rc-update: add 'export' sub-command

allows users to export variables into the starting environment of
services, with usage `rc-update export FOO NYA=MEW`

Author: navi-desu

man/rc-update.8

@@ -27,6 +27,10 @@
 .Ar service
 .Op Ar runlevel ...
 .Nm
+.Op Fl a , -all
+.Ar export
+.Ar variable ...
+.Nm
 .Op Fl u , -update
 .Op Fl v , -verbose
 .Ar show
@@ -59,6 +63,10 @@ Delete the
 from the
 .Ar runlevel
 or the current one if none given.
+.It Ar export Ar variable ...
+Exports listed
+.Ar variables
+to the starting environment of all services.
 .It Ar show
 Show all enabled services and the runlevels they belong to.  If you specify
 runlevels to show, then only those will be included in the output.

src/rc-update/rc-update.c

@@ -35,6 +35,7 @@ const char *extraopts = NULL;
 const char *usagestring = ""							\
 	"Usage: rc-update [options] add <service> [<runlevel>...]\n"	\
 	"   or: rc-update [options] del <service> [<runlevel>...]\n"	\
+	"   or: rc-update [options] export <variables>...\n"	\
 	"   or: rc-update [options] [show [<runlevel>...]]";
 const char getoptstring[] = "asu" getoptstring_COMMON;
 const struct option longopts[] = {
@@ -50,6 +51,8 @@ const char * const longopts_help[] = {
 	longopts_help_COMMON
 };
 
+extern const char **environ;
+
 /* Return the number of changes made:
  *  -1 = no changes (error)
  *   0 = no changes (nothing to do)
@@ -190,11 +193,26 @@ show(RC_STRINGLIST *runlevels, bool verbose)
 	rc_stringlist_free(services);
 }
 
+static void
+export(char *variable)
+{
+	char *value = variable;
+	variable = strsep(&value, "=");
+
+	if (!value && !(value = getenv(variable))) {
+		ewarn("%s: environment variable %s not set, skipping.", applet, variable);
+		return;
+	}
+
+	rc_export_variable(variable, value);
+}
+
 enum update_action {
 	DO_NONE,
 	DO_ADD,
 	DO_DELETE,
 	DO_SHOW,
+	DO_EXPORT
 };
 
 int main(int argc, char **argv)
@@ -239,6 +257,8 @@ int main(int argc, char **argv)
 			action = DO_DELETE;
 		} else if (strcmp(argv[optind], "show") == 0) {
 			action = DO_SHOW;
+		} else if (strcmp(argv[optind], "export") == 0) {
+			action = DO_EXPORT;
 		} else {
 			eerror("%s: invalid command '%s'", applet, argv[optind]);
 			usage(EXIT_FAILURE);
@@ -249,20 +269,22 @@ int main(int argc, char **argv)
 		action = DO_SHOW;
 
 	if (optind >= argc && action != DO_SHOW) {
-		eerror("%s: no service specified", applet);
+		eerror("%s: no %s specified", applet, action == DO_EXPORT ? "variable" : "service");
 		usage(EXIT_FAILURE);
 	}
 
-	service = argv[optind];
-	optind++;
+	if (action != DO_EXPORT) {
+		service = argv[optind];
+		optind++;
 
-	runlevels = rc_stringlist_new();
-	while (optind < argc) {
-		if (rc_runlevel_exists(argv[optind])) {
-			rc_stringlist_add(runlevels, argv[optind++]);
-		} else {
-			rc_stringlist_free(runlevels);
-			eerrorx("%s: '%s' is not a valid runlevel", applet, argv[optind]);
+		runlevels = rc_stringlist_new();
+		while (optind < argc) {
+			if (rc_runlevel_exists(argv[optind])) {
+				rc_stringlist_add(runlevels, argv[optind++]);
+			} else {
+				rc_stringlist_free(runlevels);
+				eerrorx("%s: '%s' is not a valid runlevel", applet, argv[optind]);
+			}
 		}
 	}
 
@@ -283,6 +305,10 @@ int main(int argc, char **argv)
 		rc_stringlist_sort(&runlevels);
 		show(runlevels, verbose);
 		goto exit;
+	case DO_EXPORT:
+		while (optind < argc)
+			export(argv[optind++]);
+		return 0;
 	case DO_ADD:
 		if (all_runlevels) {
 			rc_stringlist_free(runlevels);