correctly read collection plugin

programs/mpl-core/src/plugins/utils.rs

@@ -106,6 +106,34 @@ pub fn fetch_plugin(
     ))
 }
 
+/// Fetch the collection plugin from the registry.
+pub fn fetch_collection_plugin(
+    account: &AccountInfo,
+    plugin_type: PluginType,
+) -> Result<(Vec<Authority>, Plugin, usize), ProgramError> {
+    let collection = CollectionData::load(account, 0)?;
+
+    let header = PluginHeader::load(account, collection.get_size())?;
+    let PluginRegistry { registry, .. } =
+        PluginRegistry::load(account, header.plugin_registry_offset)?;
+
+    // Find the plugin in the registry.
+    let registry_record = registry
+        .iter()
+        .find(|record| record.plugin_type == plugin_type)
+        .ok_or(MplCoreError::PluginNotFound)?;
+
+    // Deserialize the plugin.
+    let plugin = Plugin::deserialize(&mut &(*account.data).borrow()[registry_record.offset..])?;
+
+    // Return the plugin and its authorities.
+    Ok((
+        registry_record.authorities.clone(),
+        plugin,
+        registry_record.offset,
+    ))
+}
+
 /// Fetch the plugin registry.
 pub fn fetch_plugins(account: &AccountInfo) -> Result<Vec<RegistryRecord>, ProgramError> {
     let asset = Asset::load(account, 0)?;

programs/mpl-core/src/state/update_authority.rs

@@ -8,7 +8,7 @@ use crate::{
         BurnAccounts, CompressAccounts, CreateAccounts, DecompressAccounts, TransferAccounts,
         UpdateAccounts,
     },
-    plugins::{fetch_plugin, CheckResult, PluginType, ValidationResult},
+    plugins::{fetch_collection_plugin, CheckResult, PluginType, ValidationResult},
     processor::CreateArgs,
     state::{Authority, CollectionData, SolanaAccount},
     utils::assert_collection_authority,
@@ -69,7 +69,7 @@ impl UpdateAuthority {
                 };
 
                 let maybe_update_delegate =
-                    fetch_plugin(collection_info, PluginType::UpdateDelegate);
+                    fetch_collection_plugin(collection_info, PluginType::UpdateDelegate);
 
                 if let Ok((mut authorities, _, _)) = maybe_update_delegate {
                     authorities.push(Authority::UpdateAuthority);