving the minimum or maximum element for this type contains a case that is always true or always false (file:'src/uucore/src/lib/features/memo.rs', line:121)

and format!() (should be easy)