410 lines
11 KiB
C
410 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/time.h>
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#include <sys/utsname.h>
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#include <unistd.h>
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#include <utmpx.h>
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "hostname-util.h"
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#include "io-util.h"
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#include "macro.h"
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#include "memory-util.h"
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#include "path-util.h"
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#include "string-util.h"
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#include "terminal-util.h"
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#include "time-util.h"
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#include "user-util.h"
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#include "utmp-wtmp.h"
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int utmp_get_runlevel(int *runlevel, int *previous) {
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_cleanup_(utxent_cleanup) bool utmpx = false;
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struct utmpx *found, lookup = { .ut_type = RUN_LVL };
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const char *e;
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assert(runlevel);
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/* If these values are set in the environment this takes
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* precedence. Presumably, sysvinit does this to work around a
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* race condition that would otherwise exist where we'd always
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* go to disk and hence might read runlevel data that might be
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* very new and not apply to the current script being executed. */
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e = getenv("RUNLEVEL");
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if (e && e[0] > 0) {
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*runlevel = e[0];
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if (previous) {
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/* $PREVLEVEL seems to be an Upstart thing */
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e = getenv("PREVLEVEL");
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if (e && e[0] > 0)
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*previous = e[0];
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else
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*previous = 0;
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}
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return 0;
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}
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if (utmpxname(_PATH_UTMPX) < 0)
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return -errno;
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utmpx = utxent_start();
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found = getutxid(&lookup);
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if (!found)
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return -errno;
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*runlevel = found->ut_pid & 0xFF;
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if (previous)
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*previous = (found->ut_pid >> 8) & 0xFF;
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return 0;
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}
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static void init_timestamp(struct utmpx *store, usec_t t) {
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assert(store);
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if (t <= 0)
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t = now(CLOCK_REALTIME);
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store->ut_tv.tv_sec = t / USEC_PER_SEC;
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store->ut_tv.tv_usec = t % USEC_PER_SEC;
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}
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static void init_entry(struct utmpx *store, usec_t t) {
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struct utsname uts = {};
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assert(store);
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init_timestamp(store, t);
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if (uname(&uts) >= 0)
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strncpy(store->ut_host, uts.release, sizeof(store->ut_host));
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strncpy(store->ut_line, "~", sizeof(store->ut_line)); /* or ~~ ? */
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strncpy(store->ut_id, "~~", sizeof(store->ut_id));
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}
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static int write_entry_utmp(const struct utmpx *store) {
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_cleanup_(utxent_cleanup) bool utmpx = false;
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assert(store);
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/* utmp is similar to wtmp, but there is only one entry for
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* each entry type resp. user; i.e. basically a key/value
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* table. */
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if (utmpxname(_PATH_UTMPX) < 0)
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return -errno;
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utmpx = utxent_start();
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if (pututxline(store))
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return 0;
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if (errno == ENOENT) {
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/* If utmp/wtmp have been disabled, that's a good thing, hence ignore the error. */
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log_debug_errno(errno, "Not writing utmp: %m");
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return 0;
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}
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return -errno;
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}
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static int write_entry_wtmp(const struct utmpx *store) {
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assert(store);
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/* wtmp is a simple append-only file where each entry is
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* simply appended to the end; i.e. basically a log. */
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errno = 0;
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updwtmpx(_PATH_WTMPX, store);
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if (errno == ENOENT) {
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/* If utmp/wtmp have been disabled, that's a good thing, hence ignore the error. */
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log_debug_errno(errno, "Not writing wtmp: %m");
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return 0;
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}
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if (errno == EROFS) {
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log_warning_errno(errno, "Failed to write wtmp record, ignoring: %m");
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return 0;
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}
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return -errno;
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}
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static int write_utmp_wtmp(const struct utmpx *store_utmp, const struct utmpx *store_wtmp) {
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int r, s;
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r = write_entry_utmp(store_utmp);
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s = write_entry_wtmp(store_wtmp);
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return r < 0 ? r : s;
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}
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static int write_entry_both(const struct utmpx *store) {
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return write_utmp_wtmp(store, store);
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}
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int utmp_put_shutdown(void) {
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struct utmpx store = {};
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init_entry(&store, 0);
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store.ut_type = RUN_LVL;
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strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));
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return write_entry_both(&store);
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}
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int utmp_put_reboot(usec_t t) {
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struct utmpx store = {};
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init_entry(&store, t);
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store.ut_type = BOOT_TIME;
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strncpy(store.ut_user, "reboot", sizeof(store.ut_user));
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return write_entry_both(&store);
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}
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static void copy_suffix(char *buf, size_t buf_size, const char *src) {
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size_t l;
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l = strlen(src);
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if (l < buf_size)
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strncpy(buf, src, buf_size);
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else
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memcpy(buf, src + l - buf_size, buf_size);
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}
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int utmp_put_init_process(const char *id, pid_t pid, pid_t sid, const char *line, int ut_type, const char *user) {
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struct utmpx store = {
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.ut_type = INIT_PROCESS,
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.ut_pid = pid,
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.ut_session = sid,
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};
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int r;
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assert(id);
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init_timestamp(&store, 0);
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/* Copy the whole string if it fits, or just the suffix without the terminating NUL. */
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copy_suffix(store.ut_id, sizeof(store.ut_id), id);
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if (line)
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strncpy_exact(store.ut_line, line, sizeof(store.ut_line));
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r = write_entry_both(&store);
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if (r < 0)
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return r;
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if (IN_SET(ut_type, LOGIN_PROCESS, USER_PROCESS)) {
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store.ut_type = LOGIN_PROCESS;
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r = write_entry_both(&store);
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if (r < 0)
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return r;
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}
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if (ut_type == USER_PROCESS) {
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store.ut_type = USER_PROCESS;
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strncpy(store.ut_user, user, sizeof(store.ut_user)-1);
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r = write_entry_both(&store);
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if (r < 0)
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return r;
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}
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return 0;
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}
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int utmp_put_dead_process(const char *id, pid_t pid, int code, int status) {
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struct utmpx lookup = {
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.ut_type = INIT_PROCESS /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */
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}, store, store_wtmp, *found;
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assert(id);
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setutxent();
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/* Copy the whole string if it fits, or just the suffix without the terminating NUL. */
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copy_suffix(store.ut_id, sizeof(store.ut_id), id);
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found = getutxid(&lookup);
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if (!found)
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return 0;
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if (found->ut_pid != pid)
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return 0;
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memcpy(&store, found, sizeof(store));
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store.ut_type = DEAD_PROCESS;
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store.ut_exit.e_termination = code;
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store.ut_exit.e_exit = status;
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zero(store.ut_user);
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zero(store.ut_host);
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zero(store.ut_tv);
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memcpy(&store_wtmp, &store, sizeof(store_wtmp));
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/* wtmp wants the current time */
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init_timestamp(&store_wtmp, 0);
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return write_utmp_wtmp(&store, &store_wtmp);
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}
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int utmp_put_runlevel(int runlevel, int previous) {
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struct utmpx store = {};
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int r;
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assert(runlevel > 0);
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if (previous <= 0) {
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/* Find the old runlevel automatically */
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r = utmp_get_runlevel(&previous, NULL);
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if (r < 0) {
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if (r != -ESRCH)
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return r;
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previous = 0;
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}
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}
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if (previous == runlevel)
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return 0;
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init_entry(&store, 0);
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store.ut_type = RUN_LVL;
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store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
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strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));
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return write_entry_both(&store);
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}
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#define TIMEOUT_USEC (50 * USEC_PER_MSEC)
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static int write_to_terminal(const char *tty, const char *message) {
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_cleanup_close_ int fd = -1;
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const char *p;
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size_t left;
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usec_t end;
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assert(tty);
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assert(message);
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fd = open(tty, O_WRONLY|O_NONBLOCK|O_NOCTTY|O_CLOEXEC);
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if (fd < 0 || !isatty(fd))
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return -errno;
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p = message;
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left = strlen(message);
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end = now(CLOCK_MONOTONIC) + TIMEOUT_USEC;
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while (left > 0) {
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ssize_t n;
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usec_t t;
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int k;
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t = now(CLOCK_MONOTONIC);
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if (t >= end)
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return -ETIME;
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k = fd_wait_for_event(fd, POLLOUT, end - t);
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if (k < 0)
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return k;
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if (k == 0)
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return -ETIME;
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n = write(fd, p, left);
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if (n < 0) {
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if (errno == EAGAIN)
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continue;
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return -errno;
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}
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assert((size_t) n <= left);
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p += n;
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left -= n;
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}
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return 0;
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}
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int utmp_wall(
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const char *message,
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const char *username,
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const char *origin_tty,
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bool (*match_tty)(const char *tty, void *userdata),
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void *userdata) {
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_cleanup_free_ char *text = NULL, *hn = NULL, *un = NULL, *stdin_tty = NULL;
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char date[FORMAT_TIMESTAMP_MAX];
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struct utmpx *u;
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int r;
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hn = gethostname_malloc();
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if (!hn)
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return -ENOMEM;
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if (!username) {
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un = getlogname_malloc();
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if (!un)
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return -ENOMEM;
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}
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if (!origin_tty) {
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getttyname_harder(STDIN_FILENO, &stdin_tty);
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origin_tty = stdin_tty;
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}
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if (asprintf(&text,
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"\a\r\n"
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"Broadcast message from %s@%s%s%s (%s):\r\n\r\n"
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"%s\r\n\r\n",
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un ?: username, hn,
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origin_tty ? " on " : "", strempty(origin_tty),
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format_timestamp(date, sizeof(date), now(CLOCK_REALTIME)),
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message) < 0)
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return -ENOMEM;
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setutxent();
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r = 0;
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while ((u = getutxent())) {
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_cleanup_free_ char *buf = NULL;
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const char *path;
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int q;
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if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0)
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continue;
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/* this access is fine, because STRLEN("/dev/") << 32 (UT_LINESIZE) */
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if (path_startswith(u->ut_line, "/dev/"))
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path = u->ut_line;
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else {
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if (asprintf(&buf, "/dev/%.*s", (int) sizeof(u->ut_line), u->ut_line) < 0)
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return -ENOMEM;
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path = buf;
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}
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if (!match_tty || match_tty(path, userdata)) {
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q = write_to_terminal(path, text);
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if (q < 0)
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r = q;
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}
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}
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return r;
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}
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