GNU coreutils date-like time zone formatting

[jarkonik]

Pull request adds additional string formatting options for time zones using multiple colons as syntax, which are identical to formatting options in GNU coreutils date ( https://man7.org/linux/man-pages/man1/date.1.html )

This would fix uutils/coreutils#3780

The pull request adds additional format specifiers for chrono::format::strftime.

In addition to currently implemented %z and %:z PR adds 2 new time zone formatting identifiers:

1. %::z -Offset from the local time to UTC with seconds.
   Example output: +09:30:00
2. %:::z - Offset from the local time to UTC without minutes.
   Example output: +09

[djc]

Would you mind documenting in the PR description the intended behavior?

[sylvestre]

@jarkonik ping ? :)

[jarkonik]

I've expanded the PR description a bit. If more information is needed please let me know what should I change/add.

[djc]

Seems reasonable. Some minor suggestions below.

[djc]

Thanks, this looks good to me.

[djc]

@esheppa any opinions?

[esheppa]

Looks good, just one thing I'd noticed is that potentially it could loop forever if the input was like %:::::::::: ...etc. I've set up a PR to @jarkonik which proposes two alternative implementations (one is commented out) - jarkonik#1

My concern with the looping forever is that the strftime items can be used to validate user input, so it could be a DOS attack

[esheppa]

Thanks @jarkonik, if possible, do you mind making a couple of fixes in the docs?

Resolved

[djc]

Thanks!

[sylvestre]

Well done!
Sorry for the question but how often do you release ? :)