master 79e1bff269 2/2: Improve rename-file fix (bug#34069)

[Paul Eggert]

branch: master
commit 79e1bff2694444a27036b08e8fa2a6619b40dc2a
Author: Paul Eggert <eggert@cs.ucla.edu>
Commit: Paul Eggert <eggert@cs.ucla.edu>

    Improve rename-file fix (bug#34069)
    
    * src/fileio.c (Frename_file): No need for a special case to
    rename a fifo, since we already tried and failed to rename it.
    Also improve symlink handling, in that if readlink fails report an
    error rather than trying to treat the link as a regular file.
---
 src/fileio.c | 35 ++++++++++++-----------------------
 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/src/fileio.c b/src/fileio.c
index a50f8d67c1..789f3d509e 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -134,6 +134,7 @@ static dev_t timestamp_file_system;
    is added here.  */
 static Lisp_Object Vwrite_region_annotation_buffers;
 
+static Lisp_Object emacs_readlinkat (int, char const *);
 static Lisp_Object file_name_directory (Lisp_Object);
 static bool a_write (int, Lisp_Object, ptrdiff_t, ptrdiff_t,
                     Lisp_Object *, struct coding_system *);
@@ -2710,31 +2711,19 @@ This is what happens in interactive use with M-x.  */)
     }
   if (dirp)
     call4 (Qcopy_directory, file, newname, Qt, Qnil);
-  else
-    {
-      Lisp_Object symlink_target
-       = (S_ISLNK (file_st.st_mode)
-          ? check_emacs_readlinkat (AT_FDCWD, file, SSDATA (encoded_file))
-          : Qnil);
-      if (!NILP (symlink_target))
-       Fmake_symbolic_link (symlink_target, newname, ok_if_already_exists);
-      else if (S_ISFIFO (file_st.st_mode))
-       {
-         /* If it's a FIFO, calling `copy-file' will hang if it's a
-            inter-file system move, so do it here.  (It will signal
-            an error in that case, but it won't hang in any case.)  */
-         if (!NILP (ok_if_already_exists))
-           barf_or_query_if_file_exists (newname, false,
-                                         "rename to it",
-                                         FIXNUMP (ok_if_already_exists),
-                                         false);
-         if (rename (SSDATA (encoded_file), SSDATA (encoded_newname)) != 0)
-           report_file_errno ("Renaming", list2 (file, newname), errno);
-         return Qnil;
-       }
+  else if (S_ISREG (file_st.st_mode))
+    Fcopy_file (file, newname, ok_if_already_exists, Qt, Qt, Qt);
+  else if (S_ISLNK (file_st.st_mode))
+    {
+      Lisp_Object target = emacs_readlinkat (AT_FDCWD,
+                                            SSDATA (encoded_file));
+      if (!NILP (target))
+       Fmake_symbolic_link (target, newname, ok_if_already_exists);
       else
-       Fcopy_file (file, newname, ok_if_already_exists, Qt, Qt, Qt);
+       report_file_error ("Renaming", list2 (file, newname));
     }
+  else
+    report_file_errno ("Renaming", list2 (file, newname), rename_errno);
 
   specpdl_ref count = SPECPDL_INDEX ();
   specbind (Qdelete_by_moving_to_trash, Qnil);