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authorLudovic Courtès <ludo@gnu.org>2019-04-06 22:27:57 +0200
committerLudovic Courtès <ludo@gnu.org>2019-04-10 17:09:47 +0200
commit72eda0624be89ed18302fd7d7f22976071ab020c (patch)
tree8ce31092c5a3710dab305116d18d5829b50487a0 /guix/store
parent08d0f950b3ad936b859064c070be16548684cbd1 (diff)
Add (guix store roots).
* guix/store/roots.scm, tests/store-roots.scm: New files. * Makefile.am (STORE_MODULES): Add guix/store/roots.scm. (SCM_TESTS): Add tests/store-roots.scm.
Diffstat (limited to 'guix/store')
-rw-r--r--guix/store/roots.scm120
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diff --git a/guix/store/roots.scm b/guix/store/roots.scm
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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)))