ccze - A robust log colorizer, plugin infrastructure
/* Plugin support */
typedef void (*ccze_plugin_startup_t) (void);
typedef void (*ccze_plugin_shutdown_t) (void);
typedef int (*ccze_plugin_handle_t) (const char *str, size_t length,
CCZE_DEFINE_PLUGIN (name, type, desc);
/* Display */
void ccze_addstr (ccze_color_t col, const char *str);
void ccze_newline (void);
void ccze_space (void);
void ccze_wordcolor_process_one (char *word, int slookup);
/* Helpers */
ccze_color_t ccze_http_action (const char *method);
void ccze_print_date (const char *date);
/* Command line */
char **ccze_plugin_argv_get (const char *name);
const char *ccze_plugin_name_get (void);
This manual page attempts to outline the internals of CCZE plugins:
how they work, how they are implemented, and how to add new ones.
There are four required entry points in a plugin: a startup, a shutdown
and a handler routine (more on these later), and an informational
The startup function must be of type ccze_plugin_startup_t. This is
called right after the module is loaded. Its purpose is to initialise
all kinds of module-specific global variables, such as the regular
The shutdown function is its counterpart: this is used to deallocate
any memory reserved by the startup code.
The core part of a plugin is the handler, of type ccze_plugin_handle_t.
This does the actual coloring. The string to process is passed in the
str argument, its length in length. The third argument, rest is a
pointer to a string. Unlike the first two, this argument is used only
When a handler processed a string, it must return a non-zero value, in
case it could not process it, the handler must return with zero. If
the string could be processed only partially, the part which was deemed
unknown by the handler must be passed back in the rest variable.
The fourth part, although the smallest part, is the most important.
Without this, the module is useless, it cannot be loaded. This part
tells CCZE what the startup, shutdown and handler functions are called.
To encourage good style, the little details of this structure will not
be disclosed in this manual page. Instead, the helper macro,
CCZE_DEFINE_PLUGIN will be explained.
CCZE_DEFINE_PLUGIN is the macro to use if one wants to make the plugin
loadable. Its first argument is an unquoted string: the name of the
plugin. The second part is the type of the plugin, it can be FULL,
PARTIAL or ANY. The last argument is a short description of the plugin.
It is assumed that the three functions mentioned earlier are called
ccze_name_setup, ccze_name_shutdown and ccze_name_handle, respectively.
A FULL plugin is one that accepts raw input, untouched by any other
plugin before, and processes it. On the other hand, a PARTIAL plugin
relies on previous ones preprocessing the input. For example, syslog
is a full plugin, on which ulogd, a partial plugin relies. The syslog
plugin processes the raw input from the logfile, adds colour to most of
it, save the actual message sent by a process, that is left to
subsequent plugins, like ulogd. An ANY plugin is one can act as both
With CCZE_DEFINE_PLUGINS one can place more than one plugin into one
There are two other helper functions, ccze_plugin_argv_get and
ccze_plugin_name_get. One can pass arguments to CCZE plugins, and these
is the function to retrieve them. While ccze_plugin_name_get returns
the name of the current plugin, ccze_plugin_argv_get returns a
NULL-terminated array, with each entry containing an argument.
The so-called display methods are the only supported interface to emit
something to the display. These handle both the normal, ncurses-based,
and the HTML output. This is a kind of abstraction so plugins will not
have to worry about the differences between the output formats.
The most important one is ccze_addstr, which takes a color (see ccze.h
for a list of supported color tags) and a string, and displays it
appropriately. The ccze_space and ccze_newline functions emit a space
and a newline, respectively.
Our last function, ccze_wordcolor_process_one passes word to the word
colourising engine. If the second argument, slookup is non-zero, the
engine will perform service lookups (like getent and friends).
We only have two helper methods: ccze_print_date, which simply prints
out the date in the appropriate colour, and ccze_http_action, which
given a HTTP method, returns the associated colour, in a format
suitable for ccze_addstr.
static char **ccze_foo_argv;
ccze_foo_handle (const char *str, size_t length, char **rest)
int i = 1;
if (strstr (str, "foo"))
ccze_addstr (CCZE_COLOR_GOODWORD, str);
if (strstr (str, ccze_foo_argv[i]))
ccze_addstr (CCZE_COLOR_GOODWORD, str);
ccze_foo_argv = ccze_plugin_argv_get (ccze_plugin_name_get ());
CCZE_DEFINE_PLUGIN (foo, PARTIAL, "Partial FOO coloriser.");
ccze was written by Gergely Nagy <email@example.com>, based
on colorize by Istvan Karaszi <firstname.lastname@example.org>.