I don't think you meant to use those chars in your example
script..? Can you please add the actual ones here?

And what was the configure line used to configure PHP?

oops, mozilla mangled those characters.

begin 644 l.php
M/#]P:'`*<V5T;&]C86QE*$Q#7T%,3"P@(G)U7U)5+DM/23@M4B(I.R`*96-H
M;R!S971L;V-A;&4H3$-?04Q,+"`B(BDL(")<;B(["FEF("AE<F5G:2@BT2(L
M("+Q\2(I*2![(&5C:&\@(F]K7&XB.R!](&5L<V4@>R!E8VAO(")B861<;B([
M?0II9B`H<')E9U]M871C:"@B+]$O:2(L("+Q\2(I*2![(&5C:&\@(F]K7&XB
=.R!](&5L<V4@>R!E8VAO(")B861<;B([?0H_/@H`
`
end

'./configure' '--without-x' '--disable-debug' '--with-apxs=/usr/local/apache/bin/apxs' '--with-mod_charset' '--enable-dba' '--with-gdbm=/usr/local' '--with-db4=/usr/local' '--enable-dbase' '--enable-ftp' '--enable-sockets' '--enable-inline-optimization' '--enable-memory-limit' '--with-mysql' '--with-gd' '--enable-gd-native-ttf' '--with-zlib=/usr' '--with-jpeg-dir=/usr/local' '--with-png-dir=/usr/local' '--with-freetype-dir=/usr/local' '--enable-exif' '--enable-calendar' '--enable-wddx' '--with-gmp' '--with-openssl=/usr' '--with-iconv=/usr/local' '--with-imap=shared,/usr/local' '--with-curl=/usr/local' '--with-dom=shared,/usr/local' '--with-dom-xslt=shared,/usr/local' '--with-dom-exslt=shared,/usr/local' '--enable-xslt=shared' '--with-xslt-sablot=shared,/usr/local' '--with-iconv-dir=/usr/local' '--with-expat-dir=/usr/local' '--with-zip=/usr/local' '--with-pdflib' '--with-tiff-dir=/usr/local'

Try this patch and see if it fixes the problem.
http://bb.prohost.org/reg.txt

No, it does not.

Ilia: your patch doesn't seem to deal with it correctly, as isalpha() expects signed integer indeed. A char value can be any of the numbers, -128 to 127, so if you cast it to unsigned integer, you never got a value in range of 0 to 255. So you should first cast it to unsigned char, and then make it signed integer.

Can you try this one again:
http://www.voltex.jp/patches/regpatch.diff

Note: This problem is known to not be reproduced with glibc and unfortunately I don't have a freebsd box atm.

This one is OK.  Should I write a test case?

Yup, if possible. The following is just a template (supposed to be put in ext/standard/tests/reg). Please try to avoid using non-ascii characters in the test case. Thanks in advance.

--TEST--
Bug #25669 (eregi() with non-ascii characters)
--SKIP--
<?php
setlocale(LC_ALL, "de_DE.ISO8859-1") || die('SKIP de_DE.ISO8859-1 locale not sup
ported by this system');
?>
--FILE--
<?php
setlocale(LC_ALL, "de_DE.ISO8859-1");
var_dump((bool)eregi("\xc4\xcb\xf6", "\xe4\xeb\xd6"));
var_dump((bool)eregi("\xc4", "\xe1"));
var_dump((bool)preg_match("/\xc4\xcb\xf6/i", "\xe4\xeb\xd6"));
var_dump((bool)preg_match("/\xc4/i", "\xe1"));
?>
--EXPECT--
bool(true)
bool(false)
bool(true)
bool(false)

This template is a complete test case actually. I did not have to modify it in any way.

Ok, I'm closing the bug.
Thanks for helping make php better.

(The fix will go to 4.3.4-rc2 or later versions)