transfer hook example with PDAs

token/transfer-hook-example/src/processor.rs

@@ -36,6 +36,27 @@ fn check_token_account_is_transferring(account_info: &AccountInfo) -> Result<(),
     }
 }
 
+fn check_extra_meta(
+    account_info: &AccountInfo,
+    extra_meta: &AccountMeta,
+) -> Result<(), ProgramError> {
+    if !(&extra_meta.pubkey == account_info.key
+        && extra_meta.is_signer == account_info.is_signer
+        && extra_meta.is_writable == account_info.is_writable)
+    {
+        return Err(TransferHookError::IncorrectAccount.into());
+    }
+    Ok(())
+}
+
+fn next_extra_account_meta<'a>(
+    extra_account_metas_iter: &mut impl Iterator<Item = &'a ExtraAccountMeta>,
+) -> Result<&'a ExtraAccountMeta, ProgramError> {
+    extra_account_metas_iter
+        .next()
+        .ok_or(ProgramError::NotEnoughAccountKeys)
+}
+
 /// Processes an [Execute](enum.TransferHookInstruction.html) instruction.
 pub fn process_execute(
     program_id: &Pubkey,