guix-devel/guix/describe.scm

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018, 2019 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 (guix packages)
#:use-module ((guix utils) #:select (location-file))
#:use-module ((guix store) #:select (%store-prefix store-path?))
#:use-module ((guix config) #:select (%state-directory))
#:use-module (srfi srfi-1)
#:use-module (ice-9 match)
#:export (current-profile
current-profile-date
current-profile-entries
package-path-entries
package-provenance))
;;; 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-date)
"Return the creation date of the current profile (produced by 'guix pull'),
as a number of seconds since the Epoch, or #f if it could not be determined."
;; Normally 'current-profile' will return ~/.config/guix/current. We need
;; to 'readlink' once to get '/var/guix/…/guix-profile', whose mtime is the
;; piece of information we're looking for.
(let loop ((profile (current-profile)))
(match profile
(#f #f)
((? store-path?) #f)
(file
(if (string-prefix? %state-directory file)
(and=> (lstat file) stat:mtime)
(catch 'system-error
(lambda ()
(let ((target (readlink file)))
(loop (if (string-prefix? "/" target)
target
(string-append (dirname file) "/" target)))))
(const #f)))))))
(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 current-channel-entries
(mlambda ()
"Return manifest entries corresponding to extra channels--i.e., not the
'guix' channel."
(remove (lambda (entry)
(string=? (manifest-entry-name entry) "guix"))
(current-profile-entries))))
(define (package-path-entries)
"Return two values: the list of package path entries to be added to the
package search path, and the list to be added to %LOAD-COMPILED-PATH. These
entries are taken from the 'guix pull' profile the calling process lives in,
when applicable."
;; Filter out Guix itself.
(unzip2 (map (lambda (entry)
(list (string-append (manifest-entry-item entry)
"/share/guile/site/"
(effective-version))
(string-append (manifest-entry-item entry)
"/lib/guile/" (effective-version)
"/site-ccache")))
(current-channel-entries))))
(define (package-provenance package)
"Return the provenance of PACKAGE as an sexp for use as the 'provenance'
property of manifest entries, or #f if it could not be determined."
(define (entry-source entry)
(match (assq 'source
(manifest-entry-properties entry))
(('source value) value)
(_ #f)))
(match (and=> (package-location package) location-file)
(#f #f)
(file
(let ((file (if (string-prefix? "/" file)
file
(search-path %load-path file))))
(and file
(string-prefix? (%store-prefix) file)
;; Always store information about the 'guix' channel and
;; optionally about the specific channel FILE comes from.
(or (let ((main (and=> (find (lambda (entry)
(string=? "guix"
(manifest-entry-name entry)))
(current-profile-entries))
entry-source))
(extra (any (lambda (entry)
(let ((item (manifest-entry-item entry)))
(and (string-prefix? item file)
(entry-source entry))))
(current-profile-entries))))
(and main
`(,main
,@(if extra (list extra) '()))))))))))