&author.jelmer;
TAKAHASHIMotonobu
monyo@home.monyo.com
25 March 2003
Unicode/Charsets
Features and Benefits
Every industry eventually matures. One of the great areas of maturation is in
the focus that has been given over the past decade to make it possible for anyone
anywhere to use a computer. It has not always been that way, in fact, not so long
ago it was common for software to be written for exclusive use in the country of
origin.
Of all the effort that has been brought to bear on providing native language support
for all computer users, the efforts of the Openi18n organisation is deserving of
special mention.
Samba-2.x supported a single locale through a mechanism called
codepages. Samba-3 is destined to become a truly trans-global
file and printer sharing platform.
What are charsets and unicode?
Computers communicate in numbers. In texts, each number will be
translated to a corresponding letter. The meaning that will be assigned
to a certain number depends on the character set(charset)
that is used.
A charset can be seen as a table that is used to translate numbers to
letters. Not all computers use the same charset (there are charsets
with German umlauts, Japanese characters, etc). Usually a charset contains
256 characters, which means that storing a character with it takes
exactly one byte.
There are also charsets that support even more characters,
but those need twice(or even more) as much storage space. These
charsets can contain 256 * 256 = 65536 characters, which
is more then all possible characters one could think of. They are called
multibyte charsets (because they use more then one byte to
store one character).
A standardised multibyte charset is unicode.
A big advantage of using a multibyte charset is that you only need one; there
is no need to make sure two computers use the same charset when they are
communicating.
Old windows clients use single-byte charsets, named
'codepages' by Microsoft. However, there is no support for
negotiating the charset to be used in the smb protocol. Thus, you
have to make sure you are using the same charset when talking to an older client.
Newer clients (Windows NT, 2K, XP) talk unicode over the wire.
Samba and charsets
As of samba 3.0, samba can (and will) talk unicode over the wire. Internally,
samba knows of three kinds of character sets:
unix charset
This is the charset used internally by your operating system.
The default is UTF-8, which is fine for most
systems. The default in previous samba releases was ASCII.
display charset
This is the charset samba will use to print messages
on your screen. It should generally be the same as the unix charset.
dos charset
This is the charset samba uses when communicating with
DOS and Windows 9x clients. It will talk unicode to all newer clients.
The default depends on the charsets you have installed on your system.
Run testparm -v | grep "dos charset" to see
what the default is on your system.
Conversion from old names
Because previous samba versions did not do any charset conversion,
characters in filenames are usually not correct in the unix charset but only
for the local charset used by the DOS/Windows clients.
Bjoern Jacke has written a utility named convm that can convert whole directory
structures to different charsets with one single command.
Japanese charsets
Samba doesn't work correctly with Japanese charsets yet. Here are
points of attention when setting it up:
You should set mangling methodhash
There are various iconv() implementations around and not
all of them work equally well. glibc2's iconv() has a critical problem
in CP932. libiconv-1.8 works with CP932 but still has some problems and
does not work with EUC-JP.
You should set dos charsetCP932, not
Shift_JIS, SJIS...
Currently only unix charsetCP932
will work (but still has some problems...) because of iconv() issues.
unix charsetEUC-JP doesn't work well because of
iconv() issues.
Currently Samba 3.0 does not support unix charsetUTF8-MAC/CAP/HEX/JIS*
More information (in Japanese) is available at: http://www.atmarkit.co.jp/flinux/special/samba3/samba3a.html.
Common errors
CP850.so can't be found
Samba is complaining about a missing CP850.so file
.
CP850 is the default dos charset. The dos charset is used to convert data to the codepage used by your dos clients. If you don't have any dos clients, you can safely ignore this message.
CP850 should be supported by your local iconv implementation. Make sure you have all the required packages installed. If you compiled samba from source, make sure configure found iconv.