78 lines
2.7 KiB
C
78 lines
2.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "bus-error.h"
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#include "bus-locator.h"
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#include "parse-util.h"
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#include "path-util.h"
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#include "proc-cmdline.h"
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#include "signal-util.h"
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#include "stat-util.h"
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#include "systemctl-switch-root.h"
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#include "systemctl-util.h"
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#include "systemctl.h"
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int switch_root(int argc, char *argv[], void *userdata) {
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_free_ char *cmdline_init = NULL;
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const char *root, *init;
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sd_bus *bus;
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int r;
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if (arg_transport != BUS_TRANSPORT_LOCAL)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Cannot switch root remotely.");
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if (argc < 2 || argc > 3)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Wrong number of arguments.");
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root = argv[1];
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if (argc >= 3)
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init = argv[2];
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else {
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r = proc_cmdline_get_key("init", 0, &cmdline_init);
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if (r < 0)
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log_debug_errno(r, "Failed to parse /proc/cmdline: %m");
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init = cmdline_init;
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}
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init = empty_to_null(init);
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if (init) {
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const char *root_systemd_path = NULL, *root_init_path = NULL;
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root_systemd_path = prefix_roota(root, "/" SYSTEMD_BINARY_PATH);
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root_init_path = prefix_roota(root, init);
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/* If the passed init is actually the same as the systemd binary, then let's suppress it. */
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if (files_same(root_init_path, root_systemd_path, 0) > 0)
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init = NULL;
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}
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/* Instruct PID1 to exclude us from its killing spree applied during the transition. Otherwise we
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* would exit with a failure status even though the switch to the new root has succeed. */
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assert(saved_argv);
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assert(saved_argv[0]);
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saved_argv[0][0] = '@';
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r = acquire_bus(BUS_MANAGER, &bus);
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if (r < 0)
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return r;
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/* If we are slow to exit after the root switch, the new systemd instance will send us a signal to
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* terminate. Just ignore it and exit normally. This way the unit does not end up as failed. */
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r = ignore_signals(SIGTERM, -1);
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if (r < 0)
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log_warning_errno(r, "Failed to change disposition of SIGTERM to ignore: %m");
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log_debug("Switching root - root: %s; init: %s", root, strna(init));
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r = bus_call_method(bus, bus_systemd_mgr, "SwitchRoot", &error, NULL, "ss", root, init);
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if (r < 0) {
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(void) default_signals(SIGTERM, -1);
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return log_error_errno(r, "Failed to switch root: %s", bus_error_message(&error, r));
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}
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return 0;
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}
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