config: add pidfile directive, defaults to $(rundir)/knot.pid

issue #67

src/knot/conf/cf-parse.y

@@ -531,11 +531,7 @@ system:
  | system NSID TEXT ';' { new_config->nsid = $3.t; new_config->nsid_len = strlen(new_config->nsid); }
  | system STORAGE TEXT ';' { new_config->storage = $3.t; }
  | system RUNDIR TEXT ';' { new_config->rundir = $3.t; }
- | system PIDFILE TEXT ';' {
-      fprintf(stderr, "warning: Config option 'system.pidfile' is deprecated "
-	         "and has no effect. Use 'rundir' instead.\n");
-      free($3.t);
- }
+ | system PIDFILE TEXT ';' { new_config->pidfile = $3.t; }
  | system KEY TSIG_ALGO_NAME TEXT ';' {
      fprintf(stderr, "warning: Config option 'system.key' is deprecated "
 		     "and has no effect.\n");

src/knot/conf/conf.c

@@ -680,6 +680,10 @@ void conf_truncate(conf_t *conf, int unload_hooks)
 		free(conf->rundir);
 		conf->rundir = 0;
 	}
+	if (conf->pidfile) {
+		free(conf->pidfile);
+		conf->pidfile = 0;
+	}
 	if (conf->nsid) {
 		free(conf->nsid);
 		conf->nsid = 0;

src/knot/conf/conf.h

@@ -194,7 +194,8 @@ typedef struct conf_t {
 	char *hostname; /*!< Host name to return on CH TXT hostname.{bind,server} */
 	char *version;  /*!< Version for CH TXT version.{bind|server} */
 	char *storage;  /*!< Persistent storage path for databases and such. */
-	char *rundir;  /*!< Run-time directory path. */
+	char *rundir;   /*!< Run-time directory path. */
+	char *pidfile;  /*!< PID file location. */
 	char *nsid;     /*!< Server's NSID. */
 	size_t nsid_len;/*!< Server's NSID length. */
 	int   workers;  /*!< Number of workers per interface. */

src/knot/ctl/process.c

@@ -39,8 +39,12 @@ char* pid_filename()
 
 	/* Read configuration. */
 	char* ret = NULL;
-	if (conf() && conf()->rundir != NULL) {
-		ret = strcdup(conf()->rundir, "/knot.pid");
+
+	if (conf()) {
+		if (conf()->pidfile != NULL)
+			ret = strdup(conf()->pidfile);
+		else if (conf()->rundir != NULL)
+			ret = strcdup(conf()->rundir, "/knot.pid");
 	}
 
 	rcu_read_unlock();