[OpenWrt-Devel] [PATCH] babeld: use procd to start, stop, and respawn

[Baptiste Jonglez]

Hi,

Note that babeld is maintained in https://github.com/openwrt-routing/packages.
Nevertheless, comments inline.

On Sun, Sep 07, 2014 at 05:56:32PM -0400, Tristan Plumb wrote:
> Changes the babeld init script to utilize procd and

Nice, it was a requested feature:

  https://github.com/openwrt-routing/packages/issues/17

Could you separate your patch into three patches? (procd support, hotplug
script, pidfile hack)

> adds a hotplug.d file to restart babeld when interfaces go up or down.

Somebody provided a patch for this just a few days ago, see:

  https://github.com/openwrt-routing/packages/pull/52

However, see the comments: this should not be needed, as babeld detects
when an interface is brought up and then starts using it.  What is your
use-case?

> Additionally adds a patch to the babeld source is to prevent the
> attempted recreation of a pidfile when babeld restarts uncleanly. This is
> also possible to do by passing -I '' on the command line, however procd
> interprets an empty argument terminating the list, and thus cannot supply
> empty arguments to programs it manages.

Patching babeld itself is a workaround.  Why not tackle the root issue?
It seems that you encountered crashes in babeld, so that should be fixed,
instead of working around the crashes.  I did experience a few babeld
crashes myself, but never managed to find where they came from.

> Signed-off-by: Tristan Plumb <tristan at trstn.net>
> ---
> diff --git a/babeld/Makefile b/babeld/Makefile
> index e939310..70fcd64 100644
> --- a/babeld/Makefile
> +++ b/babeld/Makefile
> @@ -54,6 +54,8 @@ define Package/babeld/install
>  	$(INSTALL_CONF) ./files/babeld.config $(1)/etc/config/babeld
>  	$(INSTALL_DIR) $(1)/etc/init.d
>  	$(INSTALL_BIN) ./files/babeld.init $(1)/etc/init.d/babeld
> +	$(INSTALL_DIR) $(1)/etc/hotplug.d/iface
> +	$(INSTALL_DATA) ./files/babeld.hotplug $(1)/etc/hotplug.d/iface/25-babeld
>  endef
>  
>  $(eval $(call BuildPackage,babeld))
> diff --git a/babeld/files/babeld.hotplug b/babeld/files/babeld.hotplug
> new file mode 100644
> index 0000000..3fe674a
> --- /dev/null
> +++ b/babeld/files/babeld.hotplug
> @@ -0,0 +1,6 @@
> +#!/bin/sh
> +
> +[ "$ACTION" = ifup ] || exit 0
> +
> +/etc/init.d/babeld enabled && /etc/init.d/babeld restart
> +
> diff --git a/babeld/files/babeld.init b/babeld/files/babeld.init
> index 180fc7e..de8d73b 100755
> --- a/babeld/files/babeld.init
> +++ b/babeld/files/babeld.init
> @@ -2,9 +2,9 @@
>  
>  . /lib/functions/network.sh
>  
> +USE_PROCD=1
>  START=70
>  
> -pidfile='/var/run/babeld.pid'
>  CONFIGFILE='/var/etc/babeld.conf'
>  OTHERCONFIGFILE="/etc/babeld.conf"
>  EXTRA_COMMANDS="status"
> @@ -197,7 +197,7 @@ babel_config_cb() {
>  	esac
>  }
>  
> -start() {
> +start_service() {
>  	mkdir -p /var/lib
>  	# Start by emptying the generated config file
>  	>"$CONFIGFILE"
> @@ -213,26 +213,17 @@ start() {
>  	config_foreach parse_old_global_options general
>  	# Parse filters separately, since we know which options we expect
>  	config_foreach babel_filter filter
> +	procd_open_instance
>  	# Using multiple config files is supported since babeld 1.5.1
> -	/usr/sbin/babeld -D -I "$pidfile" -c "$OTHERCONFIGFILE" -c "$CONFIGFILE"
> -	# Wait for the pidfile to appear
> -	for i in 1 2
> -	do
> -		[ -f "$pidfile" ] || sleep 1
> -	done
> -	[ -f "$pidfile" ] || (echo "Failed to start babeld"; exit 42)
> +	procd_set_param command /usr/sbin/babeld -c "$OTHERCONFIGFILE" -c "$CONFIGFILE"
> +	procd_set_param respawn
> +	procd_close_instance
>  }
>  
> -stop() {
> -	[ -f "$pidfile" ] && kill $(cat $pidfile)
> -  # avoid race-condition on restart: wait for
> -  # babeld to die for real.
> -  [ -f "$pidfile" ] && sleep 1
> -  [ -f "$pidfile" ] && sleep 1
> -  [ -f "$pidfile" ] && sleep 1
> -  [ -f "$pidfile" ] && exit 42
> +service_triggers() {
> +	procd_add_reload_trigger babeld
>  }
>  
>  status() {
> -	[ -f "$pidfile" ] && kill -USR1 $(cat $pidfile)
> +	kill -USR1 $(pidof babeld)
>  }
> diff --git a/babeld/patches/001-no-default-pidfile.patch b/babeld/patches/001-no-default-pidfile.patch
> new file mode 100644
> index 0000000..74ac6b4
> --- /dev/null
> +++ b/babeld/patches/001-no-default-pidfile.patch
> @@ -0,0 +1,21 @@
> +diff --git a/babeld.c b/babeld.c
> +index 656c9da..88e4aec 100644
> +--- a/babeld.c
> ++++ b/babeld.c
> +@@ -66,7 +66,7 @@ int resend_delay = -1;
> + int random_id = 0;
> + int do_daemonise = 0;
> + const char *logfile = NULL,
> +-    *pidfile = "/var/run/babeld.pid",
> ++    *pidfile = NULL,
> +     *state_file = "/var/lib/babel-state";
> + 
> + unsigned char *receive_buffer = NULL;
> +@@ -251,6 +251,7 @@ main(int argc, char **argv)
> +             break;
> +         case 'D':
> +             do_daemonise = 1;
> ++            pidfile = "/var/run/babeld.pid";
> +             break;
> +         case 'L':
> +             logfile = optarg;
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