Revert "strchriscntrl: reject C1 control bytes (0x80-0x9F)"

[alejandro-colomar]

C1 control bytes are more complicated than that. They're represented as two bytes in UTF-8.

Commit 19d725d, has issues, rejecting otherwise valid UTF-8 multi-byte characters.

We could in theory do correct parsing of UTF, possibly parsing the multi-byte sequences, or translating to wchar_t. However, that would complicate the source code well beyond what I'd be comfortable with.

Instead, let's revert this, and claim no intention to support UTF-8. If an admin uses a UTF-8 locale while reading /etc/passwd, that's their own fault.

Reverts: 19d725d (2026-03-13; "strchriscntrl: reject C1 control bytes (0x80-0x9F)")
Fixes: 19d725d (2026-03-13; "strchriscntrl: reject C1 control bytes (0x80-0x9F)")
Closes: #1598
Reported-by: @grawity
Cc: @KhaelK138
Cc: @stoeckmann

---

Revisions:

v2

• Add CAVEATS to passwd(5), documenting that the C locale should be used when reading /etc/passwd.

$ git rd 
1:  a2a94f2d = 1:  a2a94f2d Revert "strchriscntrl: reject C1 control bytes (0x80-0x9F)"
-:  -------- > 2:  61263b74 man/passwd.5.xml: CAVEATS: Add section

[ikerexxe]

Is there any place where claim no intention to support UTF-8 is stated?

[alejandro-colomar]

Is there any place where claim no intention to support UTF-8 is stated?

I guess we could use release notes. And/or maybe we should add something to passwd(5) in a CAVEATS section.

[ikerexxe]

I prefer the second option, as people are more likely to read it.

Do you want to use this PR to update it, or shall we leave it for later?

[alejandro-colomar]

I prefer the second option, as people are more likely to read it.

Do you want to use this PR to update it, or shall we leave it for later?

I'll update this PR.

[alejandro-colomar]

I prefer the second option, as people are more likely to read it.
Do you want to use this PR to update it, or shall we leave it for later?

I'll update this PR.

Done.

[ikerexxe]

LGTM! Thank you for taking care of this patch.

I won’t merge it just yet, in case any native English speakers would like to review the updated documentation

[hallyn]

Not entirely comfortable with it. I see I have UTF8 as my locale on my laptop. But I agree that we're inviting trouble if we try to do the parsing.