>From 062ade7fe5cdbae36f4b488761e6367beb6e3a41 Mon Sep 17 00:00:00 2001
From: Kai Tetzlaff <emacs@tetzco.de>
Date: Mon, 28 Feb 2022 11:08:07 +0100
Subject: [PATCH 1/4] Fix bug in sieve-manage--append-to-log, improve
 sieve-manage buffer config

Also update/add some comments/docs.

* lisp/net/sieve-manage.el
sieve-manage--coding-system: New constant.
(sieve-manage--set-internal-buffer-properties): New function.
(sieve-manage-open-server): Use `sieve-manage--coding-system'.
(sieve-manage--append-to-log): Use
`sieve-manage--set-internal-buffer-properties' to fix log buffer creation.
(sieve-manage-encode)
(sieve-manage-make-process-buffer): Use
`sieve-manage--set-internal-buffer-properties'.
---
 lisp/net/sieve-manage.el | 50 +++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 14 deletions(-)

diff --git a/lisp/net/sieve-manage.el b/lisp/net/sieve-manage.el
index 5bee4f4c4ad..4f0f9b1891b 100644
--- a/lisp/net/sieve-manage.el
+++ b/lisp/net/sieve-manage.el
@@ -58,7 +58,7 @@
 ;;
 ;; References:
 ;;
-;; draft-martin-managesieve-02.txt,
+;; RFC5804,
 ;; "A Protocol for Remotely Managing Sieve Scripts",
 ;; by Tim Martin.
 ;;
@@ -145,6 +145,15 @@ sieve-manage-ignore-starttls
   :type 'boolean)
 
 ;; Internal variables:
+(defconst sieve-manage--coding-system 'raw-text-unix
+  "Use 'raw-text-unix coding system for (network) communication.
+
+Sets the coding system used for the internal (process, log)
+buffers and the network stream created to communicate with the
+managesieve server.  Using 'raw-text encoding enables unibyte
+mode and makes sure that sent/received octets (bytes) remain
+untouched by the coding system.  The explicit use of `-unix`
+avoids EOL conversions (and thus keeps CRLF (\"\\r\\n\") intact).")
 
 (defconst sieve-manage-local-variables '(sieve-manage-server
 					 sieve-manage-port
@@ -167,6 +176,24 @@ sieve-manage-process
 (defvar sieve-manage-capability nil)
 
 ;; Internal utility functions
+(defun sieve-manage--set-internal-buffer-properties (buffer)
+  "Set BUFFER properties for internally used buffers.
+
+Used for process and log buffers, this function makes sure that
+those buffers keep received and sent data intact by:
+- setting the coding system to 'sieve-manage--coding-system',
+- setting `after-change-functions' to nil to avoid those
+  functions messing with buffer content.
+Also disables undo (to save a bit of memory and improve
+performance).
+
+Returns BUFFER."
+  (with-current-buffer buffer
+    (set-buffer-file-coding-system sieve-manage--coding-system)
+    (setq-local after-change-functions nil)
+    (buffer-disable-undo)
+    (current-buffer)))
+
 (defun sieve-manage--append-to-log (&rest args)
   "Append ARGS to sieve-manage log buffer.
 
@@ -175,10 +202,8 @@ sieve-manage--append-to-log
 `sieve-manage-log'. If it is nil, logging is disabled."
   (when sieve-manage-log
     (with-current-buffer (or (get-buffer sieve-manage-log)
-                             (with-current-buffer
-                                 (get-buffer-create sieve-manage-log)
-                               (set-buffer-multibyte nil)
-                               (buffer-disable-undo)))
+                             (sieve-manage--set-internal-buffer-properties
+                                 (get-buffer-create sieve-manage-log)))
       (goto-char (point-max))
       (apply #'insert args))))
 
@@ -204,7 +229,7 @@ sieve-manage--error
 
 (defun sieve-manage-encode (utf8-string)
   "Convert UTF8-STRING to managesieve protocol octets."
-  (encode-coding-string utf8-string 'raw-text t))
+  (encode-coding-string utf8-string sieve-manage--coding-system t))
 
 (defun sieve-manage-decode (octets &optional buffer)
   "Convert managesieve protocol OCTETS to utf-8 string.
@@ -216,13 +241,11 @@ sieve-manage-decode
 
 (defun sieve-manage-make-process-buffer ()
   (with-current-buffer
-      (generate-new-buffer (format " *sieve %s:%s*"
-                                   sieve-manage-server
-                                   sieve-manage-port))
+      (sieve-manage--set-internal-buffer-properties
+       (generate-new-buffer (format " *sieve %s:%s*"
+                                    sieve-manage-server
+                                    sieve-manage-port)))
     (mapc #'make-local-variable sieve-manage-local-variables)
-    (set-buffer-multibyte nil)
-    (setq-local after-change-functions nil)
-    (buffer-disable-undo)
     (current-buffer)))
 
 (defun sieve-manage-erase (&optional p buffer)
@@ -244,8 +267,7 @@ sieve-manage-open-server
                  (open-network-stream
                   "SIEVE" buffer server port
                   :type stream
-                  ;; eol type unix is required to preserve "\r\n"
-                  :coding 'raw-text-unix
+                  :coding `(binary . ,sieve-manage--coding-system)
                   :capability-command "CAPABILITY\r\n"
                   :end-of-command "^\\(OK\\|NO\\).*\n"
                   :success "^OK.*\n"
-- 
2.39.0