Subject: bug#60943: 28.2; ‘tramp-handle-file-regular-p’ misses symlinks

From: Michael Albinus <[email-masked]>
Date: Fri, 20 Jan 2023 11:56:07 +0100

Greg Pfeil <[email-masked]> writes:

Hi Greg,

> I think sockets (where the 0th char is ?s) are also considered regular
> files. Also, I think that patch checks whether the truename is a
> regular file, but I believe /all/ symlinks are considered regular.

No, neither sockets nor symlinks to directories count as regular
files. See the Elisp manual (info "(elisp) Kinds of Files")

A socket is an "other I/O device" according to the description. And
symlinks are regular files only, if they point to a regular file.

> It just changes the equality check to check for the set of valid
> values. If we had the mode as a number, we could just check the one
> bit for regular files (which I think is what ‘file-regular-p’ does).

You can always check yourself in Emacs with a local file. For example,
if you have a socket like "/run/user/1000/bus":

--8<---------------cut here---------------start------------->8---
(file-exists-p (concat (getenv "XDG_RUNTIME_DIR") "/bus"))
=> t

(file-attribute-modes (file-attributes (concat (getenv "XDG_RUNTIME_DIR") "/bus")))
=> "srw-rw-rw-"

(file-regular-p (concat (getenv "XDG_RUNTIME_DIR") "/bus"))
=> nil
--8<---------------cut here---------------end--------------->8---

Or

--8<---------------cut here---------------start------------->8---
(make-directory "/tmp/foo")
(file-attribute-modes (file-attributes "/tmp/foo"))
=> "drwxr-xr-x"

(make-symbolic-link "/tmp/foo" "/tmp/bar")
(file-attribute-modes (file-attributes "/tmp/bar"))
=> "lrwxrwxrwx"

(file-regular-p "/tmp/bar")
=> nil
--8<---------------cut here---------------end--------------->8---

for symbolic links.

Best regards, Michael.