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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <unistd.h>
#include "fs-util.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 overriden by kernel command line systemd.unit= setting");
else if (!value && runlevel_to_target(key))
log_warning("Offline system update overriden 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_set_prohibit_ipc(true);
log_set_target(LOG_TARGET_AUTO);
log_parse_environment();
log_open();
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;
}
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