Add file name handler support for file-system-info

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

* etc/NEWS: Mention get-free-disk-space working on remote systems.

* lisp/files.el (get-free-disk-space): Do not block on remote systems.

* src/w32fns.c (Ffile_system_info):
* src/fileio.c (Ffile_system_info): Call file name handler if exists.
(syms_of_fileio): Add Qfile_system_info.

2 files changed, 24 insertions, 0 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 11370279d1b..d460f123a82 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5789,6 +5789,18 @@ If the underlying system call fails, value is nil.  */)
   (Lisp_Object filename)
 {
   Lisp_Object encoded = ENCODE_FILE (Fexpand_file_name (filename, Qnil));
+
+  /* If the file name has special constructs in it,
+     call the corresponding file handler.  */
+  Lisp_Object handler = Ffind_file_name_handler (encoded, Qfile_system_info);
+  if (!NILP (handler))
+    {
+      Lisp_Object result = call2 (handler, Qfile_system_info, encoded);
+      if (CONSP (result) || NILP (result))
+        return result;
+      error ("Invalid handler in `file-name-handler-alist'");
+    }
+
   struct fs_usage u;
   if (get_fs_usage (SSDATA (encoded), NULL, &u) != 0)
     return Qnil;
@@ -5870,6 +5882,7 @@ syms_of_fileio (void)
   DEFSYM (Qwrite_region, "write-region");
   DEFSYM (Qverify_visited_file_modtime, "verify-visited-file-modtime");
   DEFSYM (Qset_visited_file_modtime, "set-visited-file-modtime");
+  DEFSYM (Qfile_system_info, "file-system-info");
 
   /* The symbol bound to coding-system-for-read when
      insert-file-contents is called for recovering a file.  This is not
diff --git a/src/w32fns.c b/src/w32fns.c
index efbd81b22d9..e3de22d68ab 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -9336,6 +9336,17 @@ If the underlying system call fails, value is nil.  */)
   filename = Fexpand_file_name (filename, Qnil);
   encoded = ENCODE_FILE (filename);
 
+  /* If the file name has special constructs in it,
+     call the corresponding file handler.  */
+  Lisp_Object handler = Ffind_file_name_handler (encoded, Qfile_system_info);
+  if (!NILP (handler))
+    {
+      value = call2 (handler, Qfile_system_info, encoded);
+      if (CONSP (value) || NILP (value))
+        return value;
+      error ("Invalid handler in `file-name-handler-alist'");
+    }
+
   value = Qnil;
 
   /* Determining the required information on Windows turns out, sadly,