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|
;;; gnus-cloud.el --- storing and retrieving data via IMAP
;; Copyright (C) 2014-2020 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: mail
;; 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 <https://www.gnu.org/licenses/>.
;;; Commentary:
;; The name gnus-cloud parodizes but otherwise has little to do with
;; "cloud computing", a misleading term normally best avoided. See:
;; https://www.gnu.org/philosophy/words-to-avoid.html#CloudComputing
;;; Code:
(require 'parse-time)
(require 'nnimap)
(eval-when-compile (require 'epg)) ;; setf-method for `epg-context-armor'
(autoload 'epg-make-context "epg")
(autoload 'epg-context-set-passphrase-callback "epg")
(autoload 'epg-decrypt-string "epg")
(autoload 'epg-encrypt-string "epg")
(defgroup gnus-cloud nil
"Syncing Gnus data via IMAP."
:version "25.1"
:group 'gnus)
(defcustom gnus-cloud-synced-files
'(;;"~/.authinfo"
"~/.authinfo.gpg"
"~/.gnus.el"
(:directory "~/News" :match ".*.SCORE\\'"))
"List of files that should be kept up-to-date via the cloud.
Each element may be either a string or a property list.
The latter should have a :directory element whose value is a string,
and a :match element whose value is a regular expression to match
against the basename of files in said directory."
:group 'gnus-cloud
:type '(repeat (choice (string :tag "File")
(plist :tag "Property list"))))
(defcustom gnus-cloud-storage-method (if (featurep 'epg) 'epg 'base64-gzip)
"Storage method for cloud data, defaults to EPG if that's available."
:version "26.1"
:group 'gnus-cloud
:type '(radio (const :tag "No encoding" nil)
(const :tag "Base64" base64)
(const :tag "Base64+gzip" base64-gzip)
(const :tag "EPG" epg)))
(defcustom gnus-cloud-interactive t
"Whether Gnus Cloud changes should be confirmed."
:version "26.1"
:group 'gnus-cloud
:type 'boolean)
(defvar gnus-cloud-group-name "Emacs-Cloud")
(defvar gnus-cloud-covered-servers nil)
(defvar gnus-cloud-version 1)
(defvar gnus-cloud-sequence 1)
(defcustom gnus-cloud-method nil
"The IMAP select method used to store the cloud data.
See also `gnus-server-set-cloud-method-server' for an
easy interactive way to set this from the Server buffer."
:group 'gnus-cloud
:type '(radio (const :tag "Not set" nil)
(string :tag "A Gnus server name as a string")))
(defun gnus-cloud-make-chunk (elems)
(with-temp-buffer
(insert (format "Gnus-Cloud-Version %s\n" gnus-cloud-version))
(insert (gnus-cloud-insert-data elems))
(buffer-string)))
(defun gnus-cloud-insert-data (elems)
(mm-with-unibyte-buffer
(dolist (elem elems)
(cond
((eq (plist-get elem :type) :file)
(let (length data)
(mm-with-unibyte-buffer
(insert-file-contents-literally (plist-get elem :file-name))
(setq length (buffer-size)
data (buffer-string)))
(insert (format "(:type :file :file-name %S :timestamp %S :length %d)\n"
(plist-get elem :file-name)
(plist-get elem :timestamp)
length))
(insert data)
(insert "\n")))
((eq (plist-get elem :type) :newsrc-data)
(let ((print-level nil)
(print-length nil))
(print elem (current-buffer)))
(insert "\n"))
((eq (plist-get elem :type) :delete)
(insert (format "(:type :delete :file-name %S)\n"
(plist-get elem :file-name))))))
(gnus-cloud-encode-data)
(buffer-string)))
(defun gnus-cloud-encode-data ()
(cond
((eq gnus-cloud-storage-method 'base64-gzip)
(progn
(call-process-region (point-min) (point-max) "gzip"
t (current-buffer) nil
"-c")
(base64-encode-region (point-min) (point-max))))
((eq gnus-cloud-storage-method 'base64)
(base64-encode-region (point-min) (point-max)))
((eq gnus-cloud-storage-method 'epg)
(let ((context (epg-make-context 'OpenPGP))
cipher)
(setf (epg-context-armor context) t)
(setf (epg-context-textmode context) t)
(let ((data (epg-encrypt-string context
(buffer-substring-no-properties
(point-min)
(point-max))
nil)))
(delete-region (point-min) (point-max))
(insert data))))
((null gnus-cloud-storage-method)
(gnus-message 5 "Leaving cloud data plaintext"))
(t (gnus-error 1 "Invalid cloud storage method %S"
gnus-cloud-storage-method))))
(defun gnus-cloud-decode-data ()
(cond
((memq gnus-cloud-storage-method '(base64 base64-gzip))
(base64-decode-region (point-min) (point-max)))
((eq gnus-cloud-storage-method 'base64-gzip)
(call-process-region (point-min) (point-max) "gunzip"
t (current-buffer) nil
"-c"))
((eq gnus-cloud-storage-method 'epg)
(let* ((context (epg-make-context 'OpenPGP))
(data (epg-decrypt-string context (buffer-substring-no-properties
(point-min)
(point-max)))))
(delete-region (point-min) (point-max))
(insert data)))
((null gnus-cloud-storage-method)
(gnus-message 5 "Reading cloud data as plaintext"))
(t (gnus-error 1 "Invalid cloud storage method %S"
gnus-cloud-storage-method))))
(defun gnus-cloud-parse-chunk ()
(save-excursion
(unless (looking-at "Gnus-Cloud-Version \\([0-9]+\\)")
(error "Not a valid Cloud chunk in the current buffer"))
(forward-line 1)
(let ((version (string-to-number (match-string 1)))
(data (buffer-substring (point) (point-max))))
(mm-with-unibyte-buffer
(insert data)
(cond
((= version 1)
(gnus-cloud-decode-data)
(goto-char (point-min))
(gnus-cloud-parse-version-1))
(t
(error "Unsupported Cloud chunk version %s" version)))))))
(defun gnus-cloud-parse-version-1 ()
(let ((elems nil))
(while (not (eobp))
(while (and (not (eobp))
(not (looking-at "(:type")))
(forward-line 1))
(unless (eobp)
(let ((spec (ignore-errors (read (current-buffer))))
length)
(when (consp spec)
(cond
((memq (plist-get spec :type) '(:file :delete))
(setq length (plist-get spec :length))
(push (append spec
(list
:contents (buffer-substring (1+ (point))
(+ (point) 1 length))))
elems)
(goto-char (+ (point) 1 length)))
((memq (plist-get spec :type) '(:newsrc-data))
(push spec elems)))))))
(nreverse elems)))
(defun gnus-cloud-update-all (elems)
(dolist (elem elems)
(let ((type (plist-get elem :type)))
(cond
((eq type :newsrc-data)
(gnus-cloud-update-newsrc-data (plist-get elem :name) elem))
((memq type '(:delete :file))
(gnus-cloud-update-file elem type))
(t
(gnus-message 1 "Unknown type %s; ignoring" type))))))
(defun gnus-cloud-update-newsrc-data (group elem &optional force-older)
"Update the newsrc data for GROUP from ELEM.
Use old data if FORCE-OLDER is not nil."
(let* ((contents (plist-get elem :contents))
(date (or (plist-get elem :timestamp) "0"))
(now (gnus-cloud-timestamp nil))
(newer (string-lessp date now))
(group-info (gnus-get-info group)))
(if (and contents
(stringp (nth 0 contents))
(integerp (nth 1 contents)))
(if group-info
(if (equal (format "%S" group-info)
(format "%S" contents))
(gnus-message 3 "Skipping cloud update of group %s, the info is the same" group)
(if (and newer (not force-older))
(gnus-message 3 "Skipping outdated cloud info for group %s, the info is from %s (now is %s)" group date now)
(when (or (not gnus-cloud-interactive)
(gnus-y-or-n-p
(format "%s has older different info in the cloud as of %s, update it here? "
group date)))
(gnus-message 2 "Installing cloud update of group %s" group)
(gnus-set-info group contents)
(gnus-group-update-group group))))
(gnus-error 1 "Sorry, group %s is not subscribed" group))
(gnus-error 1 "Sorry, could not update newsrc for group %s (invalid data %S)"
group elem))))
(defun gnus-cloud-update-file (elem op)
"Apply Gnus Cloud data ELEM and operation OP to a file."
(let* ((file-name (plist-get elem :file-name))
(date (plist-get elem :timestamp))
(contents (plist-get elem :contents))
(exists (file-exists-p file-name)))
(if (gnus-cloud-file-covered-p file-name)
(cond
((eq op :delete)
(if (and exists
;; prompt only if the file exists already
(or (not gnus-cloud-interactive)
(gnus-y-or-n-p (format "%s has been deleted as of %s, delete it locally? "
file-name date))))
(rename-file file-name (car (find-backup-file-name file-name)))
(gnus-message 3 "%s was already deleted before the cloud got it" file-name)))
((eq op :file)
(when (or (not exists)
(and exists
(mm-with-unibyte-buffer
(insert-file-contents-literally file-name)
(not (equal (buffer-string) contents)))
;; prompt only if the file exists already
(or (not gnus-cloud-interactive)
(gnus-y-or-n-p (format "%s has updated contents as of %s, update it? "
file-name date)))))
(gnus-cloud-replace-file file-name date contents))))
(gnus-message 2 "%s isn't covered by the cloud; ignoring" file-name))))
(defun gnus-cloud-replace-file (file-name date new-contents)
(mm-with-unibyte-buffer
(insert new-contents)
(when (file-exists-p file-name)
(rename-file file-name (car (find-backup-file-name file-name))))
(write-region (point-min) (point-max) file-name)
(set-file-times file-name (parse-iso8601-time-string date))))
(defun gnus-cloud-file-covered-p (file-name)
(let ((matched nil))
(dolist (elem gnus-cloud-synced-files)
(cond
((stringp elem)
;; This seems fragile. String comparison, with no
;; expand-file-name to resolve ~, etc.
(when (equal elem file-name)
(setq matched t)))
((consp elem)
(when (and (equal (directory-file-name (plist-get elem :directory))
(directory-file-name (file-name-directory file-name)))
(string-match (plist-get elem :match)
(file-name-nondirectory file-name)))
(setq matched t)))))
matched))
(defun gnus-cloud-all-files ()
(let ((files nil))
(dolist (elem gnus-cloud-synced-files)
(cond
((stringp elem)
(push elem files))
((consp elem)
(dolist (file (directory-files (plist-get elem :directory)
nil
(plist-get elem :match)))
(push (format "%s/%s"
(directory-file-name (plist-get elem :directory))
file)
files)))))
(nreverse files)))
(defvar gnus-cloud-file-timestamps nil)
(defun gnus-cloud-files-to-upload (&optional full)
(let ((files nil)
timestamp)
(dolist (file (gnus-cloud-all-files))
(if (file-exists-p file)
(when (setq timestamp (gnus-cloud-file-new-p file full))
(push `(:type :file :file-name ,file :timestamp ,timestamp) files))
(when (assoc file gnus-cloud-file-timestamps)
(push `(:type :delete :file-name ,file) files))))
(nreverse files)))
(defun gnus-cloud-timestamp (time)
"Return a general timestamp string for TIME."
(format-time-string "%FT%T%z" time))
(defun gnus-cloud-file-new-p (file full)
(let ((timestamp (gnus-cloud-timestamp (file-attribute-modification-time
(file-attributes file))))
(old (cadr (assoc file gnus-cloud-file-timestamps))))
(when (or full
(null old)
(string< old timestamp))
timestamp)))
(declare-function gnus-activate-group "gnus-start"
(group &optional scan dont-check method dont-sub-check))
(declare-function gnus-subscribe-group "gnus-start"
(group &optional previous method))
(defun gnus-cloud-ensure-cloud-group ()
(let ((method (if (stringp gnus-cloud-method)
(gnus-server-to-method gnus-cloud-method)
gnus-cloud-method)))
(unless (or (gnus-active gnus-cloud-group-name)
(gnus-activate-group gnus-cloud-group-name nil nil
gnus-cloud-method))
(and (gnus-request-create-group gnus-cloud-group-name gnus-cloud-method)
(gnus-activate-group gnus-cloud-group-name nil nil gnus-cloud-method)
(gnus-subscribe-group gnus-cloud-group-name)))))
(defun gnus-cloud-upload-all-data ()
"Upload all data (newsrc and files) to the Gnus Cloud."
(interactive)
(gnus-cloud-upload-data t))
(autoload 'gnus-group-refresh-group "gnus-group")
(defun gnus-cloud-upload-data (&optional full)
"Upload data (newsrc and files) to the Gnus Cloud.
When FULL is t, upload everything, not just a difference from the last full."
(interactive)
(gnus-cloud-ensure-cloud-group)
(with-temp-buffer
(let ((elems (append
(gnus-cloud-files-to-upload full)
(gnus-cloud-collect-full-newsrc)))
(group (gnus-group-full-name gnus-cloud-group-name gnus-cloud-method)))
(insert (format "Subject: (sequence: %s type: %s storage-method: %s)\n"
(or gnus-cloud-sequence "UNKNOWN")
(if full :full :partial)
gnus-cloud-storage-method))
(insert "From: nobody@gnus.cloud.invalid\n")
(insert "\n")
(insert (gnus-cloud-make-chunk elems))
(if (gnus-request-accept-article gnus-cloud-group-name gnus-cloud-method
t t)
(progn
(setq gnus-cloud-sequence (1+ (or gnus-cloud-sequence 0)))
(gnus-cloud-add-timestamps elems)
(gnus-message 3 "Uploaded Gnus Cloud data successfully to %s" group)
(gnus-group-refresh-group group))
(gnus-error 2 "Failed to upload Gnus Cloud data to %s" group)))))
(defun gnus-cloud-add-timestamps (elems)
(dolist (elem elems)
(let* ((file-name (plist-get elem :file-name))
(old (assoc file-name gnus-cloud-file-timestamps)))
(when old
(setq gnus-cloud-file-timestamps
(delq old gnus-cloud-file-timestamps)))
(push (list file-name (plist-get elem :timestamp))
gnus-cloud-file-timestamps))))
(defun gnus-cloud-available-chunks ()
(gnus-activate-group gnus-cloud-group-name nil nil gnus-cloud-method)
(let* ((group (gnus-group-full-name gnus-cloud-group-name gnus-cloud-method))
(active (gnus-active group))
headers head)
(when (gnus-retrieve-headers (gnus-uncompress-range active) group)
(with-current-buffer nntp-server-buffer
(goto-char (point-min))
(while (and (not (eobp))
(setq head (nnheader-parse-head)))
(push head headers))))
(sort (nreverse headers)
(lambda (h1 h2)
(> (gnus-cloud-chunk-sequence (mail-header-subject h1))
(gnus-cloud-chunk-sequence (mail-header-subject h2)))))))
(defun gnus-cloud-chunk-sequence (string)
(if (string-match "sequence: \\([0-9]+\\)" string)
(string-to-number (match-string 1 string))
0))
;; TODO: use this
(defun gnus-cloud-prune-old-chunks (headers)
(let ((headers (reverse headers))
(found nil))
(while (and headers
(not found))
(when (string-match "type: :full" (mail-header-subject (car headers)))
(setq found t))
(pop headers))
;; All the chunks that are older than the newest :full chunk can be
;; deleted.
(when headers
(gnus-request-expire-articles
(mapcar (lambda (h)
(mail-header-number h))
(nreverse headers))
(gnus-group-full-name gnus-cloud-group-name gnus-cloud-method)))))
(defun gnus-cloud-download-all-data ()
"Download the Gnus Cloud data and install it.
Starts at `gnus-cloud-sequence' in the sequence."
(interactive)
(gnus-cloud-download-data t))
(defun gnus-cloud-download-data (&optional update sequence-override)
"Download the Gnus Cloud data and install it if UPDATE is t.
When SEQUENCE-OVERRIDE is given, start at that sequence number
instead of `gnus-cloud-sequence'.
When UPDATE is t, returns the result of calling `gnus-cloud-update-all'.
Otherwise, returns the Gnus Cloud data chunks."
(let ((articles nil)
chunks)
(dolist (header (gnus-cloud-available-chunks))
(when (> (gnus-cloud-chunk-sequence (mail-header-subject header))
(or sequence-override gnus-cloud-sequence -1))
(if (string-match (format "storage-method: %s" gnus-cloud-storage-method)
(mail-header-subject header))
(push (mail-header-number header) articles)
(gnus-message 1 "Skipping article %s because it didn't match the Gnus Cloud method %s: %s"
(mail-header-number header)
gnus-cloud-storage-method
(mail-header-subject header)))))
(when articles
(nnimap-request-articles (nreverse articles) gnus-cloud-group-name)
(with-current-buffer nntp-server-buffer
(goto-char (point-min))
(while (re-search-forward "^Gnus-Cloud-Version " nil t)
(beginning-of-line)
(push (gnus-cloud-parse-chunk) chunks)
(forward-line 1))))
(if update
(mapcar #'gnus-cloud-update-all chunks)
chunks)))
(defun gnus-cloud-server-p (server)
(member server gnus-cloud-covered-servers))
(defun gnus-cloud-host-server-p (server)
(equal gnus-cloud-method server))
(defun gnus-cloud-host-acceptable-method-p (server)
(eq (car-safe (gnus-server-to-method server)) 'nnimap))
(defun gnus-cloud-collect-full-newsrc ()
"Collect all the Gnus newsrc data in a portable format."
(let ((infos nil))
(dolist (info (cdr gnus-newsrc-alist))
(when (gnus-cloud-server-p
(gnus-method-to-server
(gnus-find-method-for-group (gnus-info-group info))))
(push `(:type :newsrc-data :name ,(gnus-info-group info) :contents ,info :timestamp ,(gnus-cloud-timestamp nil))
infos)))
infos))
(provide 'gnus-cloud)
;;; gnus-cloud.el ends here
|
