/* SPDX-License-Identifier: LGPL-2.1+ */ #include #include #include "fs-util.h" #include "generator.h" #include "log.h" #include "proc-cmdline.h" #include "special.h" #include "string-util.h" #include "util.h" /* * Implements the logic described in systemd.offline-updates(7). */ static const char *arg_dest = "/tmp"; static int generate_symlink(void) { const char *p = NULL; if (laccess("/system-update", F_OK) < 0) { if (errno == ENOENT) return 0; log_error_errno(errno, "Failed to check for system update: %m"); return -EINVAL; } p = strjoina(arg_dest, "/" SPECIAL_DEFAULT_TARGET); if (symlink(SYSTEM_DATA_UNIT_PATH "/system-update.target", p) < 0) return log_error_errno(errno, "Failed to create symlink %s: %m", p); return 1; } static int parse_proc_cmdline_item(const char *key, const char *value, void *data) { assert(key); /* Check if a run level is specified on the kernel command line. The * command line has higher priority than any on-disk configuration, so * it'll make any symlink we create moot. */ if (streq(key, "systemd.unit") && !proc_cmdline_value_missing(key, value)) log_warning("Offline system update overridden by kernel command line systemd.unit= setting"); else if (!value && runlevel_to_target(key)) log_warning("Offline system update overridden by runlevel \"%s\" on the kernel command line", key); return 0; } int main(int argc, char *argv[]) { int r, k; if (argc > 1 && argc != 4) { log_error("This program takes three or no arguments."); return EXIT_FAILURE; } if (argc > 1) arg_dest = argv[2]; log_setup_generator(); umask(0022); r = generate_symlink(); if (r > 0) { k = proc_cmdline_parse(parse_proc_cmdline_item, NULL, 0); if (k < 0) log_warning_errno(k, "Failed to parse kernel command line, ignoring: %m"); } return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; }