services: 'user-processes-service-type' can now be extended.
* gnu/services/base.scm (user-processes-shepherd-service): New procedure, taken from former 'user-processes-service-type'. Add REQUIREMENTS argument; remove GRACE-DELAY argument. (user-processes-service-type): Redefine in terms of 'service-type'. (user-processes-service): Remove. (file-system-service-type): Extend USER-PROCESSES-SERVICE-TYPE. * gnu/system.scm (essential-services): Use USER-PROCESSES-SERVICE-TYPE directly.
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Ludovic Courtès
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8785bd7759
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@ -57,7 +57,7 @@
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file-system-service-type
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user-unmount-service
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swap-service
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user-processes-service
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user-processes-service-type
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host-name-service
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console-keymap-service
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%default-console-font
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@ -162,6 +162,129 @@
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;;;
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;;; Code:
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;;;
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;;; User processes.
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;;;
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(define %do-not-kill-file
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;; Name of the file listing PIDs of processes that must survive when halting
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;; the system. Typical example is user-space file systems.
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"/etc/shepherd/do-not-kill")
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(define (user-processes-shepherd-service requirements)
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"Return the 'user-processes' Shepherd service with dependencies on
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REQUIREMENTS (a list of service names).
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This is a synchronization point used to make sure user processes and daemons
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get started only after crucial initial services have been started---file
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system mounts, etc. This is similar to the 'sysvinit' target in systemd."
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(define grace-delay
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;; Delay after sending SIGTERM and before sending SIGKILL.
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4)
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(list (shepherd-service
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(documentation "When stopped, terminate all user processes.")
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(provision '(user-processes))
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(requirement requirements)
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(start #~(const #t))
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(stop #~(lambda _
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(define (kill-except omit signal)
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;; Kill all the processes with SIGNAL except those listed
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;; in OMIT and the current process.
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(let ((omit (cons (getpid) omit)))
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(for-each (lambda (pid)
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(unless (memv pid omit)
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(false-if-exception
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(kill pid signal))))
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(processes))))
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(define omitted-pids
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;; List of PIDs that must not be killed.
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(if (file-exists? #$%do-not-kill-file)
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(map string->number
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(call-with-input-file #$%do-not-kill-file
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(compose string-tokenize
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(@ (ice-9 rdelim) read-string))))
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'()))
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(define (now)
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(car (gettimeofday)))
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(define (sleep* n)
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;; Really sleep N seconds.
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;; Work around <http://bugs.gnu.org/19581>.
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(define start (now))
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(let loop ((elapsed 0))
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(when (> n elapsed)
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(sleep (- n elapsed))
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(loop (- (now) start)))))
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(define lset= (@ (srfi srfi-1) lset=))
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(display "sending all processes the TERM signal\n")
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(if (null? omitted-pids)
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(begin
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;; Easy: terminate all of them.
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(kill -1 SIGTERM)
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(sleep* #$grace-delay)
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(kill -1 SIGKILL))
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(begin
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;; Kill them all except OMITTED-PIDS. XXX: We would
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;; like to (kill -1 SIGSTOP) to get a fixed list of
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;; processes, like 'killall5' does, but that seems
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;; unreliable.
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(kill-except omitted-pids SIGTERM)
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(sleep* #$grace-delay)
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(kill-except omitted-pids SIGKILL)
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(delete-file #$%do-not-kill-file)))
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(let wait ()
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;; Reap children, if any, so that we don't end up with
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;; zombies and enter an infinite loop.
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(let reap-children ()
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(define result
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(false-if-exception
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(waitpid WAIT_ANY (if (null? omitted-pids)
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0
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WNOHANG))))
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(when (and (pair? result)
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(not (zero? (car result))))
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(reap-children)))
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(let ((pids (processes)))
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(unless (lset= = pids (cons 1 omitted-pids))
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(format #t "waiting for process termination\
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(processes left: ~s)~%"
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pids)
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(sleep* 2)
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(wait))))
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(display "all processes have been terminated\n")
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#f))
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(respawn? #f))))
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(define user-processes-service-type
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(service-type
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(name 'user-processes)
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(extensions (list (service-extension shepherd-root-service-type
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user-processes-shepherd-service)))
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(compose concatenate)
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(extend append)
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;; The value is the list of Shepherd services 'user-processes' depends on.
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;; Extensions can add new services to this list.
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(default-value '())
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(description "The @code{user-processes} service is responsible for
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terminating all the processes so that the root file system can be re-mounted
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read-only, just before rebooting/halting. Processes still running after a few
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seconds after @code{SIGTERM} has been sent are terminated with
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@code{SIGKILL}.")))
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;;;
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;;; File systems.
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@ -349,7 +472,11 @@ FILE-SYSTEM."
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(list (service-extension shepherd-root-service-type
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file-system-shepherd-services)
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(service-extension fstab-service-type
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identity)))
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identity)
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;; Have 'user-processes' depend on 'file-systems'.
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(service-extension user-processes-service-type
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(const '(file-systems)))))
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(compose concatenate)
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(extend append)
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(description
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@ -389,111 +516,6 @@ file systems, as well as corresponding @file{/etc/fstab} entries.")))
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in KNOWN-MOUNT-POINTS when it is stopped."
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(service user-unmount-service-type known-mount-points))
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(define %do-not-kill-file
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;; Name of the file listing PIDs of processes that must survive when halting
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;; the system. Typical example is user-space file systems.
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"/etc/shepherd/do-not-kill")
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(define user-processes-service-type
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(shepherd-service-type
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'user-processes
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(lambda (grace-delay)
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(shepherd-service
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(documentation "When stopped, terminate all user processes.")
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(provision '(user-processes))
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(requirement '(file-systems))
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(start #~(const #t))
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(stop #~(lambda _
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(define (kill-except omit signal)
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;; Kill all the processes with SIGNAL except those listed
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;; in OMIT and the current process.
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(let ((omit (cons (getpid) omit)))
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(for-each (lambda (pid)
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(unless (memv pid omit)
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(false-if-exception
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(kill pid signal))))
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(processes))))
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(define omitted-pids
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;; List of PIDs that must not be killed.
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(if (file-exists? #$%do-not-kill-file)
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(map string->number
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(call-with-input-file #$%do-not-kill-file
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(compose string-tokenize
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(@ (ice-9 rdelim) read-string))))
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'()))
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(define (now)
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(car (gettimeofday)))
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(define (sleep* n)
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;; Really sleep N seconds.
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;; Work around <http://bugs.gnu.org/19581>.
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(define start (now))
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(let loop ((elapsed 0))
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(when (> n elapsed)
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(sleep (- n elapsed))
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(loop (- (now) start)))))
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(define lset= (@ (srfi srfi-1) lset=))
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(display "sending all processes the TERM signal\n")
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(if (null? omitted-pids)
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(begin
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;; Easy: terminate all of them.
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(kill -1 SIGTERM)
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(sleep* #$grace-delay)
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(kill -1 SIGKILL))
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(begin
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;; Kill them all except OMITTED-PIDS. XXX: We would
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;; like to (kill -1 SIGSTOP) to get a fixed list of
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;; processes, like 'killall5' does, but that seems
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;; unreliable.
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(kill-except omitted-pids SIGTERM)
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(sleep* #$grace-delay)
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(kill-except omitted-pids SIGKILL)
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(delete-file #$%do-not-kill-file)))
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(let wait ()
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;; Reap children, if any, so that we don't end up with
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;; zombies and enter an infinite loop.
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(let reap-children ()
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(define result
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(false-if-exception
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(waitpid WAIT_ANY (if (null? omitted-pids)
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0
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WNOHANG))))
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(when (and (pair? result)
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(not (zero? (car result))))
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(reap-children)))
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(let ((pids (processes)))
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(unless (lset= = pids (cons 1 omitted-pids))
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(format #t "waiting for process termination\
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(processes left: ~s)~%"
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pids)
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(sleep* 2)
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(wait))))
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(display "all processes have been terminated\n")
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#f))
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(respawn? #f)))))
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(define* (user-processes-service #:key (grace-delay 4))
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"Return the service that is responsible for terminating all the processes so
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that the root file system can be re-mounted read-only, just before
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rebooting/halting. Processes still running GRACE-DELAY seconds after SIGTERM
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has been sent are terminated with SIGKILL.
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The returned service will depend on 'file-systems', meaning that it is
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considered started after all the auto-mount file systems have been mounted.
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All the services that spawn processes must depend on this one so that they are
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stopped before 'kill' is called."
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(service user-processes-service-type grace-delay))
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;;;
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;;; Preserve entropy to seed /dev/urandom on boot.
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@ -449,7 +449,7 @@ a container or that of a \"bare metal\" system."
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(other-fs (non-boot-file-system-service os))
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(unmount (user-unmount-service known-fs))
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(swaps (swap-services os))
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(procs (user-processes-service))
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(procs (service user-processes-service-type))
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(host-name (host-name-service (operating-system-host-name os)))
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(entries (operating-system-directory-base-entries
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os #:container? container?)))
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