How to Write an Eggdrop Module

Note: This is for a simple module of 1 source file.

  1.  Create a src/mod/MODULE.mod directory in your Eggdrop directory
      (where MODULE is the module name) and cd to it.

  2.  Copy the file 'Makefile' from src/mod/woobie.mod and replace all
      occurrences of 'woobie' with your module name. This should ensure
      that your module gets compiled.

  3.  Next, you want to create a file called MODULE.c (MODULE is the
      module name again).

  4.  You MUST include the following in your source code:

          #define MODULE_NAME "module-name"

    This should be defined to the same name you will be using when you
    load your module.

        #define MAKING_MODULENAME

    MODULENAME is the name of your module (MODULE_NAME), but in all
    caps.

        #include "../module.h"

    This provides access to Eggdrop's global function table. Examine
    src/mod/module.h closely to find a list of functions available.

        #include any other standard c header files you might need. 

    Note that stdio.h, string.h, stdlib.h, and sys/types.h are already
    included.

        Function *global;

    This variable provides access to all the Eggdrop functions; without
    it, you can't call any Eggdrop functions (the module won't even
    load).

MODULE REQUIREMENTS

In most modules, all functions/variables (except global and
MODULE_start) should be static. This will drastically reduce the size of
modules on decent systems.

Throughout this step, MODULE refers to the module name. Note that
"MODULE_NAME" should literally be "MODULE_NAME".

MODULE_start

    char *MODULE_start(Function *func_table)

This function is called when the module is first loaded. There are
several things that need to be done in this function

    global = func_table;

This allows you to make calls to the global function table.

    module_register(MODULE_NAME, MODULE_table, MAJOR, MINOR);

This records details about the module for other modules and Eggdrop
itself to access. MAJOR and MINOR are ints, where MAJOR is the module's
major version number and MINOR is a minor version number. MODULE_table
is a function table (see below).

    module_depend(MODULE_NAME, "another-module", MAJOR, MINOR);

This lets Eggdrop know that your module NEEDS "another-module" of major
version 'MAJOR' and at least minor version 'MINOR' to run, and hence
should try to load it if it's not already loaded. This will return 1 on
success, or 0 if it can't be done (at which stage you should return an
error).

Any other initialization stuff you desire should also be included in
this function. See below for various things you can do.

You also will need to return a value. Returning NULL implies the module
loaded successfully. Returning a non-NULL STRING is an error message.
The module (and any other dependent modules) will stop loading and an
error will be returned.

MODULE_table

    static Function *MODULE_table = {
           MODULE_start,
           MODULE_close,
           MODULE_expmem,
           MODULE_report,
           any_other_functions,
           you_want_to_export
    };

This is a table of functions which any other module can access. The
first 4 functions are FIXED. You MUST have them; they provide important
module information.

MODULE_close ()

    static char *MODULE_close ()

This is called when the module is unloaded. Apart from tidying any
relevant data (I suggest you be thorough, we don't want any trailing
garbage from modules), you MUST do the following:

    module_undepend(MODULE_NAME);

This lets Eggdrop know your module no longer depends on any other
modules.

Return a value. NULL implies success; any non-NULL STRING implies that
the module cannot be unloaded for some reason, and hence the bot should
not unload it (see the blowfish module for an example).

MODULE_expmem

    static int MODULE_expmem ()

    This should tally all memory you allocate/deallocate within the module
    (using nmalloc, nfree, etc) in bytes. It's used by memory debugging to
    track memory faults, and it is used by .status to total up memory usage.

MODULE_report

    static void MODULE_report (int idx)

This should provide a relatively short report of the module's status
(for the module and status commands).

These functions are available to modules. MANY more available functions
can be found in src/mod/module.h.

Additional functions

nmalloc

    void *nmalloc(int j);

This allocates j bytes of memory.

nfree

    void nfree(void *a);

This frees an nmalloc'd block of memory.

Context

    Context;

Actually a macro -- records the current position in execution (for
debugging). Using Context is no longer recommended, because it uses too
many resources and a core file provides much more information.

dprintf

    void dprintf(int idx, char *format, ...)

This acts like a normal printf() function, but it outputs to
log/socket/idx. idx is a normal dcc idx, or if < 0 is a sock number.

  Other destinations:

      DP_LOG    - send to log file
      DP_STDOUT - send to stdout
      DP_MODE   - send via mode queue to the server
      DP_SERVER - send via normal queue to the server
      DP_HELP   - send via help queue to server

module_entry

    const module_entry *module_find(char *module_name, int major, int minor);

Searches for a loaded module (matching major, >= minor), and returns
info about it.

    Members of module_entry:

    char *name;      - module name
    int major;       - real major version
    int minor;       - real minor version
    Function *funcs; - function table (see above)

module_rename

    void module_rename(char *old_module_name, char *new_module_name)

This renames a module from old_module_name to new_module_name.

add_hook/del_hook

    void add_hook(int hook_num, Function *funcs)
    void del_hook(int hook_num, Function *funcs)

These are used for adding or removing hooks to/from Eggdrop code that
are triggered on various events. Valid hooks are:

    HOOK_SECONDLY   - called every second
    HOOK_MINUTELY   - called every minute
    HOOK_5MINUTELY  - called every 5 minutes
    HOOK_HOURLY     - called every hour (hourly-updates minutes past)
    HOOK_DAILY      - called when the logfiles are switched

    HOOK_READ_USERFILE - called when the userfile is read
    HOOK_USERFILE      - called when the userfile is written
    HOOK_PRE_REHASH    - called just before a rehash
    HOOK_REHASH        - called just after a rehash
    HOOK_IDLE          - called whenever the dcc connections have been
                         idle for a whole second
    HOOK_BACKUP        - called when a user/channel file backup is done
    HOOK_LOADED        - called when Eggdrop is first loaded
    HOOK_DIE           - called when Eggdrop is about to die

module_load/unload

    char *module_unload (char *module_name);
    char *module_load (char *module_name);

Tries to load or unload the specified module; returns 0 on success, or
an error message.

add/rem_tcl_commands

    void add_tcl_commands(tcl_cmds *tab);
    void rem_tcl_commands(tcl_cmds *tab);

Provides a quick way to create and remove a table of Tcl commands. The
table is in the form of:

    {char *func_name, Function *function_to_call}

Use { NULL, NULL } to indicate the end of the list.

add/rem_tcl_ints

    void add_tcl_ints(tcl_ints *);
    void rem_tcl_ints(tcl_ints *);

Provides a quick way to create and remove a table of links from C int
variables to Tcl variables (add_tcl_ints checks to see if the Tcl
variable exists and copies it over the C one). The format of table is:

    {char *variable_name, int *variable, int readonly}

Use {NULL, NULL, 0} to indicate the end of the list.

add/rem_tcl_strings

    void add_tcl_strings(tcl_strings *);
    void rem_tcl_strings(tcl_strings *);

Provides a quick way to create and remove a table of links from C string
variables to Tcl variables (add_tcl_ints checks to see if the Tcl
variable exists and copies it over the C one). The format of table is:

    {char *variable_name, char *string, int length, int flags}

Use {NULL, NULL, 0, 0} to indicate the end of the list. Use 0 for length
if you want a const string. Use STR_DIR for flags if you want a '/'
constantly appended; use STR_PROTECT if you want the variable set in the
config file, but not during normal usage.

add/rem_builtins

    void add_builtins(p_tcl_hash_list table, cmd_t *cc);
    void rem_builtins(p_tcl_hash_list table, cmd_t *cc);

This adds binds to one of Eggdrop's bind tables. The format of the table
is:

    {char *command, char *flags, Function *function, char *displayname}

Use {NULL, NULL, NULL, NULL} to indicate the end of the list.

This works EXACTLY like the Tcl 'bind' command. displayname is what Tcl
sees this function's proc name as (in .binds all).

function is called with exactly the same args as a Tcl binding is with
type conversion taken into account (e.g. idx's are ints). Return values
are much the same as Tcl bindings. Use int 0/1 for those which require
0/1, or char * for those which require a string (auch as filt). Return
nothing if no return value is required.

putlog

    void putlog (int logmode, char *channel, char *format, ...)

Adds text to a logfile (determined by logmode and channel). This text
will also output to any users' consoles if they have the specified
console mode enabled.

WHAT TO DO WITH A MODULE?

If you have written a module and feel that you wish to share it with the
rest of the Eggdrop community, find us in #eggdrop on Libera. Make sure
you have a nice descriptive text (modulename.desc) to describe it, and
make sure to mention in your text file which version Eggdrop the module
is written for.
