samba-mirror/lib/param/README

libsamba-hostconfig
-------------------

This directory contains "libsamba-hostconfig". 

The libsamba-hostconfig library provides access to all host-wide configuration
such as the configured shares, default parameter values and host secret keys.


Adding a parameter
------------------

To add or change an smb.conf option, in general you only have to add
the documentation to docs-xml/smbdotconf, or change it.
In addition to that, if special defaults are needed, the functions
loadparm_init() in lib/param/loadparm.c and/or init_globals() in
source3/param/loadparm.c need to be adapted accordingly.
The rest is generated for you.

It is important to get the attributes right in the <samba:parameter ...>
tag of the xml files.  These determine the details of the generated code.

- Supported attributes are name, context, type, constant, function,
  generated_function, synonym, parm, enumlist, handler, and deprecated.
- Supported contexts are 'G' (for global) and 'S' (for share).
- Supported types are boolean, boolean-rev, boolean-auto, list,
  cmdlist, string, ustring, char, integer, bytes, octal, and enum.



Using smb.conf parameters in the code
-------------------------------------

Call the lpcfg_*() function.  To get the lp_ctx, have the caller pass
it to you.  To get a lp_ctx for the source3/param loadparm system, use:

struct loadparm_context *lp_ctx = loadparm_init_s3(tmp_ctx, loadparm_s3_helpers());

Remember to talloc_unlink(tmp_ctx, lp_ctx) the result when you are done!

To get a lp_ctx for the lib/param loadparm system, typically the
pointer is already set up by popt at startup, and is passed down from
cmdline_lp_ctx.

In pure source3/ code, you may use lp_*() functions, but are
encouraged to use the lpcfg_*() functions so that code can be made
common.


How does loadparm_init_s3() work?
---------------------------------

loadparm_s3_helpers() returns a initialised table of function
pointers, pointing at all global lp_*() functions, except for those
that return substituted strings (% macros).  The lpcfg_*() function
then calls this plugged in function, allowing the one function and
pattern to use either loadparm system.


There is a lot of generated code, here, what generates what?
------------------------------------------------------------

The regular format of the CPP macros in param_functions.c is used to
generate up the prototypes (mkproto.pl, mks3param_proto.pl), the service
and globals table (mkparamdefs.pl), the glue table (mmks3param.pl) and
the initilisation of the glue table (mks3param_ctx_table.pl).

I have tried combining some of these, but it just makes the scripts more
complex.

The CPP macros are defined in and expand in lib/param/loadparm.c and
source3/param/loadparm.c to read the values from the generated
stuctures.  They are CPP #included into these files so that the same
macro has two definitions, depending on the system it is loading into.


Why was this done, rather than a 'proper' fix, or just using one system or the other?
-------------------------------------------------------------------------------------

This was done to allow merging from both ends - merging more parts of
the loadparm handling, and merging code that needs to read the
smb.conf, without having to do it all at once.  Ideally
param_functions.c would be generated from param_table.c or (even
better) our XML manpage source, and the CPP macros would instead be
generated expanded as generated C files, but this is a task nobody has
taken on yet.