1 files changed, 157 insertions, 0 deletions
diff --git a/src/sulogin-shell/sulogin-shell.c b/src/sulogin-shell/sulogin-shell.c
new file mode 100644
index 0000000..b26663d
--- /dev/null
+++ b/src/sulogin-shell/sulogin-shell.c
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2017 Felipe Sateler
+***/
+
+#include <errno.h>
+#include <sys/prctl.h>
+
+#include "sd-bus.h"
+
+#include "bus-error.h"
+#include "bus-locator.h"
+#include "bus-unit-util.h"
+#include "bus-util.h"
+#include "constants.h"
+#include "env-util.h"
+#include "initrd-util.h"
+#include "log.h"
+#include "main-func.h"
+#include "proc-cmdline.h"
+#include "process-util.h"
+#include "signal-util.h"
+#include "special.h"
+#include "unit-def.h"
+
+static int target_is_inactive(sd_bus *bus, const char *target) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_free_ char *path = NULL, *state = NULL;
+        int r;
+
+        path = unit_dbus_path_from_name(target);
+        if (!path)
+                return log_oom();
+
+        r = sd_bus_get_property_string(bus,
+                                       "org.freedesktop.systemd1",
+                                       path,
+                                       "org.freedesktop.systemd1.Unit",
+                                       "ActiveState",
+                                       &error,
+                                       &state);
+        if (r < 0)
+                return log_error_errno(r, "Failed to retrieve unit state: %s", bus_error_message(&error, r));
+
+        return streq_ptr(state, "inactive");
+}
+
+static int start_target(sd_bus *bus, const char *target) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        int r;
+
+        log_info("Starting %s", target);
+
+        /* Start this unit only if we can replace basic.target with it */
+        r = bus_call_method(
+                        bus,
+                        bus_systemd_mgr,
+                        "StartUnit",
+                        &error,
+                        NULL,
+                        "ss", target, "isolate");
+
+        if (r < 0)
+                return log_error_errno(r, "Failed to start %s: %s", target, bus_error_message(&error, r));
+
+        return 0;
+}
+
+static int fork_wait(const char* const cmdline[]) {
+        pid_t pid;
+        int r;
+
+        r = safe_fork("(sulogin)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                /* Child */
+                execv(cmdline[0], (char**) cmdline);
+                log_error_errno(errno, "Failed to execute %s: %m", cmdline[0]);
+                _exit(EXIT_FAILURE); /* Operational error */
+        }
+
+        return wait_for_terminate_and_check(cmdline[0], pid, WAIT_LOG_ABNORMAL);
+}
+
+static void print_mode(const char* mode) {
+        printf("You are in %s mode. After logging in, type \"journalctl -xb\" to view\n"
+               "system logs, \"systemctl reboot\" to reboot, or \"exit\"\n" "to continue bootup.\n", mode);
+        fflush(stdout);
+}
+
+static int run(int argc, char *argv[]) {
+        const char* sulogin_cmdline[] = {
+                SULOGIN,
+                NULL,             /* --force */
+                NULL
+        };
+        bool force = false;
+        int r;
+
+        log_setup();
+
+        print_mode(argc > 1 ? argv[1] : "");
+
+        if (getenv_bool("SYSTEMD_SULOGIN_FORCE") > 0)
+                force = true;
+
+        if (!force) {
+                /* We look the argument in the kernel cmdline under the same name as the environment variable
+                 * to express that this is not supported at the same level as the regular kernel cmdline
+                 * switches. */
+                r = proc_cmdline_get_bool("SYSTEMD_SULOGIN_FORCE", /* flags = */ 0, &force);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to parse SYSTEMD_SULOGIN_FORCE from kernel command line, ignoring: %m");
+        }
+
+        if (force)
+                /* allows passwordless logins if root account is locked. */
+                sulogin_cmdline[1] = "--force";
+
+        for (;;) {
+                _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
+
+                (void) fork_wait(sulogin_cmdline);
+
+                r = bus_connect_system_systemd(&bus);
+                if (r < 0) {
+                        log_warning_errno(r, "Failed to get D-Bus connection: %m");
+                        goto fallback;
+                }
+
+                log_info("Reloading system manager configuration.");
+                r = bus_service_manager_reload(bus);
+                if (r < 0)
+                        goto fallback;
+
+                const char *target = in_initrd() ? SPECIAL_INITRD_TARGET : SPECIAL_DEFAULT_TARGET;
+
+                r = target_is_inactive(bus, target);
+                if (r < 0)
+                        goto fallback;
+                if (!r) {
+                        log_warning("%s is not inactive. Please review the %s setting.", target, target);
+                        goto fallback;
+                }
+
+                if (start_target(bus, target) >= 0)
+                        break;
+
+        fallback:
+                log_warning("Fallback to the single-user shell.");
+        }
+
+        return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);