Documentation.

conf/conf.c

@@ -6,6 +6,37 @@
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
 
+/**
+ * DOC: Configuration manager
+ *
+ * Configuration of BIRD is complex, but straightforward. There exist three
+ * modules taking care of the configuration: config manager (which takes care
+ * of storage of config information and controls switching between configs),
+ * lexical analyser and parser.
+ *
+ * The configuration manager stores each config as a &config structure
+ * accompanied by a linear pool from which all information associated
+ * with the config and pointed to by the &config structure is allocated.
+ *
+ * There can exist up four different configurations at one time: an active
+ * one (pointed to by @config), configuration we are just switching from
+ * (@old_config), one queued for the next reconfiguration (@future_config;
+ * if it's non-%NULL and the user wants to reconfigure once again, we just
+ * free the previous queued config and replace it with the new one) and
+ * finally a config being parsed (@new_config).
+ *
+ * Loading of new configuration is very simple: just call config_alloc()
+ * to get a new &config structure, then use config_parse() to parse a
+ * configuration file and fill all information in the structure
+ * and finally ask the config manager to switch to the new
+ * config by calling config_commit().
+ *
+ * CLI commands are parsed in a very similar way -- there is also a stripped-down
+ * &config structure associated with them and they are lexed and parsed by the
+ * same functions, only a special fake token is prepended before the command
+ * text to make the parser recognize only the rules corresponding to CLI commands.
+ */
+
 #include <setjmp.h>
 #include <stdarg.h>
 
@@ -29,6 +60,14 @@ static event *config_event;
 int shutting_down;
 bird_clock_t boot_time;
 
+/**
+ * config_alloc - allocate a new configuration
+ * @name: name of the config
+ *
+ * This function creates new &config structure, attaches a resource
+ * pool and a linear memory pool to it and makes it available for
+ * further use. Returns a pointer to the structure.
+ */
 struct config *
 config_alloc(byte *name)
 {
@@ -45,6 +84,19 @@ config_alloc(byte *name)
   return c;
 }
 
+/**
+ * config_parse - parse a configuration
+ * @c: configuration
+ *
+ * config_parse() reads input by calling a hook function pointed to
+ * by @cf_read_hook and parses it according to the configuration
+ * grammar. It also calls all the preconfig and postconfig hooks
+ * before resp. after parsing.
+ *
+ * Result: 1 if the config has been parsed successfully, 0 if any
+ * error has occured (such as anybody calling cf_error()) and
+ * the @err_msg field has been set to the error message.
+ */
 int
 config_parse(struct config *c)
 {
@@ -66,6 +118,13 @@ config_parse(struct config *c)
   return 1;
 }
 
+/**
+ * cli_parse - parse a CLI command
+ * @c: temporary config structure
+ *
+ * cli_parse() is similar to config_parse(), but instead of a configuration,
+ * it parses a CLI command. See the CLI module for more information.
+ */
 int
 cli_parse(struct config *c)
 {
@@ -79,6 +138,13 @@ cli_parse(struct config *c)
   return 1;
 }
 
+/**
+ * config_free - free a configuration
+ * @c: configuration to be freed
+ *
+ * This function takes a &config structure and frees all resources
+ * associated with it.
+ */
 void
 config_free(struct config *c)
 {
@@ -169,6 +235,27 @@ config_done(void *unused)
     }
 }
 
+/**
+ * config_commit - commit a configuration
+ * @c: new configuration
+ *
+ * When a configuration is parsed and prepared for use, the
+ * config_commit() function starts the process of reconfiguration.
+ * It checks whether there is already a reconfiguration in progress
+ * in which case it just queues the new config for later processing.
+ * Else it notifies all modules about the new configuration by calling
+ * their commit() functions which can either accept it immediately
+ * or call config_add_obstacle() to report that they need some time
+ * to complete the reconfiguration. After all such obstacles are removed
+ * using config_del_obstacle(), the old configuration is freed and
+ * everything runs according to the new one.
+ *
+ * Result: %CONF_DONE if the configuration has been accepted immediately,
+ * %CONF_PROGRESS if it will take some time to switch to it, %CONF_QUEUED
+ * if it's been queued due to another reconfiguration being in progress now
+ * or %CONF_SHUTDOWN if BIRD is in shutdown mode and no new configurations
+ * are accepted.
+ */
 int
 config_commit(struct config *c)
 {
@@ -208,6 +295,12 @@ config_commit(struct config *c)
   return CONF_PROGRESS;
 }
 
+/**
+ * order_shutdown - order BIRD shutdown
+ *
+ * This function initiates shutdown of BIRD. It's accomplished by asking
+ * for switching to an empty configuration.
+ */
 void
 order_shutdown(void)
 {
@@ -225,6 +318,14 @@ order_shutdown(void)
   shutting_down = 1;
 }
 
+/**
+ * cf_error - report a configuration error
+ * @msg: printf-like format string
+ *
+ * cf_error() can be called during execution of config_parse(), that is
+ * from the parser, a preconfig hook or a postconfig hook, to report an
+ * error in the configuration.
+ */
 void
 cf_error(char *msg, ...)
 {
@@ -239,6 +340,15 @@ cf_error(char *msg, ...)
   longjmp(conf_jmpbuf, 1);
 }
 
+/**
+ * cfg_strdup - copy a string to config memory
+ * @c: string to copy
+ *
+ * cfg_strdup() creates a new copy of the string in the memory
+ * pool associated with the configuration being currently parsed.
+ * It's often used when a string literal occurs in the configuration
+ * and we want to preserve it for further use.
+ */
 char *
 cfg_strdup(char *c)
 {