From cad8ec5980d63253586d9f884649c45eed0667a1 Mon Sep 17 00:00:00 2001
From: Harald Hoyer <harald@redhat.com>
Date: Thu, 6 Mar 2014 16:35:02 +0100
Subject: [PATCH] systemctl: for switch-root check, if we switch to a systemd
 init

If "systemctl switch-root" is called with a specific "INIT" or
/proc/cmdline contains "init=", then systemd would not serialize
itsself.

Let systemctl check, if the new init is in the standard systemd
installation path and if so, clear the INIT parameter,
to let systemd serialize itsself.

Conflicts:
	src/systemctl/systemctl.c

(cherry picked from commit f39d4a08e746e703d562076a0f622eb91dbdcd3e)

Related: #1111199
---
 src/shared/util.h         | 13 +++++++++++++
 src/systemctl/systemctl.c | 35 ++++++++++++++++++++++++++---------
 2 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/src/shared/util.h b/src/shared/util.h
index 631a385..d11fa07 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -726,6 +726,19 @@ int unlink_noerrno(const char *path);
                 _c_;                                    \
         })
 
+#define strappenda3(a, b, c)                                    \
+        ({                                                      \
+                const char *_a_ = (a), *_b_ = (b), *_c_ = (c);  \
+                char *_d_;                                      \
+                size_t _x_, _y_, _z_;                           \
+                _x_ = strlen(_a_);                              \
+                _y_ = strlen(_b_);                              \
+                _z_ = strlen(_c_);                              \
+                _d_ = alloca(_x_ + _y_ + _z_ + 1);              \
+                strcpy(stpcpy(stpcpy(_d_, _a_), _b_), _c_);     \
+                _d_;                                            \
+        })
+
 #define procfs_file_alloca(pid, field)                                  \
         ({                                                              \
                 pid_t _pid_ = (pid);                                    \
diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index c738daf..1ca4fd3 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -4143,9 +4143,10 @@ static int show_enviroment(DBusConnection *bus, char **args) {
 }
 
 static int switch_root(DBusConnection *bus, char **args) {
+        _cleanup_free_ char *cmdline_init = NULL;
+        const char *root, *init;
         unsigned l;
-        const char *root;
-        _cleanup_free_ char *init = NULL;
+        int r;
 
         l = strv_length(args);
         if (l < 2 || l > 3) {
@@ -4156,19 +4157,35 @@ static int switch_root(DBusConnection *bus, char **args) {
         root = args[1];
 
         if (l >= 3)
-                init = strdup(args[2]);
+                init = args[2];
         else {
-                parse_env_file("/proc/cmdline", WHITESPACE,
-                               "init", &init,
-                               NULL);
+                r = parse_env_file("/proc/cmdline", WHITESPACE,
+                                   "init", &cmdline_init,
+                                   NULL);
+                if (r < 0)
+                        log_debug("Failed to parse /proc/cmdline: %s", strerror(-r));
 
-                if (!init)
-                        init = strdup("");
+                init = cmdline_init;
         }
         if (!init)
                 return log_oom();
 
-        log_debug("switching root - root: %s; init: %s", root, init);
+        if (isempty(init))
+                init = NULL;
+
+        if (init) {
+                const char *root_systemd_path = NULL, *root_init_path = NULL;
+
+                root_systemd_path = strappenda(root, "/" SYSTEMD_BINARY_PATH);
+                root_init_path = strappenda3(root, "/", init);
+
+                /* If the passed init is actually the same as the
+                 * systemd binary, then let's suppress it. */
+                if (files_same(root_init_path, root_systemd_path) > 0)
+                        init = NULL;
+        }
+
+        log_debug("Switching root - root: %s; init: %s", root, strna(init));
 
         return bus_method_call_with_reply(
                         bus,