gh-143346: Fix calculation of the line width for wrapped Base64 in plistlib

Lib/plistlib.py

@@ -384,7 +384,7 @@ def write_bytes(self, data):
  self._indent_level -= 1
  maxlinelength = max(
  16,
- 76 - len(self.indent.replace(b"\t", b" " * 8) * self._indent_level))
+ 76 - len((self.indent * self._indent_level).expandtabs()))
 
  for line in _encode_base64(data, maxlinelength).split(b"\n"):
  if line:

Lib/test/test_plistlib.py

@@ -509,6 +509,69 @@ def test_bytes(self):
  data2 = plistlib.dumps(pl2)
  self.assertEqual(data, data2)
 
+ def test_bytes_indent(self):
+ header = (
+ b'<?xml version="1.0" encoding="UTF-8"?>\n'
+ b'<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">\n'
+ b'<plist version="1.0">\n')
+ data = [{'bytes': bytes(range(50))}]
+ pl = plistlib.dumps(data)
+ self.assertEqual(pl, header +
+ b'<array>\n'
+ b'\t<dict>\n'
+ b'\t\t<key>bytes</key>\n'
+ b'\t\t<data>\n'
+ b'\t\tAAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKiss\n'
+ b'\t\tLS4vMDE=\n'
+ b'\t\t</data>\n'
+ b'\t</dict>\n'
+ b'</array>\n'
+ b'</plist>\n')
+
+ def dumps_with_indent(data, indent):
+ fp = BytesIO()
+ writer = plistlib._PlistWriter(fp, indent=indent)
+ writer.write(data)
+ return fp.getvalue()
+
+ pl = dumps_with_indent(data, b' ')
+ self.assertEqual(pl, header +
+ b'<array>\n'
+ b' <dict>\n'
+ b' <key>bytes</key>\n'
+ b' <data>\n'
+ b' AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4vMDE=\n'
+ b' </data>\n'
+ b' </dict>\n'
+ b'</array>\n'
+ b'</plist>\n')
+
+ pl = dumps_with_indent(data, b' \t')
+ self.assertEqual(pl, header +
+ b'<array>\n'
+ b' \t<dict>\n'
+ b' \t \t<key>bytes</key>\n'
+ b' \t \t<data>\n'
+ b' \t \tAAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKiss\n'
+ b' \t \tLS4vMDE=\n'
+ b' \t \t</data>\n'
+ b' \t</dict>\n'
+ b'</array>\n'
+ b'</plist>\n')
+
+ pl = dumps_with_indent(data, b'\t ')
+ self.assertEqual(pl, header +
+ b'<array>\n'
+ b'\t <dict>\n'
+ b'\t \t <key>bytes</key>\n'
+ b'\t \t <data>\n'
+ b'\t \t AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygp\n'
+ b'\t \t KissLS4vMDE=\n'
+ b'\t \t </data>\n'
+ b'\t </dict>\n'
+ b'</array>\n'
+ b'</plist>\n')
+
  def test_loads_str_with_xml_fmt(self):
  pl = self._create()
  b = plistlib.dumps(pl)
@@ -581,7 +644,6 @@ def test_appleformatting(self):
  self.assertEqual(data, TESTDATA[fmt],
  "generated data was not identical to Apple's output")
 
-
  def test_appleformattingfromliteral(self):
  self.maxDiff = None
  for fmt in ALL_FORMATS:

Misc/NEWS.d/next/Library/2026-01-02-12-55-52.gh-issue-143346.iTekce.rst

@@ -0,0 +1,2 @@
+Fix incorrect wrapping of the Base64 data in :class:`!plistlib._PlistWriter`
+when the indent contains a mix of tabs and spaces.