How to add a shorter bar under or over a letter in math mode?

Question

I am reading Apostol's Calculus, the upper and lower integrals appear with a shorter bar

but this is not the case for \overline and \underline, the following pic was typeset with \overline and \underline

but this has two problems:

1. the bar over letter I is too long, so is the bar under the letter I
2. since the letter I is oblique, the bar doesn't move with the letter.

so, is there a way to typeset the upper and lower integrals as same as the book?