Fix Bug#30946

* doc/misc/tramp.texi (Multi-hops): Mention host name checks.

* lisp/net/tramp.el (tramp-set-syntax, tramp-dissect-file-name)
(tramp-debug-message, tramp-handle-shell-command):
* lisp/net/tramp-adb.el (tramp-adb-handle-shell-command):
* lisp/net/tramp-archive.el (tramp-archive-file-name-handler)
(tramp-archive-dissect-file-name):
* lisp/net/tramp-gvfs.el (tramp-gvfs-file-name-handler): Adapt callees.

* lisp/net/tramp-compat.el (tramp-compat-user-error): Move defsubst ---

* lisp/net/tramp-sh.el (tramp-compute-multi-hops): Check for proper
host names in multi-hop.  (Bug#30946)

* lisp/net/tramp.el (tramp-user-error): ... here.  Make it a defun.

* test/lisp/net/tramp-tests.el (tramp-test03-file-name-host-rules):
New test.

1 files changed, 23 insertions, 0 deletions

diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index dfb01126f70..5e79a4bce6f 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -1722,6 +1722,28 @@ handled properly.  BODY shall not contain a timeout."
   ;; Default values in tramp-smb.el.
   (should (string-equal (file-remote-p "/smb::" 'user) nil)))
 
+;; The following test is inspired by Bug#30946.
+(ert-deftest tramp-test03-file-name-host-rules ()
+  "Check host name rules for host-less methods."
+  (skip-unless (tramp--test-enabled))
+  (skip-unless (tramp--test-sh-p))
+
+  ;; Host names must match rules in case the command template of a
+  ;; method doesn't use them.
+  (dolist (m '("su" "sg" "sudo" "doas" "ksu"))
+    ;; Single hop.  The host name must match `tramp-local-host-regexp'.
+    (should-error
+     (find-file (format "/%s:foo:" m))
+     :type 'user-error)
+    ;; Multi hop.  The host name must match the previous hop.
+    (should-error
+     (find-file
+      (format
+       "%s|%s:foo:"
+       (substring (file-remote-p tramp-test-temporary-file-directory) nil -1)
+       m))
+     :type 'user-error)))
+
 (ert-deftest tramp-test04-substitute-in-file-name ()
   "Check `substitute-in-file-name'."
   (should (string-equal (substitute-in-file-name "/method:host:///foo") "/foo"))
@@ -1836,6 +1858,7 @@ handled properly.  BODY shall not contain a timeout."
   ;; Mark as failed until bug has been fixed.
   :expected-result :failed
   (skip-unless (tramp--test-enabled))
+
   ;; These are the methods the test doesn't fail.
   (when (or (tramp--test-adb-p) (tramp--test-gvfs-p)
             (tramp-smb-file-name-p tramp-test-temporary-file-directory))