From 6fad6b4113750d3aabea633685bc272f98a2ef83 Mon Sep 17 00:00:00 2001
From: Garret Rieger <grieger@google.com>
Date: Wed, 6 Jul 2022 19:18:27 +0000
Subject: [PATCH] [repacker] add tests for special casing of 24bit offsets.

---
 src/test-repacker.cc | 84 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/src/test-repacker.cc b/src/test-repacker.cc
index 69863b562..4bc731d8e 100644
--- a/src/test-repacker.cc
+++ b/src/test-repacker.cc
@@ -57,6 +57,14 @@ static void add_offset (unsigned id,
   c->add_link (*offset, id);
 }
 
+static void add_24_offset (unsigned id,
+                           hb_serialize_context_t* c)
+{
+  OT::Offset24* offset = c->start_embed<OT::Offset24> ();
+  c->extend_min (offset);
+  c->add_link (*offset, id);
+}
+
 static void add_wide_offset (unsigned id,
                              hb_serialize_context_t* c)
 {
@@ -812,6 +820,51 @@ populate_serializer_virtual_link (hb_serialize_context_t* c)
   c->end_serialize();
 }
 
+static void
+populate_serializer_with_24_and_32_bit_offsets (hb_serialize_context_t* c)
+{
+  std::string large_string(60000, 'a');
+  c->start_serialize<char> ();
+
+  unsigned obj_f = add_object ("f", 1, c);
+  unsigned obj_g = add_object ("g", 1, c);
+  unsigned obj_j = add_object ("j", 1, c);
+  unsigned obj_k = add_object ("k", 1, c);
+
+  start_object (large_string.c_str (), 40000, c);
+  add_offset (obj_f, c);
+  unsigned obj_c = c->pop_pack (false);
+
+  start_object (large_string.c_str (), 40000, c);
+  add_offset (obj_g, c);
+  unsigned obj_d = c->pop_pack (false);
+
+  start_object (large_string.c_str (), 40000, c);
+  add_offset (obj_j, c);
+  unsigned obj_h = c->pop_pack (false);
+
+  start_object (large_string.c_str (), 40000, c);
+  add_offset (obj_k, c);
+  unsigned obj_i = c->pop_pack (false);
+
+  start_object ("e", 1, c);
+  add_wide_offset (obj_h, c);
+  add_wide_offset (obj_i, c);
+  unsigned obj_e = c->pop_pack (false);
+
+  start_object ("b", 1, c);
+  add_24_offset (obj_c, c);
+  add_24_offset (obj_d, c);
+  add_24_offset (obj_e, c);
+  unsigned obj_b = c->pop_pack (false);
+
+  start_object ("a", 1, c);
+  add_24_offset (obj_b, c);
+  c->pop_pack (false);
+
+  c->end_serialize();
+}
+
 static void test_sort_shortest ()
 {
   size_t buffer_size = 100;
@@ -1129,6 +1182,36 @@ static void test_resolve_overflows_via_isolation_spaces ()
   hb_blob_destroy (out);
 }
 
+static void test_resolve_mixed_overflows_via_isolation_spaces ()
+{
+  size_t buffer_size = 200000;
+  void* buffer = malloc (buffer_size);
+  hb_serialize_context_t c (buffer, buffer_size);
+  populate_serializer_with_24_and_32_bit_offsets (&c);
+  graph_t graph (c.object_graph ());
+
+  assert (c.offset_overflow ());
+  hb_blob_t* out = hb_resolve_overflows (c.object_graph (), HB_TAG ('G', 'S', 'U', 'B'), 0);
+  assert (out);
+  hb_bytes_t result = out->as_bytes ();
+
+  unsigned expected_length =
+      // Objects
+      7 +
+      4 * 40000;
+
+  expected_length +=
+      // Links
+      2 * 4 +  // 32
+      4 * 3 +  // 24
+      4 * 2;   // 16
+
+  assert (result.length == expected_length);
+
+  free (buffer);
+  hb_blob_destroy (out);
+}
+
 static void test_resolve_overflows_via_splitting_spaces ()
 {
   size_t buffer_size = 160000;
@@ -1270,6 +1353,7 @@ main (int argc, char **argv)
   test_resolve_overflows_via_isolating_16bit_space_2 ();
   test_resolve_overflows_via_splitting_spaces ();
   test_resolve_overflows_via_splitting_spaces_2 ();
+  test_resolve_mixed_overflows_via_isolation_spaces ();
   test_duplicate_leaf ();
   test_duplicate_interior ();
   test_virtual_link ();