Extend memory-info for remote systems

* doc/lispref/files.texi (Magic File Names): Add memory-info.

* doc/lispref/internals.texi (Garbage Collection): memory-info can
also retrieve values from remote systems.

* etc/NEWS: Document changes in memory-info.  Fix typos.

* lisp/files.el (warn-maybe-out-of-memory): Ensure local memory info.

* lisp/net/tramp.el (tramp-handle-memory-info): New defun.
(tramp-file-name-for-operation)
* lisp/net/tramp-adb.el (tramp-adb-file-name-handler-alist):
* lisp/net/tramp-archive.el (tramp-archive-file-name-handler-alist):
* lisp/net/tramp-crypt.el (tramp-crypt-file-name-handler-alist):
* lisp/net/tramp-gvfs.el (tramp-gvfs-file-name-handler-alist):
* lisp/net/tramp-rclone.el (tramp-rclone-file-name-handler-alist):
* lisp/net/tramp-sh.el (tramp-sh-file-name-handler-alist):
* lisp/net/tramp-smb.el (tramp-smb-file-name-handler-alist):
* lisp/net/tramp-sshfs.el (tramp-sshfs-file-name-handler-alist)
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-file-name-handler-alist):
Add 'memory-info'.

* lisp/net/tramp-sshfs.el (tramp-sshfs-handle-exec-path):
Let-bind `process-file-side-effects'.

* src/alloc.c (Fmemory_info): Support remote systems.
(Qmemory_info): Declare.

* test/lisp/net/tramp-tests.el (tramp-test31-memory-info): New test.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 0653f2e0ccc..980085d3292 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -7435,9 +7435,17 @@ DEFUN ("memory-info", Fmemory_info, Smemory_info, 0, 0, 0,
        doc: /* Return a list of (TOTAL-RAM FREE-RAM TOTAL-SWAP FREE-SWAP).
 All values are in Kbytes.  If there is no swap space,
 last two values are zero.  If the system is not supported
-or memory information can't be obtained, return nil.  */)
+or memory information can't be obtained, return nil.
+If `default-directory’ is remote, return memory information of the
+respective remote host.  */)
   (void)
 {
+  Lisp_Object handler
+    = Ffind_file_name_handler (BVAR (current_buffer, directory),
+                               Qmemory_info);
+  if (!NILP (handler))
+    return call1 (handler, Qmemory_info);
+
 #if defined HAVE_LINUX_SYSINFO
   struct sysinfo si;
   uintmax_t units;
@@ -7859,6 +7867,8 @@ do hash-consing of the objects allocated to pure space.  */);
                doc: /* Non-nil means Emacs cannot get much more Lisp memory.  */);
   Vmemory_full = Qnil;
 
+  DEFSYM (Qmemory_info, "memory-info");
+
   DEFSYM (Qconses, "conses");
   DEFSYM (Qsymbols, "symbols");
   DEFSYM (Qstrings, "strings");