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|
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 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 store roots)
#:use-module (guix config)
#:use-module ((guix store) #:select (store-path? %gc-roots-directory))
#:use-module (guix sets)
#:use-module (guix build syscalls)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:use-module (ice-9 regex)
#:re-export (%gc-roots-directory)
#:export (gc-roots
user-owned?))
;;; Commentary:
;;;
;;; This module provides tools to list and access garbage collector roots ("GC
;;; roots").
;;;
;;; Code:
(define %profile-directory
;; Directory where user profiles are stored.
;; XXX: This is redundant with the definition in (guix profiles) and not
;; entirely needed since in practice /var/guix/gcroots/profiles links to
;; it.
(string-append %state-directory "/profiles"))
(define (gc-roots)
"Return the list of garbage collector roots (\"GC roots\"). This includes
\"regular\" roots fount in %GC-ROOTS-DIRECTORY as well as indirect roots that
are user-controlled symlinks stored anywhere on the file system."
(define (regular? file)
(match file
(((or "." "..") . _) #f)
(_ #t)))
(define (file-type=? type)
(match-lambda
((file . properties)
(match (assq-ref properties 'type)
('unknown
(let ((stat (lstat file)))
(eq? type (stat:type stat))))
(actual-type
(eq? type actual-type))))))
(define directory?
(file-type=? 'directory))
(define symlink?
(file-type=? 'symlink))
(define canonical-root
(match-lambda
((file . properties)
(let ((target (readlink file)))
(cond ((store-path? target)
;; Regular root: FILE points to the store.
file)
;; Indirect root: FILE points to a user-controlled file outside
;; the store.
((string-prefix? "/" target)
target)
(else
(string-append (dirname file) "/" target)))))))
(let loop ((directories (list %gc-roots-directory
%profile-directory))
(roots '())
(visited (set)))
(match directories
(()
roots)
((directory . rest)
(if (set-contains? visited directory)
(loop rest roots visited)
(let*-values (((scope)
(cut string-append directory "/" <>))
((sub-directories files)
(partition directory?
(map (match-lambda
((file . properties)
(cons (scope file) properties)))
(scandir* directory regular?)))))
(loop (append rest (map first sub-directories))
(append (map canonical-root (filter symlink? files))
roots)
(set-insert directory visited))))))))
(define* (user-owned? root #:optional (uid (getuid)))
"Return true if ROOT exists and is owned by UID, false otherwise."
;; If ROOT is an indirect root, then perhaps it no longer exists. Thus,
;; catch 'system-error' exceptions.
(catch 'system-error
(lambda ()
(define stat
(lstat root))
(= (stat:uid stat) uid))
(const #f)))
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