tx.file: refuse to parse legacy TX files for signing ops

See 852cdeda

Instead of checking before signing, check before parsing.

mmgen/tx/file.py

@@ -22,6 +22,7 @@ tx.file: Transaction file operations for the MMGen suite
 
 import os, json
 
+from ..cfg import gc
 from ..util import ymsg, make_chksum_6, die
 from ..obj import MMGenObject, HexStr, MMGenTxID, CoinTxID, MMGenTxComment
 
@@ -133,6 +134,13 @@ class MMGenTxFile(MMGenObject):
 		tx = self.tx
 		tx.file_format = 'legacy'
 
+		if 'sign' in gc.prog_name:
+			m = 'Request to sign legacy-format transaction. Has your online installation been compromised?'
+			if tx.cfg.test_suite:
+				ymsg(m)
+			else:
+				die('LegacyTxSignRequestError', m)
+
 		def deserialize(raw_data, *, desc):
 			from ast import literal_eval
 			try:

mmgen/tx/unsigned.py

@@ -13,7 +13,7 @@ tx.unsigned: unsigned transaction class
 """
 
 from .completed import Completed
-from ..util import die, remove_dups
+from ..util import remove_dups
 
 class Unsigned(Completed):
 	desc = 'unsigned transaction'
@@ -23,11 +23,6 @@ class Unsigned(Completed):
 	# Return signed object or False.  Don’t exit or raise exception, unless fatal:
 	async def sign(self, keys, *, tx_num_str=''):
 
-		if self.file_format == 'legacy': # fatal
-			die('LegacyTxSignRequestError',
-				'Request to sign legacy-format transaction. '
-				'Has your online installation been compromised?')
-
 		try:
 			self.check_correct_chain()
 		except Exception as e:

test/cmdtest_d/autosign.py

@@ -930,6 +930,8 @@ class CmdTestAutosign(CmdTestAutosignBase):
 		if exc_exit_val:
 			return do_return()
 
+		t.expect('compromised')
+
 		t.expect(
 			f'{self.tx_count} {tx_desc}{suf(self.tx_count)} signed' if self.tx_count else
 			f'No unsigned {tx_desc}s')