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diff --git a/source/internals.doc b/source/internals.doc index c8cc6dd1367..971f2567388 100644 --- a/source/internals.doc +++ b/source/internals.doc @@ -6,75 +6,6 @@ understood by anyone wishing to add features to Samba. -============================================================================= -This section describes character set handling in Samba, as implemented in -Samba 3.0 and above - -In the past Samba had very ad-hoc character set handling. Scattered -throughout the code were numerous calls which converted particular -strings to/from DOS codepages. The problem is that there was no way of -telling if a particular char* is in dos codepage or unix -codepage. This led to a nightmare of code that tried to cope with -particular cases without handlingt the general case. - -The new system works like this: - -- all char* strings inside Samba are "unix" strings. These are - multi-byte strings that are in the charset defined by the "unix - charset" option in smb.conf. - -- there is no single fixed character set for unix strings, but any - character set that is used does need the following properties: - * must not contain NULLs except for termination - * must be 7-bit compatible with C strings, so that a constant - string or character in C will be byte-for-byte identical to the - equivalent string in the chosen character set. - * when you uppercase or lowercase a string it does not become - longer than the original string - * must be able to correctly hold all characters that your client - will throw at it - For example, UTF-8 is fine, and most multi-byte asian character sets - are fine, but UCS2 could not be used for unix strings as they - contain nulls. - -- when you need to put a string into a buffer that will be sent on the - wire, or you need a string in a character set format that is - compatible with the clients character set then you need to use a - pull_ or push_ function. The pull_ functions pull a string from a - wire buffer into a (multi-byte) unix string. The push_ functions - push a string out to a wire buffer. - -- the two main pull_ and push_ functions you need to understand are - pull_string and push_string. These functions take a base pointer - that should point at the start of the SMB packet that the string is - in. The functions will check the flags field in this packet to - automatically determine if the packet is marked as a unicode packet, - and they will choose whether to use unicode for this string based on - that flag. You may also force this decision using the STR_UNICODE or - STR_ASCII flags. For use in smbd/ and libsmb/ there are wrapper - functions clistr_ and srvstr_ that call the pull_/push_ functions - with the appropriate first argument. - - You may also call the pull_ascii/pull_ucs2 or push_ascii/push_ucs2 - functions if you know that a particular string is ascii or - unicode. There are also a number of other convenience functions in - charcnv.c that call the pull_/push_ functions with particularly - common arguments, such as pull_ascii_pstring() - -The biggest thing to remember is that internal (unix) strings in Samba -may now contain multi-byte characters. This means you cannot assume -that characters are always 1 byte long. Often this means that you will -have to convert strings to ucs2 and back again in order to do some -(seemingly) simple task. For examples of how to do this see functions -like strchr_m(). I know this is very slow, and we will eventually -speed it up but right now we want this stuff correct not fast. - -Other rules: - - - all lp_ functions now return unix strings. The magic "DOS" flag on - parameters is gone. - - all vfs functions take unix strings. Don't convert when passing to - them ============================================================================= |