master 12c3461b45: Handle root permissions on remote files

[Michael Albinus]

branch: master
commit 12c3461b455bf06551060ed6061f7df84967ae97
Author: Michael Albinus <michael.albinus@gmx.de>
Commit: Michael Albinus <michael.albinus@gmx.de>

    Handle root permissions on remote files
    
    * lisp/net/tramp.el (tramp-check-cached-permissions): Check also
    for remote uid/gid being 0.  (Bug#57238)
    
    * lisp/net/tramp-sh.el (tramp-do-file-attributes-with-ls):
    Convert numeric uid/gid strings into real strings.
    (tramp-sh-get-signal-strings): Use `zerop'.
    
    * lisp/net/tramp.el (tramp-root-id-string, tramp-root-id-integer):
    New defconsts.
    (tramp-handle-find-backup-file-name, tramp-handle-lock-file)
    (tramp-local-host-p, tramp-handle-make-auto-save-file-name)
    * lisp/net/tramp-sh.el (tramp-default-method-alist)
    (ramp-default-user-alist, tramp-find-shell):
    * lisp/net/tramp-sudoedit.el (tramp-default-user-alist): Use them.
---
 lisp/net/tramp-sh.el       | 17 ++++++++++++-----
 lisp/net/tramp-sudoedit.el |  3 ++-
 lisp/net/tramp.el          | 35 +++++++++++++++++++++++------------
 3 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index f2e3c48235..4a9cf2e699 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -410,11 +410,12 @@ The string is used in `tramp-methods'.")
                 (tramp-copy-keep-date       t)))
 
  (add-to-list 'tramp-default-method-alist
-             `(,tramp-local-host-regexp "\\`root\\'" "su"))
+             `(,tramp-local-host-regexp
+               ,(format "\\`%s\\'" tramp-root-id-string) "su"))
 
  (add-to-list 'tramp-default-user-alist
              `(,(concat "\\`" (regexp-opt '("su" "sudo" "doas" "ksu")) "\\'")
-               nil "root"))
+               nil ,tramp-root-id-string))
  ;; Do not add "ssh" based methods, otherwise ~/.ssh/config would be ignored.
  ;; Do not add "plink" based methods, they ask interactively for the user.
  (add-to-list 'tramp-default-user-alist
@@ -1314,8 +1315,12 @@ component is used as the target of the symlink."
           ;; ... uid and gid
           (setq res-uid-string (read (current-buffer)))
           (setq res-gid-string (read (current-buffer)))
+         (when (natnump res-uid-string)
+           (setq res-uid-string (number-to-string res-uid-string)))
           (unless (stringp res-uid-string)
            (setq res-uid-string (symbol-name res-uid-string)))
+         (when (natnump res-gid-string)
+           (setq res-gid-string (number-to-string res-gid-string)))
           (unless (stringp res-gid-string)
            (setq res-gid-string (symbol-name res-gid-string)))
           ;; ... size
@@ -3096,7 +3101,7 @@ implementation will be used."
         (cond
          ;; Some predefined values, which aren't reported sometimes,
          ;; or would raise problems (all Stopped signals).
-         ((= i 0) 0)
+         ((zerop i) 0)
          ((string-equal (nth i signals) "HUP") "Hangup")
          ((string-equal (nth i signals) "INT") "Interrupt")
          ((string-equal (nth i signals) "QUIT") "Quit")
@@ -4272,8 +4277,10 @@ file exists and nonzero exit status otherwise."
              (with-tramp-connection-property vec "remote-shell"
                ;; CCC: "root" does not exist always, see my QNAP
                ;; TS-459.  Which check could we apply instead?
-               (tramp-send-command vec "echo ~root" t)
-               (if (or (string-match-p "^~root$" (buffer-string))
+               (tramp-send-command
+                vec (format "echo ~%s" tramp-root-id-string) t)
+               (if (or (string-match-p
+                        (format "^~%s$" tramp-root-id-string) (buffer-string))
                        ;; The default shell (ksh93) of OpenSolaris
                        ;; and Solaris is buggy.  We've got reports
                        ;; for "SunOS 5.10" and "SunOS 5.11" so far.
diff --git a/lisp/net/tramp-sudoedit.el b/lisp/net/tramp-sudoedit.el
index 3564a1b7b4..0de2e0ef69 100644
--- a/lisp/net/tramp-sudoedit.el
+++ b/lisp/net/tramp-sudoedit.el
@@ -48,7 +48,8 @@
                                   ("-p" "Password:") ("--")))
                (tramp-password-previous-hop t)))
 
- (add-to-list 'tramp-default-user-alist '("\\`sudoedit\\'" nil "root"))
+ (add-to-list 'tramp-default-user-alist
+             `("\\`sudoedit\\'" nil ,tramp-root-id-string))
 
  (tramp-set-completion-function
   tramp-sudoedit-method tramp-completion-function-alist-su))
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 5ffc4f1b88..046d814547 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -1055,6 +1055,12 @@ Derived from `tramp-postfix-host-format'.")
 (defconst tramp-unknown-id-integer -1
   "Integer used to denote an unknown user or group.")
 
+(defconst tramp-root-id-string "root"
+  "String used to denote the root user or group.")
+
+(defconst tramp-root-id-integer 0
+  "Integer used to denote the root user or group.")
+
 ;;; File name format:
 
 (defun tramp-build-remote-file-name-spec-regexp ()
@@ -4097,9 +4103,10 @@ Let-bind it when necessary.")
        (when (and (not tramp-allow-unsafe-temporary-files)
                   (not backup-inhibited)
                   (file-in-directory-p (car result) temporary-file-directory)
-                  (zerop (or (file-attribute-user-id
-                              (file-attributes filename 'integer))
-                             tramp-unknown-id-integer))
+                  (= (or (file-attribute-user-id
+                          (file-attributes filename 'integer))
+                         tramp-unknown-id-integer)
+                     tramp-root-id-integer)
                   (not (with-tramp-connection-property
                            (tramp-get-process v) "unsafe-temporary-file"
                          (yes-or-no-p
@@ -4482,9 +4489,10 @@ Do not set it manually, it is used buffer-local in 
`tramp-get-lock-pid'.")
          (when (and (not tramp-allow-unsafe-temporary-files)
                     create-lockfiles
                     (file-in-directory-p lockname temporary-file-directory)
-                    (zerop (or (file-attribute-user-id
-                                (file-attributes file 'integer))
-                               tramp-unknown-id-integer))
+                    (= (or (file-attribute-user-id
+                            (file-attributes file 'integer))
+                           tramp-unknown-id-integer)
+                       tramp-root-id-integer)
                     (not (with-tramp-connection-property
                              (tramp-get-process v) "unsafe-temporary-file"
                            (yes-or-no-p
@@ -5840,14 +5848,16 @@ be granted."
      ;; User accessible and owned by user.
      (and
       (eq access (aref (file-attribute-modes file-attr) offset))
-      (or (equal remote-uid tramp-unknown-id-integer)
+      (or (equal remote-uid tramp-root-id-integer)
+         (equal remote-uid tramp-unknown-id-integer)
          (equal remote-uid (file-attribute-user-id file-attr))
          (equal tramp-unknown-id-integer (file-attribute-user-id file-attr))))
      ;; Group accessible and owned by user's principal group.
      (and
       (eq access
          (aref (file-attribute-modes file-attr) (+ offset 3)))
-      (or (equal remote-gid tramp-unknown-id-integer)
+      (or (equal remote-gid tramp-root-id-integer)
+         (equal remote-gid tramp-unknown-id-integer)
          (equal remote-gid (file-attribute-group-id file-attr))
          (equal tramp-unknown-id-integer
                 (file-attribute-group-id file-attr)))))))
@@ -6007,7 +6017,7 @@ This handles also chrooted environments, which are not 
regarded as local."
       (tramp-make-tramp-file-name vec tramp-compat-temporary-file-directory))
      ;; On some systems, chown runs only for root.
      (or (zerop (user-uid))
-        (zerop (tramp-get-remote-uid vec 'integer))))))
+        (= (tramp-get-remote-uid vec 'integer) tramp-root-id-integer)))))
 
 (defun tramp-get-remote-tmpdir (vec)
   "Return directory for temporary files on the remote host identified by VEC."
@@ -6093,9 +6103,10 @@ this file, if that variable is non-nil."
        (when (and (not tramp-allow-unsafe-temporary-files)
                   auto-save-default
                   (file-in-directory-p result temporary-file-directory)
-                  (zerop (or (file-attribute-user-id
-                              (file-attributes filename 'integer))
-                             tramp-unknown-id-integer))
+                  (= (or (file-attribute-user-id
+                          (file-attributes filename 'integer))
+                         tramp-unknown-id-integer)
+                     tramp-root-id-integer)
                   (not (with-tramp-connection-property
                            (tramp-get-process v) "unsafe-temporary-file"
                          (yes-or-no-p