[v2,5/5] Avoid re-opening and reading configuration file

diff --git a/core/artifacts_versions.c b/core/artifacts_versions.c
index 9c1251c..90b5b32 100644
--- a/core/artifacts_versions.c
+++ b/core/artifacts_versions.c
@@ -129,10 +129,10 @@  static int versions_settings(void *setting, void *data)
 	return 0;
 }
 
-void get_sw_versions(char *cfgname, struct swupdate_cfg *sw)
+void get_sw_versions(swupdate_cfg_handle *handle, struct swupdate_cfg *sw)
 {
 	/* Try to read versions from configuration file */
-	if (cfgname && read_module_settings(cfgname, "versions", versions_settings, sw) == 0) {
+	if (handle != NULL && read_module_settings(handle, "versions", versions_settings, sw) == 0) {
 		return;
 	}
 	/* If not found, fall back to a legacy file in the format "<image name> <version>" */
@@ -140,7 +140,7 @@  void get_sw_versions(char *cfgname, struct swupdate_cfg *sw)
 }
 #else
 
-void get_sw_versions(char __attribute__ ((__unused__)) *cfgname,
+void get_sw_versions(swupdate_cfg_handle  __attribute__ ((__unused__))*handle,
 			struct swupdate_cfg *sw)
 {
 	read_sw_version_file(sw);
diff --git a/core/pctl.c b/core/pctl.c
index 01ad540..481f077 100644
--- a/core/pctl.c
+++ b/core/pctl.c
@@ -165,19 +165,16 @@  static int spawn_process(struct swupdate_task *task,
 	}
 }
 
-static void start_swupdate_subprocess(sourcetype type,
-			const char *name, const char *cfgfile,
+static void start_swupdate_subprocess(sourcetype type, const char *name,
+			uid_t run_as_userid, gid_t run_as_groupid,
+			const char* cfgfile,
 			int argc, char **argv,
 			swupdate_process start,
 			const char *cmdline)
 {
-	uid_t uid;
-	gid_t gid;
-
-	read_settings_user_id(cfgfile, name, &uid, &gid);
 	procs[nprocs].name = name;
 	procs[nprocs].type = type;
-	if (spawn_process(&procs[nprocs], uid, gid, cfgfile, argc, argv, start, cmdline) < 0) {
+	if (spawn_process(&procs[nprocs], run_as_userid, run_as_groupid, cfgfile, argc, argv, start, cmdline) < 0) {
 		ERROR("Spawning %s failed, exiting process...", name);
 		exit(1);
 	}
@@ -188,19 +185,22 @@  static void start_swupdate_subprocess(sourcetype type,
 
 
 void start_subprocess_from_file(sourcetype type, const char *name,
+			uid_t run_as_userid, gid_t run_as_groupid,
 			const char *cfgfile,
 			int argc, char **argv,
 			const char *cmdline)
 {
-	start_swupdate_subprocess(type, name, cfgfile, argc, argv, NULL, cmdline);
+	start_swupdate_subprocess(type, name, run_as_userid, run_as_groupid, cfgfile, argc, argv, NULL, cmdline);
 }
 
-void start_subprocess(sourcetype type, const char *name, const char *cfgfile,
+void start_subprocess(sourcetype type, const char *name,
+			uid_t run_as_userid, gid_t run_as_groupid,
+			const char *cfgfile,
 			int argc, char **argv,
 			swupdate_process start)
 {
 
-	start_swupdate_subprocess(type, name, cfgfile, argc, argv, start, NULL);
+	start_swupdate_subprocess(type, name, run_as_userid, run_as_groupid, cfgfile, argc, argv, start, NULL);
 }
 
 /*
diff --git a/core/swupdate.c b/core/swupdate.c
index f783c72..8e97567 100644
--- a/core/swupdate.c
+++ b/core/swupdate.c
@@ -548,13 +548,18 @@  int main(int argc, char **argv)
 		}
 	}
 
+	swupdate_cfg_handle *p_handle = NULL;
 	/* Load configuration file */
 	if (cfgfname != NULL) {
+		swupdate_cfg_handle handle;
+		int ret = swupdate_cfg_init(&handle, cfgfname);
+
 		/*
 		 * 'globals' section is mandatory if configuration file is specified.
 		 */
-		int ret = read_module_settings(cfgfname, "globals",
-					       read_globals_settings, &swcfg);
+		if (ret == 0) {
+			ret = read_module_settings(&handle, "globals", read_globals_settings, &swcfg);
+		}
 		if (ret != 0) {
 			/*
 			 * Exit on -ENODATA or -EINVAL errors.
@@ -563,6 +568,7 @@  int main(int argc, char **argv)
 			    "Error parsing configuration file: %s, exiting.\n",
 			    ret == -ENODATA ? "'globals' section missing"
 					    : "cannot read");
+			swupdate_cfg_destroy(&handle);
 			exit(EXIT_FAILURE);
 		}
 
@@ -572,11 +578,11 @@  int main(int argc, char **argv)
 		 * The following sections are optional, hence -ENODATA error code is
 		 * ignored if the section is not found. -EINVAL will not happen here.
 		 */
-		(void)read_module_settings(cfgfname, "logcolors",
-					   read_console_settings, &swcfg);
+		(void)read_module_settings(&handle, "logcolors", read_console_settings, &swcfg);
+		(void)read_module_settings(&handle, "processes", read_processes_settings, &swcfg);
 
-		(void)read_module_settings(cfgfname, "processes",
-					   read_processes_settings, &swcfg);
+		/* save the handle for later usage */
+		p_handle = &handle;
 	}
 
 	/*
@@ -828,7 +834,7 @@  int main(int argc, char **argv)
 	}
 
 	/* Read sw-versions */
-	get_sw_versions(cfgfname, &swcfg);
+	get_sw_versions(p_handle, &swcfg);
 
 	/*
 	 *  Start daemon if just a check is required
@@ -841,7 +847,10 @@  int main(int argc, char **argv)
 	/* Start embedded web server */
 #if defined(CONFIG_MONGOOSE)
 	if (opt_w) {
-		start_subprocess(SOURCE_WEBSERVER, "webserver",
+		uid_t uid;
+		gid_t gid;
+		read_settings_user_id(p_handle, "webserver", &uid, &gid);
+		start_subprocess(SOURCE_WEBSERVER, "webserver", uid, gid,
 				 cfgfname, ac, av,
 				 start_mongoose);
 		freeargs(av);
@@ -850,7 +859,10 @@  int main(int argc, char **argv)
 
 #if defined(CONFIG_SURICATTA)
 	if (opt_u) {
-		start_subprocess(SOURCE_SURICATTA, "suricatta",
+		uid_t uid;
+		gid_t gid;
+		read_settings_user_id(p_handle, "suricatta", &uid, &gid);
+		start_subprocess(SOURCE_SURICATTA, "suricatta", uid, gid,
 				 cfgfname, argcount,
 				 argvalues, start_suricatta);
 
@@ -860,7 +872,10 @@  int main(int argc, char **argv)
 
 #ifdef CONFIG_DOWNLOAD
 	if (opt_d) {
-		start_subprocess(SOURCE_DOWNLOADER, "download",
+		uid_t uid;
+		gid_t gid;
+		read_settings_user_id(p_handle, "download", &uid, &gid);
+		start_subprocess(SOURCE_DOWNLOADER, "download", uid, gid,
 				 cfgfname, dwlac,
 				 dwlav, start_download);
 		freeargs(dwlav);
@@ -877,7 +892,10 @@  int main(int argc, char **argv)
 
 		dwlav[dwlac] = NULL;
 
-		start_subprocess_from_file(SOURCE_UNKNOWN, proc->name,
+		uid_t uid;
+		gid_t gid;
+		read_settings_user_id(p_handle, proc->name, &uid, &gid);
+		start_subprocess_from_file(SOURCE_UNKNOWN, proc->name, uid, gid,
 					   cfgfname, dwlac,
 					   dwlav, dwlav[0]);
 
@@ -904,6 +922,10 @@  int main(int argc, char **argv)
 	sa.sa_handler = sigterm_handler;
 	sigaction(SIGTERM, &sa, NULL);
 
+	if (p_handle != NULL) {
+		swupdate_cfg_destroy(p_handle);
+	}
+
 	/*
 	 * Go into supervisor loop
 	 */
diff --git a/corelib/downloader.c b/corelib/downloader.c
index cda5cb1..600e4c8 100644
--- a/corelib/downloader.c
+++ b/corelib/downloader.c
@@ -108,7 +108,12 @@  static channel_data_t channel_options = {
 int start_download(const char *fname, int argc, char *argv[])
 {
 	if (fname) {
-		read_module_settings(fname, "download", download_settings, &channel_options);
+		swupdate_cfg_handle handle;
+		int ret = swupdate_cfg_init(&handle, fname);
+		if (ret == 0) {
+			read_module_settings(&handle, "download", download_settings, &channel_options);
+		}
+		swupdate_cfg_destroy(&handle);
 	}
 
 	/* reset to optind=1 to parse download's argument vector */
diff --git a/corelib/swupdate_settings.c b/corelib/swupdate_settings.c
index 1802436..53f0d89 100644
--- a/corelib/swupdate_settings.c
+++ b/corelib/swupdate_settings.c
@@ -10,6 +10,7 @@ 
  * starting swupdate with a long list of parameters.
  */
 
+#include <libconfig.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -53,6 +54,9 @@  static int read_settings_file(config_t *cfg, const char *filename)
 {
 	int ret;
 
+ 	if (!filename)
+		return -EINVAL;
+
 	DEBUG("Reading config file %s", filename);
 	ret = config_read_file(cfg, filename);
 	if (ret != CONFIG_TRUE) {
@@ -67,36 +71,23 @@  static int read_settings_file(config_t *cfg, const char *filename)
 	return ret;
 }
 
-int read_module_settings(const char *filename, const char *module, settings_callback fcn, void *data)
+int read_module_settings(swupdate_cfg_handle *handle, const char *module, settings_callback fcn, void *data)
 {
-	config_t cfg;
 	config_setting_t *elem;
 
-	if (!fcn || !filename)
-		return -EINVAL;
-
-	memset(&cfg, 0, sizeof(cfg));
-	config_init(&cfg);
-
-	if (read_settings_file(&cfg, filename) != CONFIG_TRUE) {
-		config_destroy(&cfg);
-		ERROR("Error reading configuration file, skipping....");
+	if (handle == NULL || !fcn)
 		return -EINVAL;
-	}
 
-	elem = find_settings_node(&cfg, module);
+	elem = find_settings_node(&handle->cfg, module);
 
 	if (!elem) {
 		DEBUG("No config settings found for module %s", module);
-		config_destroy(&cfg);
 		return -ENODATA;
 	}
 
 	DEBUG("Reading config settings for module %s", module);
 	fcn(elem, data);
 
-	config_destroy(&cfg);
-
 	return 0;
 }
 
@@ -110,7 +101,7 @@  static int get_run_as(void *elem, void *data)
 	return 0;
 }
 
-int read_settings_user_id(const char *filename, const char *module, uid_t *userid, gid_t *groupid)
+int read_settings_user_id(swupdate_cfg_handle *handle, const char *module, uid_t *userid, gid_t *groupid)
 {
 	struct run_as ids;
 	int ret;
@@ -118,7 +109,7 @@  int read_settings_user_id(const char *filename, const char *module, uid_t *useri
 	*userid = ids.userid = getuid();
 	*groupid = ids.groupid = getgid();
 
-	ret = read_module_settings(filename, module, get_run_as, &ids);
+	ret = read_module_settings(handle, module, get_run_as, &ids);
 	if (ret)
 		return -EINVAL;
 
@@ -162,3 +153,25 @@  int settings_into_dict(void *settings, void *data)
 
 	return 0;
 }
+
+/*
+ * Initialize handle with the settings found in filename.
+ * This allocates memory which needs to be released in swupdate_cfg_destroy().
+ */
+int swupdate_cfg_init(swupdate_cfg_handle *handle, const char *filename)
+{
+	config_init(&handle->cfg);
+	if (read_settings_file(&handle->cfg, filename) != CONFIG_TRUE) {
+		ERROR("Error reading configuration file %s", filename);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * This releases (internally) allocated memory by handle.
+ */
+void swupdate_cfg_destroy(swupdate_cfg_handle *handle)
+{
+	config_destroy(&handle->cfg);
+}
diff --git a/include/parselib.h b/include/parselib.h
index 5cbc255..84a51e2 100644
--- a/include/parselib.h
+++ b/include/parselib.h
@@ -85,8 +85,6 @@  void *get_node_json(json_object *root, const char **nodes);
 #define get_node_json(root, nodes)	(NULL)
 #endif
 
-typedef int (*settings_callback)(void *elem, void *data);
-
 const char *get_field_string(parsertype p, void *e, const char *path);
 void get_field_string_with_size(parsertype p, void *e, const char *path,
 				char *d, size_t n);
diff --git a/include/pctl.h b/include/pctl.h
index de5f3b5..84cf549 100644
--- a/include/pctl.h
+++ b/include/pctl.h
@@ -9,6 +9,7 @@ 
 #define _SWUPDATE_PCTL_H
 
 #include <swupdate_status.h>
+#include <sys/types.h>
 
 extern int pid;
 extern int sw_sockfd;
@@ -28,11 +29,15 @@  pthread_t start_thread(void *(* start_routine) (void *), void *arg);
 
 typedef int (*swupdate_process)(const char *cfgname, int argc, char **argv);
 
-void start_subprocess(sourcetype type, const char *name, const char *cfgfile,
+void start_subprocess(sourcetype type, const char *name,
+			uid_t run_as_userid, gid_t run_as_groupid,
+			const char *cfgfile,
 			int argc, char **argv,
 			swupdate_process start);
 
-void start_subprocess_from_file(sourcetype type, const char *name, const char *cfgfile,
+void start_subprocess_from_file(sourcetype type, const char *name,
+			uid_t run_as_userid, gid_t run_as_groupid,
+			const char *cfgfile,
 			int argc, char **argv,
 			const char *cmd);
 
diff --git a/include/swupdate_settings.h b/include/swupdate_settings.h
index c3b083d..3da7777 100644
--- a/include/swupdate_settings.h
+++ b/include/swupdate_settings.h
@@ -8,24 +8,48 @@ 
 #ifndef _SWUPDATE_SETTINGS_H
 #define _SWUPDATE_SETTINGS_H
 
+#include <unistd.h>
+
+typedef int (*settings_callback)(void *elem, void *data);
+
 #ifdef CONFIG_LIBCONFIG
-int read_module_settings(const char *filename, const char *module, settings_callback fcn, void *data);
-int read_settings_user_id(const char *filename, const char *module, uid_t *userid, gid_t *groupid);
+
+#include <libconfig.h>
+
+typedef struct {
+	config_t cfg;
+} swupdate_cfg_handle;
+
+int swupdate_cfg_init(swupdate_cfg_handle *handle, const char *filename);
+void swupdate_cfg_destroy(swupdate_cfg_handle *handle);
+int read_module_settings(swupdate_cfg_handle *handle, const char *module, settings_callback fcn, void *data);
+int read_settings_user_id(swupdate_cfg_handle *handle, const char *module, uid_t *userid, gid_t *groupid);
 int settings_into_dict(void *settings, void *data);
 #else
-#include <unistd.h>
-static inline int read_module_settings(const char __attribute__ ((__unused__))*filename,
-		const char __attribute__ ((__unused__)) *module,
-		settings_callback __attribute__ ((__unused__)) fcn,
-		void __attribute__ ((__unused__)) *data)
+
+typedef struct {} swupdate_cfg_handle;
+
+static inline int swupdate_cfg_init(swupdate_cfg_handle __attribute__ ((__unused__))*handle,
+		const char __attribute__ ((__unused__))*filename)
 {
 	return -1;
 }
 
+static inline void swupdate_cfg_destroy(swupdate_cfg_handle __attribute__ ((__unused__))*handle) {
+	return;
+}
+
+static inline int read_module_settings(swupdate_cfg_handle __attribute__ ((__unused__))*handle,
+		const char __attribute__ ((__unused__))*module,
+		settings_callback __attribute__ ((__unused__))fcn,
+		void __attribute__ ((__unused__))*data) {
+	return -1;
+};
+
 /*
  * Without LIBCONFIG, let run with current user
  */
-static inline int read_settings_user_id(const char __attribute__ ((__unused__))*filename,
+static inline int read_settings_user_id(swupdate_cfg_handle __attribute__ ((__unused__))*handle,
 					const char __attribute__ ((__unused__))*module,
 					uid_t *userid, gid_t *groupid)
 {
diff --git a/include/util.h b/include/util.h
index a0edd3e..ad2e90c 100644
--- a/include/util.h
+++ b/include/util.h
@@ -17,6 +17,7 @@ 
 #endif
 #include "swupdate.h"
 #include "swupdate_status.h"
+#include "swupdate_settings.h"
 #include "compat.h"
 
 #define NOTIFY_BUF_SIZE 	2048
@@ -208,7 +209,7 @@  char *substring(const char *src, int first, int len);
 size_t snescape(char *dst, size_t n, const char *src);
 void freeargs (char **argv);
 int get_hw_revision(struct hw_type *hw);
-void get_sw_versions(char *cfgfname, struct swupdate_cfg *sw);
+void get_sw_versions(swupdate_cfg_handle *handle, struct swupdate_cfg *sw);
 int compare_versions(const char* left_version, const char* right_version);
 int hwid_match(const char* rev, const char* hwrev);
 int check_hw_compatibility(struct swupdate_cfg *cfg);
diff --git a/mongoose/mongoose_interface.c b/mongoose/mongoose_interface.c
index cae9e89..9014a71 100644
--- a/mongoose/mongoose_interface.c
+++ b/mongoose/mongoose_interface.c
@@ -504,7 +504,12 @@  int start_mongoose(const char *cfgfname, int argc, char *argv[])
 	watchdog_conn = 0;
 
 	if (cfgfname) {
-		read_module_settings(cfgfname, "webserver", mongoose_settings, &opts);
+		swupdate_cfg_handle handle;
+		int ret = swupdate_cfg_init(&handle, cfgfname);
+		if (ret == 0) {
+			read_module_settings(&handle, "webserver", mongoose_settings, &opts);
+		}
+		swupdate_cfg_destroy(&handle);
 	}
 
 	optind = 1;
diff --git a/suricatta/server_general.c b/suricatta/server_general.c
index 1803981..a12ee4b 100644
--- a/suricatta/server_general.c
+++ b/suricatta/server_general.c
@@ -604,11 +604,11 @@  server_op_res_t server_start(char *fname, int argc, char *argv[])
 	LIST_INIT(&server_general.configdata);
 
 	if (fname) {
-
-		read_module_settings(fname, "gservice", server_general_settings,
-					NULL);
-		read_module_settings(fname, "identify", settings_into_dict,
-					&server_general.configdata);
+		swupdate_cfg_handle handle;
+		swupdate_cfg_init(&handle, fname);
+		read_module_settings(&handle, "gservice", server_general_settings, NULL);
+		read_module_settings(&handle, "identify", settings_into_dict, &server_general.configdata);
+		swupdate_cfg_destroy(&handle);
 	}
 
 	if (loglevel >= DEBUGLEVEL) {
diff --git a/suricatta/server_hawkbit.c b/suricatta/server_hawkbit.c
index df48180..e95ea68 100644
--- a/suricatta/server_hawkbit.c
+++ b/suricatta/server_hawkbit.c
@@ -1650,19 +1650,21 @@  server_op_res_t server_start(char *fname, int argc, char *argv[])
 	LIST_INIT(&server_hawkbit.configdata);
 
 	if (fname) {
+		swupdate_cfg_handle handle;
+		swupdate_cfg_init(&handle, fname);
+
 		/*
 		 * Search "suricatta" section to be compatible with past
 		 */
-		read_module_settings(fname, "suricatta", server_hawkbit_settings,
-					NULL);
+		read_module_settings(&handle, "suricatta", server_hawkbit_settings, NULL);
 		/*
 		 * Then try "hawkBit" because each server has its own
 		 * section
 		 */
-		read_module_settings(fname, "hawkbit", server_hawkbit_settings,
-					NULL);
-		read_module_settings(fname, "identify", settings_into_dict,
-					&server_hawkbit.configdata);
+		read_module_settings(&handle, "hawkbit", server_hawkbit_settings, NULL);
+		read_module_settings(&handle, "identify", settings_into_dict, &server_hawkbit.configdata);
+
+		swupdate_cfg_destroy(&handle);
 	}
 
 	if (loglevel >= DEBUGLEVEL) {
diff --git a/suricatta/suricatta.c b/suricatta/suricatta.c
index 9e07efb..83b517a 100644
--- a/suricatta/suricatta.c
+++ b/suricatta/suricatta.c
@@ -181,9 +181,14 @@  int start_suricatta(const char *cfgfname, int argc, char *argv[])
 	 * First check for common properties that do not depend
 	 * from server implementation
 	 */
-	if (cfgfname)
-		read_module_settings(cfgfname, "suricatta", suricatta_settings,
-					NULL);
+	if (cfgfname) {
+		swupdate_cfg_handle handle;
+		int ret = swupdate_cfg_init(&handle, cfgfname);
+		if (ret == 0) {
+			read_module_settings(&handle, "suricatta", suricatta_settings, NULL);
+		}
+		swupdate_cfg_destroy(&handle);
+	}
 	optind = 1;
 	opterr = 0;