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#!@GUILE@ -ds
!#
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2017 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/>.
;;;
;;; List files being used at run time; these files are garbage collector
;;; roots. This is equivalent to `find-runtime-roots.pl' in Nix.
;;;
(use-modules (ice-9 ftw)
(ice-9 regex)
(ice-9 rdelim)
(ice-9 match)
(srfi srfi-1)
(srfi srfi-26)
(rnrs io ports))
(define %proc-directory
;; Mount point of Linuxish /proc file system.
"/proc")
(define %store-directory
(or (getenv "NIX_STORE_DIR")
"@storedir@"))
(define (proc-file-roots dir file)
"Return a one-element list containing the file pointed to by DIR/FILE,
or the empty list."
(or (and=> (false-if-exception (readlink (string-append dir "/" file)))
list)
'()))
(define proc-exe-roots (cut proc-file-roots <> "exe"))
(define proc-cwd-roots (cut proc-file-roots <> "cwd"))
(define (proc-fd-roots dir)
"Return the list of store files referenced by DIR, which is a
/proc/XYZ directory."
(let ((dir (string-append dir "/fd")))
(filter-map (lambda (file)
(let ((target (false-if-exception
(readlink (string-append dir "/" file)))))
(and target
(string-prefix? "/" target)
target)))
(or (scandir dir string->number) '()))))
(define (proc-maps-roots dir)
"Return the list of store files referenced by DIR, which is a
/proc/XYZ directory."
(define %file-mapping-line
(make-regexp "^.*[[:blank:]]+/([^ ]+)$"))
(call-with-input-file (string-append dir "/maps")
(lambda (maps)
(let loop ((line (read-line maps))
(roots '()))
(cond ((eof-object? line)
roots)
((regexp-exec %file-mapping-line line)
=>
(lambda (match)
(let ((file (string-append "/"
(match:substring match 1))))
(loop (read-line maps)
(cons file roots)))))
(else
(loop (read-line maps) roots)))))))
(define (proc-environ-roots dir)
"Return the list of store files referenced by DIR/environ, where DIR is a
/proc/XYZ directory."
(define split-on-nul
(cute string-tokenize <>
(char-set-complement (char-set #\nul))))
(define (rhs-file-names str)
(let ((equal (string-index str #\=)))
(if equal
(let* ((str (substring str (+ 1 equal)))
(rx (string-append (regexp-quote %store-directory)
"/[0-9a-z]{32}-[a-zA-Z0-9\\._+-]+")))
(map match:substring (list-matches rx str)))
'())))
(define environ
(string-append dir "/environ"))
(append-map rhs-file-names
(split-on-nul
(call-with-input-file environ
get-string-all))))
(define (referenced-files)
"Return the list of referenced store items."
(append-map (lambda (pid)
(let ((proc (string-append %proc-directory "/" pid)))
(catch 'system-error
(lambda ()
(append (proc-exe-roots proc)
(proc-cwd-roots proc)
(proc-fd-roots proc)
(proc-maps-roots proc)
(proc-environ-roots proc)))
(lambda args
;; There's a TOCTTOU race that we need to handle.
(if (= ENOENT (system-error-errno args))
'()
(apply throw args))))))
(scandir %proc-directory string->number
(lambda (a b)
(< (string->number a) (string->number b))))))
(define canonicalize-store-item
(let ((prefix (+ 1 (string-length %store-directory))))
(lambda (file)
"Return #f if FILE is not a store item; otherwise, return the store file
name without any sub-directory components."
(and (string-prefix? %store-directory file)
(string-append %store-directory "/"
(let ((base (string-drop file prefix)))
(match (string-index base #\/)
(#f base)
(slash (string-take base slash)))))))))
(for-each (cut simple-format #t "~a~%" <>)
(delete-duplicates
(filter-map canonicalize-store-item (referenced-files))))
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