@karelzak could you review this please?

There was a discussion about it years ago: https://www.spinics.net/lists/util-linux-ng/msg16750.html (probably my mistake that it was not resolved).

• strcasecmp() is locale-sensitive, but we do not need locales in this case (hex codes). It would probably be better to use include/cctype.h:c_strncasecmp(), which always works with ASCII
• libmount/src/cache.c:cache_find_tag() may also compare tags
• libblkid/src/evaluate.c:evaluate_by_udev() generates a symlink path to use udevd to verify the tag. It seems we need to try lower-case and upper-case path
• libblkid/src/evaluate.c:verify_tag() may also compare the tag (the code is not used by default, but it should be probably nice to improve it too)

Maybe you can add to include/strutils.c a new function ul_hexcmp() to compare two hex strings in locales and case-independent way.

Generic function, just to compare hex values sounds better than strcasecmp, I agree.

The UUID string format isn't just hex, like it also includes dashes, so if we compare UUID strings here, it shall be ul_uuidcmp, which would accept only [0-9a-f-] set of characters?

Thank you for listing other functions that does compare tags, I'm not very familiar with this code. I will send a v2 later then, thank you!

Ah, good point. You're right; it's not about hex only.