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author | Jelmer Vernooij <jelmer@samba.org> | 2002-10-28 19:43:04 +0000 |
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committer | Jelmer Vernooij <jelmer@samba.org> | 2002-10-28 19:43:04 +0000 |
commit | dedc2c87757509f63e5979845664daaf62417c9a (patch) | |
tree | 5e7f7cba65e3653c9d59fb9a16db1ccc48de7720 | |
parent | 26b9d7d12e6eff09473153a14822761e8a1300c2 (diff) | |
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diff --git a/source3/internals.doc b/source3/internals.doc deleted file mode 100644 index c8cc6dd136..0000000000 --- a/source3/internals.doc +++ /dev/null @@ -1,281 +0,0 @@ -internals.txt, 8 May 1996 -Written by David Chappell <David.Chappell@mail.trincoll.edu>. - -This document describes some of the internal functions which must be -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 - - -============================================================================= -This section describes the macros defined in byteorder.h. These macros -are used extensively in the Samba code. - ------------------------------------------------------------------------------ -CVAL(buf,pos) - -returns the byte at offset pos within buffer buf as an unsigned character. - ------------------------------------------------------------------------------ -PVAL(buf,pos) - -returns the value of CVAL(buf,pos) cast to type unsigned integer. - ------------------------------------------------------------------------------ -SCVAL(buf,pos,val) - -sets the byte at offset pos within buffer buf to value val. - ------------------------------------------------------------------------------ -SVAL(buf,pos) - -returns the value of the unsigned short (16 bit) little-endian integer at -offset pos within buffer buf. An integer of this type is sometimes -refered to as "USHORT". - ------------------------------------------------------------------------------ -IVAL(buf,pos) - -returns the value of the unsigned 32 bit little-endian integer at offset -pos within buffer buf. - ------------------------------------------------------------------------------ -SVALS(buf,pos) - -returns the value of the signed short (16 bit) little-endian integer at -offset pos within buffer buf. - ------------------------------------------------------------------------------ -IVALS(buf,pos) - -returns the value of the signed 32 bit little-endian integer at offset pos -within buffer buf. - ------------------------------------------------------------------------------ -SSVAL(buf,pos,val) - -sets the unsigned short (16 bit) little-endian integer at offset pos within -buffer buf to value val. - ------------------------------------------------------------------------------ -SIVAL(buf,pos,val) - -sets the unsigned 32 bit little-endian integer at offset pos within buffer -buf to the value val. - ------------------------------------------------------------------------------ -SSVALS(buf,pos,val) - -sets the short (16 bit) signed little-endian integer at offset pos within -buffer buf to the value val. - ------------------------------------------------------------------------------ -SIVALS(buf,pos,val) - -sets the signed 32 bit little-endian integer at offset pos withing buffer -buf to the value val. - ------------------------------------------------------------------------------ -RSVAL(buf,pos) - -returns the value of the unsigned short (16 bit) big-endian integer at -offset pos within buffer buf. - ------------------------------------------------------------------------------ -RIVAL(buf,pos) - -returns the value of the unsigned 32 bit big-endian integer at offset -pos within buffer buf. - ------------------------------------------------------------------------------ -RSSVAL(buf,pos,val) - -sets the value of the unsigned short (16 bit) big-endian integer at -offset pos within buffer buf to value val. -refered to as "USHORT". - ------------------------------------------------------------------------------ -RSIVAL(buf,pos,val) - -sets the value of the unsigned 32 bit big-endian integer at offset -pos within buffer buf to value val. - - - - - -============================================================================= -This section describes the functions need to make a LAN Manager RPC call. -This information had been obtained by examining the Samba code and the LAN -Manager 2.0 API documentation. It should not be considered entirely -reliable. - ------------------------------------------------------------------------------ -call_api(int prcnt, int drcnt, int mprcnt, int mdrcnt, - char *param, char *data, char **rparam, char **rdata); - -This function is defined in client.c. It uses an SMB transaction to call a -remote api. - -The parameters are as follows: - -prcnt: the number of bytes of parameters begin sent. -drcnt: the number of bytes of data begin sent. -mprcnt: the maximum number of bytes of parameters which should be returned -mdrcnt: the maximum number of bytes of data which should be returned -param: a pointer to the parameters to be sent. -data: a pointer to the data to be sent. -rparam: a pointer to a pointer which will be set to point to the returned - paramters. The caller of call_api() must deallocate this memory. -rdata: a pointer to a pointer which will be set to point to the returned - data. The caller of call_api() must deallocate this memory. - ------------------------------------------------------------------------------ -These are the parameters which you ought to send, in the order of their -appearance in the parameter block: - -* An unsigned 16 bit integer API number. You should set this value with -SSVAL(). I do not know where these numbers are described. - -* An ASCIIZ string describing the parameters to the API function as defined -in the LAN Manager documentation. The first parameter, which is the server -name, is ommited. This string is based uppon the API function as described -in the manual, not the data which is actually passed. - -* An ASCIIZ string describing the data structure which ought to be returned. - -* Any parameters which appear in the function call, as defined in the LAN -Manager API documentation, after the "Server" and up to and including the -"uLevel" parameters. - -* An unsigned 16 bit integer which gives the size in bytes of the buffer we -will use to receive the returned array of data structures. Presumably this -should be the same as mdrcnt. This value should be set with SSVAL(). - -* An ASCIIZ string describing substructures which should be returned. If no -substructures apply, this string is of zero length. - ------------------------------------------------------------------------------ -The code in client.c always calls call_api() with no data. It is unclear -when a non-zero length data buffer would be sent. - ------------------------------------------------------------------------------ -The returned parameters (pointed to by rparam), in their order of appearance -are: - -* An unsigned 16 bit integer which contains the API function's return code. -This value should be read with SVAL(). - -* An adjustment which tells the amount by which pointers in the returned -data should be adjusted. This value should be read with SVAL(). Basically, -the address of the start of the returned data buffer should have the returned -pointer value added to it and then have this value subtracted from it in -order to obtain the currect offset into the returned data buffer. - -* A count of the number of elements in the array of structures returned. -It is also possible that this may sometimes be the number of bytes returned. - ------------------------------------------------------------------------------ -When call_api() returns, rparam points to the returned parameters. The -first if these is the result code. It will be zero if the API call -suceeded. This value by be read with "SVAL(rparam,0)". - -The second parameter may be read as "SVAL(rparam,2)". It is a 16 bit offset -which indicates what the base address of the returned data buffer was when -it was built on the server. It should be used to correct pointer before -use. - -The returned data buffer contains the array of returned data structures. -Note that all pointers must be adjusted before use. The function -fix_char_ptr() in client.c can be used for this purpose. - -The third parameter (which may be read as "SVAL(rparam,4)") has something to -do with indicating the amount of data returned or possibly the amount of -data which can be returned if enough buffer space is allowed. - ------------------------------------------------------------------------------ -Certain data structures are described by means of ASCIIz strings containing -code characters. These are the code characters: - -W a type byte little-endian unsigned integer -N a count of substructures which follow -D a four byte little-endian unsigned integer -B a byte (with optional count expressed as trailing ASCII digits) -z a four byte offset to a NULL terminated string -l a four byte offset to non-string user data -b an offset to data (with count expressed as trailing ASCII digits) -r pointer to returned data buffer??? -L length in bytes of returned data buffer??? -h number of bytes of information available??? - ----------------------------------------------------------------------------- |