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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include "sd-login.h"
#include "errno-util.h"
#include "fd-util.h"
#include "hostname-util.h"
#include "io-util.h"
#include "path-util.h"
#include "string-util.h"
#include "terminal-util.h"
#include "user-util.h"
#include "utmp-wtmp.h"
#include "wall.h"
#if ENABLE_UTMP || ENABLE_LOGIND
#define TIMEOUT_USEC (50 * USEC_PER_MSEC)
static int write_to_terminal(const char *tty, const char *message) {
_cleanup_close_ int fd = -EBADF;
assert(tty);
assert(message);
fd = open(tty, O_WRONLY|O_NONBLOCK|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return -errno;
if (!isatty_safe(fd))
return -errno;
return loop_write_full(fd, message, SIZE_MAX, TIMEOUT_USEC);
}
static int wall_utmp(
const char *message,
bool (*match_tty)(const char *tty, bool is_local, void *userdata),
void *userdata) {
#if ENABLE_UTMP
_unused_ _cleanup_(utxent_cleanup) bool utmpx = false;
struct utmpx *u;
int r = 0;
assert(message);
/* libc's setutxent() unfortunately doesn't inform us about success, i.e. whether /var/run/utmp
* exists. Hence we have to check manually first. */
if (access(_PATH_UTMPX, F_OK) < 0) {
if (errno == ENOENT)
return -ENOPROTOOPT;
return -errno;
}
utmpx = utxent_start();
while ((u = getutxent())) {
_cleanup_free_ char *p = NULL;
const char *tty_path;
bool is_local;
if (u->ut_type != USER_PROCESS || isempty(u->ut_user))
continue;
/* This access is fine, because strlen("/dev/") < 32 (UT_LINESIZE) */
if (path_startswith(u->ut_line, "/dev/"))
tty_path = u->ut_line;
else {
if (asprintf(&p, "/dev/%.*s", (int) sizeof(u->ut_line), u->ut_line) < 0)
return -ENOMEM;
tty_path = p;
}
/* It seems that the address field is always set for remote logins. For local logins and
* other local entries, we get [0,0,0,0]. */
is_local = eqzero(u->ut_addr_v6);
if (!match_tty || match_tty(tty_path, is_local, userdata))
RET_GATHER(r, write_to_terminal(tty_path, message));
}
return r;
#else
return -ENOPROTOOPT;
#endif
}
static int wall_logind(
const char *message,
bool (*match_tty)(const char *tty, bool is_local, void *userdata),
void *userdata) {
#if ENABLE_LOGIND
_cleanup_strv_free_ char **sessions = NULL;
int r;
assert(message);
r = sd_get_sessions(&sessions);
if (r <= 0)
return r;
r = 0;
STRV_FOREACH(s, sessions) {
_cleanup_free_ char *tty_path = NULL, *tty = NULL, *rhost = NULL;
bool is_local;
int q;
q = sd_session_get_tty(*s, &tty);
if (IN_SET(q, -ENXIO, -ENODATA))
continue;
if (q < 0)
return RET_GATHER(r, q);
tty_path = strjoin("/dev/", tty);
if (!tty_path)
return -ENOMEM;
(void) sd_session_get_remote_host(*s, &rhost);
is_local = !rhost;
if (!match_tty || match_tty(tty_path, is_local, userdata))
RET_GATHER(r, write_to_terminal(tty_path, message));
}
return r;
#else
return -ENOPROTOOPT;
#endif
}
int wall(
const char *message,
const char *username,
const char *origin_tty,
bool (*match_tty)(const char *tty, bool is_local, void *userdata),
void *userdata) {
_cleanup_free_ char *text = NULL, *hostname = NULL, *username_alloc = NULL, *stdin_tty = NULL;
int r;
assert(message);
hostname = gethostname_malloc();
if (!hostname)
return -ENOMEM;
if (!username) {
username_alloc = getlogname_malloc();
if (!username_alloc)
return -ENOMEM;
username = username_alloc;
}
if (!origin_tty) {
(void) getttyname_harder(STDIN_FILENO, &stdin_tty);
origin_tty = stdin_tty;
}
if (asprintf(&text,
"\r\n"
"Broadcast message from %s@%s%s%s (%s):\r\n\r\n"
"%s\r\n\r\n",
username, hostname,
origin_tty ? " on " : "", strempty(origin_tty),
FORMAT_TIMESTAMP(now(CLOCK_REALTIME)),
message) < 0)
return -ENOMEM;
r = wall_utmp(text, match_tty, userdata);
if (r == -ENOPROTOOPT)
r = wall_logind(text, match_tty, userdata);
return r == -ENOPROTOOPT ? 0 : r;
}
#endif
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