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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
|
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2020 John Soo <jsoo1@asu.edu>
;;;
;;; 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 scripts processes)
#:use-module ((guix store) #:select (%store-prefix))
#:use-module (guix scripts)
#:use-module (guix ui)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-9 gnu)
#:use-module (srfi srfi-37)
#:use-module (ice-9 ftw)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 format)
#:export (process?
process-id
process-parent-id
process-command
processes
daemon-session?
daemon-session-process
daemon-session-client
daemon-session-children
daemon-session-locks-held
daemon-sessions
guix-processes))
;; Process as can be found in /proc on GNU/Linux.
(define-record-type <process>
(process id parent command)
process?
(id process-id) ;integer
(parent process-parent-id) ;integer | #f
(command process-command)) ;list of strings
(define (write-process process port)
(format port "#<process ~a>" (process-id process)))
(set-record-type-printer! <process> write-process)
(define (read-status-ppid port)
"Read the PPID from PORT, an input port on a /proc/PID/status file. Return
#f for PID 1 and kernel pseudo-processes."
(let loop ()
(match (read-line port)
((? eof-object?) #f)
(line
(if (string-prefix? "PPid:" line)
(string->number (string-trim-both (string-drop line 5)))
(loop))))))
(define %not-nul
(char-set-complement (char-set #\nul)))
(define (read-command-line port)
"Read the zero-split command line from PORT, a /proc/PID/cmdline file, and
return it as a list."
(string-tokenize (read-string port) %not-nul))
(define (processes)
"Return a list of process records representing the currently alive
processes."
;; This assumes a Linux-compatible /proc file system. There exists one for
;; GNU/Hurd.
(filter-map (lambda (pid)
;; There's a TOCTTOU race here. If we get ENOENT, simply
;; ignore PID.
(catch 'system-error
(lambda ()
(define ppid
(call-with-input-file (string-append "/proc/" pid "/status")
read-status-ppid))
(define command
(call-with-input-file (string-append "/proc/" pid "/cmdline")
read-command-line))
(process (string->number pid) ppid command))
(lambda args
(if (= ENOENT (system-error-errno args))
#f
(apply throw args)))))
(scandir "/proc" string->number)))
(define (process-open-files process)
"Return the list of files currently open by PROCESS."
(let ((directory (string-append "/proc/"
(number->string (process-id process))
"/fd")))
(filter-map (lambda (fd)
;; There's a TOCTTOU race here, hence the 'catch'.
(catch 'system-error
(lambda ()
(readlink (string-append directory "/" fd)))
(lambda args
(if (= ENOENT (system-error-errno args))
#f
(apply throw args)))))
(or (scandir directory string->number) '()))))
;; Daemon session.
(define-record-type <daemon-session>
(daemon-session process client children locks)
daemon-session?
(process daemon-session-process) ;<process>
(client daemon-session-client) ;<process>
(children daemon-session-children) ;list of <process>
(locks daemon-session-locks-held)) ;list of strings
(define (daemon-sessions)
"Return two values: the list of <daemon-session> denoting the currently
active sessions, and the master 'guix-daemon' process."
(define (lock-file? file)
(and (string-prefix? (%store-prefix) file)
(string-suffix? ".lock" file)))
(let* ((processes (processes))
(daemons (filter (lambda (process)
(match (process-command process)
((argv0 _ ...)
(string=? (basename argv0) "guix-daemon"))
(_ #f)))
processes))
(children (filter (lambda (process)
(match (process-command process)
((argv0 (= string->number argv1) _ ...)
(integer? argv1))
(_ #f)))
daemons))
(master (remove (lambda (process)
(memq process children))
daemons)))
(define (lookup-process pid)
(find (lambda (process)
(and (process-id process)
(= pid (process-id process))))
processes))
(define (lookup-children pid)
(filter (lambda (process)
(and (process-parent-id process)
(= pid (process-parent-id process))))
processes))
(define (child-process->session process)
(match (process-command process)
((argv0 (= string->number client) _ ...)
(let ((files (process-open-files process))
(client (lookup-process client)))
;; After a client has died, there's a window during which its
;; corresponding 'guix-daemon' process is still alive, in which
;; case 'lookup-process' returns #f. In that case ignore the
;; session.
(and client
(daemon-session process client
(lookup-children
(process-id process))
(filter lock-file? files)))))))
(values (filter-map child-process->session children)
master)))
(define (daemon-session->recutils session port)
"Display SESSION information in recutils format on PORT."
(format port "SessionPID: ~a~%"
(process-id (daemon-session-process session)))
(format port "ClientPID: ~a~%"
(process-id (daemon-session-client session)))
(format port "ClientCommand:~{ ~a~}~%"
(process-command (daemon-session-client session)))
(for-each (lambda (lock)
(format port "LockHeld: ~a~%" lock))
(daemon-session-locks-held session))
(for-each (lambda (process)
(format port "ChildPID: ~a~%"
(process-id process))
(format port "ChildCommand: :~{ ~a~}~%"
(process-command process)))
(daemon-session-children session)))
;;;
;;; Options.
;;;
(define %options
(list (option '(#\h "help") #f #f
(lambda args
(show-help)
(exit 0)))
(option '(#\V "version") #f #f
(lambda args
(show-version-and-exit "guix processes")))))
(define (show-help)
(display (G_ "Usage: guix processes
List the current Guix sessions and their processes."))
(newline)
(display (G_ "
-h, --help display this help and exit"))
(display (G_ "
-V, --version display version information and exit"))
(newline)
(show-bug-report-information))
;;;
;;; Entry point.
;;;
(define-command (guix-processes . args)
(category plumbing)
(synopsis "list currently running sessions")
(define options
(args-fold* args %options
(lambda (opt name arg result)
(leave (G_ "~A: unrecognized option~%") name))
cons
'()))
(with-paginated-output-port port
(for-each (lambda (session)
(daemon-session->recutils session port)
(newline port))
(daemon-sessions))
;; Pass 'R' (instead of 'r') so 'less' correctly estimates line length.
#:less-options "FRX"))
|
