Clears input after quitting the REPL.

README

@@ -65,47 +65,17 @@ at /usr/lib/x86_64-linux-gnu.
 
 First, try it out.
 
---8<-------------------------------------------------------->8---
 $ cd /path/to/loop/home
-$ ./loop --help
-NAME:
-  loop - An NNTP server for a circle of friends.
-
-USAGE:
-  loop [options] [arguments ...]
-
-OPTIONS:
-      --change-passwd <VALUE>   <username> <new-password> changes password
-      --create-account <VALUE>  <username> <invited-by> creates a new account
-      --help                    display usage information and exit
-      --logging                 turn on debug logging on stderr
-      --version                 display version and exit
-  -l, --list-accounts           lists accounts
-  -r, --repl                    run a REPL on port 4006
-  -s, --server                  runs NNTP server reading from stdout
-
-AUTHORS:
-  Circling Skies <loop@antartida.xyz>
-
-LICENSE:
-  GPL v3
---8<-------------------------------------------------------->8---
-
-You can talk to the NNTP server with -s:
-
---8<-------------------------------------------------------->8---
-$ ./loop -s
+$ ./loop
 200 Welcome! Say ``help'' for a menu.
 quit
 205 Good-bye.
---8<-------------------------------------------------------->8---
 
-It's time to create an account for you.  Whenever you run loop, make
-sure you're in its home directory because it will look for the file
-accounts.lisp always relatively to the current working directory of
-the process.  The same applies if you set up a cron job later
-on---make sure the job, too, sets LOOP's home directory as its current
-working directory.
+It runs.  Whenever you run loop, make sure you're in its home
+directory because it will look for the file accounts.lisp always
+relatively to the current working directory of the process.  The same
+applies if you set up a cron job later on---make sure the job, too,
+sets LOOP's home directory as its current working directory.
 
 (*) Create your account
 
@@ -151,6 +121,28 @@ never done this, it will be better education if you learn to use
 daemontools and ucspi-tcp before going live with a LOOP community.
 It's easy and fun.
 
+(*) LOOP's REPL
+
+LOOP is totally hackable.  Even if you're remotely connected, you can
+have total control over the loop process with the repl command:
+
+$ telnet example.com 119
+Trying example.com...
+Connected to example.com.
+Escape character is '^]'.
+200 Welcome! Say ``help'' for a menu.
+login you <secret>
+200 Welcome, YOU.
+repl
+LOOP> *client*
+#S(CLIENT :GROUP NIL :ARTICLE 1 :USERNAME YOU :AUTH? YES)
+LOOP> (list-groups)
+(comp.editors.emacs comp.lisp comp.programming comp.unix
+       humanities.poetry local.control.news local.havoc local.system.reports
+       local.test local.users.evalu math.calculus math.havoc)
+LOOP> quit
+200 Okay, no more REPL hacking.
+
 (*) Cron jobs
 
 If you'd like to remove inactive accounts, we wrote

loop.nw

@@ -377,8 +377,32 @@ LOOP> (list-groups)
 (local.control.news local.test)
 \end{verbatim}
 
-We implement it by creating a [[repl]] procedure in \lp's package with
-an option handled by [[cli/command]].
+The REPL can also be use in the middle of an NNTP conversation, which
+is useful for debugging.  All authenticated users can use it, making
+passwords only a barrier to spammers, not to your circle of friends,
+since everyone can find a way to log in with anyone's account, change
+their passwords or just do whatever they want to \lxxp\ process or
+databases.
+
+As the comment below explains, we need to [[clear-output]] in the
+[[*standard-input*]] to avoid the following problem:
+%
+\begin{verbatim}
+repl
+LOOP> quit
+200 Okay, no more REPL hacking.
+400 I beg your pardon?
+\end{verbatim}
+%
+What happens is that [[read]] consumes just the symbol \verb|quit|, so
+there remains a \verb|\n| or \verb|\r\n| in the [[*standard-input*]],
+which we need to wipe out, or [[nntp-read-line]] will consume an empty
+line, which is what causes that 400 response\footnote{Months ago I
+pondered whether I should ignore an empty command or whether I should
+write back an empty response such as this one---I beg your pardon?  I
+decided to not ignore.  By not ignoring, [[read]] now called my
+attention to the fact that a trailing \verb|\r\n| is left, which seems
+good to know.}.
 
 <<Loop's REPL>>=
 (defun repl (r)
@@ -2006,9 +2030,9 @@ all or it has been discussed with the community beforehand.
 
 \subsection{{\tt REPL}}
 
-Opens a REPL for the pleasure of hacking \lp.  The only thing we
-require is that the user be authenticated.  This means that any user
-has total control over \lp. XXX: implement an option
+Mean for hackers, \lp\ is totally {\em hackable}.  After
+authentication, users can say {\tt repl} to have complete control over
+their \lxxp\ process.  XXX: we should implement an option
 [[--disable-repl]] so that REPL hacking is turned off.  (This would
 mean your users are not true hackers.)