Update Files chapter in Lisp manual.

* doc/lispref/files.texi (Files): Mention magic file names as arguments.
(Reading from Files): Copyedits.
(File Attributes): Mention how to change file modes.
(Changing Files): Use standard "file permissions" terminology.
Add xref to File Attributes node.
(Locating Files): Document locate-user-emacs-file.
(Unique File Names): Recommend against using make-temp-name.

* src/buffer.c (Fget_file_buffer): Protect against invalid file
handler return value.

* src/fileio.c (Vfile_name_handler_alist): Doc fix.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/buffer.c b/src/buffer.c
index a6f61a1936a..71a5e199c6f 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -272,7 +272,11 @@ See also `find-buffer-visiting'.  */)
      call the corresponding file handler.  */
   handler = Ffind_file_name_handler (filename, Qget_file_buffer);
   if (!NILP (handler))
-    return call2 (handler, Qget_file_buffer, filename);
+    {
+      Lisp_Object handled_buf = call2 (handler, Qget_file_buffer,
+                                       filename);
+      return BUFFERP (handled_buf) ? handled_buf : Qnil;
+    }
 
   for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail))
     {