chore(3p/exwm): Subtree EXWM ... again

Upstream EXWM is now sort-of unmaintained[0], but some important PRs
are pending[1] which I would like to absorb here somehow.

[0]: https://github.com/ch11ng/exwm/issues/845
[1]: https://github.com/ch11ng/exwm/pull/848

git-subtree-dir: third_party/exwm
git-subtree-mainline: 7894d7e178ac542f2542b71b10cb34e99080acd7
git-subtree-split: 0368127976bda29d35eed788edfe74644ecd3845
Change-Id: I078358c0ea1d2bac99111748ce9c137d2804ac4e

1 files changed, 800 insertions, 0 deletions

diff --git a/third_party/exwm/exwm-xim.el b/third_party/exwm/exwm-xim.el
new file mode 100644
index 000000000000..acf718e27fd3
--- /dev/null
+++ b/third_party/exwm/exwm-xim.el
@@ -0,0 +1,800 @@
+;;; exwm-xim.el --- XIM Module for EXWM  -*- lexical-binding: t -*-
+
+;; Copyright (C) 2019-2020 Free Software Foundation, Inc.
+
+;; Author: Chris Feng <chris.w.feng@gmail.com>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This module adds XIM support for EXWM and allows sending characters
+;; generated by any Emacs's builtin input method (info node `Input Methods')
+;; to X windows.
+
+;; This module is essentially an X input method server utilizing Emacs as
+;; its backend.  It talks with X windows through the XIM protocol.  The XIM
+;; protocol is quite flexible by itself, stating that an implementation can
+;; create network connections of various types as well as make use of an
+;; existing X connection for communication, and that an IM server may
+;; support multiple transport versions, various input styles and several
+;; event flow modals, etc.  Here we only make choices that are most popular
+;; among other IM servers and more importantly, practical for Emacs to act
+;; as an IM server:
+;;
+;; + Packets are transported on top of an X connection like most IMEs.
+;; + Only transport version 0.0 (i.e. only-CM & Property-with-CM) is
+;;   supported (same as "IM Server Developers Kit", adopted by most IMEs).
+;; + Only support static event flow, on-demand-synchronous method.
+;; + Only "root-window" input style is supported.
+
+;; To use this module, first load and enable it as follows:
+;;
+;;    (require 'exwm-xim)
+;;    (exwm-xim-enable)
+;;
+;; A keybinding for `toggle-input-method' is probably required to turn on &
+;; off an input method (default to `default-input-method').  It's bound to
+;; 'C-\' by default and can be made reachable when working with X windows:
+;;
+;;    (push ?\C-\\ exwm-input-prefix-keys)
+;;
+;; It's also required (and error-prone) to setup environment variables to
+;; make applications actually use this input method.  Typically the
+;; following lines should be inserted into '~/.xinitrc'.
+;;
+;;    export XMODIFIERS=@im=exwm-xim
+;;    export GTK_IM_MODULE=xim
+;;    export QT_IM_MODULE=xim
+;;    export CLUTTER_IM_MODULE=xim
+
+;; References:
+;; + XIM (http://www.x.org/releases/X11R7.6/doc/libX11/specs/XIM/xim.html)
+;; + IMdkit (http://xorg.freedesktop.org/archive/unsupported/lib/IMdkit/)
+;; + UIM (https://github.com/uim/uim)
+
+;;; Code:
+
+(eval-when-compile (require 'cl-lib))
+
+(require 'xcb-keysyms)
+(require 'xcb-xim)
+
+(require 'exwm-core)
+(require 'exwm-input)
+
+(defconst exwm-xim--locales
+  "@locale=\
+aa,af,ak,am,an,anp,ar,as,ast,ayc,az,be,bem,ber,bg,bhb,bho,bn,bo,br,brx,bs,byn,\
+ca,ce,cmn,crh,cs,csb,cv,cy,da,de,doi,dv,dz,el,en,es,et,eu,fa,ff,fi,fil,fo,fr,\
+fur,fy,ga,gd,gez,gl,gu,gv,ha,hak,he,hi,hne,hr,hsb,ht,hu,hy,ia,id,ig,ik,is,it,\
+iu,iw,ja,ka,kk,kl,km,kn,ko,kok,ks,ku,kw,ky,lb,lg,li,li,lij,lo,lt,lv,lzh,mag,\
+mai,mg,mhr,mi,mk,ml,mn,mni,mr,ms,mt,my,nan,nb,nds,ne,nhn,niu,nl,nn,nr,nso,oc,\
+om,or,os,pa,pa,pap,pl,ps,pt,quz,raj,ro,ru,rw,sa,sat,sc,sd,se,shs,si,sid,sk,sl,\
+so,sq,sr,ss,st,sv,sw,szl,ta,tcy,te,tg,th,the,ti,tig,tk,tl,tn,tr,ts,tt,ug,uk,\
+unm,ur,uz,ve,vi,wa,wae,wal,wo,xh,yi,yo,yue,zh,zu,\
+C,no"
+  "All supported locales (stolen from glibc).")
+
+(defconst exwm-xim--default-error
+  (make-instance 'xim:error
+                 :im-id 0
+                 :ic-id 0
+                 :flag xim:error-flag:invalid-both
+                 :error-code xim:error-code:bad-something
+                 :length 0
+                 :type 0
+                 :detail nil)
+  "Default error returned to clients.")
+
+(defconst exwm-xim--default-im-attrs
+  (list (make-instance 'xim:XIMATTR
+                       :id 0
+                       :type xim:ATTRIBUTE-VALUE-TYPE:xim-styles
+                       :length (length xlib:XNQueryInputStyle)
+                       :attribute xlib:XNQueryInputStyle))
+  "Default IM attrs returned to clients.")
+
+(defconst exwm-xim--default-ic-attrs
+  (list (make-instance 'xim:XICATTR
+                       :id 0
+                       :type xim:ATTRIBUTE-VALUE-TYPE:long-data
+                       :length (length xlib:XNInputStyle)
+                       :attribute xlib:XNInputStyle)
+        (make-instance 'xim:XICATTR
+                       :id 1
+                       :type xim:ATTRIBUTE-VALUE-TYPE:window
+                       :length (length xlib:XNClientWindow)
+                       :attribute xlib:XNClientWindow)
+        ;; Required by e.g. xterm.
+        (make-instance 'xim:XICATTR
+                       :id 2
+                       :type xim:ATTRIBUTE-VALUE-TYPE:window
+                       :length (length xlib:XNFocusWindow)
+                       :attribute xlib:XNFocusWindow))
+  "Default IC attrs returned to clients.")
+
+(defconst exwm-xim--default-styles
+  (make-instance 'xim:XIMStyles
+                 :number nil
+                 :styles (list (logior xlib:XIMPreeditNothing
+                                       xlib:XIMStatusNothing)))
+  "Default styles: root-window, i.e. no preediting or status display support.")
+
+(defconst exwm-xim--default-attributes
+  (list (make-instance 'xim:XIMATTRIBUTE
+                       :id 0
+                       :length nil
+                       :value exwm-xim--default-styles))
+  "Default IM/IC attributes returned to clients.")
+
+(defvar exwm-xim--conn nil
+  "The X connection for initiating other XIM connections.")
+(defvar exwm-xim--event-xwin nil
+  "X window for initiating new XIM connections.")
+(defvar exwm-xim--server-client-plist '(nil nil)
+  "Plist mapping server window to [X connection, client window, byte-order].")
+(defvar exwm-xim--client-server-plist '(nil nil)
+  "Plist mapping client window to server window.")
+(defvar exwm-xim--property-index 0 "For generating a unique property name.")
+(defvar exwm-xim--im-id 0 "Last IM ID.")
+(defvar exwm-xim--ic-id 0 "Last IC ID.")
+
+;; X11 atoms.
+(defvar exwm-xim--@server nil)
+(defvar exwm-xim--LOCALES nil)
+(defvar exwm-xim--TRANSPORT nil)
+(defvar exwm-xim--XIM_SERVERS nil)
+(defvar exwm-xim--_XIM_PROTOCOL nil)
+(defvar exwm-xim--_XIM_XCONNECT nil)
+
+(defun exwm-xim--on-SelectionRequest (data _synthetic)
+  "Handle SelectionRequest events on IMS window.
+
+Such events would be received when clients query for LOCALES or TRANSPORT."
+  (exwm--log)
+  (let ((evt (make-instance 'xcb:SelectionRequest))
+        value fake-event)
+    (xcb:unmarshal evt data)
+    (with-slots (time requestor selection target property) evt
+      (setq value (cond ((= target exwm-xim--LOCALES)
+                         ;; Return supported locales.
+                         exwm-xim--locales)
+                        ((= target exwm-xim--TRANSPORT)
+                         ;; Use XIM over an X connection.
+                         "@transport=X/")))
+      (when value
+        ;; Change the property.
+        (xcb:+request exwm-xim--conn
+            (make-instance 'xcb:ChangeProperty
+                           :mode xcb:PropMode:Replace
+                           :window requestor
+                           :property property
+                           :type target
+                           :format 8
+                           :data-len (length value)
+                           :data value))
+        ;; Send a SelectionNotify event.
+        (setq fake-event (make-instance 'xcb:SelectionNotify
+                                        :time time
+                                        :requestor requestor
+                                        :selection selection
+                                        :target target
+                                        :property property))
+        (xcb:+request exwm-xim--conn
+            (make-instance 'xcb:SendEvent
+                           :propagate 0
+                           :destination requestor
+                           :event-mask xcb:EventMask:NoEvent
+                           :event (xcb:marshal fake-event exwm-xim--conn)))
+        (xcb:flush exwm-xim--conn)))))
+
+(cl-defun exwm-xim--on-ClientMessage-0 (data _synthetic)
+  "Handle ClientMessage event on IMS window (new connection).
+
+Such events would be received when clients request for _XIM_XCONNECT.
+A new X connection and server window would be created to communicate with
+this client."
+  (exwm--log)
+  (let ((evt (make-instance 'xcb:ClientMessage))
+        conn client-xwin server-xwin)
+    (xcb:unmarshal evt data)
+    (with-slots (window type data) evt
+      (unless (= type exwm-xim--_XIM_XCONNECT)
+        ;; Only handle _XIM_XCONNECT.
+        (exwm--log "Ignore ClientMessage %s" type)
+        (cl-return-from exwm-xim--on-ClientMessage-0))
+      (setq client-xwin (elt (slot-value data 'data32) 0)
+            ;; Create a new X connection and a new server window.
+            conn (xcb:connect)
+            server-xwin (xcb:generate-id conn))
+      (set-process-query-on-exit-flag (slot-value conn 'process) nil)
+      ;; Store this client.
+      (plist-put exwm-xim--server-client-plist server-xwin
+                 `[,conn ,client-xwin nil])
+      (plist-put exwm-xim--client-server-plist client-xwin server-xwin)
+      ;; Select DestroyNotify events on this client window.
+      (xcb:+request exwm-xim--conn
+          (make-instance 'xcb:ChangeWindowAttributes
+                         :window client-xwin
+                         :value-mask xcb:CW:EventMask
+                         :event-mask xcb:EventMask:StructureNotify))
+      (xcb:flush exwm-xim--conn)
+      ;; Handle ClientMessage events from this new connection.
+      (xcb:+event conn 'xcb:ClientMessage #'exwm-xim--on-ClientMessage)
+      ;; Create a communication window.
+      (xcb:+request conn
+          (make-instance 'xcb:CreateWindow
+                         :depth 0
+                         :wid server-xwin
+                         :parent exwm--root
+                         :x 0
+                         :y 0
+                         :width 1
+                         :height 1
+                         :border-width 0
+                         :class xcb:WindowClass:InputOutput
+                         :visual 0
+                         :value-mask xcb:CW:OverrideRedirect
+                         :override-redirect 1))
+      (xcb:flush conn)
+      ;; Send connection establishment ClientMessage.
+      (setf window client-xwin
+            (slot-value data 'data32) `(,server-xwin 0 0 0 0))
+      (slot-makeunbound data 'data8)
+      (slot-makeunbound data 'data16)
+      (xcb:+request exwm-xim--conn
+          (make-instance 'xcb:SendEvent
+                         :propagate 0
+                         :destination client-xwin
+                         :event-mask xcb:EventMask:NoEvent
+                         :event (xcb:marshal evt exwm-xim--conn)))
+      (xcb:flush exwm-xim--conn))))
+
+(cl-defun exwm-xim--on-ClientMessage (data _synthetic)
+  "Handle ClientMessage event on IMS communication window (request).
+
+Such events would be received when clients request for _XIM_PROTOCOL.
+The actual XIM request is in client message data or a property."
+  (exwm--log)
+  (let ((evt (make-instance 'xcb:ClientMessage))
+        conn client-xwin server-xwin)
+    (xcb:unmarshal evt data)
+    (with-slots (format window type data) evt
+      (unless (= type exwm-xim--_XIM_PROTOCOL)
+        (exwm--log "Ignore ClientMessage %s" type)
+        (cl-return-from exwm-xim--on-ClientMessage))
+      (setq server-xwin window
+            conn (plist-get exwm-xim--server-client-plist server-xwin)
+            client-xwin (elt conn 1)
+            conn (elt conn 0))
+      (cond ((= format 8)
+             ;; Data.
+             (exwm-xim--on-request (vconcat (slot-value data 'data8))
+                                   conn client-xwin server-xwin))
+            ((= format 32)
+             ;; Atom.
+             (with-slots (data32) data
+               (with-slots (value)
+                   (xcb:+request-unchecked+reply conn
+                       (make-instance 'xcb:GetProperty
+                                      :delete 1
+                                      :window server-xwin
+                                      :property (elt data32 1)
+                                      :type xcb:GetPropertyType:Any
+                                      :long-offset 0
+                                      :long-length (elt data32 0)))
+                 (when (> (length value) 0)
+                   (exwm-xim--on-request value conn client-xwin
+                                         server-xwin)))))))))
+
+(defun exwm-xim--on-request (data conn client-xwin server-xwin)
+  "Handle an XIM reuqest."
+  (exwm--log)
+  (let ((opcode (elt data 0))
+        ;; Let-bind `xim:lsb' to make pack/unpack functions work correctly.
+        (xim:lsb (elt (plist-get exwm-xim--server-client-plist server-xwin) 2))
+        req replies)
+    (cond ((= opcode xim:opcode:error)
+           (exwm--log "ERROR: %s" data))
+          ((= opcode xim:opcode:connect)
+           (exwm--log "CONNECT")
+           (setq xim:lsb (= (elt data 4) xim:connect-byte-order:lsb-first))
+           ;; Store byte-order.
+           (setf (elt (plist-get exwm-xim--server-client-plist server-xwin) 2)
+                 xim:lsb)
+           (setq req (make-instance 'xim:connect))
+           (xcb:unmarshal req data)
+           (if (and (= (slot-value req 'major-version) 1)
+                    (= (slot-value req 'minor-version) 0)
+                    ;; Do not support authentication.
+                    (= (slot-value req 'number) 0))
+               ;; Accept the connection.
+               (push (make-instance 'xim:connect-reply) replies)
+             ;; Deny it.
+             (push exwm-xim--default-error replies)))
+          ((memq opcode (list xim:opcode:auth-required
+                              xim:opcode:auth-reply
+                              xim:opcode:auth-next
+                              xim:opcode:auth-ng))
+           (exwm--log "AUTH: %d" opcode)
+           ;; Deny any attempt to make authentication.
+           (push exwm-xim--default-error replies))
+          ((= opcode xim:opcode:disconnect)
+           (exwm--log "DISCONNECT")
+           ;; Gracefully disconnect from the client.
+           (exwm-xim--make-request (make-instance 'xim:disconnect-reply)
+                                   conn client-xwin)
+           ;; Destroy the communication window & connection.
+           (xcb:+request conn
+               (make-instance 'xcb:DestroyWindow
+                              :window server-xwin))
+           (xcb:disconnect conn)
+           ;; Clean up cache.
+           (cl-remf exwm-xim--server-client-plist server-xwin)
+           (cl-remf exwm-xim--client-server-plist client-xwin))
+          ((= opcode xim:opcode:open)
+           (exwm--log "OPEN")
+           ;; Note: We make no check here.
+           (setq exwm-xim--im-id (if (< exwm-xim--im-id #xffff)
+                                     (1+ exwm-xim--im-id)
+                                   1))
+           (setq replies
+                 (list
+                  (make-instance 'xim:open-reply
+                                 :im-id exwm-xim--im-id
+                                 :im-attrs-length nil
+                                 :im-attrs exwm-xim--default-im-attrs
+                                 :ic-attrs-length nil
+                                 :ic-attrs exwm-xim--default-ic-attrs)
+                  (make-instance 'xim:set-event-mask
+                                 :im-id exwm-xim--im-id
+                                 :ic-id 0
+                                 ;; Static event flow.
+                                 :forward-event-mask xcb:EventMask:KeyPress
+                                 ;; on-demand-synchronous method.
+                                 :synchronous-event-mask
+                                 xcb:EventMask:NoEvent))))
+          ((= opcode xim:opcode:close)
+           (exwm--log "CLOSE")
+           (setq req (make-instance 'xim:close))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:close-reply
+                                :im-id (slot-value req 'im-id))
+                 replies))
+          ((= opcode xim:opcode:trigger-notify)
+           (exwm--log "TRIGGER-NOTIFY")
+           ;; Only static event flow modal is supported.
+           (push exwm-xim--default-error replies))
+          ((= opcode xim:opcode:encoding-negotiation)
+           (exwm--log "ENCODING-NEGOTIATION")
+           (setq req (make-instance 'xim:encoding-negotiation))
+           (xcb:unmarshal req data)
+           (let ((index (cl-position "COMPOUND_TEXT"
+                                     (mapcar (lambda (i) (slot-value i 'name))
+                                             (slot-value req 'names))
+                                     :test #'equal)))
+             (unless index
+               ;; Fallback to portable character encoding (a subset of ASCII).
+               (setq index -1))
+             (push (make-instance 'xim:encoding-negotiation-reply
+                                  :im-id (slot-value req 'im-id)
+                                  :category
+                                  xim:encoding-negotiation-reply-category:name
+                                  :index index)
+                   replies)))
+          ((= opcode xim:opcode:query-extension)
+           (exwm--log "QUERY-EXTENSION")
+           (setq req (make-instance 'xim:query-extension))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:query-extension-reply
+                                :im-id (slot-value req 'im-id)
+                                ;; No extension support.
+                                :length 0
+                                :extensions nil)
+                 replies))
+          ((= opcode xim:opcode:set-im-values)
+           (exwm--log "SET-IM-VALUES")
+           ;; There's only one possible input method attribute.
+           (setq req (make-instance 'xim:set-im-values))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:set-im-values-reply
+                                :im-id (slot-value req 'im-id))
+                 replies))
+          ((= opcode xim:opcode:get-im-values)
+           (exwm--log "GET-IM-VALUES")
+           (setq req (make-instance 'xim:get-im-values))
+           (let (im-attributes-id)
+             (xcb:unmarshal req data)
+             (setq im-attributes-id (slot-value req 'im-attributes-id))
+             (if (cl-notevery (lambda (i) (= i 0)) im-attributes-id)
+                 ;; Only support one IM attributes.
+                 (push (make-instance 'xim:error
+                                      :im-id (slot-value req 'im-id)
+                                      :ic-id 0
+                                      :flag xim:error-flag:invalid-ic-id
+                                      :error-code xim:error-code:bad-something
+                                      :length 0
+                                      :type 0
+                                      :detail nil)
+                       replies)
+               (push
+                (make-instance 'xim:get-im-values-reply
+                               :im-id (slot-value req 'im-id)
+                               :length nil
+                               :im-attributes exwm-xim--default-attributes)
+                replies))))
+          ((= opcode xim:opcode:create-ic)
+           (exwm--log "CREATE-IC")
+           (setq req (make-instance 'xim:create-ic))
+           (xcb:unmarshal req data)
+           ;; Note: The ic-attributes slot is ignored.
+           (setq exwm-xim--ic-id (if (< exwm-xim--ic-id #xffff)
+                                     (1+ exwm-xim--ic-id)
+                                   1))
+           (push (make-instance 'xim:create-ic-reply
+                                :im-id (slot-value req 'im-id)
+                                :ic-id exwm-xim--ic-id)
+                 replies))
+          ((= opcode xim:opcode:destroy-ic)
+           (exwm--log "DESTROY-IC")
+           (setq req (make-instance 'xim:destroy-ic))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:destroy-ic-reply
+                                :im-id (slot-value req 'im-id)
+                                :ic-id (slot-value req 'ic-id))
+                 replies))
+          ((= opcode xim:opcode:set-ic-values)
+           (exwm--log "SET-IC-VALUES")
+           (setq req (make-instance 'xim:set-ic-values))
+           (xcb:unmarshal req data)
+           ;; We don't distinguish between input contexts.
+           (push (make-instance 'xim:set-ic-values-reply
+                                :im-id (slot-value req 'im-id)
+                                :ic-id (slot-value req 'ic-id))
+                 replies))
+          ((= opcode xim:opcode:get-ic-values)
+           (exwm--log "GET-IC-VALUES")
+           (setq req (make-instance 'xim:get-ic-values))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:get-ic-values-reply
+                                :im-id (slot-value req 'im-id)
+                                :ic-id (slot-value req 'ic-id)
+                                :length nil
+                                :ic-attributes exwm-xim--default-attributes)
+                 replies))
+          ((= opcode xim:opcode:set-ic-focus)
+           (exwm--log "SET-IC-FOCUS")
+           ;; All input contexts are the same.
+           )
+          ((= opcode xim:opcode:unset-ic-focus)
+           (exwm--log "UNSET-IC-FOCUS")
+           ;; All input contexts are the same.
+           )
+          ((= opcode xim:opcode:forward-event)
+           (exwm--log "FORWARD-EVENT")
+           (setq req (make-instance 'xim:forward-event))
+           (xcb:unmarshal req data)
+           (exwm-xim--handle-forward-event-request req xim:lsb conn
+                                                   client-xwin))
+          ((= opcode xim:opcode:sync)
+           (exwm--log "SYNC")
+           (setq req (make-instance 'xim:sync))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:sync-reply
+                                :im-id (slot-value req 'im-id)
+                                :ic-id (slot-value req 'ic-id))
+                 replies))
+          ((= opcode xim:opcode:sync-reply)
+           (exwm--log "SYNC-REPLY"))
+          ((= opcode xim:opcode:reset-ic)
+           (exwm--log "RESET-IC")
+           ;; No context-specific data saved.
+           (setq req (make-instance 'xim:reset-ic))
+           (xcb:unmarshal req data)
+           (push (make-instance 'xim:reset-ic-reply
+                                :im-id (slot-value req 'im-id)
+                                :ic-id (slot-value req 'ic-id)
+                                :length 0
+                                :string "")
+                 replies))
+          ((memq opcode (list xim:opcode:str-conversion-reply
+                              xim:opcode:preedit-start-reply
+                              xim:opcode:preedit-caret-reply))
+           (exwm--log "PREEDIT: %d" opcode)
+           ;; No preedit support.
+           (push exwm-xim--default-error replies))
+          (t
+           (exwm--log "Bad protocol")
+           (push exwm-xim--default-error replies)))
+    ;; Actually send the replies.
+    (when replies
+      (mapc (lambda (reply)
+              (exwm-xim--make-request reply conn client-xwin))
+            replies)
+      (xcb:flush conn))))
+
+(defun exwm-xim--handle-forward-event-request (req lsb conn client-xwin)
+  (let ((im-func (with-current-buffer (window-buffer)
+                   input-method-function))
+        key-event keysym keysyms event result)
+    ;; Note: The flag slot is ignored.
+    ;; Do conversion in client's byte-order.
+    (let ((xcb:lsb lsb))
+      (setq key-event (make-instance 'xcb:KeyPress))
+      (xcb:unmarshal key-event (slot-value req 'event)))
+    (with-slots (detail state) key-event
+      (setq keysym (xcb:keysyms:keycode->keysym exwm-xim--conn detail
+                                                state))
+      (when (/= (car keysym) 0)
+        (setq event (xcb:keysyms:keysym->event
+                     exwm-xim--conn
+                     (car keysym)
+                     (logand state (lognot (cdr keysym)))))))
+    (while (or (slot-value req 'event) unread-command-events)
+      (unless (slot-value req 'event)
+        (setq event (pop unread-command-events))
+        ;; Handle events in (t . EVENT) format.
+        (when (and (consp event)
+                   (eq (car event) t))
+          (setq event (cdr event))))
+      (if (or (not im-func)
+              ;; `list' is the default method.
+              (eq im-func #'list)
+              (not event)
+              ;; Select only printable keys.
+              (not (integerp event)) (> #x20 event) (< #x7e event))
+          ;; Either there is no active input method, or invalid key
+          ;; is detected.
+          (with-slots ((raw-event event)
+                       im-id ic-id serial-number)
+              req
+            (if raw-event
+                (setq event raw-event)
+              (setq keysyms (xcb:keysyms:event->keysyms exwm-xim--conn event))
+              (with-slots (detail state) key-event
+                (setf detail (xcb:keysyms:keysym->keycode exwm-xim--conn
+                                                          (caar keysyms))
+                      state (cdar keysyms)))
+              (setq event (let ((xcb:lsb lsb))
+                            (xcb:marshal key-event conn))))
+            (when event
+              (exwm-xim--make-request
+               (make-instance 'xim:forward-event
+                              :im-id im-id
+                              :ic-id ic-id
+                              :flag xim:commit-flag:synchronous
+                              :serial-number serial-number
+                              :event event)
+               conn client-xwin)))
+        (when (eq exwm--selected-input-mode 'char-mode)
+          ;; Grab keyboard temporarily for char-mode.
+          (exwm-input--grab-keyboard))
+        (unwind-protect
+            (with-temp-buffer
+              ;; Always show key strokes.
+              (let ((input-method-use-echo-area t)
+                    (exwm-input-line-mode-passthrough t))
+                (setq result (funcall im-func event))
+                ;; Clear echo area for the input method.
+                (message nil)
+                ;; This also works for portable character encoding.
+                (setq result
+                      (encode-coding-string (concat result)
+                                            'compound-text-with-extensions))
+                (exwm-xim--make-request
+                 (make-instance 'xim:commit-x-lookup-chars
+                                :im-id (slot-value req 'im-id)
+                                :ic-id (slot-value req 'ic-id)
+                                :flag (logior xim:commit-flag:synchronous
+                                              xim:commit-flag:x-lookup-chars)
+                                :length (length result)
+                                :string result)
+                 conn client-xwin)))
+          (when (eq exwm--selected-input-mode 'char-mode)
+            (exwm-input--release-keyboard))))
+      (xcb:flush conn)
+      (setf event nil
+            (slot-value req 'event) nil))))
+
+(defun exwm-xim--make-request (req conn client-xwin)
+  "Make an XIM request REQ via connection CONN.
+
+CLIENT-XWIN would receive a ClientMessage event either telling the client
+the request data or where to fetch the data."
+  (exwm--log)
+  (let ((data (xcb:marshal req))
+        property format client-message-data client-message)
+    (if (<= (length data) 20)
+        ;; Send short requests directly with client messages.
+        (setq format 8
+              ;; Pad to 20 bytes.
+              data (append data (make-list (- 20 (length data)) 0))
+              client-message-data (make-instance 'xcb:ClientMessageData
+                                                 :data8 data))
+      ;; Send long requests with properties.
+      (setq property (exwm--intern-atom (format "_EXWM_XIM_%x"
+                                                exwm-xim--property-index)))
+      (cl-incf exwm-xim--property-index)
+      (xcb:+request conn
+          (make-instance 'xcb:ChangeProperty
+                         :mode xcb:PropMode:Append
+                         :window client-xwin
+                         :property property
+                         :type xcb:Atom:STRING
+                         :format 8
+                         :data-len (length data)
+                         :data data))
+      ;; Also send a client message to notify the client about this property.
+      (setq format 32
+            client-message-data (make-instance 'xcb:ClientMessageData
+                                               :data32 `(,(length data)
+                                                         ,property
+                                                         ;; Pad to 20 bytes.
+                                                         0 0 0))))
+    ;; Send the client message.
+    (setq client-message (make-instance 'xcb:ClientMessage
+                                        :format format
+                                        :window client-xwin
+                                        :type exwm-xim--_XIM_PROTOCOL
+                                        :data client-message-data))
+    (xcb:+request conn
+        (make-instance 'xcb:SendEvent
+                       :propagate 0
+                       :destination client-xwin
+                       :event-mask xcb:EventMask:NoEvent
+                       :event (xcb:marshal client-message conn)))))
+
+(defun exwm-xim--on-DestroyNotify (data synthetic)
+  "Do cleanups on receiving DestroyNotify event.
+
+Such event would be received when the client window is destroyed."
+  (exwm--log)
+  (unless synthetic
+    (let ((evt (make-instance 'xcb:DestroyNotify))
+          conn client-xwin server-xwin)
+      (xcb:unmarshal evt data)
+      (setq client-xwin (slot-value evt 'window)
+            server-xwin (plist-get exwm-xim--client-server-plist client-xwin))
+      (when server-xwin
+        (setq conn (aref (plist-get exwm-xim--server-client-plist server-xwin)
+                         0))
+        (cl-remf exwm-xim--server-client-plist server-xwin)
+        (cl-remf exwm-xim--client-server-plist client-xwin)
+        ;; Destroy the communication window & connection.
+        (xcb:+request conn
+            (make-instance 'xcb:DestroyWindow
+                           :window server-xwin))
+        (xcb:disconnect conn)))))
+
+(cl-defun exwm-xim--init ()
+  "Initialize the XIM module."
+  (exwm--log)
+  (when exwm-xim--conn
+    (cl-return-from exwm-xim--init))
+  ;; Initialize atoms.
+  (setq exwm-xim--@server (exwm--intern-atom "@server=exwm-xim")
+        exwm-xim--LOCALES (exwm--intern-atom "LOCALES")
+        exwm-xim--TRANSPORT (exwm--intern-atom "TRANSPORT")
+        exwm-xim--XIM_SERVERS (exwm--intern-atom "XIM_SERVERS")
+        exwm-xim--_XIM_PROTOCOL (exwm--intern-atom "_XIM_PROTOCOL")
+        exwm-xim--_XIM_XCONNECT (exwm--intern-atom "_XIM_XCONNECT"))
+  ;; Create a new connection and event window.
+  (setq exwm-xim--conn (xcb:connect)
+        exwm-xim--event-xwin (xcb:generate-id exwm-xim--conn))
+  (set-process-query-on-exit-flag (slot-value exwm-xim--conn 'process) nil)
+  ;; Initialize xcb:keysyms module.
+  (xcb:keysyms:init exwm-xim--conn)
+  ;; Listen to SelectionRequest event for connection establishment.
+  (xcb:+event exwm-xim--conn 'xcb:SelectionRequest
+              #'exwm-xim--on-SelectionRequest)
+  ;; Listen to ClientMessage event on IMS window for new XIM connection.
+  (xcb:+event exwm-xim--conn 'xcb:ClientMessage #'exwm-xim--on-ClientMessage-0)
+  ;; Listen to DestroyNotify event to do cleanups.
+  (xcb:+event exwm-xim--conn 'xcb:DestroyNotify #'exwm-xim--on-DestroyNotify)
+  ;; Create the event window.
+  (xcb:+request exwm-xim--conn
+      (make-instance 'xcb:CreateWindow
+                     :depth 0
+                     :wid exwm-xim--event-xwin
+                     :parent exwm--root
+                     :x 0
+                     :y 0
+                     :width 1
+                     :height 1
+                     :border-width 0
+                     :class xcb:WindowClass:InputOutput
+                     :visual 0
+                     :value-mask xcb:CW:OverrideRedirect
+                     :override-redirect 1))
+  ;; Set the selection owner.
+  (xcb:+request exwm-xim--conn
+      (make-instance 'xcb:SetSelectionOwner
+                     :owner exwm-xim--event-xwin
+                     :selection exwm-xim--@server
+                     :time xcb:Time:CurrentTime))
+  ;; Set XIM_SERVERS property on the root window.
+  (xcb:+request exwm-xim--conn
+      (make-instance 'xcb:ChangeProperty
+                     :mode xcb:PropMode:Prepend
+                     :window exwm--root
+                     :property exwm-xim--XIM_SERVERS
+                     :type xcb:Atom:ATOM
+                     :format 32
+                     :data-len 1
+                     :data (funcall (if xcb:lsb
+                                        #'xcb:-pack-u4-lsb
+                                      #'xcb:-pack-u4)
+                                    exwm-xim--@server)))
+  (xcb:flush exwm-xim--conn))
+
+(cl-defun exwm-xim--exit ()
+  "Exit the XIM module."
+  (exwm--log)
+  ;; Close IMS communication connections.
+  (mapc (lambda (i)
+          (when (vectorp i)
+            (xcb:disconnect (elt i 0))))
+        exwm-xim--server-client-plist)
+  ;; Close the IMS connection.
+  (unless exwm-xim--conn
+    (cl-return-from exwm-xim--exit))
+  ;; Remove exwm-xim from XIM_SERVERS.
+  (let ((reply (xcb:+request-unchecked+reply exwm-xim--conn
+                   (make-instance 'xcb:GetProperty
+                                  :delete 1
+                                  :window exwm--root
+                                  :property exwm-xim--XIM_SERVERS
+                                  :type xcb:Atom:ATOM
+                                  :long-offset 0
+                                  :long-length 1000)))
+        unpacked-reply pack unpack)
+    (unless reply
+      (cl-return-from exwm-xim--exit))
+    (setq reply (slot-value reply 'value))
+    (unless (> (length reply) 4)
+      (cl-return-from exwm-xim--exit))
+    (setq reply (vconcat reply)
+          pack (if xcb:lsb #'xcb:-pack-u4-lsb #'xcb:-pack-u4)
+          unpack (if xcb:lsb #'xcb:-unpack-u4-lsb #'xcb:-unpack-u4))
+    (dotimes (i (/ (length reply) 4))
+      (push (funcall unpack reply (* i 4)) unpacked-reply))
+    (setq unpacked-reply (delq exwm-xim--@server unpacked-reply)
+          reply (mapcar pack unpacked-reply))
+    (xcb:+request exwm-xim--conn
+        (make-instance 'xcb:ChangeProperty
+                       :mode xcb:PropMode:Replace
+                       :window exwm--root
+                       :property exwm-xim--XIM_SERVERS
+                       :type xcb:Atom:ATOM
+                       :format 32
+                       :data-len (length reply)
+                       :data reply))
+    (xcb:flush exwm-xim--conn))
+  (xcb:disconnect exwm-xim--conn)
+  (setq exwm-xim--conn nil))
+
+(defun exwm-xim-enable ()
+  "Enable XIM support for EXWM."
+  (exwm--log)
+  (add-hook 'exwm-init-hook #'exwm-xim--init)
+  (add-hook 'exwm-exit-hook #'exwm-xim--exit))
+
+
+
+(provide 'exwm-xim)
+
+;;; exwm-xim.el ends here