odhcpd: change "-c" cmd line arg to take a dir

After the TZ support was added, odhcpd now reads two cfg files
potentially. Instead of adding a separate switch for the system UCI
file, I've changed the "-c" argument to take a directory. This is more
future-proof and also serves as a preparation for the global DUID PR
(which will necessitate reading from the UCI "network" file as well).

While I was at it, I also made some tiny improvements to the
odhcpd_reload() function to avoid an unnecessary allocation.

Signed-off-by: David Härdeman <david@hardeman.nu>
Link: https://github.com/openwrt/odhcpd/pull/291
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

3 files changed, 35 insertions, 13 deletions

diff --git a/src/config.c b/src/config.c
index 3e916ad..7bff307 100644
--- a/src/config.c
+++ b/src/config.c
@@ -41,14 +41,13 @@ struct config config = {
 	.dhcp_hostsfile = NULL,
 	.ra_piofolder = NULL,
 	.ra_piofolder_fd = -1,
-	.uci_cfgfile = "dhcp",
+	.uci_cfgdir = NULL,
 	.log_level = LOG_WARNING,
 	.log_level_cmdline = false,
 	.log_syslog = true,
 };
 
 struct sys_conf sys_conf = {
-	.uci_cfgfile = "system",
 	.posix_tz = NULL, // "timezone"
 	.posix_tz_len = 0,
 	.tzdb_tz = NULL, // "zonename"
@@ -2226,16 +2225,27 @@ void odhcpd_reload(void)
 {
 	struct uci_context *uci = uci_alloc_context();
 	struct interface *master = NULL, *i, *tmp;
+	char *uci_dhcp_path = "dhcp";
+	char *uci_system_path = "system";
 
 	if (!uci)
 		return;
 
+	if (config.uci_cfgdir) {
+		size_t dlen = strlen(config.uci_cfgdir);
+
+		uci_dhcp_path = alloca(dlen + sizeof("/dhcp"));
+		sprintf(uci_dhcp_path, "%s/dhcp", config.uci_cfgdir);
+		uci_system_path = alloca(dlen + sizeof("/system"));
+		sprintf(uci_system_path, "%s/system", config.uci_cfgdir);
+	}
+
 	vlist_update(&leases);
 	avl_for_each_element(&interfaces, i, avl)
 		clean_interface(i);
 
 	struct uci_package *dhcp = NULL;
-	if (!uci_load(uci, config.uci_cfgfile, &dhcp)) {
+	if (!uci_load(uci, uci_dhcp_path, &dhcp)) {
 		struct uci_element *e;
 
 		/* 1. Global settings */
@@ -2268,9 +2278,10 @@ void odhcpd_reload(void)
 		}
 		ipv6_pxe_dump();
 	}
+	uci_unload(uci, dhcp);
 
 	struct uci_package *system = NULL;
-	if (!uci_load(uci, sys_conf.uci_cfgfile, &system) && config.enable_tz == true) {
+	if (config.enable_tz && !uci_load(uci, uci_system_path, &system)) {
 		struct uci_element *e;
 
 		/* 1. System settings */
@@ -2280,12 +2291,12 @@ void odhcpd_reload(void)
 				set_timezone_info_from_uci(s);
 		}
 	}
+	uci_unload(uci, system);
 
 	if (config.dhcp_statefile) {
-		char *path = strdup(config.dhcp_statefile);
+		char *path = strdupa(config.dhcp_statefile);
 
 		mkdir_p(dirname(path), 0755);
-		free(path);
 	}
 
 	if (config.ra_piofolder) {
@@ -2374,8 +2385,6 @@ void odhcpd_reload(void)
 			close_interface(i);
 	}
 
-	uci_unload(uci, dhcp);
-	uci_unload(uci, system);
 	uci_free_context(uci);
 }
 
diff --git a/src/odhcpd.c b/src/odhcpd.c
index 0f314bf..38d96fd 100644
--- a/src/odhcpd.c
+++ b/src/odhcpd.c
@@ -91,7 +91,7 @@ static void print_usage(const char *app)
 #endif /* EXT_CER_ID */
 	       "\n"
 	       "\n"
-	       "	-c <path>	Use an alternative configuration file\n"
+	       "	-c <dir>	Read UCI configuration files from <dir>\n"
 	       "	-l <int>	Specify log level 0..7 (default %d)\n"
 	       "	-f		Log to stderr instead of syslog\n"
 	       "	-h		Print this help text and exit\n",
@@ -117,9 +117,23 @@ int main(int argc, char **argv)
 	while ((opt = getopt(argc, argv, "c:l:fh")) != -1) {
 		switch (opt) {
 		case 'c':
-			config.uci_cfgfile = realpath(optarg, NULL);
-			fprintf(stderr, "Configuration will be read from %s\n", config.uci_cfgfile);
+			struct stat sb;
+			char *path;
+
+			free(config.uci_cfgdir);
+			config.uci_cfgdir = NULL;
+
+			path = realpath(optarg, NULL);
+			if (!path || stat(path, &sb) || !S_ISDIR(sb.st_mode)) {
+				fprintf(stderr, "%s is not a directory, ignoring\n", optarg);
+				free(path);
+				break;
+			}
+
+			fprintf(stderr, "Configuration will be read from %s\n", path);
+			config.uci_cfgdir = path;
 			break;
+
 		case 'l':
 			config.log_level = (atoi(optarg) & LOG_PRIMASK);
 			config.log_level_cmdline = true;
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 693da99..f2e2e74 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -194,7 +194,7 @@ struct config {
 	char *ra_piofolder;
 	int ra_piofolder_fd;
 
-	char *uci_cfgfile;
+	char *uci_cfgdir;
 	int log_level;
 	bool log_level_cmdline;
 	bool log_syslog;
@@ -203,7 +203,6 @@ struct config {
 struct sys_conf {
 	uint8_t *posix_tz;
 	size_t posix_tz_len;
-	char *uci_cfgfile;
 	uint8_t *tzdb_tz;
 	size_t tzdb_tz_len;
 };