Package: emacs;
Reported by: sbaugh <at> catern.com
Date: Wed, 13 Sep 2023 02:25:01 UTC
Severity: normal
Tags: patch
Found in version 29.0.92
Done: Eli Zaretskii <eliz <at> gnu.org>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: sbaugh <at> catern.com To: Eli Zaretskii <eliz <at> gnu.org> Cc: jporterbugs <at> gmail.com, 65902 <at> debbugs.gnu.org, sbaugh <at> janestreet.com Subject: bug#65902: 29.0.92; emacsclient-mail.desktop fails due to complicated escaping Date: Sat, 23 Sep 2023 20:24:07 +0000 (UTC)
[Message part 1 (text/plain, inline)]
Eli Zaretskii <eliz <at> gnu.org> writes: >> From: sbaugh <at> catern.com >> Date: Fri, 22 Sep 2023 01:36:47 +0000 (UTC) >> Cc: Spencer Baugh <sbaugh <at> janestreet.com>, jporterbugs <at> gmail.com, >> 65902 <at> debbugs.gnu.org >> >> > Currently, when emacsclient is invoked like this: >> > >> > $ emacsclient --eval '(func args)' foo bar >> > >> > we send to the server the following commands: >> > >> > -eval (func args) >> > -eval foo >> > -eval bar >> > >> > IOW, every command-line argument after --eval is treated as being >> > implicitly preceded with --eval. >> > >> > With your proposal, how will the server know that some of "-eval foo" >> > commands should cause foo to be added to server-eval-args-left instead >> > of being evaluated as it does now? >> >> As in the attached patch. > > I wish you'd accompanied the patch with some plain-text description of > the idea, to make it easier to understand and to avoid unnecessary > misunderstandings. Ah, well, the basic idea is that for each -eval request we receive in the protocol, we accumulate the argument as a string into a single list (instead of immediately turning it into a closure which calls server-eval-and-print). Then we let-bind server-eval-args-left to that list around the calls to to server-eval-and-print, and consume each argument from the list one by one. > IIUC, this kind of solution is fine by me, but the protocol of > accessing and using server-eval-args-left in the Lisp expressions > specified on the emacsclient command line should be well-documented to > avoid any confusion and UB. Added a docstring and included it in NEWS. I would have put it in the manual, but it seems rather niche to put in the Emacs manual and I didn't see a natural place to put it in the Emacs Lisp manual.
[0001-Add-server-eval-args-left-to-server.el.patch (text/x-patch, inline)]
From cf7fcda1374491cc73a751d5636f36a95b2e8669 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh <at> catern.com>
Date: Thu, 21 Sep 2023 21:35:50 -0400
Subject: [PATCH] Add server-eval-args-left to server.el
Passing arbitrary arguments to functions through emacsclient --eval
requires complicated escaping to avoid them being parsed as Lisp (as
seen in emacsclient-mail.desktop before this change).
This new variable server-eval-args-left allows access to the arguments
before they are parsed as Lisp. By removing arguments from the
variable before they're parsed, a snippet of Lisp can consume
arguments, as in emacsclient-mail.desktop.
org-protocol might be able to use this as well, which might allow it
to drop its current advice on server-visit-files.
* etc/emacsclient-mail.desktop: Use server-eval-args-left. (bug#65902)
* lisp/server.el (server-eval-args-left): Add.
(server-process-filter, server-execute): Make -eval arguments
available through server-eval-args-left.
* lisp/startup.el (argv): Mention server-eval-args-left in docstring.
* etc/NEWS: Announce server-eval-args-left.
---
etc/NEWS | 10 ++++++++++
etc/emacsclient-mail.desktop | 7 ++-----
lisp/server.el | 35 ++++++++++++++++++++++++++++-------
lisp/startup.el | 5 ++++-
4 files changed, 44 insertions(+), 13 deletions(-)
diff --git a/etc/NEWS b/etc/NEWS
index cd4c414a64c..de1d79fcb98 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -121,6 +121,16 @@ Anything following the symbol 'mode-line-format-right-align' in
right-aligned to is controlled by the new user option
'mode-line-right-align-edge'.
+** Emacs Server and Client
+
+---
+*** 'server-eval-args-left' can be used to pop subsequent eval args
+When '--eval' is passed to emacsclient and Emacs is evaluating each
+argument, this variable is set to those which have not yet been
+evaluated. It can be used to 'pop' arguments to prevent them from
+being evaluated, which is useful when those arguments contain
+arbitrary data.
+
* Editing Changes in Emacs 30.1
diff --git a/etc/emacsclient-mail.desktop b/etc/emacsclient-mail.desktop
index 0a2420ddead..5962fa1764c 100644
--- a/etc/emacsclient-mail.desktop
+++ b/etc/emacsclient-mail.desktop
@@ -1,10 +1,7 @@
[Desktop Entry]
Categories=Network;Email;
Comment=GNU Emacs is an extensible, customizable text editor - and more
-# We want to pass the following commands to the shell wrapper:
-# u=$(echo "$1" | sed 's/[\"]/\\&/g'); exec emacsclient --alternate-editor= --display="$DISPLAY" --eval "(message-mailto \"$u\")"
-# Special chars '"', '$', and '\' must be escaped as '\\"', '\\$', and '\\\\'.
-Exec=sh -c "u=\\$(echo \\"\\$1\\" | sed 's/[\\\\\\"]/\\\\\\\\&/g'); exec emacsclient --alternate-editor= --display=\\"\\$DISPLAY\\" --eval \\"(message-mailto \\\\\\"\\$u\\\\\\")\\"" sh %u
+Exec=emacsclient --alternate-editor= --eval '(message-mailto (pop server-eval-args-left))' %u
Icon=emacs
Name=Emacs (Mail, Client)
MimeType=x-scheme-handler/mailto;
@@ -16,7 +13,7 @@ Actions=new-window;new-instance;
[Desktop Action new-window]
Name=New Window
-Exec=sh -c "u=\\$(echo \\"\\$1\\" | sed 's/[\\\\\\"]/\\\\\\\\&/g'); exec emacsclient --alternate-editor= --create-frame --eval \\"(message-mailto \\\\\\"\\$u\\\\\\")\\"" sh %u
+Exec=emacsclient --alternate-editor= --create-frame --eval '(message-mailto (pop server-eval-args-left))' %u
[Desktop Action new-instance]
Name=New Instance
diff --git a/lisp/server.el b/lisp/server.el
index c3325e5a24c..65f28cdea23 100644
--- a/lisp/server.el
+++ b/lisp/server.el
@@ -1189,6 +1189,7 @@ server-process-filter
parent-id ; Window ID for XEmbed
dontkill ; t if client should not be killed.
commands
+ evalexprs
dir
use-current-frame
frame-parameters ;parameters for newly created frame
@@ -1319,8 +1320,7 @@ server-process-filter
(let ((expr (pop args-left)))
(if coding-system
(setq expr (decode-coding-string expr coding-system)))
- (push (lambda () (server-eval-and-print expr proc))
- commands)
+ (push expr evalexprs)
(setq filepos nil)))
;; -env NAME=VALUE: An environment variable.
@@ -1345,7 +1345,7 @@ server-process-filter
;; arguments, use an existing frame.
(and nowait
(not (eq tty-name 'window-system))
- (or files commands)
+ (or files commands evalexprs)
(setq use-current-frame t))
(setq frame
@@ -1394,7 +1394,7 @@ server-process-filter
(let ((default-directory
(if (and dir (file-directory-p dir))
dir default-directory)))
- (server-execute proc files nowait commands
+ (server-execute proc files nowait commands evalexprs
dontkill frame tty-name)))))
(when (or frame files)
@@ -1404,22 +1404,43 @@ server-process-filter
;; condition-case
(t (server-return-error proc err))))
-(defun server-execute (proc files nowait commands dontkill frame tty-name)
+(defvar server-eval-args-left nil
+ "List of eval args not yet processed.
+
+When the server receives a request to eval one or more strings,
+it stores them in this variable. Then, until this variable is
+nil, it `pop's a string from this variable and evaluates it with
+`server-eval-and-print'. Adding or removing strings from this
+variable during this process will affect what is evaluated.
+
+This allows an expression passed to \"emacsclient --eval\" to
+consume one or more subsequent arguments before they're parsed or
+evaluated, with (pop server-eval-args-left). This is useful if
+those arguments are arbitrary strings which should not be
+evaluated.
+
+See also `command-line-args-left' for a similar variable which
+works for command line invocations of \"emacs\".")
+
+(defun server-execute (proc files nowait commands evalexprs dontkill frame tty-name)
;; This is run from timers and process-filters, i.e. "asynchronously".
;; But w.r.t the user, this is not really asynchronous since the timer
;; is run after 0s and the process-filter is run in response to the
;; user running `emacsclient'. So it is OK to override the
- ;; inhibit-quit flag, which is good since `commands' (as well as
+ ;; inhibit-quit flag, which is good since `evalexprs' (as well as
;; find-file-noselect via the major-mode) can run arbitrary code,
;; including code that needs to wait.
(with-local-quit
(condition-case err
(let ((buffers (server-visit-files files proc nowait)))
(mapc 'funcall (nreverse commands))
+ (let ((server-eval-args-left (nreverse evalexprs)))
+ (while server-eval-args-left
+ (server-eval-and-print (pop server-eval-args-left) proc)))
;; If we were told only to open a new client, obey
;; `initial-buffer-choice' if it specifies a file
;; or a function.
- (unless (or files commands)
+ (unless (or files commands evalexprs)
(let ((buf
(cond ((stringp initial-buffer-choice)
(find-file-noselect initial-buffer-choice))
diff --git a/lisp/startup.el b/lisp/startup.el
index 7f601668369..f2c84751211 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -120,7 +120,10 @@ command-switch-alist
"List of command-line args not yet processed.
This is a convenience alias, so that one can write (pop argv)
inside of --eval command line arguments in order to access
-following arguments."))
+following arguments.
+
+See also `server-eval-args-left' for a similar variable which
+works for invocations of \"emacsclient --eval\"."))
(internal-make-var-non-special 'argv)
(defvar command-line-args-left nil
--
2.41.0
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