bug#19192: 25.0.50; TRAMP uses `dired-listing-switches' for ftp-connection

[Rasmus]

Hi,

Michael Albinus <michael.albinus@gmx.de> writes:

>> So according to the note in `ange-ftp-get-files' there's the following
>> node on using dired-actual-switches or dired-listing-switches
>>
>>     ;; This is an efficiency hack. We try to
>>     ;; anticipate what sort of listing dired
>>     ;; might want, and cache just such a listing.
>>
>> Switches are checked with `ange-ftp-switches-ok'.  (man "sftp") has a
>> nice list of
>> switches supported.  Unfortunately, I don't really find anything on
>> supported ls in the manpage of ftp or the info manual...
>>
>> Option I: I can limit accepted ls flags by ange-ftp to the subset
>> supported by sftp.  
>>
>> Option I+: I could add a defcustom to allow the current more liberal
>> behavior akin to ange-ftp-passive-host-alist and
>> ange-ftp-try-passive-mode.
>>
>> Option II would be to add build-in support for something like the
>> --group-directories-first in dired, since now, if scrub off
>> --group-directories-first, a dired-ftp buffer will look different from a
>> local dired buffer...
>>
>> For now I will go with Option I.
>
> Well, I'm a little bit confused. In the beginning, you have spoken about
> "ftp". Now you've switched to "sftp". These are very different cases,
> and ange-ftp.el is *not* responsible for sftp connections.
>
> Could you, please, clarify?

That comment is obsolete.  See why here:

     http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19192#20

I tried all long commands with my ftp server (Debian-hosted) and discard
the ones that breaks ls over ftp.  

Feel free to try the attached patch.

Cheers,
Rasmus

-- 
If you can mix business and politics wonderful things can happen!

>From 6fd921e7d7deb88c5a3f172022b64a0539edbdd6 Mon Sep 17 00:00:00 2001
From: Rasmus <rasmus@gmx.us>
Date: Sat, 29 Nov 2014 13:12:10 +0100
Subject: [PATCH] ange-ftp.el: Disallow more dired ls-flags

* net/ange-ftp.el (ange-ftp-switches-ok): Disallow flags causing
trouble with ls over ftp.  These flags result in ls returning no
output, causing Tramp-breakage.

Fixes: debbugs:19192
---
 lisp/ChangeLog       |  6 ++++++
 lisp/net/ange-ftp.el | 12 +++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 2a450a7..7d0992e 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2014-11-29  Rasmus Pank Roulund  <emacs@pank.eu>
+
+       * net/ange-ftp.el (ange-ftp-switches-ok): Disallow flags causing
+       trouble with ls over ftp.  These flags result in ls returning no
+       output, causing Tramp-breakage.  (bug#19192)
+
 2014-11-29  Stephen Berman  <stephen.berman@gmx.net>
            Stefan Monnier  <monnier@iro.umontreal.ca>

diff --git a/lisp/net/ange-ftp.el b/lisp/net/ange-ftp.el
index d7632ed..a2b0b46 100644
--- a/lisp/net/ange-ftp.el
+++ b/lisp/net/ange-ftp.el
@@ -2831,16 +2831,26 @@ match subdirectories as well.")
                      files ange-ftp-files-hashtable)))

 (defun ange-ftp-switches-ok (switches)
-  "Return SWITCHES (a string) if suitable for our use."
+  "Return SWITCHES (a string) if suitable for use with ls over ftp."
   (and (stringp switches)
        ;; We allow the A switch, which lists all files except "." and
        ;; "..".  This is OK because we manually insert these entries
        ;; in the hash table.
        (string-match
        "--\\(almost-\\)?all\\>\\|\\(\\`\\| \\)-[[:alpha:]]*[aA]" switches)
+       ;; Allow flags starting with a single dash
        (string-match "\\(\\`\\| \\)-[[:alpha:]]*l" switches)
+       ;; Disallow recursive flag
        (not (string-match
             "--recursive\\>\\|\\(\\`\\| \\)-[[:alpha:]]*R" switches))
+       ;; Disallow most long flags from (man "ls"), version 8.23 of July 2014.
+       (not (string-match
+             (concat
+              "--\\(block-size\\|color\\|format\\|group-directories-first\\|"
+              
"human-readable\\|dereference-command-line\\|hide\\|indicator-style\\|"
+              
"dereference-command-line-symlink-to-dir\\|inode\\|ignore\\|dereference\\|"
+              
"numeric-uid-gid\\|indicator-style\\|hide-control-chars\\|quoting-style\\|"
+              "sort\\|time\\|time-style\\|width\\)")))
        switches))

 (defun ange-ftp-get-files (directory &optional no-error)
--
2.1.3