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293 lines
11 KiB
EmacsLisp
293 lines
11 KiB
EmacsLisp
;;; epg-config.el --- configuration of the EasyPG Library
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;; Copyright (C) 2006-2021 Free Software Foundation, Inc.
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;; Author: Daiki Ueno <ueno@unixuser.org>
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;; Keywords: PGP, GnuPG
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;; Package: epg
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Code:
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(eval-when-compile (require 'cl-lib))
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(defconst epg-package-name "epg"
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"Name of this package.")
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(defconst epg-version-number "1.0.0"
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"Version number of this package.")
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(define-obsolete-variable-alias 'epg-bug-report-address
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'report-emacs-bug-address "27.1")
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(defgroup epg ()
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"Interface to the GNU Privacy Guard (GnuPG)."
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:tag "EasyPG"
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:version "23.1"
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:group 'data
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:group 'external)
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(defcustom epg-gpg-program (if (executable-find "gpg2")
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"gpg2"
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"gpg")
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"Say what gpg program to prefer (if it satisfies minimum requirements).
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If this variable is \"gpg2\", but the version of gpg2 installed
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is less than `epg-gpg2-minimum-version', then version 1 of
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GnuPG (i.e., \"gpg\") will be used instead. If the version of
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version 1 is less than `epg-gpg-minimum-version', then that won't
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be used either.
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If you want to explicitly specify what gpg program to use, you
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have to use \\[customize] instead (see the info node `Easy
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Customization'). Setting this variable without \\[customize] has
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no effect."
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:version "25.1"
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:type 'string)
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(defcustom epg-gpgsm-program "gpgsm"
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"The `gpgsm' executable.
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Setting this variable directly does not take effect;
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instead use \\[customize] (see the info node `Easy Customization')."
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:type 'string)
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(defcustom epg-gpgconf-program "gpgconf"
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"The `gpgconf' executable."
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:version "25.1"
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:type 'string)
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(defcustom epg-gpg-home-directory nil
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"The directory which contains the configuration files of `epg-gpg-program'."
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:type '(choice (const :tag "Default" nil) directory))
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(defcustom epg-passphrase-coding-system nil
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"Coding system to use with messages from `epg-gpg-program'."
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:type 'symbol)
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(define-obsolete-variable-alias
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'epa-pinentry-mode 'epg-pinentry-mode "27.1")
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;; In the doc string below, we say "symbol `error'" to avoid producing
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;; a hyperlink for `error' the function.
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(defcustom epg-pinentry-mode nil
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"The pinentry mode.
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GnuPG 2.1 or later has an option to control the behavior of
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Pinentry invocation. The value should be the symbol `error',
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`ask', `cancel', or `loopback'. See the GnuPG manual for the
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meanings.
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A particularly useful mode is `loopback', which redirects all
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Pinentry queries to the caller, so Emacs can query passphrase
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through the minibuffer, instead of external Pinentry program."
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:type '(choice (const nil)
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(const ask)
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(const cancel)
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(const error)
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(const loopback))
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:version "27.1")
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(defcustom epg-debug nil
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"If non-nil, debug output goes to the \" *epg-debug*\" buffer.
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Note that the buffer name starts with a space."
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:type 'boolean)
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(defconst epg-gpg-minimum-version "1.4.3")
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(defconst epg-gpg2-minimum-version "2.1.6")
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(defconst epg-config--program-alist
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`((OpenPGP
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epg-gpg-program
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("gpg2" . ,epg-gpg2-minimum-version)
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("gpg" . ((,epg-gpg-minimum-version . "2.0")
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,epg-gpg2-minimum-version)))
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(CMS
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epg-gpgsm-program
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("gpgsm" . "2.0.4")))
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"Alist used to obtain the usable configuration of executables.
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The first element of each entry is protocol symbol, which is
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either `OpenPGP' or `CMS'. The second element is a symbol where
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the executable name is remembered. The rest of the entry is an
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alist mapping executable names to the minimum required version
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suitable for the use with Emacs.")
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(defconst epg-config--configuration-constructor-alist
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'((OpenPGP . epg-config--make-gpg-configuration)
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(CMS . epg-config--make-gpgsm-configuration))
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"Alist used to obtain the usable configuration of executables.
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The first element of each entry is protocol symbol, which is
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either `OpenPGP' or `CMS'. The second element is a function
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which constructs a configuration object (actually a plist).")
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(defvar epg--configurations nil)
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;;;###autoload
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(defun epg-find-configuration (protocol &optional no-cache program-alist)
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"Find or create a usable configuration to handle PROTOCOL.
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This function first looks at the existing configuration found by
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the previous invocation of this function, unless NO-CACHE is non-nil.
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Then it walks through PROGRAM-ALIST or
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`epg-config--program-alist'. If `epg-gpg-program' or
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`epg-gpgsm-program' is already set with custom, use it.
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Otherwise, it tries the programs listed in the entry until the
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version requirement is met."
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(unless program-alist
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(setq program-alist epg-config--program-alist))
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(let ((entry (assq protocol program-alist)))
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(unless entry
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(error "Unknown protocol %S" protocol))
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(cl-destructuring-bind (symbol . alist)
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(cdr entry)
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(let ((constructor
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(alist-get protocol epg-config--configuration-constructor-alist)))
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(or (and (not no-cache) (alist-get protocol epg--configurations))
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;; If the executable value is already set with M-x
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;; customize, use it without checking.
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(if (and symbol (or (get symbol 'saved-value)
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(get symbol 'customized-value)))
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(let ((configuration
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(funcall constructor (symbol-value symbol))))
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(push (cons protocol configuration) epg--configurations)
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configuration)
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(catch 'found
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(dolist (program-version alist)
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(let ((executable (executable-find (car program-version))))
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(when executable
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(let ((configuration
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(funcall constructor executable)))
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(when (ignore-errors
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(epg-check-configuration configuration
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(cdr program-version))
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t)
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(unless no-cache
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(push (cons protocol configuration)
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epg--configurations))
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(throw 'found configuration)))))))))))))
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;; Create an `epg-configuration' object for `gpg', using PROGRAM.
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(defun epg-config--make-gpg-configuration (program)
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(let (config groups type args)
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(with-temp-buffer
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;; The caller might have bound coding-system-for-* to something
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;; like 'no-conversion, but the below needs to call PROGRAM
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;; expecting human-readable text in both directions (since we
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;; are going to parse the output as text), so let Emacs guess
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;; the encoding of that text by its usual encoding-detection
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;; machinery.
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(let ((coding-system-for-read 'undecided)
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(coding-system-for-write 'undecided))
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(apply #'call-process program nil (list t nil) nil
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(append (if epg-gpg-home-directory
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(list "--homedir" epg-gpg-home-directory))
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'("--with-colons" "--list-config"))))
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(goto-char (point-min))
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(while (re-search-forward "^cfg:\\([^:]+\\):\\(.*\\)" nil t)
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(setq type (intern (match-string 1))
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args (match-string 2))
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(cond
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((eq type 'group)
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(if (string-match "\\`\\([^:]+\\):" args)
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(setq groups
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(cons (cons (downcase (match-string 1 args))
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(delete "" (split-string
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(substring args
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(match-end 0))
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";")))
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groups))
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(if epg-debug
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(message "Invalid group configuration: %S" args))))
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((memq type '(pubkey cipher digest compress))
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(if (string-match "\\`\\([0-9]+\\)\\(;[0-9]+\\)*" args)
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(setq config
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(cons (cons type
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(mapcar #'string-to-number
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(delete "" (split-string args ";"))))
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config))
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(if epg-debug
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(message "Invalid %S algorithm configuration: %S"
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type args))))
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(t
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(setq config (cons (cons type args) config))))))
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(push (cons 'program program) config)
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(if groups
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(cons (cons 'groups groups) config)
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config)))
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;; Create an `epg-configuration' object for `gpgsm', using PROGRAM.
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(defun epg-config--make-gpgsm-configuration (program)
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(with-temp-buffer
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(call-process program nil (list t nil) nil "--version")
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(goto-char (point-min))
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(when (looking-at "\\S-+ (")
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(goto-char (match-end 0))
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(backward-char)
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(forward-sexp)
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(skip-syntax-forward "-" (point-at-eol))
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(list (cons 'program program)
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(cons 'version (buffer-substring (point) (point-at-eol)))))))
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;;;###autoload
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(defun epg-configuration ()
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"Return a list of internal configuration parameters of `epg-gpg-program'."
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(declare (obsolete epg-find-configuration "25.1"))
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(epg-config--make-gpg-configuration epg-gpg-program))
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;;;###autoload
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(defun epg-check-configuration (config &optional req-versions)
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"Verify that a sufficient version of GnuPG is installed.
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CONFIG should be a `epg-configuration' object (a plist).
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REQ-VERSIONS should be a list with elements of the form (MIN
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. MAX) where MIN and MAX are version strings indicating a
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semi-open range of acceptable versions. REQ-VERSIONS may also be
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a single minimum version string."
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(let ((version (alist-get 'version config)))
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(unless (stringp version)
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(error "Undetermined version: %S" version))
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(catch 'version-ok
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(pcase-dolist ((or `(,min . ,max)
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(and min (let max nil)))
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(if (listp req-versions) req-versions
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(list req-versions)))
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(when (and (version<= (or min epg-gpg-minimum-version)
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version)
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(or (null max)
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(version< version max)))
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(throw 'version-ok t)))
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(error "Unsupported version: %s" version))))
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(defun epg-required-version-p (protocol required-version)
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"Verify a sufficient version of GnuPG for specific protocol.
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PROTOCOL is symbol, either `OpenPGP' or `CMS'. REQUIRED-VERSION
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is a string containing the required version number. Return
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non-nil if that version or higher is installed."
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(let ((version (cdr (assq 'version (epg-find-configuration protocol)))))
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(and (stringp version)
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(version<= required-version version))))
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;;;###autoload
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(defun epg-expand-group (config group)
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"Look at CONFIG and try to expand GROUP."
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(let ((entry (assq 'groups config)))
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(if (and entry
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(setq entry (assoc (downcase group) (cdr entry))))
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(cdr entry))))
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(provide 'epg-config)
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;;; epg-config.el ends here
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