[thirdparty/systemd.git] / src / shared / utmp-wtmp.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <stdio.h>
#include <stdlib.h>
#include <sys/utsname.h>
#include <utmpx.h>

#include "log.h"
#include "memory-util.h"
#include "string-util.h"
#include "time-util.h"
#include "utmp-wtmp.h"

int utmp_get_runlevel(int *runlevel, int *previous) {
        _unused_ _cleanup_(utxent_cleanup) bool utmpx = false;
        struct utmpx *found, lookup = { .ut_type = RUN_LVL };
        const char *e;

        assert(runlevel);

        /* If these values are set in the environment this takes
         * precedence. Presumably, sysvinit does this to work around a
         * race condition that would otherwise exist where we'd always
         * go to disk and hence might read runlevel data that might be
         * very new and not apply to the current script being executed. */

        e = getenv("RUNLEVEL");
        if (!isempty(e)) {
                *runlevel = e[0];
                if (previous)
                        *previous = 0;

                return 0;
        }

        if (utmpxname(UTMPX_FILE) < 0)
                return -errno;

        utmpx = utxent_start();

        found = getutxid(&lookup);
        if (!found)
                return -errno;

        *runlevel = found->ut_pid & 0xFF;
        if (previous)
                *previous = (found->ut_pid >> 8) & 0xFF;

        return 0;
}

static void init_timestamp(struct utmpx *store, usec_t t) {
        assert(store);

        if (t <= 0)
                t = now(CLOCK_REALTIME);

        store->ut_tv.tv_sec = t / USEC_PER_SEC;
        store->ut_tv.tv_usec = t % USEC_PER_SEC;
}

static void init_entry(struct utmpx *store, usec_t t) {
        struct utsname uts = {};

        assert(store);

        init_timestamp(store, t);

        if (uname(&uts) >= 0)
                strncpy(store->ut_host, uts.release, sizeof(store->ut_host));

        strncpy(store->ut_line, "~", sizeof(store->ut_line));  /* or ~~ ? */
        strncpy(store->ut_id, "~~", sizeof(store->ut_id));
}

static int write_entry_utmp(const struct utmpx *store) {
        _unused_ _cleanup_(utxent_cleanup) bool utmpx = false;

        assert(store);

        /* utmp is similar to wtmp, but there is only one entry for
         * each entry type resp. user; i.e. basically a key/value
         * table. */

        if (utmpxname(UTMPX_FILE) < 0)
                return -errno;

        utmpx = utxent_start();

        if (pututxline(store))
                return 0;
        if (errno == ENOENT) {
                /* If utmp/wtmp have been disabled, that's a good thing, hence ignore the error. */
                log_debug_errno(errno, "Not writing utmp: %m");
                return 0;
        }
        return -errno;
}

static int write_entry_wtmp(const struct utmpx *store) {
        assert(store);

        /* wtmp is a simple append-only file where each entry is
         * simply appended to the end; i.e. basically a log. */

        errno = 0;
        updwtmpx(WTMPX_FILE, store);
        if (errno == ENOENT) {
                /* If utmp/wtmp have been disabled, that's a good thing, hence ignore the error. */
                log_debug_errno(errno, "Not writing wtmp: %m");
                return 0;
        }
        if (errno == EROFS) {
                log_warning_errno(errno, "Failed to write wtmp record, ignoring: %m");
                return 0;
        }
        return -errno;
}

static int write_utmp_wtmp(const struct utmpx *store_utmp, const struct utmpx *store_wtmp) {
        int r, s;

        r = write_entry_utmp(store_utmp);
        s = write_entry_wtmp(store_wtmp);
        return r < 0 ? r : s;
}

static int write_entry_both(const struct utmpx *store) {
        return write_utmp_wtmp(store, store);
}

int utmp_put_shutdown(void) {
        struct utmpx store = {};

        init_entry(&store, 0);

        store.ut_type = RUN_LVL;
        strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));

        return write_entry_both(&store);
}

int utmp_put_reboot(usec_t t) {
        struct utmpx store = {};

        init_entry(&store, t);

        store.ut_type = BOOT_TIME;
        strncpy(store.ut_user, "reboot", sizeof(store.ut_user));

        return write_entry_both(&store);
}

static void copy_suffix(char *buf, size_t buf_size, const char *src) {
        size_t l;

        l = strlen(src);
        if (l < buf_size)
                strncpy(buf, src, buf_size);
        else
                memcpy(buf, src + l - buf_size, buf_size);
}

int utmp_put_init_process(const char *id, pid_t pid, pid_t sid, const char *line, int ut_type, const char *user) {
        struct utmpx store = {
                .ut_type = INIT_PROCESS,
                .ut_pid = pid,
                .ut_session = sid,
        };
        int r;

        assert(id);
        assert(ut_type != USER_PROCESS || user);

        init_timestamp(&store, 0);

        /* Copy the whole string if it fits, or just the suffix without the terminating NUL. */
        copy_suffix(store.ut_id, sizeof(store.ut_id), id);

        if (line)
                strncpy_exact(store.ut_line, line, sizeof(store.ut_line));

        r = write_entry_both(&store);
        if (r < 0)
                return r;

        if (IN_SET(ut_type, LOGIN_PROCESS, USER_PROCESS)) {
                store.ut_type = LOGIN_PROCESS;
                r = write_entry_both(&store);
                if (r < 0)
                        return r;
        }

        if (ut_type == USER_PROCESS) {
                store.ut_type = USER_PROCESS;
                strncpy(store.ut_user, user, sizeof(store.ut_user)-1);
                r = write_entry_both(&store);
                if (r < 0)
                        return r;
        }

        return 0;
}

int utmp_put_dead_process(const char *id, pid_t pid, int code, int status) {
        _unused_ _cleanup_(utxent_cleanup) bool utmpx = false;
        struct utmpx lookup = {
                .ut_type = INIT_PROCESS /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */
        }, store, store_wtmp, *found;

        assert(id);

        utmpx = utxent_start();

        /* Copy the whole string if it fits, or just the suffix without the terminating NUL. */
        copy_suffix(lookup.ut_id, sizeof(lookup.ut_id), id);

        found = getutxid(&lookup);
        if (!found)
                return 0;

        if (found->ut_pid != pid)
                return 0;

        memcpy(&store, found, sizeof(store));
        store.ut_type = DEAD_PROCESS;
        store.ut_exit.e_termination = code;
        store.ut_exit.e_exit = status;

        zero(store.ut_user);
        zero(store.ut_host);
        zero(store.ut_tv);

        memcpy(&store_wtmp, &store, sizeof(store_wtmp));
        /* wtmp wants the current time */
        init_timestamp(&store_wtmp, 0);

        return write_utmp_wtmp(&store, &store_wtmp);
}

int utmp_put_runlevel(int runlevel, int previous) {
        struct utmpx store = {};
        int r;

        assert(runlevel > 0);

        if (previous <= 0) {
                /* Find the old runlevel automatically */

                r = utmp_get_runlevel(&previous, NULL);
                if (r < 0) {
                        if (r != -ESRCH)
                                return r;

                        previous = 0;
                }
        }

        if (previous == runlevel)
                return 0;

        init_entry(&store, 0);

        store.ut_type = RUN_LVL;
        store.ut_pid = (runlevel & 0xFF) | ((previous & 0xFF) << 8);
        strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));

        return write_entry_both(&store);
}
Commit	Line	Data
	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
	2
	3	#include <stdio.h>
	4	#include <stdlib.h>
	5	#include <sys/utsname.h>
	6	#include <utmpx.h>
	7
	8	#include "log.h"
	9	#include "memory-util.h"
	10	#include "string-util.h"
	11	#include "time-util.h"
	12	#include "utmp-wtmp.h"
	13
	14	int utmp_get_runlevel(int runlevel, int previous) {
	15	_unused_ _cleanup_(utxent_cleanup) bool utmpx = false;
	16	struct utmpx *found, lookup = { .ut_type = RUN_LVL };
	17	const char *e;
	18
	19	assert(runlevel);
	20
	21	/* If these values are set in the environment this takes
	22	* precedence. Presumably, sysvinit does this to work around a
	23	* race condition that would otherwise exist where we'd always
	24	* go to disk and hence might read runlevel data that might be
	25	* very new and not apply to the current script being executed. */
	26
	27	e = getenv("RUNLEVEL");
	28	if (!isempty(e)) {
	29	*runlevel = e[0];
	30	if (previous)
	31	*previous = 0;
	32
	33	return 0;
	34	}
	35
	36	if (utmpxname(UTMPX_FILE) < 0)
	37	return -errno;
	38
	39	utmpx = utxent_start();
	40
	41	found = getutxid(&lookup);
	42	if (!found)
	43	return -errno;
	44
	45	*runlevel = found->ut_pid & 0xFF;
	46	if (previous)
	47	*previous = (found->ut_pid >> 8) & 0xFF;
	48
	49	return 0;
	50	}
	51
	52	static void init_timestamp(struct utmpx *store, usec_t t) {
	53	assert(store);
	54
	55	if (t <= 0)
	56	t = now(CLOCK_REALTIME);
	57
	58	store->ut_tv.tv_sec = t / USEC_PER_SEC;
	59	store->ut_tv.tv_usec = t % USEC_PER_SEC;
	60	}
	61
	62	static void init_entry(struct utmpx *store, usec_t t) {
	63	struct utsname uts = {};
	64
	65	assert(store);
	66
	67	init_timestamp(store, t);
	68
	69	if (uname(&uts) >= 0)
	70	strncpy(store->ut_host, uts.release, sizeof(store->ut_host));
	71
	72	strncpy(store->ut_line, "~", sizeof(store->ut_line)); /* or ~~ ? */
	73	strncpy(store->ut_id, "~~", sizeof(store->ut_id));
	74	}
	75
	76	static int write_entry_utmp(const struct utmpx *store) {
	77	_unused_ _cleanup_(utxent_cleanup) bool utmpx = false;
	78
	79	assert(store);
	80
	81	/* utmp is similar to wtmp, but there is only one entry for
	82	* each entry type resp. user; i.e. basically a key/value
	83	* table. */
	84
	85	if (utmpxname(UTMPX_FILE) < 0)
	86	return -errno;
	87
	88	utmpx = utxent_start();
	89
	90	if (pututxline(store))
	91	return 0;
	92	if (errno == ENOENT) {
	93	/* If utmp/wtmp have been disabled, that's a good thing, hence ignore the error. */
	94	log_debug_errno(errno, "Not writing utmp: %m");
	95	return 0;
	96	}
	97	return -errno;
	98	}
	99
	100	static int write_entry_wtmp(const struct utmpx *store) {
	101	assert(store);
	102
	103	/* wtmp is a simple append-only file where each entry is
	104	* simply appended to the end; i.e. basically a log. */
	105
	106	errno = 0;
	107	updwtmpx(WTMPX_FILE, store);
	108	if (errno == ENOENT) {
	109	/* If utmp/wtmp have been disabled, that's a good thing, hence ignore the error. */
	110	log_debug_errno(errno, "Not writing wtmp: %m");
	111	return 0;
	112	}
	113	if (errno == EROFS) {
	114	log_warning_errno(errno, "Failed to write wtmp record, ignoring: %m");
	115	return 0;
	116	}
	117	return -errno;
	118	}
	119
	120	static int write_utmp_wtmp(const struct utmpx store_utmp, const struct utmpx store_wtmp) {
	121	int r, s;
	122
	123	r = write_entry_utmp(store_utmp);
	124	s = write_entry_wtmp(store_wtmp);
	125	return r < 0 ? r : s;
	126	}
	127
	128	static int write_entry_both(const struct utmpx *store) {
	129	return write_utmp_wtmp(store, store);
	130	}
	131
	132	int utmp_put_shutdown(void) {
	133	struct utmpx store = {};
	134
	135	init_entry(&store, 0);
	136
	137	store.ut_type = RUN_LVL;
	138	strncpy(store.ut_user, "shutdown", sizeof(store.ut_user));
	139
	140	return write_entry_both(&store);
	141	}
	142
	143	int utmp_put_reboot(usec_t t) {
	144	struct utmpx store = {};
	145
	146	init_entry(&store, t);
	147
	148	store.ut_type = BOOT_TIME;
	149	strncpy(store.ut_user, "reboot", sizeof(store.ut_user));
	150
	151	return write_entry_both(&store);
	152	}
	153
	154	static void copy_suffix(char buf, size_t buf_size, const char src) {
	155	size_t l;
	156
	157	l = strlen(src);
	158	if (l < buf_size)
	159	strncpy(buf, src, buf_size);
	160	else
	161	memcpy(buf, src + l - buf_size, buf_size);
	162	}
	163
	164	int utmp_put_init_process(const char id, pid_t pid, pid_t sid, const char line, int ut_type, const char *user) {
	165	struct utmpx store = {
	166	.ut_type = INIT_PROCESS,
	167	.ut_pid = pid,
	168	.ut_session = sid,
	169	};
	170	int r;
	171
	172	assert(id);
	173	assert(ut_type != USER_PROCESS \|\| user);
	174
	175	init_timestamp(&store, 0);
	176
	177	/* Copy the whole string if it fits, or just the suffix without the terminating NUL. */
	178	copy_suffix(store.ut_id, sizeof(store.ut_id), id);
	179
	180	if (line)
	181	strncpy_exact(store.ut_line, line, sizeof(store.ut_line));
	182
	183	r = write_entry_both(&store);
	184	if (r < 0)
	185	return r;
	186
	187	if (IN_SET(ut_type, LOGIN_PROCESS, USER_PROCESS)) {
	188	store.ut_type = LOGIN_PROCESS;
	189	r = write_entry_both(&store);
	190	if (r < 0)
	191	return r;
	192	}
	193
	194	if (ut_type == USER_PROCESS) {
	195	store.ut_type = USER_PROCESS;
	196	strncpy(store.ut_user, user, sizeof(store.ut_user)-1);
	197	r = write_entry_both(&store);
	198	if (r < 0)
	199	return r;
	200	}
	201
	202	return 0;
	203	}
	204
	205	int utmp_put_dead_process(const char *id, pid_t pid, int code, int status) {
	206	_unused_ _cleanup_(utxent_cleanup) bool utmpx = false;
	207	struct utmpx lookup = {
	208	.ut_type = INIT_PROCESS /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */
	209	}, store, store_wtmp, *found;
	210
	211	assert(id);
	212
	213	utmpx = utxent_start();
	214
	215	/* Copy the whole string if it fits, or just the suffix without the terminating NUL. */
	216	copy_suffix(lookup.ut_id, sizeof(lookup.ut_id), id);
	217
	218	found = getutxid(&lookup);
	219	if (!found)
	220	return 0;
	221
	222	if (found->ut_pid != pid)
	223	return 0;
	224
	225	memcpy(&store, found, sizeof(store));
	226	store.ut_type = DEAD_PROCESS;
	227	store.ut_exit.e_termination = code;
	228	store.ut_exit.e_exit = status;
	229
	230	zero(store.ut_user);
	231	zero(store.ut_host);
	232	zero(store.ut_tv);
	233
	234	memcpy(&store_wtmp, &store, sizeof(store_wtmp));
	235	/* wtmp wants the current time */
	236	init_timestamp(&store_wtmp, 0);
	237
	238	return write_utmp_wtmp(&store, &store_wtmp);
	239	}
	240
	241	int utmp_put_runlevel(int runlevel, int previous) {
	242	struct utmpx store = {};
	243	int r;
	244
	245	assert(runlevel > 0);
	246
	247	if (previous <= 0) {
	248	/* Find the old runlevel automatically */
	249
	250	r = utmp_get_runlevel(&previous, NULL);
	251	if (r < 0) {
	252	if (r != -ESRCH)
	253	return r;
	254
	255	previous = 0;
	256	}
	257	}
	258
	259	if (previous == runlevel)
	260	return 0;
	261
	262	init_entry(&store, 0);
	263
	264	store.ut_type = RUN_LVL;
	265	store.ut_pid = (runlevel & 0xFF) \| ((previous & 0xFF) << 8);
	266	strncpy(store.ut_user, "runlevel", sizeof(store.ut_user));
	267
	268	return write_entry_both(&store);
	269	}