[Gptfdisk-general] Recent popt change seems to cause sgdisk segfault

[Adrian V. <adr...@gm...>]

Hello,

I'm running into a segmentation fault in `sgdisk --version`, that
seems to originate from the strdup call introduced in commit
5d5e76d369a412bfb3d2cebb5fc0a7509cef878d. There's a backtrace in the
downstream bug report[1], if you'd like to see it (though it's not
very interesting, so I won't bother to copy it here)

Here's my theory of what's going on:
- sgdisk parses the `--version` option & prints its version. Then
continues running
- sgdisk calls `poptGetArg`. In this situation, `poptGetArg` probably
returns NULL, since there's no  arguments on the command line
- Prior to 5d5e76d, this would have been OK (you check immediately
afterward & exit cleanly if `poptGetArg` returns NULL). However, now,
you end up calling `strdup(NULL)`, which leads to a segfault

I haven't looked too closely at your codebase, and I'm not very
familiar with popt's behavior, so I'm not certain that this is what's
happening, but it seems to make sense as a theory. Let me know if
there's anything I can do to assist you with fixing this bug

Thank you,
Adrian Vovk

[1]: https://gitlab.com/carbonOS/build-meta/-/issues/104