Bring the Gnus Cloud package into working order.

* lisp/gnus/gnus-sync.el: Removed in favor of gnus-cloud.el.

* lisp/gnus/gnus-cloud.el: Autoload EPG functions. Change storage format to
simplify non-file data.
(gnus-cloud-storage-method): New defcustom to support nil, Base64,
Base64+gzip, or EPG encoding on the Gnus Cloud IMAP server. Defaults to
EPG if that's available, Base64+gzip otherwise.
(gnus-cloud-interactive): New defcustom to make Gnus Cloud operations
interactive, defaults to enabled.
(gnus-cloud-group-name): New variable for the Gnus Cloud group name.
(gnus-cloud-make-chunk): Tag with "Gnus-Cloud-Version" instead of just
"Version".
(gnus-cloud-insert-data): Simplify and support :newsrc-data entries.
(gnus-cloud-encode-data, gnus-cloud-decode-data): Support various
storage methods as per gnus-cloud-storage-method.
(gnus-cloud-parse-chunk): Look for "Gnus-Cloud-Version" marker.
(gnus-cloud-parse-version-1): Fix parsing loop bug. Handle :newsrc-data
entries.
(gnus-cloud-update-all): Handle :newsrc-data entries and dispatch to
file and data handlers.
(gnus-cloud-update-newsrc-data): New function to handle :newrsc-data
entries.
(gnus-cloud-update-file): Rework to support gnus-cloud-interactive and
be more careful.
(gnus-cloud-delete-file): Remove; merged into gnus-cloud-update-file.
(gnus-cloud-file-covered-p, gnus-cloud-all-files)
(gnus-cloud-files-to-upload, gnus-cloud-ensure-cloud-group)
(gnus-cloud-add-timestamps, gnus-cloud-available-chunks)
(gnus-cloud-prune-old-chunks): Fix indentation.
(gnus-cloud-timestamp): New function to make a standard Gnus Cloud
timestamp.
(gnus-cloud-file-new-p): Use it.
(gnus-cloud-upload-all-data): Add interactive convenience function to
upload all data.
(gnus-cloud-upload-data): Make interactive; collect files and newsrc
data separately; refresh Gnus Cloud group after insert.
(gnus-cloud-download-all-data): Add interactive convenience function to
download all data.
(gnus-cloud-download-data): Rework to support "Gnus-Cloud-Version"
marker and different storage methods.
(gnus-cloud-host-server-p): New function to check if a server is the
Gnus Cloud host.
(gnus-cloud-collect-full-newsrc): Tag entries with :newsrc-data.
(gnus-cloud-host-acceptable-method-p): New function so
other code can check if a server method can host the Gnus cloud.
(gnus-cloud-storage-method): Use 'radio instead of 'choice for better UI.
(gnus-cloud-method): Make this a defcustom and note how to set it.

* lisp/gnus/gnus-group.el (gnus-group-cloud-map): Add Gnus Cloud autoloaded
keybindings under the `~' prefix.

* lisp/gnus/gnus-srvr.el (gnus-server-mode-map, gnus-server-make-menu-bar)
(gnus-server-cloud, gnus-server-cloud-host)
(gnus-server-font-lock-keywords, gnus-server-insert-server-line)
(gnus-server-toggle-cloud-method-server): Support Gnus Cloud
synchronized servers and synchronization host server toggling (`i' and
`I') and visual display.
(gnus-server-toggle-cloud-method-server): Use
gnus-cloud-host-acceptable-method-p.
(gnus-server-toggle-cloud-method-server): Use custom-set-variables to
set the gnus-cloud-method. Ask the user if it's OK to upload the data
right now.

* doc/misc/gnus.texi: Document Gnus Cloud package.

1 files changed, 96 insertions, 0 deletions

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index df673fc099..2473d26cc1 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -828,6 +828,7 @@ Various
 * Thwarting Email Spam::        Simple ways to avoid unsolicited commercial email.
 * Spam Package::                A package for filtering and processing spam.
 * The Gnus Registry::           A package for tracking messages by Message-ID.
+* The Gnus Cloud::              A package for synchronizing Gnus marks.
 * Other modes::                 Interaction with other modes.
 * Various Various::             Things that are really various.
 
@@ -22208,6 +22209,7 @@ to you, using @kbd{G b u} and updating the group will usually fix this.
 * Thwarting Email Spam::        Simple ways to avoid unsolicited commercial email.
 * Spam Package::                A package for filtering and processing spam.
 * The Gnus Registry::           A package for tracking messages by Message-ID.
+* The Gnus Cloud::              A package for synchronizing Gnus marks.
 * Other modes::                 Interaction with other modes.
 * Various Various::             Things that are really various.
 @end menu
@@ -26166,6 +26168,100 @@ default this is just @code{(marks)} so the custom registry marks are
 precious.
 @end defvar
 
+@node The Gnus Cloud
+@section The Gnus Cloud
+@cindex cloud
+@cindex gnus-cloud
+@cindex synchronization
+@cindex sync
+@cindex synch
+
+The Gnus Cloud is a way to synchronize marks and general files and
+data across multiple machines.
+
+Very often, you want all your marks (what articles you've read, which
+ones were important, and so on) to be synchronized between several
+machines. With IMAP, that's built into the protocol, so you can read
+nnimap groups from many machines and they are automatically
+synchronized. But NNTP, nnrss, and many other backends do not store
+marks, so you have to do it locally.
+
+The Gnus Cloud package stores the marks, plus any files you choose, on
+an IMAP server in a special folder. It's like a
+DropTorrentSyncBoxOakTree(TM).
+
+@menu
+* Gnus Cloud Setup::
+* Gnus Cloud Usage::
+@end menu
+
+@node Gnus Cloud Setup
+@subsection Gnus Cloud Setup
+
+Setting up the Gnus Cloud takes less than a minute. From the Group
+buffer:
+
+Press @kbd{^} to go to the Server buffer. Here you'll see all the
+servers that Gnus knows. @xref{Server Buffer}.
+
+Then press @kbd{i} to mark any servers as cloud-synchronized (their marks are synchronized).
+
+Then press @kbd{I} to mark a single server as the cloud host (it must
+be an IMAP server, and will host a special IMAP folder with all the
+synchronization data). This will set the variable
+@code{gnus-cloud-method} (using the Customize facilities), then ask
+you to optionally upload your first CloudSynchronizationDataPack(TM).
+
+@node Gnus Cloud Usage
+@subsection Gnus Cloud Usage
+
+After setting up, you can use these shortcuts from the Group buffer:
+
+@table @kbd
+@item ~ RET
+@item ~ d
+@findex gnus-cloud-download-all-data
+@cindex cloud, download
+Download the latest Gnus Cloud data.
+
+@item ~ u
+@item ~ ~
+@findex gnus-cloud-upload-all-data
+@cindex cloud, download
+Upload the local Gnus Cloud data. Creates a new
+CloudSynchronizationDataPack(TM).
+
+@end table
+
+But wait, there's more. Of course there's more. So much more. You can
+customize all of the following.
+
+@defvar gnus-cloud-synced-files
+These are the files that will be part of every
+CloudSynchronizationDataPack(TM). They are included in every upload,
+so don't synchronize a lot of large files. Files under 100Kb are best.
+@end defvar
+
+@defvar gnus-cloud-storage-method
+This is a choice from several storage methods. It's highly recommended
+to use the EPG facilities. It will be automatic if have GnuPG
+installed and EPG loaded. Otherwise, you could use Base64+gzip,
+Base64, or no encoding.
+@end defvar
+
+@defvar gnus-cloud-interactive
+When this is set, and by default it is, the Gnus Cloud package will
+ask you for confirmation here and there. Leave it on until you're
+comfortable with the package.
+@end defvar
+
+
+@defvar gnus-cloud-method
+The name of the IMAP server to store the
+CloudSynchronizationDataPack(TM)s. It's easiest to set this from the
+Server buffer (@pxref{Gnus Cloud Setup}).
+@end defvar
+
 @node Other modes
 @section Interaction with other modes