Re: X selection access in xterm (OSC 52)

[Philipp Stephani <p.stephani2@gmail.com>]

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Philipp Stephani <p.stephani2@gmail.com> schrieb am Di., 10. Feb. 2015 um
11:30 Uhr:

>
>
> Stefan Monnier <monnier@iro.umontreal.ca> schrieb am Mon Feb 09 2015 at
> 6:12:20 PM:
>
> > gnome-terminal gets adjusted to 200, so I assume that the test for >= 203
>> > should be OK and cover both xterm and hterm.
>>
>> Indeed, sounds good.  Can someone prepare a patch for that feature?
>>
>>
> I'm on it.
>

Attached a patch.

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From 06019ced7d34dade2d40d97605f6b2c1962fe67a Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Fri, 27 Feb 2015 19:51:01 +0100
Subject: [PATCH] Add support for OSC 52.

This is an xterm escape sequence to save text to the X clipboard.  Taken from
https://github.com/chromium/hterm/blob/64b3819692526f41eb960f6c9444c2c58e658f79/etc/osc52.el.
---
 lisp/term/xterm.el | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 91 insertions(+), 4 deletions(-)

diff --git a/lisp/term/xterm.el b/lisp/term/xterm.el
index 519f691..2cfc36d 100644
--- a/lisp/term/xterm.el
+++ b/lisp/term/xterm.el
@@ -37,7 +37,8 @@ If a list, assume that the listed features are supported, without checking.
 
 The relevant features are:
   modifyOtherKeys  -- if supported, more key bindings work (e.g., \"\\C-,\")
-  reportBackground -- if supported, Xterm reports its background color"
+  reportBackground -- if supported, Xterm reports its background color
+  interprogramCut  -- if supported, Xterm saves yanked text to the X selection"
   :version "24.1"
   :group 'xterm
   :type '(choice (const :tag "No" nil)
@@ -45,7 +46,24 @@ The relevant features are:
                  ;; NOTE: If you add entries here, make sure to update
                  ;; `terminal-init-xterm' as well.
                  (set (const :tag "modifyOtherKeys support" modifyOtherKeys)
-                      (const :tag "report background" reportBackground))))
+                      (const :tag "report background" reportBackground)
+                      (const :tag "X selection cut" interprogramCut))))
+
+(defcustom xterm-max-cut-length 100000
+  "Maximum number of bytes to cut into xterm using the OSC 52 sequence.
+
+The OSC 52 sequence requires a terminator byte.  Some terminals will ignore or
+mistreat a terminated sequence that is longer than a certain size, usually to
+protect users from runaway sequences.
+
+This variable allows you to tweak the maximum number of bytes that will be sent
+using the OSC 52 sequence.
+
+If you select a region larger than this size, it won't be copied to your system
+clipboard.  Since clipboard data is base 64 encoded, the actual number of
+string bytes that can be copied is 3/4 of this value."
+  :group 'xterm
+  :type 'integer)
 
 (defconst xterm-paste-ending-sequence "\e[201~"
   "Characters send by the terminal to end a bracketed paste.")
@@ -620,7 +638,13 @@ The relevant features are:
         ;; introduced) or higher, initialize the
         ;; modifyOtherKeys support.
         (when (>= version 216)
-          (terminal-init-xterm-modify-other-keys))))))
+          (terminal-init-xterm-modify-other-keys))
+        ;; In version 203 support for accessing the X selection was
+        ;; added.  Hterm reports itself as version 256 and supports it
+        ;; as well.  gnome-terminal doesn't and is excluded by this
+        ;; test.
+        (when (>= version 203)
+          (terminal-init-xterm-activate-interprogram-cut))))))
 
 (defun xterm--query (query handlers)
   "Send QUERY string to the terminal and watch for a response.
@@ -699,7 +723,10 @@ We run the first FUNCTION whose STRING matches the input events."
                     '(("\e]11;" .  xterm--report-background-handler))))
 
     (when (memq 'modifyOtherKeys xterm-extra-capabilities)
-      (terminal-init-xterm-modify-other-keys)))
+      (terminal-init-xterm-modify-other-keys))
+
+    (when (memq 'interprogramCut xterm-extra-capabilities)
+      (terminal-init-xterm-activate-interprogram-cut)))
 
   ;; Unconditionally enable bracketed paste mode: terminals that don't
   ;; support it just ignore the sequence.
@@ -719,6 +746,66 @@ We run the first FUNCTION whose STRING matches the input events."
   (push "\e[?2004l" (terminal-parameter nil 'tty-mode-reset-strings))
   (push "\e[?2004h" (terminal-parameter nil 'tty-mode-set-strings)))
 
+(defun terminal-init-xterm-activate-interprogram-cut ()
+  "Terminal initialization for interprogram cut."
+  (setq interprogram-cut-function
+        (if (string-prefix-p "screen" (getenv "TERM"))
+            #'xterm--screen-interprogram-cut
+          #'xterm--interprogram-cut)))
+ 
+(defun xterm--interprogram-cut (text)
+  "Copy TEXT to the X selection using the OSC 52 escape sequence.
+
+Set `interprogram-cut-function' to this when using a compatible terminal, and
+your system clipboard will be updated whenever you copy a region of text in
+Emacs.
+
+If the resulting OSC 52 sequence would be longer than
+`xterm-max-cut-length', then the TEXT is not sent to the system
+clipboard.
+
+This function sends a raw OSC 52 sequence and will work on a bare terminal
+emulators.  It does not work on screen or tmux terminals, since they don't
+natively support OSC 52; use `xterm--screen-interprogram-cut' for that."
+  (xterm--interprogram-cut-bytes
+   (base64-encode-string text :no-line-break)))
+
+(defun xterm--screen-interprogram-cut (text)
+  "Copy TEXT to the X selection using the OSC 52 escape sequence, for screen users.
+
+Set `interprogram-cut-function' to this when using the screen program, and your
+system clipboard will be updated whenever you copy a region of text in Emacs.
+
+If the resulting OSC 52 sequence would be longer than
+`xterm-max-cut-length', then the STRING is not sent to the system
+clipboard.
+
+This function wraps the OSC 52 in a Device Control String sequence.  This causes
+screen to pass the wrapped OSC 52 sequence along to the host terminal.  This
+function also chops long DCS sequences into multiple smaller ones to avoid
+hitting screen's max DCS length."
+  (xterm--interprogram-cut-bytes
+   (replace-regexp-in-string
+    "\n" "\e\\\eP" (base64-encode-string text) :fixedcase :literal)
+   "\eP" "\e\\"))
+
+(defun xterm--interprogram-cut-bytes (bytes &optional dcs-start dcs-end)
+  (let ((length (string-bytes bytes)))
+    (if (> length xterm-max-cut-length)
+        (progn
+          (warn "Selection too long to send to terminal: %d bytes" length)
+          (sit-for 2))
+      (send-string-to-terminal
+       (concat
+        dcs-start
+        "\e]52;"
+        (when select-enable-clipboard "c")
+        (when select-enable-primary "p")
+        ";"
+        bytes
+        "\a"
+        dcs-end)))))
+
 ;; Set up colors, for those versions of xterm that support it.
 (defvar xterm-standard-colors
   ;; The names in the comments taken from XTerm-col.ad in the xterm
-- 
2.2.0.rc0.207.ga3a616c