Add --resave flag to addfields subcommand

...to allow doing a full resave in order to eliminate any structural
issues from the input PDF at the cost of destroying any earlier
signatures.

pyhanko/cli/commands/fields.py

@@ -5,6 +5,7 @@
 from pyhanko.cli.utils import parse_field_location_spec
 from pyhanko.pdf_utils.incremental_writer import IncrementalPdfFileWriter
 from pyhanko.pdf_utils.reader import PdfFileReader
+from pyhanko.pdf_utils.writer import copy_into_new_writer
 from pyhanko.sign import fields
 
 __all__ = ['list_sigfields', 'add_sig_field']
@@ -44,9 +45,17 @@ def list_sigfields(infile, skip_status):
     required=True,
     help="Field specification (multiple allowed)",
 )
-def add_sig_field(infile, outfile, field):
+@click.option(
+    '--resave',
+    is_flag=True,
+    help="Resave the PDF document instead of creating an incremental update",
+)
+def add_sig_field(infile, outfile, field, resave):
     with pyhanko_exception_manager():
-        writer = IncrementalPdfFileWriter(infile, strict=False)
+        if resave:
+            writer = copy_into_new_writer(PdfFileReader(infile, strict=False))
+        else:
+            writer = IncrementalPdfFileWriter(infile, strict=False)
 
         for s in field:
             name, spec = parse_field_location_spec(s)

pyhanko_tests/cli_tests/test_cli_field_mgmt.py

@@ -7,7 +7,7 @@
 from pyhanko.pdf_utils.reader import PdfFileReader
 from pyhanko.sign import PdfSignatureMetadata, sign_pdf
 from pyhanko_tests.cli_tests.conftest import INPUT_PATH
-from pyhanko_tests.samples import MINIMAL_TWO_FIELDS, MINIMAL_TWO_PAGES
+from pyhanko_tests.samples import MINIMAL, MINIMAL_TWO_FIELDS, MINIMAL_TWO_PAGES
 from pyhanko_tests.signing_commons import FROM_CA
 
 
@@ -69,6 +69,57 @@ def test_list_empty_fields_without_status(cli_runner):
     assert result.output == 'Sig1\nSig2\n'
 
 
+def test_cli_add_field_incremental_update_by_default(cli_runner):
+    with open(INPUT_PATH, 'wb') as inf:
+        inf.write(MINIMAL)
+
+    output_path = 'presign.pdf'
+    result = cli_runner.invoke(
+        cli_root,
+        [
+            'sign',
+            'addfields',
+            '--field',
+            '1/0,0,100,100/Sig1',
+            INPUT_PATH,
+            output_path,
+        ],
+    )
+    assert not result.exception, result.output
+
+    with open(output_path, 'rb') as inf:
+        r = PdfFileReader(inf)
+        name = r.root['/AcroForm']['/Fields'][0]['/T']
+        assert name == 'Sig1'
+        assert r.xrefs.total_revisions == 2
+
+
+def test_cli_add_field_with_resave(cli_runner):
+    with open(INPUT_PATH, 'wb') as inf:
+        inf.write(MINIMAL)
+
+    output_path = 'presign.pdf'
+    result = cli_runner.invoke(
+        cli_root,
+        [
+            'sign',
+            'addfields',
+            '--resave',
+            '--field',
+            '1/0,0,100,100/Sig1',
+            INPUT_PATH,
+            output_path,
+        ],
+    )
+    assert not result.exception, result.output
+
+    with open(output_path, 'rb') as inf:
+        r = PdfFileReader(inf)
+        name = r.root['/AcroForm']['/Fields'][0]['/T']
+        assert name == 'Sig1'
+        assert r.xrefs.total_revisions == 1
+
+
 def test_cli_add_field_to_last_page(cli_runner):
     with open(INPUT_PATH, 'wb') as inf:
         inf.write(MINIMAL_TWO_PAGES)