core: split out reexecution code of main() into its own function
No functional changes, just an attempt to shorten main() a bit.
This commit is contained in:
Lennart Poettering
parent
0161d32b7b
commit
3c7878f94b
247
src/core/main.c
247
src/core/main.c
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@ -1589,6 +1589,130 @@ static void initialize_coredump(bool skip_setup) {
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(void) write_string_file("/proc/sys/kernel/core_pattern", "|/bin/false", 0);
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}
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static void do_reexecute(
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int argc,
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char *argv[],
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const struct rlimit *saved_rlimit_nofile,
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const struct rlimit *saved_rlimit_memlock,
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FDSet *fds,
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const char *switch_root_dir,
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const char *switch_root_init,
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const char **ret_error_message) {
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unsigned i, j, args_size;
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const char **args;
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int r;
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assert(saved_rlimit_nofile);
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assert(saved_rlimit_memlock);
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assert(ret_error_message);
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/* Close and disarm the watchdog, so that the new instance can reinitialize it, but doesn't get rebooted while
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* we do that */
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watchdog_close(true);
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/* Reset the RLIMIT_NOFILE to the kernel default, so that the new systemd can pass the kernel default to its
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* child processes */
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if (saved_rlimit_nofile->rlim_cur > 0)
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(void) setrlimit(RLIMIT_NOFILE, saved_rlimit_nofile);
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if (saved_rlimit_memlock->rlim_cur != (rlim_t) -1)
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(void) setrlimit(RLIMIT_MEMLOCK, saved_rlimit_memlock);
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if (switch_root_dir) {
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/* Kill all remaining processes from the initrd, but don't wait for them, so that we can handle the
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* SIGCHLD for them after deserializing. */
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broadcast_signal(SIGTERM, false, true);
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/* And switch root with MS_MOVE, because we remove the old directory afterwards and detach it. */
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r = switch_root(switch_root_dir, "/mnt", true, MS_MOVE);
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if (r < 0)
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log_error_errno(r, "Failed to switch root, trying to continue: %m");
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}
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args_size = MAX(6, argc+1);
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args = newa(const char*, args_size);
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if (!switch_root_init) {
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char sfd[DECIMAL_STR_MAX(int) + 1];
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/* First try to spawn ourselves with the right path, and with full serialization. We do this only if
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* the user didn't specify an explicit init to spawn. */
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assert(arg_serialization);
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assert(fds);
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xsprintf(sfd, "%i", fileno(arg_serialization));
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i = 0;
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args[i++] = SYSTEMD_BINARY_PATH;
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if (switch_root_dir)
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args[i++] = "--switched-root";
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args[i++] = arg_system ? "--system" : "--user";
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args[i++] = "--deserialize";
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args[i++] = sfd;
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args[i++] = NULL;
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assert(i <= args_size);
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/*
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* We want valgrind to print its memory usage summary before reexecution. Valgrind won't do this is on
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* its own on exec(), but it will do it on exit(). Hence, to ensure we get a summary here, fork() off
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* a child, let it exit() cleanly, so that it prints the summary, and wait() for it in the parent,
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* before proceeding into the exec().
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*/
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valgrind_summary_hack();
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(void) execv(args[0], (char* const*) args);
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log_debug_errno(errno, "Failed to execute our own binary, trying fallback: %m");
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}
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/* Try the fallback, if there is any, without any serialization. We pass the original argv[] and envp[]. (Well,
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* modulo the ordering changes due to getopt() in argv[], and some cleanups in envp[], but let's hope that
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* doesn't matter.) */
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arg_serialization = safe_fclose(arg_serialization);
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fds = fdset_free(fds);
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/* Reopen the console */
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(void) make_console_stdio();
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for (j = 1, i = 1; j < (unsigned) argc; j++)
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args[i++] = argv[j];
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args[i++] = NULL;
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assert(i <= args_size);
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/* Reenable any blocked signals, especially important if we switch from initial ramdisk to init=... */
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(void) reset_all_signal_handlers();
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(void) reset_signal_mask();
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if (switch_root_init) {
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args[0] = switch_root_init;
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(void) execv(args[0], (char* const*) args);
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log_warning_errno(errno, "Failed to execute configured init, trying fallback: %m");
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}
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args[0] = "/sbin/init";
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(void) execv(args[0], (char* const*) args);
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r = -errno;
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manager_status_printf(NULL, STATUS_TYPE_EMERGENCY,
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ANSI_HIGHLIGHT_RED " !! " ANSI_NORMAL,
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"Failed to execute /sbin/init");
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if (r == -ENOENT) {
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log_warning("No /sbin/init, trying fallback");
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args[0] = "/bin/sh";
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args[1] = NULL;
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(void) execv(args[0], (char* const*) args);
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log_error_errno(errno, "Failed to execute /bin/sh, giving up: %m");
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} else
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log_warning_errno(r, "Failed to execute /sbin/init, giving up: %m");
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*ret_error_message = "Failed to execute fallback shell";
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}
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int main(int argc, char *argv[]) {
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Manager *m = NULL;
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int r, retval = EXIT_FAILURE;
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@ -2199,121 +2323,14 @@ finish:
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mac_selinux_finish();
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if (reexecute) {
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const char **args;
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unsigned i, args_size;
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/* Close and disarm the watchdog, so that the new
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* instance can reinitialize it, but doesn't get
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* rebooted while we do that */
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watchdog_close(true);
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/* Reset the RLIMIT_NOFILE to the kernel default, so
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* that the new systemd can pass the kernel default to
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* its child processes */
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if (saved_rlimit_nofile.rlim_cur > 0)
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(void) setrlimit(RLIMIT_NOFILE, &saved_rlimit_nofile);
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if (saved_rlimit_memlock.rlim_cur != (rlim_t) -1)
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(void) setrlimit(RLIMIT_MEMLOCK, &saved_rlimit_memlock);
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if (switch_root_dir) {
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/* Kill all remaining processes from the
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* initrd, but don't wait for them, so that we
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* can handle the SIGCHLD for them after
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* deserializing. */
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broadcast_signal(SIGTERM, false, true);
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/* And switch root with MS_MOVE, because we remove the old directory afterwards and detach it. */
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r = switch_root(switch_root_dir, "/mnt", true, MS_MOVE);
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if (r < 0)
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log_error_errno(r, "Failed to switch root, trying to continue: %m");
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}
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args_size = MAX(6, argc+1);
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args = newa(const char*, args_size);
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if (!switch_root_init) {
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char sfd[DECIMAL_STR_MAX(int) + 1];
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/* First try to spawn ourselves with the right
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* path, and with full serialization. We do
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* this only if the user didn't specify an
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* explicit init to spawn. */
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assert(arg_serialization);
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assert(fds);
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xsprintf(sfd, "%i", fileno(arg_serialization));
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i = 0;
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args[i++] = SYSTEMD_BINARY_PATH;
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if (switch_root_dir)
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args[i++] = "--switched-root";
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args[i++] = arg_system ? "--system" : "--user";
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args[i++] = "--deserialize";
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args[i++] = sfd;
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args[i++] = NULL;
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assert(i <= args_size);
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/*
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* We want valgrind to print its memory usage summary before reexecution.
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* Valgrind won't do this is on its own on exec(), but it will do it on exit().
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* Hence, to ensure we get a summary here, fork() off a child, let it exit() cleanly,
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* so that it prints the summary, and wait() for it in the parent, before proceeding into the exec().
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*/
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valgrind_summary_hack();
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(void) execv(args[0], (char* const*) args);
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}
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/* Try the fallback, if there is any, without any
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* serialization. We pass the original argv[] and
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* envp[]. (Well, modulo the ordering changes due to
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* getopt() in argv[], and some cleanups in envp[],
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* but let's hope that doesn't matter.) */
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arg_serialization = safe_fclose(arg_serialization);
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fds = fdset_free(fds);
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/* Reopen the console */
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(void) make_console_stdio();
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for (j = 1, i = 1; j < (unsigned) argc; j++)
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args[i++] = argv[j];
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args[i++] = NULL;
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assert(i <= args_size);
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/* Reenable any blocked signals, especially important
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* if we switch from initial ramdisk to init=... */
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(void) reset_all_signal_handlers();
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(void) reset_signal_mask();
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if (switch_root_init) {
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args[0] = switch_root_init;
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(void) execv(args[0], (char* const*) args);
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log_warning_errno(errno, "Failed to execute configured init, trying fallback: %m");
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}
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args[0] = "/sbin/init";
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(void) execv(args[0], (char* const*) args);
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manager_status_printf(NULL, STATUS_TYPE_EMERGENCY,
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ANSI_HIGHLIGHT_RED " !! " ANSI_NORMAL,
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"Failed to execute /sbin/init");
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if (errno == ENOENT) {
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log_warning("No /sbin/init, trying fallback");
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args[0] = "/bin/sh";
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args[1] = NULL;
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(void) execv(args[0], (char* const*) args);
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log_error_errno(errno, "Failed to execute /bin/sh, giving up: %m");
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} else
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log_warning_errno(errno, "Failed to execute /sbin/init, giving up: %m");
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error_message = "Failed to execute fallback shell";
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}
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if (reexecute)
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do_reexecute(argc, argv,
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&saved_rlimit_nofile,
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&saved_rlimit_memlock,
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fds,
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switch_root_dir,
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switch_root_init,
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&error_message); /* This only returns if reexecution failed */
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arg_serialization = safe_fclose(arg_serialization);
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fds = fdset_free(fds);
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