systemctl: warn users via wall that the system goes down
diff --git a/src/utmp-wtmp.c b/src/utmp-wtmp.c
index ba0273f..5aafb7b 100644
--- a/src/utmp-wtmp.c
+++ b/src/utmp-wtmp.c
@@ -24,6 +24,9 @@
#include <assert.h>
#include <string.h>
#include <sys/utsname.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/poll.h>
#include "macro.h"
#include "utmp-wtmp.h"
@@ -212,3 +215,140 @@
return write_entry_both(&store);
}
+
+#define TIMEOUT_MSEC 50
+
+static int write_to_terminal(const char *tty, const char *message) {
+ int fd, r;
+ const char *p;
+ size_t left;
+ usec_t end;
+
+ assert(tty);
+ assert(message);
+
+ if ((fd = open(tty, O_WRONLY|O_NDELAY|O_NOCTTY|O_CLOEXEC)) < 0)
+ return -errno;
+
+ if (!isatty(fd)) {
+ r = -errno;
+ goto finish;
+ }
+
+ p = message;
+ left = strlen(message);
+
+ end = now(CLOCK_MONOTONIC) + TIMEOUT_MSEC*USEC_PER_MSEC;
+
+ while (left > 0) {
+ ssize_t n;
+ struct pollfd pollfd;
+ usec_t t;
+ int k;
+
+ t = now(CLOCK_MONOTONIC);
+
+ if (t >= end) {
+ r = -ETIME;
+ goto finish;
+ }
+
+ zero(pollfd);
+ pollfd.fd = fd;
+ pollfd.events = POLLOUT;
+
+ if ((k = poll(&pollfd, 1, (end - t) / USEC_PER_MSEC)) < 0)
+ return -errno;
+
+ if (k <= 0) {
+ r = -ETIME;
+ goto finish;
+ }
+
+ if ((n = write(fd, p, left)) < 0) {
+
+ if (errno == EAGAIN)
+ continue;
+
+ r = -errno;
+ goto finish;
+ }
+
+ assert((size_t) n <= left);
+
+ p += n;
+ left -= n;
+ }
+
+ r = 0;
+
+finish:
+ close_nointr_nofail(fd);
+
+ return r;
+}
+
+int utmp_wall(const char *message) {
+ struct utmpx *u;
+ char date[26];
+ char *text, *hn, *un, *tty;
+ int r;
+ time_t t;
+
+ if (!(hn = gethostname_malloc()) ||
+ !(un = getlogname_malloc()) ||
+ !(tty = getttyname_malloc())) {
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ time(&t);
+ assert_se(ctime_r(&t, date));
+ delete_chars(date, "\n\r");
+
+ if (asprintf(&text,
+ "\a\r\n"
+ "Broadcast message from %s@%s on %s (%s):\r\n\r\n"
+ "%s\r\n\r\n",
+ un, hn, tty, date, message) < 0) {
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ setutxent();
+
+ r = 0;
+
+ while ((u = getutxent())) {
+ int q;
+ const char *path;
+ char *buf = NULL;
+
+ if (u->ut_type != USER_PROCESS || u->ut_user[0] == 0)
+ continue;
+
+ if (path_startswith(u->ut_line, "/dev/"))
+ path = u->ut_line;
+ else {
+ if (asprintf(&buf, "/dev/%s", u->ut_line) < 0) {
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ path = buf;
+ }
+
+ if ((q = write_to_terminal(path, text)) < 0)
+ r = q;
+
+ free(buf);
+ }
+
+finish:
+ free(hn);
+ free(un);
+ free(tty);
+ free(text);
+
+ return r;
+}