<h2>Edit File: find-defined-target.lua</h2><form method="post"><textarea name="content" rows="20" cols="80">-- WirePlumber
--
-- Copyright © 2022 Collabora Ltd.
--
-- SPDX-License-Identifier: MIT
--
-- Check if the target node is defined explicitly.
-- This definition can be done in two ways.
-- 1. &quot;node.target&quot;/&quot;target.object&quot; in the node properties
-- 2. &quot;target.node&quot;/&quot;target.object&quot; in the default metadata

lutils = require (&quot;linking-utils&quot;)
cutils = require (&quot;common-utils&quot;)
log = Log.open_topic (&quot;s-linking&quot;)

SimpleEventHook {
  name = &quot;linking/find-defined-target&quot;,
  before = &quot;linking/prepare-link&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;select-target&quot; },
    },
  },
  execute = function (event)
    local source, om, si, si_props, si_flags, target =
        lutils:unwrap_select_target_event (event)

    -- bypass the hook if the target is already picked up
    if target then
      return
    end

    log:info (si, string.format (&quot;handling item %d: %s (%s)&quot;, si.id,
        tostring (si_props [&quot;node.name&quot;]), tostring (si_props [&quot;node.id&quot;])))

    local metadata = Settings.get_boolean (&quot;linking.allow-moving-streams&quot;) and
        cutils.get_default_metadata_object ()
    local dont_fallback = cutils.parseBool (si_props [&quot;node.dont-fallback&quot;])
    local dont_move = cutils.parseBool (si_props [&quot;node.dont-move&quot;])
    local target_key
    local target_value = nil
    local node_defined = false
    local target_picked = nil

    if si_props [&quot;target.object&quot;] ~= nil then
      target_value = si_props [&quot;target.object&quot;]
      target_key = &quot;object.serial&quot;
      node_defined = true
    elseif si_props [&quot;node.target&quot;] ~= nil then
      target_value = si_props [&quot;node.target&quot;]
      target_key = &quot;node.id&quot;
      node_defined = true
    end

    if metadata and not dont_move then
      local id = metadata:find (si_props [&quot;node.id&quot;], &quot;target.object&quot;)
      if id ~= nil then
        target_value = id
        target_key = &quot;object.serial&quot;
        node_defined = false
      else
        id = metadata:find (si_props [&quot;node.id&quot;], &quot;target.node&quot;)
        if id ~= nil then
          target_value = id
          target_key = &quot;node.id&quot;
          node_defined = false
        end
      end
    end

    if target_value == &quot;-1&quot; then
      target_picked = false
      target = nil
    elseif target_value and tonumber (target_value) then
      target = om:lookup {
        type = &quot;SiLinkable&quot;,
        Constraint { target_key, &quot;=&quot;, target_value },
      }
      if target and lutils.canLink (si_props, target) then
        target_picked = true
      end
    elseif target_value then
      for lnkbl in om:iterate { type = &quot;SiLinkable&quot; } do
        local target_props = lnkbl.properties
        if (target_props [&quot;node.name&quot;] == target_value or
            target_props [&quot;object.path&quot;] == target_value) and
            target_props [&quot;item.node.direction&quot;] == cutils.getTargetDirection (si_props) and
            lutils.canLink (si_props, lnkbl) then
          target_picked = true
          target = lnkbl
          break
        end
      end
    end

    local can_passthrough, passthrough_compatible
    if target then
      passthrough_compatible, can_passthrough =
      lutils.checkPassthroughCompatibility (si, target)
      if not passthrough_compatible then
        target = nil
      end
    end

    si_flags.has_defined_target = false
    if target_picked and target then
      log:info (si,
        string.format (&quot;... defined target picked: %s (%s), can_passthrough:%s&quot;,
          tostring (target.properties [&quot;node.name&quot;]),
          tostring (target.properties [&quot;node.id&quot;]),
          tostring (can_passthrough)))
      si_flags.has_node_defined_target = node_defined
      si_flags.can_passthrough = can_passthrough
      si_flags.has_defined_target = true
      event:set_data (&quot;target&quot;, target)
    elseif target_value and dont_fallback then
      -- send error to client and destroy node if linger is not set
      local linger = cutils.parseBool (si_props [&quot;node.linger&quot;])
      if not linger then
        local node = si:get_associated_proxy (&quot;node&quot;)
        lutils.sendClientError (event, node, -2, &quot;defined target not found&quot;)
        node:request_destroy ()
        log:info(si, &quot;... destroyed node as defined target was not found&quot;)
      else
        log:info(si, &quot;... waiting for defined target as dont-fallback is set&quot;)
      end
      event:stop_processing ()
    end

  end
}:register ()
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