homectl: don't use password cache if we operate on other user

src/basic/user-util.c

@@ -1072,3 +1072,16 @@ int fgetsgent_sane(FILE *stream, struct sgrp **sg) {
         return !!s;
 }
 #endif
+
+int is_this_me(const char *username) {
+        uid_t uid;
+        int r;
+
+        /* Checks if the specified username is our current one. Passed string might be a UID or a user name. */
+
+        r = get_user_creds(&username, &uid, NULL, NULL, NULL, USER_CREDS_ALLOW_MISSING);
+        if (r < 0)
+                return r;
+
+        return uid == getuid();
+}

src/basic/user-util.h

@@ -109,3 +109,5 @@ int putsgent_sane(const struct sgrp *sg, FILE *stream);
 #endif
 
 bool is_nologin_shell(const char *shell);
+
+int is_this_me(const char *username);