Add helper program for running services

We no longer need to keep entire scripts in init program (i.e. saving space)
and reduce the code and complexity of the init program.

The runsvc tool can later be extended to do more complex child setup, such
as configuring namespaces or seccomp without adding complexity or memory
footprint to init.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

6 files changed, 80 insertions, 300 deletions

diff --git a/initd/Makemodule.am b/initd/Makemodule.am
index 67515cc..f188c80 100644
--- a/initd/Makemodule.am
+++ b/initd/Makemodule.am
@@ -1,5 +1,5 @@
-init_SOURCES = initd/main.c initd/runlst.c initd/init.h initd/signal_linux.c
-init_SOURCES += initd/status.c initd/mksock.c initd/svclist.c initd/env.c
+init_SOURCES = initd/main.c initd/init.h initd/signal_linux.c initd/runsvc.c
+init_SOURCES += initd/status.c initd/mksock.c initd/svclist.c
 init_CPPFLAGS = $(AM_CPPFLAGS)
 init_CFLAGS = $(AM_CFLAGS)
 init_LDFLAGS = $(AM_LDFLAGS)
diff --git a/initd/env.c b/initd/env.c
deleted file mode 100644
index c6a9e65..0000000
--- a/initd/env.c
+++ /dev/null
@@ -1,137 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * Copyright (C) 2018 - David Oberhollenzer
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-#include <unistd.h>
-#include <string.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <fcntl.h>
-
-#include "init.h"
-#include "util.h"
-
-struct entry {
-	struct entry *next;
-	char data[];
-};
-
-extern char **environ;
-
-static void free_list(struct entry *list)
-{
-	struct entry *e;
-
-	while (list != NULL) {
-		e = list;
-		list = list->next;
-		free(e);
-	}
-}
-
-static struct entry *parse_list(rdline_t *rd)
-{
-	struct entry *e, *list = NULL;
-	char *ptr;
-
-	while (rdline(rd) == 0) {
-		ptr = rd->buffer;
-
-		while (*ptr != '\0' && *ptr != ' ' && *ptr != '=')
-			++ptr;
-
-		if (*ptr == ' ')
-			memmove(ptr, ptr + 1, strlen(ptr + 1) + 1);
-
-		if (*(ptr++) != '=') {
-			fprintf(stderr, "%s: %zu: line is not of the shape "
-					"'key = value', skipping\n",
-				rd->filename, rd->lineno);
-			continue;
-		}
-
-		if (*ptr == ' ')
-			memmove(ptr, ptr + 1, strlen(ptr + 1) + 1);
-
-		if (unescape(ptr)) {
-			fprintf(stderr, "%s: %zu: malformed string constant, "
-					"skipping\n",
-				rd->filename, rd->lineno);
-			continue;
-		}
-
-		e = calloc(1, sizeof(*e) + strlen(rd->buffer) + 1);
-		if (e == NULL)
-			goto fail_oom;
-
-		strcpy(e->data, rd->buffer);
-		e->next = list;
-		list = e;
-	}
-
-	return list;
-fail_oom:
-	fputs("out of memory\n", stderr);
-	free_list(list);
-	return NULL;
-}
-
-static struct entry *list_from_file(void)
-{
-	struct entry *list;
-	rdline_t rd;
-	int fd;
-
-	fd = open(ENVFILE, O_RDONLY);
-	if (fd < 0) {
-		perror(ENVFILE);
-		return NULL;
-	}
-
-	rdline_init(&rd, fd, ENVFILE, 0, NULL);
-	list = parse_list(&rd);
-	close(fd);
-	return list;
-}
-
-int initenv(void)
-{
-	struct entry *list, *e;
-	int i, count;
-	char **envp;
-
-	list = list_from_file();
-	if (list == NULL)
-		return -1;
-
-	for (count = 0, e = list; e != NULL; e = e->next)
-		++count;
-
-	envp = malloc((count + 1) * sizeof(char *));
-	if (envp == NULL) {
-		fputs("out of memory\n", stderr);
-		free_list(list);
-		return -1;
-	}
-
-	for (i = 0, e = list; e != NULL; e = e->next)
-		envp[i] = e->data;
-
-	envp[i] = NULL;
-
-	environ = envp;
-	return 0;
-}
diff --git a/initd/init.h b/initd/init.h
index 3510073..d07f310 100644
--- a/initd/init.h
+++ b/initd/init.h
@@ -27,7 +27,7 @@
 #include "telinit.h"
 #include "util.h"
 
-#define ENVFILE ETCPATH "/initd.env"
+#define RUNSVCBIN SCRIPTDIR "/runsvc"
 
 enum {
 	STATUS_OK = 0,
@@ -36,35 +36,20 @@ enum {
 	STATUS_STARTED,
 };
 
-/********** runlst.c **********/
+/********** runsvc.c **********/
 
 /*
-	Plow through an array of strings and execute each one, i.e. do
-	a fork() and exec().
+	Invoke the runsvc command to execute the comands of a service.
 
-	In the parent process, wait() until the child is done before
-	continuing through the list.
-
-	If ctty is not NULL, open it and redirect all I/O of the child
-	process to that file.
-
-	If everyhing works, the function returns EXIT_SUCCESS. If one child
-	does not exit with EXIT_SUCCESS, processing of the list is aborted
-	and the function returns the exit status of the failed process.
+	Returns the pid of the child process containing the runsvc instance.
 */
-int runlst_wait(exec_t *list, const char *ctty);
+pid_t runsvc(service_t *svc);
 
 /*
-	Does basically the same as runlst_wait, but asynchronously.
-
-	A child process is created that calls runlst_wait exits with the
-	result of runlst_wait. In the parent process, the function returns
-	immediately with the PID of the child process.
-
-	Alternatively, if num is 1, the child process directly exec()s the
-	given command.
+	Start a service using runsvc, but wait until the child process
+	terminats and return its exit status.
 */
-pid_t runlst(exec_t *list, const char *ctty);
+int runsvc_wait(service_t *svc);
 
 /********** status.c **********/
 
@@ -111,14 +96,6 @@ void svclist_add(service_t *svc);
 */
 service_t *svclist_remove(pid_t pid);
 
-/********** env.c **********/
-
-/*
-	Read /etc/initd.env (actually ENVFILE defined above)
-	and setup environment variables for init.
-*/
-int initenv(void);
-
 /********** signal_<platform>.c **********/
 
 /*
diff --git a/initd/main.c b/initd/main.c
index a1d6906..8adbe2f 100644
--- a/initd/main.c
+++ b/initd/main.c
@@ -48,7 +48,7 @@ static void handle_exited(service_t *svc)
 			}
 		}
 
-		svc->pid = runlst(svc->exec, svc->ctty);
+		svc->pid = runsvc(svc);
 		if (svc->pid == -1) {
 			print_status(svc->desc, STATUS_FAIL, false);
 			break;
@@ -104,16 +104,10 @@ static void start_runlevel(int level)
 		svc = cfg.targets[level];
 		cfg.targets[level] = svc->next;
 
-		if (svc->exec == NULL) {
-			print_status(svc->desc, STATUS_OK, false);
-			delsvc(svc);
-			continue;
-		}
-
 		if (svc->type == SVC_WAIT) {
 			print_status(svc->desc, STATUS_WAIT, false);
 
-			status = runlst_wait(svc->exec, svc->ctty);
+			status = runsvc_wait(svc);
 
 			print_status(svc->desc,
 				     status == EXIT_SUCCESS ?
@@ -121,7 +115,7 @@ static void start_runlevel(int level)
 				     true);
 			delsvc(svc);
 		} else {
-			svc->pid = runlst(svc->exec, svc->ctty);
+			svc->pid = runsvc(svc);
 			if (svc->pid == -1) {
 				print_status(svc->desc, STATUS_FAIL, false);
 				delsvc(svc);
@@ -193,7 +187,7 @@ int main(void)
 		return EXIT_FAILURE;
 	}
 
-	if (svcscan(SVCDIR, &cfg, 0)) {
+	if (svcscan(SVCDIR, &cfg, RDSVC_NO_EXEC | RDSVC_NO_CTTY)) {
 		fputs("Error reading service list from " SVCDIR "\n"
 			"Trying to continue anyway\n", stderr);
 	}
diff --git a/initd/runlst.c b/initd/runlst.c
deleted file mode 100644
index 83823f9..0000000
--- a/initd/runlst.c
+++ /dev/null
@@ -1,120 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * Copyright (C) 2018 - David Oberhollenzer
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-#include <sys/wait.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <fcntl.h>
-
-#include "init.h"
-
-static int child_setup(const char *ctty)
-{
-	int fd;
-
-	sigreset();
-
-	if (ctty != NULL) {
-		fd = open(ctty, O_RDWR);
-		if (fd < 0) {
-			perror(ctty);
-			return -1;
-		}
-
-		close(STDIN_FILENO);
-		close(STDOUT_FILENO);
-		close(STDERR_FILENO);
-
-		setsid();
-
-		dup2(fd, STDIN_FILENO);
-		dup2(fd, STDOUT_FILENO);
-		dup2(fd, STDERR_FILENO);
-		close(fd);
-	}
-
-	return 0;
-}
-
-static NORETURN void argv_exec(exec_t *e)
-{
-	char **argv = alloca(e->argc + 1), *ptr;
-	int i;
-
-	for (ptr = e->args, i = 0; i < e->argc; ++i, ptr += strlen(ptr) + 1)
-		argv[i] = ptr;
-
-	argv[i] = NULL;
-	execvp(argv[0], argv);
-	perror(argv[0]);
-	exit(EXIT_FAILURE);
-}
-
-int runlst_wait(exec_t *list, const char *ctty)
-{
-	pid_t ret, pid;
-	int status;
-
-	for (; list != NULL; list = list->next) {
-		pid = fork();
-
-		if (pid == 0) {
-			if (child_setup(ctty))
-				exit(EXIT_FAILURE);
-			argv_exec(list);
-		}
-
-		if (pid == -1) {
-			perror("fork");
-			return EXIT_FAILURE;
-		}
-
-		do {
-			ret = waitpid(pid, &status, 0);
-		} while (ret != pid);
-
-		if (!WIFEXITED(status))
-			return EXIT_FAILURE;
-
-		if (WEXITSTATUS(status) != EXIT_SUCCESS)
-			return WEXITSTATUS(status);
-	}
-
-	return EXIT_SUCCESS;
-}
-
-pid_t runlst(exec_t *list, const char *ctty)
-{
-	pid_t pid = fork();
-
-	if (pid == 0) {
-		if (child_setup(ctty))
-			exit(EXIT_FAILURE);
-
-		if (list->next != NULL)
-			exit(runlst_wait(list, NULL));
-
-		argv_exec(list);
-	}
-
-	if (pid == -1)
-		perror("fork");
-
-	return pid;
-}
diff --git a/initd/runsvc.c b/initd/runsvc.c
new file mode 100644
index 0000000..aba83b1
--- /dev/null
+++ b/initd/runsvc.c
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "init.h"
+
+pid_t runsvc(service_t *svc)
+{
+	char *argv[4], *envp[1];
+	pid_t pid;
+
+	argv[0] = (char *)RUNSVCBIN;
+	argv[1] = (char *)SVCDIR;
+	argv[2] = svc->fname;
+	argv[3] = NULL;
+
+	envp[0] = NULL;
+
+	pid = fork();
+
+	if (pid == -1)
+		perror("fork");
+
+	if (pid == 0) {
+		sigreset();
+		execve(argv[0], argv, envp);
+		perror(argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	return pid;
+}
+
+int runsvc_wait(service_t *svc)
+{
+	pid_t ret, pid = runsvc(svc);
+	int status;
+
+	if (pid == -1)
+		return EXIT_FAILURE;
+
+	do {
+		ret = waitpid(pid, &status, 0);
+	} while (ret != pid);
+
+	return WIFEXITED(status) ? WEXITSTATUS(status) : EXIT_FAILURE;
+}