summaryrefslogtreecommitdiff
path: root/nix/scripts/list-runtime-roots.in
blob: a6938087b5fd5d09666d67b7e818952995f35666 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
#!@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 popen)
             (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)))
                (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 (lsof-roots)
  "Return the list of roots as found by calling `lsof'."
  (define parent (getpid))

  (catch 'system-error
    (lambda ()
      (let ((pipe (catch 'system-error
                    (lambda ()
                      (open-pipe* OPEN_READ "lsof" "-n" "-w" "-F" "n"))
                    (lambda args
                      ;; In Guile 2.0.5, when (ice-9 popen) was still written
                      ;; in Scheme, 'open-pipe*' would leave the child process
                      ;; behind it when 'execlp' failed (that was mostly
                      ;; harmless though, because the uncaught exception would
                      ;; cause it to terminate after printing a backtrace.)
                      ;; Make sure that doesn't happen.
                      (if (= (getpid) parent)
                          (apply throw args)
                          (begin
                            (format (current-error-port)
                                    "failed to execute 'lsof': ~a~%"
                                    (strerror (system-error-errno args)))
                            (primitive-exit 1)))))))
        (define %file-rx
          (make-regexp "^n/(.*)$"))

        ;; We're going to read it all.
        (setvbuf pipe _IOFBF 16384)

        (let loop ((line  (read-line pipe))
                   (roots '()))
          (cond ((eof-object? line)
                 (begin
                   (close-pipe pipe)
                   roots))
                ((regexp-exec %file-rx line)
                 =>
                 (lambda (match)
                   (loop (read-line pipe)
                         (cons (string-append "/"
                                              (match:substring match 1))
                               roots))))
                (else
                 (loop (read-line pipe) roots))))))
    (lambda _
      '())))

(let ((proc (format #f "~a/~a" %proc-directory (getpid))))
  (for-each (cut simple-format #t "~a~%" <>)
            (delete-duplicates
             (let ((proc-roots (if (file-exists? proc)
                                   (append (proc-exe-roots proc)
                                           (proc-cwd-roots proc)
                                           (proc-fd-roots proc)
                                           (proc-maps-roots proc)
                                           (proc-environ-roots proc))
                                   '())))
               (append proc-roots (lsof-roots))))))