init: Only do the init process setup if launched as "init"

We base this detection on the name of the binary: "init" means we've
been started as an init system.

When not running as an init system, we can skip the basic initialisation
as systemd or any other init system would have done that for us.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>

Author: Damien Lespiau

src/init.c

@@ -1,4 +1,5 @@
 #define _GNU_SOURCE
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -40,6 +41,9 @@ struct hyper_ctl ctl;
 
 sigset_t orig_mask;
 
+/* is_init is true when hyperstart is run as the Linux init process */
+static bool is_init;
+
 static int hyper_handle_exit(struct hyper_pod *pod);
 
 static int hyper_set_win_size(char *json, int length)
@@ -1266,6 +1270,9 @@ static int hyper_loop(void)
 
 static int hyper_setup_init_process(void)
 {
+	if (!is_init)
+		return 0;
+
 	/* mount the base file systems */
 	if (mount("proc", "/proc", "proc", MS_NOSUID| MS_NODEV| MS_NOEXEC, NULL) == -1) {
 		perror("mount proc failed");
@@ -1307,7 +1314,10 @@ static int hyper_setup_init_process(void)
 
 int main(int argc, char *argv[])
 {
-	char *cmdline, *ctl_serial, *tty_serial;
+	char *binary_name, *cmdline, *ctl_serial, *tty_serial;
+
+	binary_name = basename(argv[0]);
+	is_init = strncmp(binary_name, "init", 5) == 0;
 
 	if (hyper_setup_init_process() < 0) {
 		return -1;