#!/bin/ksh93
#
# media_update
#
# Setup/teardown a service that refreshes media servers when theor directories
# are updated.
#

# Constants

# Path to the DTrace script
DIRTRAP_PATH=/lib/svc/method/dirtrap.d

# We want to watch two media directories and restart two associated daemons.
INSTANCES="/export/zones/constant/root/export/home/constant/PowerBookHome/Music/iTunes:mt-daapd /krongi/stuff/media:mediatomb"

# Set up a temporary file
trap '${TMPFILE:+rm ${TMPFILE}}' EXIT
TMPFILE=$(mktemp /tmp/$0.temp.XXXXXX)

# Read in the first argument.
CMD=$1

# Install everything and enable the media update service
function enable_media_update {
	# Write the D script into a file.
	cat >$DIRTRAP_PATH <<'EOF'
#!/usr/sbin/dtrace -wqs
 
/*
 * dirtrap.d
 *
 * Detect when new files have been written to a given directory.
 * Start a command when this happens.
 */
 
BEGIN      /* Initialize stuff. */
{
  dir = $1;
  dirlen = strlen(dir);
  flag = 0;
}
 
syscall::open:return,
syscall::open64:return
/
  !flag &&          /* Exit if we've already found a hit. */
  fds[arg0].fi_oflags & (O_WRONLY | O_RDWR) && /* Check if opened for writes */
  substr(fds[arg0].fi_pathname, 0, dirlen) == dir /* Check directory */
/
{
  flag = 1;
}

tick-60s
/flag/    /* Periodic check if we need to do something. */
{
  system($2);
  flag = 0;
}
EOF

	chown root:bin $DIRTRAP_PATH
	chmod 755 $DIRTRAP_PATH

	# Import the service manifest.
	cat >$TMPFILE <<'EOF'
<?xml version='1.0'?>
<!DOCTYPE service_bundle SYSTEM '/usr/share/lib/xml/dtd/service_bundle.dtd.1'>
<service_bundle
  type='manifest'
  name='media-update'>
  <service
    name='application/media-update'
    type='service'
    version='1'>

    <create_default_instance enabled="false" />

    <dependency
      name='multi-user'
      grouping='require_all'
      restart_on='none'
      type='service'>
      <service_fmri value='svc:/milestone/multi-user' />
    </dependency>

    <dependency
      name='zones'
      grouping='require_all'
      restart_on='none'
      type='service'>
      <service_fmri value='svc:/system/zones' />
    </dependency>

    <method_context>
      <method_credential
        user='daemon'
        privileges='basic,!file_link_any,!proc_info,dtrace_kernel,proc_owner,proc_zone' />
    </method_context>

    <exec_method
      type='method'
      name='start'
      exec='/lib/svc/method/dirtrap.d %{script/directory} \"%{script/command}\"'
      timeout_seconds='0' />

    <exec_method
      type='method'
      name='stop'
      exec=':kill'
      timeout_seconds='4' />

    <property_group
      name='startd'
      type='framework'>
      <propval
        name='duration'
        type='astring'
        value='child' />
    </property_group>

    <property_group
      name='script'
      type='application'>

      <propval
        name='directory'
        type='astring'
        value='/path/to/media' />
      <propval
        name='command'
        type='astring'
        value='/bin/pkill -HUP mt-daapd' />
    </property_group>

    <template>
      <common_name>
        <loctext xml:lang='C'>Automatic media daemon updater.</loctext>
      </common_name>
    </template>
  </service>
</service_bundle>
EOF

	svccfg import $TMPFILE

	# Configure and enable all instances of the manifest
	for instance in $INSTANCES; do
		directory=$(echo $instance | cut -d: -f1)
		daemon=$(echo $instance | cut -d: -f2)

		svccfg -s media-update add $daemon
		svccfg -s media-update:$daemon addpg script application
		svccfg -s media-update:$daemon \
			"setprop script/directory = astring: $directory"
		svccfg -s media-update:$daemon \
			"setprop script/command = astring: \"/bin/pkill -HUP $daemon\""

		svcadm enable media-update:$daemon
	done
}

# Disable and de-install everything.
function disable_media_update {
	# Disable and delete SMF services
	for instance in $INSTANCES; do
		daemon=$(echo $instance | cut -d: -f2)
		svcadm disable -s media-update:$daemon
		svccfg delete media-update:$daemon
	done
	svccfg delete media-update

	# Delete the DTrace script.
	/bin/rm -f $DIRTRAP_PATH
}

# Show a help message.
function show_help {
	echo "Usage: $1 command"
	echo "Supported commands are:"
	echo "  on"
	echo "  off"
}

#
# Main program.
#
case $CMD in
        "on" )
                enable_media_update
        ;;
        "off" )
                disable_media_update
        ;;
        * )
                show_help $0
        ;;
esac

exit 0