guix-devel/guix/describe.scm

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix 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 Guix 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 Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (guix describe)
#:use-module (guix memoization)
#:use-module (guix profiles)
#:use-module (srfi srfi-1)
#:use-module (ice-9 match)
#:export (package-path-entries))
;;; Commentary:
;;;
;;; This module provides supporting code to allow a Guix instance to find, at
;;; run time, which profile it's in (profiles created by 'guix pull'). That
;;; allows it to read meta-information about itself (e.g., repository URL and
;;; commit ID) and to find other channels available in the same profile. It's
;;; a bit like ELPA's pkg-info.el.
;;;
;;; Code:
(define current-profile
(mlambda ()
"Return the profile (created by 'guix pull') the calling process lives in,
or #f if this is not applicable."
(match (command-line)
((program . _)
(and (string-suffix? "/bin/guix" program)
;; Note: We want to do _lexical dot-dot resolution_. Using ".."
;; for real would instead take us into the /gnu/store directory
;; that ~/.config/guix/current/bin points to, whereas we want to
;; obtain ~/.config/guix/current.
(let ((candidate (dirname (dirname program))))
(and (file-exists? (string-append candidate "/manifest"))
candidate)))))))
(define current-profile-entries
(mlambda ()
"Return the list of entries in the 'guix pull' profile the calling process
lives in, or #f if this is not applicable."
(match (current-profile)
(#f '())
(profile
(let ((manifest (profile-manifest profile)))
(manifest-entries manifest))))))
(define package-path-entries
(mlambda ()
"Return a list of package path entries to be added to the package search
path. These entries are taken from the 'guix pull' profile the calling
process lives in, when applicable."
;; Filter out Guix itself.
(filter-map (lambda (entry)
(and (not (string=? (manifest-entry-name entry)
"guix"))
(string-append (manifest-entry-item entry)
"/share/guile/site/"
(effective-version))))
(current-profile-entries))))