1448786 - Avoid UTF8ToUnicodeBuffer in OSPreferences_win.cpp

Status: RESOLVED FIXED

(Core :: Internationalization, enhancement)

Description

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

UTF8ToUnicodeBuffer is going away in bug 1402247 (mostly because after my changes no Linux callers were left and I noticed a Windows caller just now).

Comment 1

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

Are locale strings arbitrary UTF-8 or are they guaranteed to be ASCII? I.e. can we use a Latin1 to UTF-16 conversion here, which involves no length calculation issues?

Comment 2

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

(In reply to Henri Sivonen (:hsivonen) from comment #0)
> UTF8ToUnicodeBuffer is going away in bug 1402247 (mostly because after my
> changes no Linux callers were left and I noticed a Windows caller just now).

(Oh, and the new code has very different assumptions about how length calculation happens than what UTF8ToUnicodeBuffer requires.)

Comment 3

[Zibi Braniecki [:zbraniecki][:gandalf]]

As used here the locale should always be ASCII, but the value comes from JS over XPIDL [0] so we cannot guarantee it wont have some UTF8 in weird cases (but that's always going to be invalid input so its ok if it doesn't match anything, just don't crash :)).

[0] https://searchfox.org/mozilla-central/source/intl/locale/mozIOSPreferences.idl#98

Comment 4

[Masatoshi Kimura [:emk]]

(In reply to Zibi Braniecki [:gandalf][:zibi] from comment #3)
> As used here the locale should always be ASCII, but the value comes from JS
> over XPIDL [0] so we cannot guarantee it wont have some UTF8 in weird cases
> (but that's always going to be invalid input so its ok if it doesn't match
> anything, just don't crash :)).

Actually locale can only contain Latin1 characters because it uses ACString. (If it uses AUTF8String or AString, it can contain arbitrary Unicode characters.)

Comment 5

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

Attachment: Bug 1448786 - Avoid UTF8ToUnicodeBuffer in OSPreferences_win.cpp.

Review commit: https://reviewboard.mozilla.org/r/231198/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/231198/

Comment 6

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

Comment on attachment 8962323 [details]
Bug 1448786 - Avoid UTF8ToUnicodeBuffer in OSPreferences_win.cpp.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/231198/diff/1-2/

Comment 7

[Henri Sivonen (:hsivonen) (not reading bugmail until 2026-07-27)]

AFAICT, we don't need a manually-declared buffer on the stack and relying on the on-stack buffer provided by nsAutoString should be fine.

Comment 8

[Zibi Braniecki [:zbraniecki][:gandalf]]

Comment on attachment 8962323 [details]
Bug 1448786 - Avoid UTF8ToUnicodeBuffer in OSPreferences_win.cpp.

https://reviewboard.mozilla.org/r/231198/#review237424

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d9f8d12c6d6e
Avoid UTF8ToUnicodeBuffer in OSPreferences_win.cpp. r=gandalf

Comment 10

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/d9f8d12c6d6e