diff options
Diffstat (limited to 'src/libshared/utmp-wtmp.c')
| -rw-r--r-- | src/libshared/utmp-wtmp.c | 445 |
1 files changed, 445 insertions, 0 deletions
diff --git a/src/libshared/utmp-wtmp.c b/src/libshared/utmp-wtmp.c new file mode 100644 index 0000000000..9750dcd817 --- /dev/null +++ b/src/libshared/utmp-wtmp.c @@ -0,0 +1,445 @@ +/*** + This file is part of systemd. + + Copyright 2010 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <errno.h> +#include <fcntl.h> +#include <poll.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/time.h> +#include <sys/utsname.h> +#include <unistd.h> +#include <utmpx.h> + +#include "alloc-util.h" +#include "fd-util.h" +#include "hostname-util.h" +#include "macro.h" +#include "path-util.h" +#include "string-util.h" +#include "terminal-util.h" +#include "time-util.h" +#include "user-util.h" +#include "util.h" +#include "utmp-wtmp.h" + +int utmp_get_runlevel(int *runlevel, int *previous) { + struct utmpx *found, lookup = { .ut_type = RUN_LVL }; + int r; + 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 does not apply to the current script being + * executed. */ + + e = getenv("RUNLEVEL"); + if (e && e[0] > 0) { + *runlevel = e[0]; + + if (previous) { + /* $PREVLEVEL seems to be an Upstart thing */ + + e = getenv("PREVLEVEL"); + if (e && e[0] > 0) + *previous = e[0]; + else + *previous = 0; + } + + return 0; + } + + if (utmpxname(_PATH_UTMPX) < 0) + return -errno; + + setutxent(); + + found = getutxid(&lookup); + if (!found) + r = -errno; + else { + int a, b; + + a = found->ut_pid & 0xFF; + b = (found->ut_pid >> 8) & 0xFF; + + *runlevel = a; + if (previous) + *previous = b; + + r = 0; + } + + endutxent(); + + return r; +} + +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) { + int r; + + 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(_PATH_UTMPX) < 0) + return -errno; + + setutxent(); + + if (!pututxline(store)) + r = -errno; + else + r = 0; + + endutxent(); + + return r; +} + +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(_PATH_WTMPX, store); + 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); + + if (r >= 0) + r = s; + + /* If utmp/wtmp have been disabled, that's a good thing, hence + * ignore the errors */ + if (r == -ENOENT) + r = 0; + + return r; +} + +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); +} + +_pure_ static const char *sanitize_id(const char *id) { + size_t l; + + assert(id); + l = strlen(id); + + if (l <= sizeof(((struct utmpx*) NULL)->ut_id)) + return id; + + return id + l - sizeof(((struct utmpx*) NULL)->ut_id); +} + +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); + + init_timestamp(&store, 0); + + /* ut_id needs only be nul-terminated if it is shorter than sizeof(ut_id) */ + strncpy(store.ut_id, sanitize_id(id), sizeof(store.ut_id)); + + if (line) + strncpy(store.ut_line, basename(line), sizeof(store.ut_line)); + + r = write_entry_both(&store); + if (r < 0) + return r; + + if (ut_type == LOGIN_PROCESS || ut_type == 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) { + struct utmpx lookup = { + .ut_type = INIT_PROCESS /* looks for DEAD_PROCESS, LOGIN_PROCESS, USER_PROCESS, too */ + }, store, store_wtmp, *found; + + assert(id); + + setutxent(); + + /* ut_id needs only be nul-terminated if it is shorter than sizeof(ut_id) */ + strncpy(lookup.ut_id, sanitize_id(id), sizeof(lookup.ut_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); +} + +#define TIMEOUT_MSEC 50 + +static int write_to_terminal(const char *tty, const char *message) { + _cleanup_close_ int fd = -1; + const char *p; + size_t left; + usec_t end; + + assert(tty); + assert(message); + + fd = open(tty, O_WRONLY|O_NDELAY|O_NOCTTY|O_CLOEXEC); + if (fd < 0 || !isatty(fd)) + return -errno; + + p = message; + left = strlen(message); + + end = now(CLOCK_MONOTONIC) + TIMEOUT_MSEC*USEC_PER_MSEC; + + while (left > 0) { + ssize_t n; + struct pollfd pollfd = { + .fd = fd, + .events = POLLOUT, + }; + usec_t t; + int k; + + t = now(CLOCK_MONOTONIC); + + if (t >= end) + return -ETIME; + + k = poll(&pollfd, 1, (end - t) / USEC_PER_MSEC); + if (k < 0) + return -errno; + + if (k == 0) + return -ETIME; + + n = write(fd, p, left); + if (n < 0) { + if (errno == EAGAIN) + continue; + + return -errno; + } + + assert((size_t) n <= left); + + p += n; + left -= n; + } + + return 0; +} + +int utmp_wall( + const char *message, + const char *username, + const char *origin_tty, + bool (*match_tty)(const char *tty, void *userdata), + void *userdata) { + + _cleanup_free_ char *text = NULL, *hn = NULL, *un = NULL, *stdin_tty = NULL; + char date[FORMAT_TIMESTAMP_MAX]; + struct utmpx *u; + int r; + + hn = gethostname_malloc(); + if (!hn) + return -ENOMEM; + if (!username) { + un = getlogname_malloc(); + if (!un) + return -ENOMEM; + } + + if (!origin_tty) { + getttyname_harder(STDIN_FILENO, &stdin_tty); + origin_tty = stdin_tty; + } + + if (asprintf(&text, + "\a\r\n" + "Broadcast message from %s@%s%s%s (%s):\r\n\r\n" + "%s\r\n\r\n", + un ?: username, hn, + origin_tty ? " on " : "", strempty(origin_tty), + format_timestamp(date, sizeof(date), now(CLOCK_REALTIME)), + message) < 0) + return -ENOMEM; + + setutxent(); + + r = 0; + + while ((u = getutxent())) { + _cleanup_free_ char *buf = NULL; + const char *path; + int q; + + if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0) + continue; + + /* this access is fine, because strlen("/dev/") << 32 (UT_LINESIZE) */ + if (path_startswith(u->ut_line, "/dev/")) + path = u->ut_line; + else { + if (asprintf(&buf, "/dev/%.*s", (int) sizeof(u->ut_line), u->ut_line) < 0) + return -ENOMEM; + + path = buf; + } + + if (!match_tty || match_tty(path, userdata)) { + q = write_to_terminal(path, text); + if (q < 0) + r = q; + } + } + + return r; +} |