From: Mike Yuan <me@yhndnzj.com>
Date: Fri, 8 Sep 2023 18:01:57 +0000 (+0800)
Subject: shared/wall: fall back to logind if utmpx database doesn't exist
X-Git-Tag: v255-rc1~540^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=560f15fc8f338beb7c8a69af631db6f30507fc46;p=thirdparty%2Fsystemd.git

shared/wall: fall back to logind if utmpx database doesn't exist
---

diff --git a/src/shared/wall.c b/src/shared/wall.c
index 9fdde59edab..d5900ef019d 100644
--- a/src/shared/wall.c
+++ b/src/shared/wall.c
@@ -36,18 +36,27 @@ static int write_to_terminal(const char *tty, const char *message) {
         return loop_write_full(fd, message, SIZE_MAX, TIMEOUT_USEC);
 }
 
-#if ENABLE_UTMP
 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())) {
@@ -77,15 +86,18 @@ static int wall_utmp(
         }
 
         return r;
-}
+
+#else
+        return -ENOPROTOOPT;
 #endif
+}
 
-#if ENABLE_LOGIND
 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;
 
@@ -120,8 +132,11 @@ static int wall_logind(
         }
 
         return r;
-}
+
+#else
+        return -ENOPROTOOPT;
 #endif
+}
 
 int wall(
         const char *message,
@@ -131,6 +146,7 @@ int wall(
         void *userdata) {
 
         _cleanup_free_ char *text = NULL, *hostname = NULL, *username_alloc = NULL, *stdin_tty = NULL;
+        int r;
 
         assert(message);
 
@@ -161,11 +177,11 @@ int wall(
                      message) < 0)
                 return -ENOMEM;
 
-#if ENABLE_UTMP
-        return wall_utmp(text, match_tty, userdata);
-#elif ENABLE_LOGIND
-        return wall_logind(text, match_tty, userdata);
-#endif
+        r = wall_utmp(text, match_tty, userdata);
+        if (r == -ENOPROTOOPT)
+                r = wall_logind(text, match_tty, userdata);
+
+        return r == -ENOPROTOOPT ? 0 : r;
 }
 
 #endif