sd-login: improve error handling

let's return ENXIO whenever we don't know something rather than ENOENT.

ENOENT suggests this was really about a file or directory, while ENXIO
is a more generic "not found" indicator.

2 files changed, 23 insertions, 9 deletions

diff --git a/src/libsystemd/sd-login/sd-login.c b/src/libsystemd/sd-login/sd-login.c
index 0eadc8c747..7d6a4b78cf 100644
--- a/src/libsystemd/sd-login/sd-login.c
+++ b/src/libsystemd/sd-login/sd-login.c
@@ -237,11 +237,13 @@ _public_ int sd_uid_get_display(uid_t uid, char **session) {
                 return r;
 
         r = parse_env_file(p, NEWLINE, "DISPLAY", &s, NULL);
+        if (r == -ENOENT)
+                return -ENXIO;
         if (r < 0)
                 return r;
 
         if (isempty(s))
-                return -ENOENT;
+                return -ENXIO;
 
         *session = s;
         s = NULL;
@@ -465,7 +467,7 @@ static int session_get_string(const char *session, const char *field, char **val
                 return r;
 
         if (isempty(s))
-                return -ENOENT;
+                return -ENXIO;
 
         *value = s;
         s = NULL;
diff --git a/src/libsystemd/sd-login/test-login.c b/src/libsystemd/sd-login/test-login.c
index 05affa442d..ddea7ffa14 100644
--- a/src/libsystemd/sd-login/test-login.c
+++ b/src/libsystemd/sd-login/test-login.c
@@ -33,7 +33,7 @@ static void test_login(void) {
         _cleanup_free_ char *pp = NULL, *qq = NULL;
         int r, k;
         uid_t u, u2;
-        char *seat, *type, *class, *display, *remote_user, *remote_host;
+        char *seat, *type, *class, *display, *remote_user, *remote_host, *display_session;
         char *session;
         char *state;
         char *session2;
@@ -50,6 +50,12 @@ static void test_login(void) {
         assert_se(sd_pid_get_owner_uid(0, &u2) == 0);
         printf("user = "UID_FMT"\n", u2);
 
+        display_session = NULL;
+        r = sd_uid_get_display(u2, &display_session);
+        assert_se(r >= 0 || r == -ENXIO);
+        printf("user's display session = %s\n", strna(display_session));
+        free(display_session);
+
         assert_se(socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == 0);
         sd_peer_get_session(pair[0], &pp);
         sd_peer_get_session(pair[1], &qq);
@@ -100,16 +106,22 @@ static void test_login(void) {
         printf("class = %s\n", class);
         free(class);
 
-        assert_se(sd_session_get_display(session, &display) >= 0);
-        printf("display = %s\n", display);
+        display = NULL;
+        r = sd_session_get_display(session, &display);
+        assert_se(r >= 0 || r == -ENXIO);
+        printf("display = %s\n", strna(display));
         free(display);
 
-        assert_se(sd_session_get_remote_user(session, &remote_user) >= 0);
-        printf("remote_user = %s\n", remote_user);
+        remote_user = NULL;
+        r = sd_session_get_remote_user(session, &remote_user);
+        assert_se(r >= 0 || r == -ENXIO);
+        printf("remote_user = %s\n", strna(remote_user));
         free(remote_user);
 
-        assert_se(sd_session_get_remote_host(session, &remote_host) >= 0);
-        printf("remote_host = %s\n", remote_host);
+        remote_host = NULL;
+        r = sd_session_get_remote_host(session, &remote_host);
+        assert_se(r >= 0 || r == -ENXIO);
+        printf("remote_host = %s\n", strna(remote_host));
         free(remote_host);
 
         assert_se(sd_session_get_seat(session, &seat) >= 0);