journalctl: give a nice hint about group membership based on ACLs of /var/log/journal

If we notice that we unprivileged and not in any of the groups which
have access to /var/log/journal, print a nice message about which groups
do.

This checks and prints all groups that are in the default ACL for
/var/log/journal, which is not necessarily correct for all journal
files, but pretty close.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/shared/util.h b/src/shared/util.h
index f75c66bb83..7a38421007 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -429,9 +429,11 @@ int socket_from_display(const char *display, char **path);
 int get_user_creds(const char **username, uid_t *uid, gid_t *gid, const char **home, const char **shell);
 int get_group_creds(const char **groupname, gid_t *gid);
 
+int in_gid(gid_t gid);
 int in_group(const char *name);
 
 char* uid_to_name(uid_t uid);
+char* gid_to_name(gid_t gid);
 
 int glob_exists(const char *path);