From f518e5a704c580b644bd136794914a4fdf3dc846 Mon Sep 17 00:00:00 2001
From: Cosimo Lupo <clupo@google.com>
Date: Wed, 15 Nov 2023 12:20:24 +0000
Subject: [PATCH] [OS/2] don't error getting/setting codepages if version=0

return empty set, or set the bits and bump the version to match
---
 Lib/fontTools/ttLib/tables/O_S_2f_2.py |  4 ++++
 Tests/ttLib/tables/O_S_2f_2_test.py    | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/Lib/fontTools/ttLib/tables/O_S_2f_2.py b/Lib/fontTools/ttLib/tables/O_S_2f_2.py
index b4126b835..edff91f58 100644
--- a/Lib/fontTools/ttLib/tables/O_S_2f_2.py
+++ b/Lib/fontTools/ttLib/tables/O_S_2f_2.py
@@ -343,6 +343,8 @@ class table_O_S_2f_2(DefaultTable.DefaultTable):
     def getCodePageRanges(self):
         """Return the set of 'ulCodePageRange*' bits currently enabled."""
         bits = set()
+        if self.version < 1:
+            return bits
         ul1, ul2 = self.ulCodePageRange1, self.ulCodePageRange2
         for i in range(32):
             if ul1 & (1 << i):
@@ -361,6 +363,8 @@ class table_O_S_2f_2(DefaultTable.DefaultTable):
                 ul2 |= 1 << (bit - 32)
             else:
                 raise ValueError(f"expected 0 <= int <= 63, found: {bit:r}")
+        if self.version < 1:
+            self.version = 1
         self.ulCodePageRange1, self.ulCodePageRange2 = ul1, ul2
 
     def recalcCodePageRanges(self, ttFont, pruneOnly=False):
diff --git a/Tests/ttLib/tables/O_S_2f_2_test.py b/Tests/ttLib/tables/O_S_2f_2_test.py
index a05c70240..71388560b 100644
--- a/Tests/ttLib/tables/O_S_2f_2_test.py
+++ b/Tests/ttLib/tables/O_S_2f_2_test.py
@@ -8,6 +8,7 @@ class OS2TableTest(unittest.TestCase):
     def makeOS2_cmap(mapping):
         font = TTFont()
         font["OS/2"] = os2 = newTable("OS/2")
+        os2.version = 4
         font["cmap"] = cmap = newTable("cmap")
         st = getTableModule("cmap").CmapSubtable.newSubtable(4)
         st.platformID, st.platEncID, st.language = 3, 1, 0
@@ -64,6 +65,11 @@ class OS2TableTest(unittest.TestCase):
 
     def test_getCodePageRanges(self):
         table = table_O_S_2f_2()
+        # version 0 doesn't define these fields so by definition defines no cp ranges
+        table.version = 0
+        self.assertEqual(table.getCodePageRanges(), set())
+        # version 1 and above do contain ulCodePageRange1 and 2 fields
+        table.version = 1
         table.ulCodePageRange1 = 0xFFFFFFFF
         table.ulCodePageRange2 = 0xFFFFFFFF
         bits = table.getCodePageRanges()
@@ -72,6 +78,7 @@ class OS2TableTest(unittest.TestCase):
 
     def test_setCodePageRanges(self):
         table = table_O_S_2f_2()
+        table.version = 4
         table.ulCodePageRange1 = 0
         table.ulCodePageRange2 = 0
         bits = set(range(64))
@@ -84,6 +91,16 @@ class OS2TableTest(unittest.TestCase):
         with self.assertRaises(ValueError):
             table.setCodePageRanges([255])
 
+    def test_setCodePageRanges_bump_version(self):
+        # Setting codepage ranges on a OS/2 table version 0 automatically makes it
+        # a version 1 table
+        table = table_O_S_2f_2()
+        table.version = 0
+        self.assertEqual(table.getCodePageRanges(), set())
+        table.setCodePageRanges({0, 1, 2})
+        self.assertEqual(table.getCodePageRanges(), {0, 1, 2})
+        self.assertEqual(table.version, 1)
+
     def test_recalcCodePageRanges(self):
         font, os2, cmap = self.makeOS2_cmap(
             {ord("A"): "A", ord("Ά"): "Alphatonos", ord("Б"): "Be"}