wall: always use utmp as fallback

Wall(1) can be compiled with systemd support to read the names of ttys
from the systemd session list. However, this may not work on all systems.
In case of failure, the best option is to use the traditional
utmp method as a fallback.

This commit uses strv (string vector) to collect tty names from both
sources (systemd and utmp) and then sends a message to all ttys.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=2283049
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/term-utils/wall.c b/term-utils/wall.c
index 125fde4383ab5b30c1cf13fd3f7172f7db922e29..22c3918bb3e64ab88a719cc7cb5d350ea2f08798 100644 (file)
--- a/term-utils/wall.c
+++ b/term-utils/wall.c
@@ -78,6 +78,7 @@
 #include "closestream.h"
 #include "timeutils.h"
 #include "pwdutils.h"
+#include "strv.h"
 
 #define        TERM_WIDTH      79
 #define        WRITE_TIME_OUT  300             /* in seconds */
@@ -190,19 +191,30 @@ static int is_gr_member(const char *login, const struct group_workspace *buf)
        return 0;
 }
 
+static int has_tty(char **ttys, char *name)
+{
+       char **str;
+
+       STRV_FOREACH(str, ttys) {
+               if (strcmp(*str, name) == 0)
+                       return 1;
+       }
+
+       return 0;
+}
+
 int main(int argc, char **argv)
 {
        int ch;
        struct iovec iov;
        struct utmpx *utmpptr;
-       char *p;
        char line[sizeof(utmpptr->ut_line) + 1];
        int print_banner = TRUE;
        struct group_workspace *group_buf = NULL;
        char *mbuf, *fname = NULL;
        size_t mbufsize;
        unsigned timeout = WRITE_TIME_OUT;
-       char **mvec = NULL;
+       char **mvec = NULL, **ttys = NULL, **str;
        int mvecsz = 0;
 
        static const struct option longopts[] = {
@@ -265,30 +277,30 @@ int main(int argc, char **argv)
                int sessions;
 
                sessions = sd_get_sessions(&sessions_list);
-               if (sessions < 0)
-                       errx(EXIT_FAILURE, _("error getting sessions: %s"),
-                               strerror(-sessions));
+               if (sessions < 0) {
+                       warnx(_("error getting sessions: %s"), strerror(-sessions));
+                       goto utmp;
+               }
 
                for (int i = 0; i < sessions; i++) {
                        char *name, *tty;
                        int r;
 
-                       if ((r = sd_session_get_username(sessions_list[i], &name)) < 0)
-                               errx(EXIT_FAILURE, _("get user name failed: %s"), strerror (-r));
-
-                       if (!(group_buf && !is_gr_member(name, group_buf))) {
-                               if (sd_session_get_tty(sessions_list[i], &tty) >= 0) {
-                                       if ((p = ttymsg(&iov, 1, tty, timeout)) != NULL)
-                                               warnx("%s", p);
-
-                                       free(tty);
-                               }
+                       if ((r = sd_session_get_username(sessions_list[i], &name)) < 0) {
+                               warnx(_("get user name failed: %s"), strerror (-r));
+                               goto utmp;
                        }
+                       if (!(group_buf && !is_gr_member(name, group_buf))
+                           && sd_session_get_tty(sessions_list[i], &tty) >= 0
+                           && strv_consume(&ttys, tty) < 0)
+                               err(EXIT_FAILURE, _("failed to allocate lines list"));
+
                        free(name);
                        free(sessions_list[i]);
                }
                free(sessions_list);
-       } else
+       }
+utmp:
 #endif
        {
                while ((utmpptr = getutxent())) {
@@ -310,12 +322,21 @@ int main(int argc, char **argv)
                                continue;
 
                        mem2strcpy(line, utmpptr->ut_line, sizeof(utmpptr->ut_line), sizeof(line));
-                       if ((p = ttymsg(&iov, 1, line, timeout)) != NULL)
-                               warnx("%s", p);
+                       if (has_tty(ttys, line))
+                               continue;
+                       if (strv_extend(&ttys, line) < 0)
+                               err(EXIT_FAILURE, _("failed to allocate lines list"));
                }
                endutxent();
        }
 
+       STRV_FOREACH(str, ttys) {
+               char *er = ttymsg(&iov, 1, *str, timeout);
+               if (er)
+                        warnx("%s", er);
+       }
+
+       strv_free(ttys);
        free(mbuf);
        free_group_workspace(group_buf);
        exit(EXIT_SUCCESS);