From 496b7282f2b8fb56cc88d7113202ef0e1d9ce22c Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Mon, 9 Mar 2015 17:21:12 +0000
Subject:  - Added s6-uevent-listener and s6-uevent-spawner  - s6-devd is now a
 wrapper around the former two  - version: bump to 2.0.2.0, still missing
 s6-devd doc

---
 INSTALL                                  |   2 +-
 doc/index.html                           |   6 +-
 doc/s6-devd.html                         |   4 +-
 doc/s6-uevent-listener.html              |  99 +++++++++++
 doc/s6-uevent-spawner.html               |  79 ++++++++
 doc/upgrade.html                         |  11 ++
 package/deps.mak                         |   8 +-
 package/info                             |   2 +-
 package/modes                            |  30 ++--
 package/targets.mak                      |   2 +
 src/minutils/deps-exe/s6-uevent-listener |   1 +
 src/minutils/deps-exe/s6-uevent-spawner  |   1 +
 src/minutils/s6-devd.c                   | 297 ++++++-------------------------
 src/minutils/s6-uevent-listener.c        | 233 ++++++++++++++++++++++++
 src/minutils/s6-uevent-spawner.c         | 234 ++++++++++++++++++++++++
 15 files changed, 747 insertions(+), 262 deletions(-)
 create mode 100644 doc/s6-uevent-listener.html
 create mode 100644 doc/s6-uevent-spawner.html
 create mode 100644 src/minutils/deps-exe/s6-uevent-listener
 create mode 100644 src/minutils/deps-exe/s6-uevent-spawner
 create mode 100644 src/minutils/s6-uevent-listener.c
 create mode 100644 src/minutils/s6-uevent-spawner.c

diff --git a/INSTALL b/INSTALL
index 641c8f9..99ee0a1 100644
--- a/INSTALL
+++ b/INSTALL
@@ -6,7 +6,7 @@ Build Instructions
 
   - A Linux-based system with a standard C development environment
   - GNU make version 4.0 or later
-  - skalibs version 2.3.1.0 or later: http://skarnet.org/software/skalibs/
+  - skalibs version 2.3.1.2 or later: http://skarnet.org/software/skalibs/
 
  This software is Linux-specific. It will run on a Linux kernel,
 version 2.6.32 or later.
diff --git a/doc/index.html b/doc/index.html
index a899be8..a0fe7d7 100644
--- a/doc/index.html
+++ b/doc/index.html
@@ -32,7 +32,7 @@
  <li> A Linux-based system with a standard C development environment </li>
  <li> GNU make, version 4.0 or later </li>
  <li> <a href="http://skarnet.org/software/skalibs/">skalibs</a> version
-2.3.1.0 or later. It's a build-time requirement. It's also a run-time
+2.3.1.2 or later. It's a build-time requirement. It's also a run-time
 requirement if you link against the shared version of the skalibs
 library. </li>
 </ul>
@@ -47,7 +47,7 @@ library. </li>
 <h3> Download </h3>
 
 <ul>
- <li> The current released version of s6-linux-utils is <a href="s6-linux-utils-2.0.1.0.tar.gz">2.0.1.0</a>. </li>
+ <li> The current released version of s6-linux-utils is <a href="s6-linux-utils-2.0.2.0.tar.gz">2.0.2.0</a>. </li>
  <li> Alternatively, you can checkout a copy of the s6-linux-utils git repository:
 <pre> git clone git://git.skarnet.org/s6-linux-utils </pre> </li>
 </ul>
@@ -79,6 +79,8 @@ the previous versions of s6-linux-utils and the current one. </li>
 <ul>
 <li><a href="s6-chroot.html">The <tt>s6-chroot</tt> program</a></li>
 <li><a href="s6-devd.html">The <tt>s6-devd</tt> program</a></li>
+<li><a href="s6-uevent-listener.html">The <tt>s6-uevent-listener</tt> program</a></li>
+<li><a href="s6-uevent-spawner.html">The <tt>s6-uevent-spawner</tt> program</a></li>
 <li><a href="s6-freeramdisk.html">The <tt>s6-freeramdisk</tt> program</a></li>
 <li><a href="s6-halt.html">The <tt>s6-halt</tt> program</a></li>
 <li><a href="s6-hostname.html">The <tt>s6-hostname</tt> program</a></li>
diff --git a/doc/s6-devd.html b/doc/s6-devd.html
index 5ae6160..c67429a 100644
--- a/doc/s6-devd.html
+++ b/doc/s6-devd.html
@@ -36,7 +36,7 @@ hotplug events, as the <em>udev</em> program does. </li>
 the event variables added to the environment, just as if <em>prog...</em>
 had been registered in <tt>/proc/sys/kernel/hotplug</tt>. </li>
  <li> However, unlike the kernel, s6-devd spawns the <em>prog...</em> helpers
-sequentially: it waits for an instance to finish before spawning another one. </li>
+sequentially: it waits for an instance to finish before spawning another one. </li>
  <li> s6-devd is a long-lived program; it exits 0 when it receives a
 SIGTERM. If a helper program is alive at that time, s6-devd waits for it to die
 before exiting. </li>
@@ -68,7 +68,7 @@ fork and logs to stderr.) </li>
 even if you are not using the <tt>-t</tt> option to s6-devd. Since helpers are
 spawned sequentially, slow helpers can make events queue up and fill the netlink
 kernel buffer. </li>
- <li> If you are using <a href="http://busybox.net/">busybox</a> and want a
+ <li> If you are using <a href="http://busybox.net/">busybox</a> and want a
 minimal udev-style dynamic <tt>/dev</tt>
 handling, <tt>/sbin/mdev</tt> is a suitable <em>prog...</em> helper. </li>
  <li> The point of s6-devd is that it runs the helpers sequentially, so it solves
diff --git a/doc/s6-uevent-listener.html b/doc/s6-uevent-listener.html
new file mode 100644
index 0000000..9050e9f
--- /dev/null
+++ b/doc/s6-uevent-listener.html
@@ -0,0 +1,99 @@
+<html>
+  <head>
+    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+    <meta http-equiv="Content-Language" content="en" />
+    <title>s6-linux-utils: the s6-uevent-listener program</title>
+    <meta name="Description" content="s6-linux-utils: the s6-uevent-listener program" />
+    <meta name="Keywords" content="s6 linux administration root utilities devd mdev udev s6-uevent-listener uevent" />
+    <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> -->
+  </head>
+<body>
+
+<p>
+<a href="index.html">s6-linux-utils</a><br />
+<a href="http://skarnet.org/software/">Software</a><br />
+<a href="http://skarnet.org/">skarnet.org</a>
+</p>
+
+<h1> The <tt>s6-uevent-listener</tt> program </h1>
+
+<p>
+<tt>s6-uevent-listener</tt> spawns a long-lived helper program.
+It then listens to the netlink interface for uevents (also called
+"hotplug" or "udev" events), and passes those events to the
+helper program's standard input, using a simple format.
+</p>
+
+<h2> Interface </h2>
+
+<pre>
+     s6-uevent-listener [ -v <em>verbosity</em> ] [ -b kbufsz ] <em>prog...</em>
+</pre>
+
+<ul>
+ <li> s6-uevent-listener spawns <em>prog...</em> with a pipe writing to
+<em>prog</em>' stdin. </li>
+ <li> s6-uevent-listener binds to the netlink interface and listens for
+hotplug events, as the <em>udev</em> program does. </li>
+ <li> It tranmits event information to <em>prog</em> via the pipe. </li>
+ <li> s6-uevent-listener, as well as <em>prog</em>, are long-lived programs.
+When it receives a SIGTERM, s6-uevent-listener stops listening; it will
+exit as soon as it has flushed its event queue to <em>prog</em>. </li>
+</ul>
+
+<h2> Options </h2>
+
+<ul>
+ <li> <tt>-v</tt>&nbsp;<em>verbosity</em>&nbsp;: be more or less verbose.
+Default verbosity is 1. 0 will only print fatal error messages, 3 will
+print warnings every time the netlink interface sends something
+unexpected. </li>
+ <li> <tt>-b</tt>&nbsp;<em>kbufsz</em>&nbsp;: try and reserve a kernel buffer of
+<em>kbufsz</em> bytes for the netlink queue. Too large a buffer wastes kernel memory;
+too small a buffer risks losing events. The default is 65536. </li>
+</ul>
+
+<h2> Protocol </h2>
+
+<ul>
+ <li> <em>prog</em> should read a series of events on its stdin, and exit
+on EOF. </li>
+ <li> An event is a series of null-terminated strings as they are sent by
+the kernel to the netlink; s6-uevent-listener adds a final empty string
+(i.e. an additional null character) to mark the end of the series. </li>
+ <li> The first string is a short description of the event; it normally
+contains the string "@/". Other strings after the first are of the form
+"VARIABLE=value", and describe the environment which a hotplug helper
+for the event (registered in <tt>/proc/sys/kernel/hotplug</tt>) would be
+spawned with. </li>
+ <li> Example (newlines added for clarity): <pre>
+add@/class/input/input9/mouse2\0
+ACTION=add\0
+DEVPATH=/class/input/input9/mouse2\0
+SUBSYSTEM=input\0
+SEQNUM=106\0
+PHYSDEVPATH=/devices/pci0000:00/0000:00:1d.1/usb2/2­2/2­2:1.0
+PHYSDEVBUS=usb\0
+PHYSDEVDRIVER=usbhid\0
+MAJOR=13\0
+MINOR=34\0
+\0 </pre> </li>
+</ul>
+
+<h2> Notes </h2>
+
+<ul>
+ <li> s6-uevent-listener is a daemon; it should be run under a proper supervision system such
+as <a href="http://skarnet.org/software/s6/">s6</a>. </li>
+<li> If you are running s6-uevent-listener, <em>prog...</em> should be the
+only program handling uevents, which means that
+<tt>/proc/sys/kernel/hotplug</tt> should be empty. </li>
+ <li> If you want the serialization benefit of the netlink, but still
+want to spawn a program such as <a href="http://busybox.net/">busybox</a>'s
+or <a href="http://landley.net/toybox/">toybox</a>'s <tt>mdev</tt>, use
+<tt><a href="s6-uevent-spawner.html">s6-uevent-spawner</a> mdev</tt> as
+s6-uevent-listener's <em>prog</em>. </li>
+</ul>
+
+</body>
+</html>
diff --git a/doc/s6-uevent-spawner.html b/doc/s6-uevent-spawner.html
new file mode 100644
index 0000000..e9be726
--- /dev/null
+++ b/doc/s6-uevent-spawner.html
@@ -0,0 +1,79 @@
+<html>
+  <head>
+    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+    <meta http-equiv="Content-Language" content="en" />
+    <title>s6-linux-utils: the s6-uevent-spawner program</title>
+    <meta name="Description" content="s6-linux-utils: the s6-uevent-spawner program" />
+    <meta name="Keywords" content="s6 linux administration root utilities devd mdev udev hotplug" />
+    <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> -->
+  </head>
+<body>
+
+<p>
+<a href="index.html">s6-linux-utils</a><br />
+<a href="http://skarnet.org/software/">Software</a><br />
+<a href="http://skarnet.org/">skarnet.org</a>
+</p>
+
+<h1> The <tt>s6-uevent-spawner</tt> program </h1>
+
+<p>
+<tt>s6-uevent-spawner</tt> listens to its standard input for
+netlink-style events, and launches a helper program for every event,
+similarly to what the hotplug interface does.
+</p>
+
+<p>
+ It is meant to be used together with
+<a href="s6-uevent-listener.html">s6-uevent-listener</a>.
+</p>
+
+<h2> Interface </h2>
+
+<pre>
+     s6-uevent-spawner [ -v <em>verbosity</em> ] [ -l <em>linevar</em> ] [ -t <em>l</em>:<em>t</em>:<em>k</em> ] <em>prog...</em>
+</pre>
+
+<ul>
+ <li> s6-uevent-spawner listens to its stdin for a series of strings
+representing kernel uevents, as formatted by
+<a href="s6-uevent-listener.html">s6-uevent-listener</a>. </li>
+ <li> For every event it reads, it spawns <em>prog...</em> with
+the event variables added to the environment, just as if <em>prog...</em>
+had been registered in <tt>/proc/sys/kernel/hotplug</tt>. However,
+it reads the events sequentially, and waits for a <em>prog</em> instance
+to finish before spawning another one. </li>
+ <li> When s6-uevent-spawner receives EOF: if an instance of
+<em>prog</em> is alive, it first waits for it to die. Then it exits
+0. </li>
+</ul>
+
+<h2> Options </h2>
+
+<ul>
+ <li> <tt>-v</tt>&nbsp;<em>verbosity</em>&nbsp;: be more or less verbose.
+Default verbosity is 1. 0 only prints fatal error messages. 3 is too much. </li>
+ <li> <tt>-l</tt> <em>linevar</em>&nbsp;: make the event description
+(i.e. the first string in the netlink message announcing the event)
+available in <em>prog</em> under the environment variable <em>linevar</em>.
+By default, this first string is ignored - it is not needed, all the
+event information is already in the other variables. </li>
+ <li> <tt>-t</tt> <em>l:t:k</em>&nbsp;: If <em>l</em>, <em>t</em> or <em>k</em> is
+specified, they specify timeouts; by default, they are infinite.
+If <em>prog...</em> is still alive after <em>l</em> milliseconds, s6-devd sends
+it a SIGTERM. Then, if <em>prog...</em> is still alive after <em>t</em> more
+milliseconds, s6-devd sends it a SIGKILL. Then, if <em>prog...</em> is still
+alive after <em>k</em> more milliseconds, s6-uevent-spawner yells and exits 99. </li>
+</ul>
+
+<h2> Notes </h2>
+
+<ul>
+ <li> The <em>prog...</em> helper should be very short-lived,
+even if you are not using the <tt>-t</tt> option to s6-devd. Since helpers are
+spawned sequentially, slow helpers can make events queue up and fill up
+buffers. </li>
+</ul>
+
+</body>
+</html>
diff --git a/doc/upgrade.html b/doc/upgrade.html
index b9dcfeb..847324d 100644
--- a/doc/upgrade.html
+++ b/doc/upgrade.html
@@ -17,6 +17,17 @@
 
 <h1> What has changed in s6-linux-utils </h1>
 
+<h2> in 2.0.2.0 </h2>
+
+<ul>
+ <li> skalibs dependency bumped to 2.3.1.1 </li>
+ <li> New commands:
+<a href="s6-uevent-listener.html">s6-uevent-listener</a> and
+<a href="s6-uevent-spawner.html">s6-uevent-spawner</a> <li>
+ <li> <a href="s6-devd.html">s6-devd</a> is now a wrapper
+around those commands. </li>
+</ul>
+
 <h2> in 2.0.1.0 </h2>
 
 <ul>
diff --git a/package/deps.mak b/package/deps.mak
index c85b123..c013b69 100644
--- a/package/deps.mak
+++ b/package/deps.mak
@@ -3,7 +3,7 @@
 #
 
 src/minutils/s6-chroot.o src/minutils/s6-chroot.lo: src/minutils/s6-chroot.c
-src/minutils/s6-devd.o src/minutils/s6-devd.lo: src/minutils/s6-devd.c
+src/minutils/s6-devd.o src/minutils/s6-devd.lo: src/minutils/s6-devd.c src/include/s6-linux-utils/config.h
 src/minutils/s6-freeramdisk.o src/minutils/s6-freeramdisk.lo: src/minutils/s6-freeramdisk.c
 src/minutils/s6-halt.o src/minutils/s6-halt.lo: src/minutils/s6-halt.c
 src/minutils/s6-hiercopy.o src/minutils/s6-hiercopy.lo: src/minutils/s6-hiercopy.c
@@ -16,6 +16,8 @@ src/minutils/s6-ps.o src/minutils/s6-ps.lo: src/minutils/s6-ps.c src/minutils/s6
 src/minutils/s6-reboot.o src/minutils/s6-reboot.lo: src/minutils/s6-reboot.c
 src/minutils/s6-swapoff.o src/minutils/s6-swapoff.lo: src/minutils/s6-swapoff.c
 src/minutils/s6-swapon.o src/minutils/s6-swapon.lo: src/minutils/s6-swapon.c
+src/minutils/s6-uevent-listener.o src/minutils/s6-uevent-listener.lo: src/minutils/s6-uevent-listener.c
+src/minutils/s6-uevent-spawner.o src/minutils/s6-uevent-spawner.lo: src/minutils/s6-uevent-spawner.c
 src/minutils/s6-umount.o src/minutils/s6-umount.lo: src/minutils/s6-umount.c
 src/minutils/s6ps_grcache.o src/minutils/s6ps_grcache.lo: src/minutils/s6ps_grcache.c src/minutils/s6-ps.h
 src/minutils/s6ps_otree.o src/minutils/s6ps_otree.lo: src/minutils/s6ps_otree.c src/minutils/s6-ps.h
@@ -51,5 +53,9 @@ s6-swapoff: private EXTRA_LIBS :=
 s6-swapoff: src/minutils/s6-swapoff.o -lskarnet
 s6-swapon: private EXTRA_LIBS :=
 s6-swapon: src/minutils/s6-swapon.o -lskarnet
+s6-uevent-listener: private EXTRA_LIBS :=
+s6-uevent-listener: src/minutils/s6-uevent-listener.o -lskarnet
+s6-uevent-spawner: private EXTRA_LIBS :=
+s6-uevent-spawner: src/minutils/s6-uevent-spawner.o -lskarnet
 s6-umount: private EXTRA_LIBS :=
 s6-umount: src/minutils/s6-umount.o -lskarnet
diff --git a/package/info b/package/info
index f55a688..79f07d5 100644
--- a/package/info
+++ b/package/info
@@ -1,4 +1,4 @@
 package=s6-linux-utils
-version=2.0.1.0
+version=2.0.2.0
 category=admin
 package_macro_name=S6_LINUX_UTILS
diff --git a/package/modes b/package/modes
index 9a1c3b1..3905269 100644
--- a/package/modes
+++ b/package/modes
@@ -1,14 +1,16 @@
-s6-chroot	0700
-s6-devd		0700
-s6-freeramdisk	0700
-s6-halt		0700
-s6-hostname	0755
-s6-logwatch	0755
-s6-mount	0700
-s6-pivotchroot	0700
-s6-poweroff	0700
-s6-ps		0755
-s6-reboot	0700
-s6-swapoff	0700
-s6-swapon	0700
-s6-umount	0700
+s6-chroot		0700
+s6-devd			0700
+s6-uevent-listener	0700
+s6-uevent-spawner	0755
+s6-freeramdisk		0700
+s6-halt			0700
+s6-hostname		0755
+s6-logwatch		0755
+s6-mount		0700
+s6-pivotchroot		0700
+s6-poweroff		0700
+s6-ps			0755
+s6-reboot		0700
+s6-swapoff		0700
+s6-swapon		0700
+s6-umount		0700
diff --git a/package/targets.mak b/package/targets.mak
index f03db13..14bc019 100644
--- a/package/targets.mak
+++ b/package/targets.mak
@@ -1,6 +1,8 @@
 BIN_TARGETS := \
 s6-chroot \
 s6-devd \
+s6-uevent-listener \
+s6-uevent-spawner \
 s6-freeramdisk \
 s6-halt \
 s6-hostname \
diff --git a/src/minutils/deps-exe/s6-uevent-listener b/src/minutils/deps-exe/s6-uevent-listener
new file mode 100644
index 0000000..e7187fe
--- /dev/null
+++ b/src/minutils/deps-exe/s6-uevent-listener
@@ -0,0 +1 @@
+-lskarnet
diff --git a/src/minutils/deps-exe/s6-uevent-spawner b/src/minutils/deps-exe/s6-uevent-spawner
new file mode 100644
index 0000000..e7187fe
--- /dev/null
+++ b/src/minutils/deps-exe/s6-uevent-spawner
@@ -0,0 +1 @@
+-lskarnet
diff --git a/src/minutils/s6-devd.c b/src/minutils/s6-devd.c
index f51550c..9df5c80 100644
--- a/src/minutils/s6-devd.c
+++ b/src/minutils/s6-devd.c
@@ -1,281 +1,96 @@
 /* ISC license. */
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-
-#include <sys/types.h>
-#include <unistd.h>
-#include <spawn.h>
-#include <signal.h>
-#include <sys/socket.h>
-#include <linux/netlink.h>
-#include <errno.h>
-#include <skalibs/allreadwrite.h>
-#include <skalibs/bytestr.h>
 #include <skalibs/uint.h>
 #include <skalibs/sgetopt.h>
 #include <skalibs/strerr2.h>
-#include <skalibs/tai.h>
-#include <skalibs/iopause.h>
-#include <skalibs/env.h>
 #include <skalibs/djbunix.h>
-#include <skalibs/sig.h>
-#include <skalibs/selfpipe.h>
+#include <s6-linux-utils/config.h>
 
-#define USAGE "s6-devd [ -q | -v ] [ -b kbufsz ] [ -t maxlife:maxterm:maxkill ] helperprogram..."
+#define USAGE "s6-devd [ -q | -v ] [ -b kbufsz ] [ -l linevar ] [ -t maxlife:maxterm:maxkill ] helperprogram..."
 #define dieusage() strerr_dieusage(100, USAGE)
 
-static unsigned int cont = 1, state = 0, verbosity = 1 ;
-static pid_t pid ;
-static tain_t lifetto = TAIN_INFINITE_RELATIVE,
-              termtto = TAIN_INFINITE_RELATIVE,
-              killtto = TAIN_INFINITE_RELATIVE,
-              deadline ;
-
-static inline int fd_recvmsg (int fd, struct msghdr *hdr)
-{
-  int r ;
-  do r = recvmsg(fd, hdr, 0) ;
-  while ((r == -1) && (errno == EINTR)) ;
-  return r ;
-}
-
-static inline int netlink_init (unsigned int kbufsz)
-{
-  struct sockaddr_nl nl = { .nl_family = AF_NETLINK, .nl_pad = 0, .nl_groups = 1, .nl_pid = 0 } ;
-  int fd = socket_internal(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT, DJBUNIX_FLAG_NB|DJBUNIX_FLAG_COE) ;
-  if (fd < 0) return -1 ;
-  if (bind(fd, (struct sockaddr *)&nl, sizeof(struct sockaddr_nl)) < 0) goto err ;
-  if (setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &kbufsz, sizeof(unsigned int)) < 0) goto err ;
-  return fd ;
- err:
-  {
-    register int e = errno ;
-    fd_close(fd) ;
-    errno = e ;
-  }
-  return -1 ;
-}
-
-static inline void on_death (void)
-{
-  pid = 0 ;
-  state = 0 ;
-  tain_add_g(&deadline, &tain_infinite_relative) ;
-  if (cont == 2) cont = 0 ;
-}
-
-static inline void on_event (char const *const *argv, char const *const *envp, char const *s, unsigned int len)
-{
-  unsigned int envlen = env_len(envp) ;
-  unsigned int n = envlen + 1 + byte_count(s, len, '\0') ;
-  int e ;
-  char const *v[n] ;
-  if (!env_merge(v, n, envp, envlen, s, len))
-    strerr_diefu1sys(111, "env_merge") ;
-  e = posix_spawnp(&pid, argv[0], 0, 0, (char *const *)argv, (char * const *)v) ;
-  if (e) { errno = e ; strerr_diefu2sys(111, "spawn ", argv[0]) ; }
-  state = 1 ;
-  tain_add_g(&deadline, &lifetto) ;
-}
-
-static inline void handle_timeout (void)
+static inline int check_targ (char const *s)
 {
-  switch (state)
-  {
-    case 0 :
-      tain_add_g(&deadline, &tain_infinite_relative) ;
-      break ;
-    case 1 :
-      kill(pid, SIGTERM) ;
-      tain_add_g(&deadline, &termtto) ;
-      state++ ;
-      break ;
-    case 2 :
-      kill(pid, SIGKILL) ;
-      tain_add_g(&deadline, &killtto) ;
-      state++ ;
-      break ;
-    case 3 :
-      strerr_dief1x(99, "child resisted SIGKILL - check your kernel logs.") ;
-    default :
-      strerr_dief1x(101, "internal error: inconsistent state. Please submit a bug-report.") ;
-  }
-}
-
-static inline void handle_signals (void)
-{
-  for (;;)
-  {
-    char c = selfpipe_read() ;
-    switch (c)
-    {
-      case -1 : strerr_diefu1sys(111, "selfpipe_read") ;
-      case 0 : return ;
-      case SIGTERM :
-        cont = pid ? 2 : 0 ;
-        break ;
-      case SIGCHLD :
-        if (!pid) wait_reap() ;
-        else
-        {
-          int wstat ;
-          int r = wait_pid_nohang(pid, &wstat) ;
-          if (r < 0)
-            if (errno != ECHILD) strerr_diefu1sys(111, "wait_pid_nohang") ;
-            else break ;
-          else if (!r) break ;
-          on_death() ;
-        }
-        break ;
-      default :
-        strerr_dief1x(101, "internal error: inconsistent signal state. Please submit a bug-report.") ;
-    }
-  }
-}
-
-static inline void handle_netlink (int fd, char const *const *argv, char const *const *envp)
-{
-  char buf[4096] ;
-  int r ;
-  {
-    struct sockaddr_nl nl;
-    struct iovec iov = { .iov_base = &buf, .iov_len = sizeof(buf) } ;
-    char ctlmsg[CMSG_SPACE(sizeof(struct ucred))] ;
-    struct msghdr msg = {
-                          .msg_name = &nl,
-                          .msg_namelen = sizeof(struct sockaddr_nl),
-                          .msg_iov = &iov,
-                          .msg_iovlen = 1,
-                          .msg_control = ctlmsg,
-                          .msg_controllen = sizeof(ctlmsg),
-                          .msg_flags = 0
-                        } ;
-    r = sanitize_read(fd_recvmsg(fd, &msg)) ;
-    if (r < 0)
-    {
-      if (errno == EPIPE)
-      {
-        if (verbosity >= 2) strerr_warnw1x("received EOF on netlink") ;
-        cont = 0 ;
-        return ;
-      }
-      else strerr_diefu1sys(111, "receive netlink message") ;
-    }
-    if (!r) return ;
-    if (r < 32 || r > 4096)
-    {
-      if (verbosity >= 2)
-        strerr_warnw2x("received and ignored netlink message ", "with invalid length") ;
-      return ;
-    }
-    if (nl.nl_pid)
-    {
-      if (verbosity >= 3)
-      {
-        char fmt[UINT_FMT] ;
-        fmt[uint_fmt(fmt, nl.nl_pid)] = 0 ;
-        strerr_warnw3x("received and ignored netlink message ", "from userspace process ", fmt) ;
-      }
-      return ;
-    }
-  }
-  {
-    unsigned int start = str_len(buf) + 1 ;
-    if (start < 5 || start > (unsigned int)r)
-    {
-      if (verbosity >= 2)
-        strerr_warnw3x("received and ignored netlink message ", "with invalid header", " length") ;
-      return ;
-    }
-    if (str_strn(buf, start, "@/", 2) >= start)
-    {
-      if (verbosity >= 2)
-        strerr_warnw2x("received and ignored netlink message ", "with invalid header") ;
-      return ;
-    }
-    on_event(argv, envp, buf + start, r - start) ;
-  }
-}
-
-static inline int make_ttos (char const *s)
-{
-  unsigned int tlife = 0, tterm = 0, tkill = 0, pos = 0 ;
-  pos += uint_scan(s + pos, &tlife) ;
+  unsigned int t = 0, pos = 0 ;
+  pos += uint_scan(s + pos, &t) ;
   if (s[pos] && s[pos++] != ':') return 0 ;
-  if (!tlife) return 1 ;
-  tain_from_millisecs(&lifetto, tlife) ;
-  pos += uint_scan(s + pos, &tterm) ;
+  if (!t) return 1 ;
+  pos += uint_scan(s + pos, &t) ;
   if (s[pos] && s[pos++] != ':') return 0 ;
-  if (!tterm) return 1 ;
-  tain_from_millisecs(&termtto, tterm) ;
-  tain_add(&termtto, &termtto, &lifetto) ;
-  pos += uint_scan(s + pos, &tkill) ;
+  if (!t) return 1 ;
+  pos += uint_scan(s + pos, &t) ;
   if (s[pos]) return 0 ;
-  if (!tkill) return 1 ;
-  tain_from_millisecs(&killtto, tkill) ;
-  tain_add(&killtto, &killtto, &termtto) ;
   return 1 ;
 }
 
 int main (int argc, char const *const *argv, char const *const *envp)
 {
-  iopause_fd x[2] = { { -1, IOPAUSE_READ, 0 }, { -1, IOPAUSE_READ, 0 } } ;
+  unsigned int kbufsz = 65536, verbosity = 1 ;
+  char const *linevar = 0 ;
+  char const *targ = 0 ;
   PROG = "s6-devd" ;
   {
-    unsigned int kbufsz = 65536 ;
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      register int opt = subgetopt_r(argc, argv, "qvb:t:", &l) ;
+      register int opt = subgetopt_r(argc, argv, "qvb:l:t:", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
         case 'q' : if (verbosity) verbosity-- ; break ;
         case 'v' : verbosity++ ; break ;
         case 'b' : if (!uint0_scan(l.arg, &kbufsz)) dieusage() ; break ;
-        case 't' : if (!make_ttos(l.arg)) dieusage() ; break ;
+        case 'l' : linevar = l.arg ; break ;
+        case 't' : if (!check_targ(l.arg)) dieusage() ; targ = l.arg ; break ;
         default : dieusage() ;
       }
     }
     argc -= l.ind ; argv += l.ind ;
-    if (!argc) strerr_dieusage(100, USAGE) ;
-    close(0) ;
-    if (open_readb("/dev/null") < 0) strerr_diefu1sys(111, "open /dev/null for reading") ;
-    x[1].fd = netlink_init(kbufsz) ;
-    if (x[1].fd < 0) strerr_diefu1sys(111, "init netlink") ;
-  }
-
-  x[0].fd = selfpipe_init() ;
-  if (x[0].fd == -1) strerr_diefu1sys(111, "init selfpipe") ;
-  if (sig_ignore(SIGPIPE) < 0) strerr_diefu1sys(111, "ignore SIGPIPE") ;
-  {
-    sigset_t set ;
-    sigemptyset(&set) ;
-    sigaddset(&set, SIGTERM) ;
-    sigaddset(&set, SIGCHLD) ;
-    if (selfpipe_trapset(&set) < 0) strerr_diefu1sys(111, "trap signals") ;
   }
+  if (!argc) strerr_dieusage(100, USAGE) ;
 
-  tain_now_g() ;
-  tain_add_g(&deadline, &tain_infinite_relative) ;
-  if (verbosity >= 2) strerr_warni1x("starting") ;
-
-  while (cont)
   {
-    register int r = iopause_g(x, 1 + !pid, &deadline) ;
-    if (r < 0) strerr_diefu1sys(111, "iopause") ;
-    else if (!r) handle_timeout() ;
-    else
+    unsigned int m = 0, pos = 0 ;
+    char fmt[UINT_FMT * 3] ;
+    char const *newargv[argc + 15] ;
+    newargv[m++] = S6_LINUX_UTILS_BINPREFIX "s6-uevent-listener" ;
+    if (verbosity != 1)
+    {
+      newargv[m++] = "-v" ;
+      newargv[m++] = fmt + pos ;
+      pos += uint_fmt(fmt + pos, verbosity) ;
+      fmt[pos++] = 0 ;
+    }
+    if (kbufsz != 65536)
+    {
+      newargv[m++] = "-k" ;
+      newargv[m++] = fmt + pos ;
+      pos += uint_fmt(fmt + pos, kbufsz) ;
+      fmt[pos++] = 0 ;
+    }
+    newargv[m++] = "--" ;
+    newargv[m++] = S6_LINUX_UTILS_BINPREFIX "s6-uevent-spawner" ;
+    if (verbosity != 1)
+    {
+      newargv[m++] = "-v" ;
+      newargv[m++] = fmt + pos ;
+      pos += uint_fmt(fmt + pos, verbosity) ;
+      fmt[pos++] = 0 ;
+    }
+    if (linevar)
+    {
+      newargv[m++] = "-l" ;
+      newargv[m++] = linevar ;
+    }
+    if (targ)
     {
-      if ((x[0].revents | x[1].revents) & IOPAUSE_EXCEPT)
-        strerr_diefu1x(111, "iopause: trouble with pipes") ;
-      if (x[0].revents & IOPAUSE_READ) handle_signals() ;
-      else if (!pid && (x[1].revents & IOPAUSE_READ))
-        handle_netlink(x[1].fd, argv, envp) ;
+      newargv[m++] = "-t" ;
+      newargv[m++] = targ ;
     }
+    newargv[m++] = "--" ;
+    while (*argv) newargv[m++] = *argv++ ;
+    newargv[m++] = 0 ;
+    pathexec_run(newargv[0], newargv, envp) ;
+    strerr_dieexec(111, newargv[0]) ;
   }
-  if (verbosity >= 2) strerr_warni1x("exiting") ;
-  return 0 ;
 }
diff --git a/src/minutils/s6-uevent-listener.c b/src/minutils/s6-uevent-listener.c
new file mode 100644
index 0000000..b2cf455
--- /dev/null
+++ b/src/minutils/s6-uevent-listener.c
@@ -0,0 +1,233 @@
+/* ISC license. */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <asm/types.h>
+#include <linux/netlink.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/uint.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/iopause.h>
+#include <skalibs/bufalloc.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/sig.h>
+#include <skalibs/selfpipe.h>
+
+#define USAGE "s6-uevent-listener [ -v verbosity ] [ -b kbufsz ] helperprogram..."
+#define dieusage() strerr_dieusage(100, USAGE)
+#define dienomem() strerr_diefu1sys(111, "build string") ;
+
+static unsigned int cont = 1, verbosity = 1 ;
+static pid_t pid ;
+
+static inline int fd_recvmsg (int fd, struct msghdr *hdr)
+{
+  int r ;
+  do r = recvmsg(fd, hdr, MSG_DONTWAIT) ;
+  while ((r == -1) && (errno == EINTR)) ;
+  return r ;
+}
+
+static inline int netlink_init_stdin (unsigned int kbufsz)
+{
+  struct sockaddr_nl nl = { .nl_family = AF_NETLINK, .nl_pad = 0, .nl_groups = 0, .nl_pid = 0 } ;
+  close(0) ;
+  return socket_internal(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT, DJBUNIX_FLAG_NB|DJBUNIX_FLAG_COE) == 0
+   && bind(0, (struct sockaddr *)&nl, sizeof(struct sockaddr_nl)) == 0
+   && setsockopt(0, SOL_SOCKET, SO_RCVBUFFORCE, &kbufsz, sizeof(unsigned int)) == 0 ;
+}
+
+static inline void handle_signals (void)
+{
+  for (;;)
+  {
+    char c = selfpipe_read() ;
+    switch (c)
+    {
+      case -1 : strerr_diefu1sys(111, "selfpipe_read") ;
+      case 0 : return ;
+      case SIGTERM :
+        cont = 0 ;
+        fd_close(0) ;
+        break ;
+      case SIGCHLD :
+      {
+        char fmt[UINT_FMT] ;
+        int wstat ;
+        int r = wait_pid_nohang(pid, &wstat) ;
+        if (r < 0)
+          if (errno != ECHILD) strerr_diefu1sys(111, "wait_pid_nohang") ;
+          else break ;
+        else if (!r) break ;
+        if (WIFSIGNALED(wstat))
+        {
+          fmt[uint_fmt(fmt, WTERMSIG(wstat))] = 0 ;
+          strerr_dief2x(1, "child crashed with signal ", fmt) ;
+        }
+        else
+        {
+          fmt[uint_fmt(fmt, WEXITSTATUS(wstat))] = 0 ;
+          strerr_dief2x(1, "child exited ", fmt) ;
+        }
+      }
+      default :
+        strerr_dief1x(101, "internal error: inconsistent signal state. Please submit a bug-report.") ;
+    }
+  }
+}
+
+static void doit (char const *s, unsigned int len)
+{
+  if (!bufalloc_put(bufalloc_1, s, len)) dienomem() ;
+}
+
+static void terminate (void)
+{
+  if (!bufalloc_put(bufalloc_1, "", 1)) dienomem() ;
+}
+
+static inline void handle_netlink (void)
+{
+  char buf[8192] ;
+  static int inmulti = 0 ;
+  struct sockaddr_nl nl;
+  struct iovec iov = { .iov_base = &buf, .iov_len = sizeof(buf) } ;
+  struct msghdr msg =
+  {
+    .msg_name = &nl,
+    .msg_namelen = sizeof(struct sockaddr_nl),
+    .msg_iov = &iov,
+    .msg_iovlen = 1,
+    .msg_control = 0,
+    .msg_controllen = 0,
+    .msg_flags = 0
+  } ;
+  struct nlmsghdr *nlh = (struct nlmsghdr *)buf ;
+  int r = sanitize_read(fd_recvmsg(0, &msg)) ;
+  if (r < 0)
+  {
+    if (errno == EPIPE)
+    {
+      if (verbosity >= 2) strerr_warnw1x("received EOF on netlink") ;
+      cont = 0 ;
+      fd_close(0) ;
+      return ;
+    }
+    else strerr_diefu1sys(111, "receive netlink message") ;
+  }
+  if (!r) return ;
+  if (msg.msg_flags & MSG_TRUNC)
+    strerr_diefu2x(111, "buffer too small for ", "netlink message") ;
+  if (nl.nl_pid)
+  {
+    if (verbosity >= 3)
+    {
+      char fmt[UINT_FMT] ;
+      fmt[uint_fmt(fmt, nl.nl_pid)] = 0 ;
+      strerr_warnw3x("netlink message", " from userspace process ", fmt) ;
+    }
+    return ;
+  }
+
+  for (; NLMSG_OK(nlh, r) ; nlh = NLMSG_NEXT(nlh, r))
+    switch (nlh->nlmsg_type)
+    {
+      case NLMSG_NOOP : break ;
+      case NLMSG_ERROR :
+        if (verbosity >= 3)
+          strerr_warnw2x("spurious NLMSG_ERROR ", "netlink message") ;
+        break ;
+      case NLMSG_DONE :
+        if (inmulti)
+        {
+          inmulti = 0 ;
+          terminate() ;
+        }
+        else if (verbosity >= 3)
+          strerr_warnw2x("spurious NLMSG_DONE ", "netlink message") ;
+        break ;
+      default :
+        if (nlh->nlmsg_flags & NLM_F_MULTI) inmulti = 1 ;
+        else if (inmulti)
+        {
+          inmulti = 0 ;
+          terminate() ;
+          if (verbosity >= 3)
+            strerr_warnw2x("unterminated multipart ", "netlink message") ;
+        }
+        doit(NLMSG_DATA(nlh), (unsigned int)NLMSG_PAYLOAD(nlh, r)) ;
+        if (!inmulti) terminate() ;
+        break ;
+    }
+}
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  iopause_fd x[3] = { { .events = IOPAUSE_READ }, { .fd = 1 }, { .fd = 0, .events = IOPAUSE_READ } } ;
+  PROG = "s6-uevent-listener" ;
+  {
+    unsigned int kbufsz = 65536 ;
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      register int opt = subgetopt_r(argc, argv, "v:b:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'v' : if (!uint0_scan(l.arg, &verbosity)) dieusage() ; break ;
+        case 'b' : if (!uint0_scan(l.arg, &kbufsz)) dieusage() ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+    if (!argc) strerr_dieusage(100, USAGE) ;
+    if (!netlink_init_stdin(kbufsz)) strerr_diefu1sys(111, "init netlink") ;
+  }
+
+  x[0].fd = selfpipe_init() ;
+  if (x[0].fd < 0) strerr_diefu1sys(111, "init selfpipe") ;
+  if (sig_ignore(SIGPIPE) < 0) strerr_diefu1sys(111, "ignore SIGPIPE") ;
+  {
+    sigset_t set ;
+    sigemptyset(&set) ;
+    sigaddset(&set, SIGTERM) ;
+    sigaddset(&set, SIGCHLD) ;
+    if (selfpipe_trapset(&set) < 0) strerr_diefu1sys(111, "trap signals") ;
+  }
+
+  {
+    int fd ;
+    pid = child_spawn1_pipe(argv[0], argv, envp, &fd, 0) ;
+    if (!pid) strerr_diefu2sys(111, "spawn ", argv[0]) ;
+    if (fd_move(1, fd) < 0) strerr_diefu1sys(111, "move pipe to stdout") ;
+  }
+
+  if (verbosity >= 2) strerr_warni1x("starting") ;
+
+  while (cont || bufalloc_len(bufalloc_1))
+  {
+    register int r ;
+    x[1].events = bufalloc_len(bufalloc_1) ? IOPAUSE_WRITE : 0 ;
+    r = iopause(x, 2 + cont, 0, 0) ;
+    if (r < 0) strerr_diefu1sys(111, "iopause") ;
+    if (!r) continue ;
+    if (x[0].revents & IOPAUSE_EXCEPT)
+      strerr_diefu1x(111, "iopause: trouble with selfpipe") ;
+    if (x[0].revents & IOPAUSE_READ) handle_signals() ;
+    if (x[1].revents & IOPAUSE_WRITE)
+      if (!bufalloc_flush(bufalloc_1)) strerr_diefu1sys(111, "flush stdout") ;
+    if (cont && x[2].revents & IOPAUSE_READ) handle_netlink() ;
+  }
+  if (verbosity >= 2) strerr_warni1x("exiting") ;
+  return 0 ;
+}
diff --git a/src/minutils/s6-uevent-spawner.c b/src/minutils/s6-uevent-spawner.c
new file mode 100644
index 0000000..b074f1f
--- /dev/null
+++ b/src/minutils/s6-uevent-spawner.c
@@ -0,0 +1,234 @@
+/* ISC license. */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <spawn.h>
+#include <signal.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <skalibs/config.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/buffer.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/uint.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/tai.h>
+#include <skalibs/iopause.h>
+#include <skalibs/env.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/sig.h>
+#include <skalibs/selfpipe.h>
+#include <skalibs/skamisc.h>
+
+#define USAGE "s6-uevent-spawner [ -v verbosity ] [ -l linevar ] [ -t maxlife:maxterm:maxkill ] helperprogram..."
+#define dieusage() strerr_dieusage(100, USAGE)
+#define dienomem() strerr_diefu1sys(111, "build string") ;
+
+static unsigned int cont = 1, state = 0, verbosity = 1 ;
+static pid_t pid ;
+static tain_t lifetto = TAIN_INFINITE_RELATIVE,
+              termtto = TAIN_INFINITE_RELATIVE,
+              killtto = TAIN_INFINITE_RELATIVE,
+              deadline ;
+
+static inline void on_death (void)
+{
+  pid = 0 ;
+  state = 0 ;
+  tain_add_g(&deadline, &tain_infinite_relative) ;
+}
+
+static inline void on_event (char const *const *argv, char const *const *envp, char const *s, unsigned int len)
+{
+  posix_spawnattr_t attr ;
+  posix_spawn_file_actions_t actions ;
+  unsigned int envlen = env_len(envp) ;
+  unsigned int n = envlen + 1 + byte_count(s, len, '\0') ;
+  int e ;
+  char const *v[n] ;
+  if (!env_merge(v, n, envp, envlen, s, len))
+    strerr_diefu1sys(111, "env_merge") ;
+
+  e = posix_spawnattr_init(&attr) ;
+  if (e) { errno = e ; strerr_diefu1sys(111, "posix_spawnattr_init") ; }
+  {
+    sigset_t set ;
+    sigemptyset(&set) ;
+    e = posix_spawnattr_setsigmask(&attr, &set) ;
+    if (e) { errno = e ; strerr_diefu1sys(111, "posix_spawnattr_setsigmask") ; }
+    sigfillset(&set) ;
+    e = posix_spawnattr_setsigdefault(&attr, &set) ;
+    if (e) { errno = e ; strerr_diefu1sys(111, "posix_spawnattr_setsigdefault") ; }
+  }
+  e = posix_spawn_file_actions_init(&actions) ;
+  if (e) { errno = e ; strerr_diefu1sys(111, "posix_spawn_file_actions_init") ; }
+  e = posix_spawn_file_actions_addopen(&actions, 0, "/dev/null", O_RDONLY, S_IRUSR) ;
+  if (e) { errno = e ; strerr_diefu1sys(111, "posix_spawn_file_actions_addopen") ; }
+  e = posix_spawnp(&pid, argv[0], &actions, &attr, (char *const *)argv, (char * const *)v) ;
+  if (e) { errno = e ; strerr_diefu2sys(111, "spawn ", argv[0]) ; }
+  posix_spawn_file_actions_destroy(&actions) ;
+  posix_spawnattr_destroy(&attr) ;
+  state = 1 ;
+  tain_add_g(&deadline, &lifetto) ;
+}
+
+static inline void handle_timeout (void)
+{
+  switch (state)
+  {
+    case 0 :
+      tain_add_g(&deadline, &tain_infinite_relative) ;
+      break ;
+    case 1 :
+      kill(pid, SIGTERM) ;
+      tain_add_g(&deadline, &termtto) ;
+      state++ ;
+      break ;
+    case 2 :
+      kill(pid, SIGKILL) ;
+      tain_add_g(&deadline, &killtto) ;
+      state++ ;
+      break ;
+    case 3 :
+      strerr_dief1x(99, "child resisted SIGKILL - check your kernel logs.") ;
+    default :
+      strerr_dief1x(101, "internal error: inconsistent state. Please submit a bug-report.") ;
+  }
+}
+
+static inline void handle_signals (void)
+{
+  for (;;)
+  {
+    char c = selfpipe_read() ;
+    switch (c)
+    {
+      case -1 : strerr_diefu1sys(111, "selfpipe_read") ;
+      case 0 : return ;
+      case SIGCHLD :
+        if (!pid) wait_reap() ;
+        else
+        {
+          int wstat ;
+          int r = wait_pid_nohang(pid, &wstat) ;
+          if (r < 0)
+            if (errno != ECHILD) strerr_diefu1sys(111, "wait_pid_nohang") ;
+            else break ;
+          else if (!r) break ;
+          on_death() ;
+        }
+        break ;
+      default :
+        strerr_dief1x(101, "internal error: inconsistent signal handling. Please submit a bug-report.") ;
+    }
+  }
+}
+
+static inline void handle_stdin (stralloc *sa, char const *linevar, char const *const *argv, char const *const *envp)
+{
+  for (;;)
+  {
+    unsigned int start ;
+    register int r ;
+    if (!sa->len && linevar)
+      if (!stralloc_cats(sa, linevar) || !stralloc_catb(sa, "=", 1))
+        dienomem() ;
+    start = sa->len ;
+    r = sanitize_read(skagetln(buffer_0, sa, 0)) ;
+    if (r < 0)
+    {
+      cont = 0 ;
+      if (errno != EPIPE && verbosity) strerr_warnwu1sys("read from stdin") ;
+    }
+    if (r <= 0) break ;
+    if (sa->len == start + 1)
+    {
+      start = linevar ? 0 : str_len(sa->s) + 1 ;
+      if (start >= sa->len)
+      {
+        if (verbosity) strerr_warnw1x("empty event!") ;
+      }
+      else on_event(argv, envp, sa->s + start, sa->len - 1 - start) ;
+      sa->len = 0 ;
+    }
+  }
+}
+
+static inline int make_ttos (char const *s)
+{
+  unsigned int tlife = 0, tterm = 0, tkill = 0, pos = 0 ;
+  pos += uint_scan(s + pos, &tlife) ;
+  if (s[pos] && s[pos++] != ':') return 0 ;
+  if (!tlife) return 1 ;
+  tain_from_millisecs(&lifetto, tlife) ;
+  pos += uint_scan(s + pos, &tterm) ;
+  if (s[pos] && s[pos++] != ':') return 0 ;
+  if (!tterm) return 1 ;
+  tain_from_millisecs(&termtto, tterm) ;
+  tain_add(&termtto, &termtto, &lifetto) ;
+  pos += uint_scan(s + pos, &tkill) ;
+  if (s[pos]) return 0 ;
+  if (!tkill) return 1 ;
+  tain_from_millisecs(&killtto, tkill) ;
+  tain_add(&killtto, &killtto, &termtto) ;
+  return 1 ;
+}
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  iopause_fd x[2] = { { .events = IOPAUSE_READ }, { .fd = 0, .events = IOPAUSE_READ } } ;
+  char const *linevar = 0 ;
+  stralloc sa = STRALLOC_ZERO ;
+  PROG = "s6-uevent-spawner" ;
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      register int opt = subgetopt_r(argc, argv, "l:v:t:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'l' : linevar = optarg ; break ;
+        case 'v' : if (!uint0_scan(l.arg, &verbosity)) dieusage() ; break ;
+        case 't' : if (!make_ttos(l.arg)) dieusage() ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+    if (!argc) strerr_dieusage(100, USAGE) ;
+  }
+  if (linevar && linevar[str_chr(linevar, '=')])
+    strerr_dief2x(100, "invalid variable: ", linevar) ;
+
+  x[0].fd = selfpipe_init() ;
+  if (x[0].fd == -1) strerr_diefu1sys(111, "init selfpipe") ;
+  if (sig_ignore(SIGPIPE) < 0) strerr_diefu1sys(111, "ignore SIGPIPE") ;
+  if (selfpipe_trap(SIGCHLD) < 0) strerr_diefu1sys(111, "trap SIGCHLD") ;
+  if (setenv("PATH", SKALIBS_DEFAULTPATH, 0) < 0)
+    strerr_diefu1sys(111, "setenv PATH") ;
+
+  tain_now_g() ;
+  tain_add_g(&deadline, &tain_infinite_relative) ;
+  if (verbosity >= 2) strerr_warni1x("starting") ;
+
+  while (cont || pid)
+  {
+    register int r = iopause_g(x, 1 + (!pid && cont), &deadline) ;
+    if (r < 0) strerr_diefu1sys(111, "iopause") ;
+    else if (!r) handle_timeout() ;
+    else
+    {
+      if (x[0].revents & IOPAUSE_EXCEPT)
+        strerr_diefu1x(111, "iopause: trouble with selfpipe") ;
+      if (x[0].revents & IOPAUSE_READ) handle_signals() ;
+      else if (!pid && cont && (x[1].revents & IOPAUSE_READ))
+        handle_stdin(&sa, linevar, argv, envp) ;
+    }
+  }
+  if (verbosity >= 2) strerr_warni1x("exiting") ;
+  return 0 ;
+}
-- 
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