Implement file locks for remote files (Bug#49261)

* doc/lispref/files.texi (Magic File Names): Add file-locked-p,
lock-file and unlock-file.

* etc/NEWS: Tramp supports file locks now.

* lisp/net/tramp-adb.el (tramp-adb-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-adb-handle-write-region): Handle LOCKNAME.

* lisp/net/tramp-archive.el (tramp-archive-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.

* lisp/net/tramp-crypt.el (tramp-crypt-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-crypt-handle-file-locked-p, tramp-crypt-handle-lock-file)
(tramp-crypt-handle-unlock-file): New defun.

* lisp/net/tramp-fuse.el (tramp-fuse-mounted-p): Simplify.
(tramp-fuse-unmount): New defun.

* lisp/net/tramp-gvfs.el (tramp-gvfs-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-gvfs-maybe-open-connection): Set "lock-pid" connection property.

* lisp/net/tramp-rclone.el (tramp-rclone-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-rclone-maybe-open-connection): Set "lock-pid" connection property.

* lisp/net/tramp-sh.el (tramp-sh-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-sh-handle-write-region): Handle LOCKNAME.

* lisp/net/tramp-smb.el (tramp-smb-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-smb-handle-copy-directory): Use `sleep-for'.
(tramp-smb-handle-write-region): Handle LOCKNAME.

* lisp/net/tramp-sshfs.el (tramp-sshfs-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-sshfs-handle-write-region): Handle LOCKNAME.
(tramp-sshfs-maybe-open-connection): Set "lock-pid" connection property.

* lisp/net/tramp-sudoedit.el (tramp-sudoedit-file-name-handler-alist):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-sudoedit-maybe-open-connection):
Set "lock-pid" connection property.

* lisp/net/tramp.el (tramp-file-name-for-operation):
Add `file-locked-p', `lock-file' and `unlock-file'.
(tramp-make-lock-name, tramp-get-lock-file, tramp-get-lock-pid)
(tramp-handle-file-locked-p, tramp-handle-lock-file)
(tramp-handle-unlock-file): New defuns.
(tramp-lock-file-contents-regexp): New regexp.
(tramp-handle-write-region): Handle LOCKNAME.

* src/filelock.c (lock_file, unlock_file_body, Ffile_locked_p):
Call handler if exists.
(Flock_file, Funlock_file): New defuns.
(Qlock_file, Qunlock_file, Qfile_locked_p): Declare symbols.
(Slock_file, Sunlock_file): Declare subroutines.

* test/lisp/net/tramp-archive-tests.el
(tramp-archive-test40-make-nearby-temp-file)
(tramp-archive-test43-file-system-info): Rename.

* test/lisp/net/tramp-tests.el (top): Set `create-lockfiles' to nil.
(tramp--test-fuse-p): New defun.
(tramp-test14-delete-directory): Use it.
(tramp-test39-lock-file): New test.
(tramp-test40-make-nearby-temp-file)
(tramp-test41-special-characters)
(tramp-test41-special-characters-with-stat)
(tramp-test41-special-characters-with-perl)
(tramp-test41-special-characters-with-ls, tramp-test42-utf8)
(tramp-test42-utf8-with-stat, tramp-test42-utf8-with-perl)
(tramp-test42-utf8-with-ls, tramp-test43-file-system-info)
(tramp-test44-asynchronous-requests, tramp-test45-auto-load)
(tramp-test45-delay-load, tramp-test45-recursive-load)
(tramp-test45-remote-load-path, tramp-test46-unload): Rename.
(tramp--test-special-characters, tramp--test-utf8)
(tramp--test-asynchronous-requests-timeout): Modify docstring.

1 files changed, 57 insertions, 1 deletions

diff --git a/src/filelock.c b/src/filelock.c
index 446a262a1ce..dcdc635c25e 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -671,6 +671,16 @@ lock_file (Lisp_Object fn)
   if (will_dump_p ())
     return;
 
+  /* If the file name has special constructs in it,
+     call the corresponding file name handler.  */
+  Lisp_Object handler;
+  handler = Ffind_file_name_handler (fn, Qlock_file);
+  if (!NILP (handler))
+    {
+      call2 (handler, Qlock_file, fn);
+      return;
+    }
+
   orig_fn = fn;
   fn = Fexpand_file_name (fn, Qnil);
 #ifdef WINDOWSNT
@@ -725,6 +735,16 @@ unlock_file_body (Lisp_Object fn)
   char *lfname;
   USE_SAFE_ALLOCA;
 
+  /* If the file name has special constructs in it,
+     call the corresponding file name handler.  */
+  Lisp_Object handler;
+  handler = Ffind_file_name_handler (fn, Qunlock_file);
+  if (!NILP (handler))
+    {
+      call2 (handler, Qunlock_file, fn);
+      return Qnil;
+    }
+
   Lisp_Object filename = Fexpand_file_name (fn, Qnil);
   fn = ENCODE_FILE (filename);
 
@@ -784,6 +804,27 @@ unlock_all_files (void)
     }
 }
 
+DEFUN ("lock-file", Flock_file, Slock_file,
+       0, 1, 0,
+       doc: /* Lock FILE.
+If the option `create-lockfiles' is nil, this does nothing.  */)
+  (Lisp_Object file)
+{
+  CHECK_STRING (file);
+  lock_file (file);
+  return Qnil;
+}
+
+DEFUN ("unlock-file", Funlock_file, Sunlock_file,
+       0, 1, 0,
+       doc: /* Unlock FILE.  */)
+  (Lisp_Object file)
+{
+  CHECK_STRING (file);
+  unlock_file (file);
+  return Qnil;
+}
+
 DEFUN ("lock-buffer", Flock_buffer, Slock_buffer,
        0, 1, 0,
        doc: /* Lock FILE, if current buffer is modified.
@@ -844,6 +885,15 @@ t if it is locked by you, else a string saying which user has locked it.  */)
   lock_info_type locker;
   USE_SAFE_ALLOCA;
 
+  /* If the file name has special constructs in it,
+     call the corresponding file name handler.  */
+  Lisp_Object handler;
+  handler = Ffind_file_name_handler (filename, Qfile_locked_p);
+  if (!NILP (handler))
+    {
+      return call2 (handler, Qfile_locked_p, filename);
+    }
+
   filename = Fexpand_file_name (filename, Qnil);
   Lisp_Object encoded_filename = ENCODE_FILE (filename);
   MAKE_LOCK_NAME (lfname, encoded_filename);
@@ -876,7 +926,13 @@ The name of the (per-buffer) lockfile is constructed by prepending a
 Info node `(emacs)Interlocking'.  */);
   create_lockfiles = true;
 
-  defsubr (&Sunlock_buffer);
+  DEFSYM (Qlock_file, "lock-file");
+  DEFSYM (Qunlock_file, "unlock-file");
+  DEFSYM (Qfile_locked_p, "file-locked-p");
+
+  defsubr (&Slock_file);
+  defsubr (&Sunlock_file);
   defsubr (&Slock_buffer);
+  defsubr (&Sunlock_buffer);
   defsubr (&Sfile_locked_p);
 }