bug#23159: 24.5; --eval bug

[npostavs]

tags 23159 patch
quit

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Tue, 29 Mar 2016 21:40:37 -0500
>> From: "Devon Sean McCullough" <Emacs-Hacker2016@jovi.net>
>> 
>> MacOSX$ Open -n /Applications/Emacs.app --args -Q --eval "(print 'foo)
>> (print 'bar)"
>> should either report an error or print foo bar.
>> The current buggy behavior silently ignores part of the argument.
>
> I think this is expected.  The manual says:
>
>   ‘--eval=EXPRESSION’
>   ‘--execute=EXPRESSION’
>        Evaluate Lisp expression EXPRESSION.
>
> It evaluates a single Lisp expression.

If we get more than that, a warning seems appropriate.

>From c9730b47893678b2283590c269ad33998a8a430a Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sat, 2 Jul 2016 20:26:35 -0400
Subject: [PATCH v1] Warn if --eval arg has text beyond 1 expression

* lisp/startup.el (command-line-1): If --eval argument has more data
than constitutes a single Lisp expression, print warning (Bug #23159).
---
 lisp/startup.el | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lisp/startup.el b/lisp/startup.el
index 761e69e..9f04a00 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -2360,7 +2360,15 @@ command-line-1
 
                     ((member argi '("-eval" "-execute"))
                      (setq inhibit-startup-screen t)
-                     (eval (read (or argval (pop command-line-args-left)))))
+                     (let* ((str-expr (or argval (pop command-line-args-left)))
+                            (read-data (read-from-string str-expr))
+                            (expr (car read-data))
+                            (end (cdr read-data)))
+                       (eval expr)
+                       (unless (= end (length str-expr))
+                         (lwarn '(command-line eval) :warning
+                                "Garbage at the end of expression: %s"
+                                (substring str-expr end)))))
 
                     ((member argi '("-L" "-directory"))
                      ;; -L :/foo adds /foo to the _end_ of load-path.
-- 
2.8.0