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[repacker] add sanitization for GSUB/LookupList/Lookup during extension promotion.

This commit is contained in:
Garret Rieger 2022-07-21 21:45:04 +00:00
parent c61c05e431
commit ede7b74584
5 changed files with 111 additions and 75 deletions
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1
src/graph/graph.hh
View File

@ -621,7 +621,6 @@ struct graph_t
clone->obj.tail = tail;
clone->distance = 0;
clone->space = 0;
printf("Creating new node from %p to %p\n", head, tail);
unsigned clone_idx = vertices_.length - 2;

16
src/graph/gsubgpos-graph.cc
View File

@ -28,6 +28,22 @@
namespace graph {
make_extension_context_t::make_extension_context_t (hb_tag_t table_tag_,
graph_t& graph_,
hb_vector_t<char>& buffer_)
: table_tag (table_tag_),
graph (graph_),
buffer (buffer_),
lookups ()
{
GSTAR* gstar = graph::GSTAR::graph_to_gstar (graph_);
if (gstar)
gstar->find_lookups (graph, lookups);
unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
buffer.alloc (num_non_ext_subtables () * extension_size);
}
unsigned make_extension_context_t::num_non_ext_subtables () {
unsigned count = 0;
for (auto l : lookups.values ())

142
src/graph/gsubgpos-graph.hh
View File

@ -35,63 +35,16 @@ namespace graph {
struct Lookup;
struct GSTAR : public OT::GSUBGPOS
{
static GSTAR* graph_to_gstar (graph_t& graph)
{
return (GSTAR*) graph.root ().obj.head;
}
const void* get_lookup_list_field_offset () const
{
switch (u.version.major) {
case 1: return &(u.version1.lookupList);
#ifndef HB_NO_BORING_EXPANSION
case 2: return &(u.version2.lookupList);
#endif
default: return 0;
}
}
void find_lookups (graph_t& graph,
hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
{
// TODO: template on types, based on gstar version.
unsigned lookup_list_idx = graph.index_for_offset (graph.root_idx (),
get_lookup_list_field_offset());
const OT::LookupList<SmallTypes>* lookupList =
(const OT::LookupList<SmallTypes>*) graph.object (lookup_list_idx).head;
for (unsigned i = 0; i < lookupList->len; i++)
{
unsigned lookup_idx = graph.index_for_offset (lookup_list_idx, &(lookupList->arrayZ[i]));
Lookup* lookup = (Lookup*) graph.object (lookup_idx).head;
lookups.set (lookup_idx, lookup);
}
}
};
struct make_extension_context_t
{
hb_tag_t table_tag;
graph_t& graph;
hb_vector_t<char> buffer;
GSTAR* gstar;
hb_hashmap_t<unsigned, graph::Lookup*> lookups;
make_extension_context_t (hb_tag_t table_tag_,
graph_t& graph_)
: table_tag (table_tag_),
graph (graph_),
buffer (),
gstar (graph::GSTAR::graph_to_gstar (graph_)),
lookups ()
{
gstar->find_lookups (graph, lookups);
unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
buffer.alloc (num_non_ext_subtables () * extension_size);
}
HB_INTERNAL make_extension_context_t (hb_tag_t table_tag_,
graph_t& graph_,
hb_vector_t<char>& buffer_);
bool in_error () const
{
@ -99,7 +52,7 @@ struct make_extension_context_t
}
private:
unsigned num_non_ext_subtables ();
HB_INTERNAL unsigned num_non_ext_subtables ();
};
struct Lookup : public OT::Lookup
@ -109,6 +62,13 @@ struct Lookup : public OT::Lookup
return subTable.len;
}
bool sanitize (graph_t::vertex_t& vertex) const
{
int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
if (vertex_len < OT::Lookup::min_size) return false;
return vertex_len >= this->get_size ();
}
bool is_extension (hb_tag_t table_tag) const
{
return lookupType == extension_type (table_tag);
@ -123,15 +83,14 @@ struct Lookup : public OT::Lookup
if (!ext_type || is_extension (c.table_tag))
{
// NOOP
printf("Already extension (obj %u).\n", this_index);
return true;
}
printf("Promoting lookup type %u (obj %u) to extension.\n",
DEBUG_MSG (SUBSET_REPACK, nullptr,
"Promoting lookup type %u (obj %u) to extension.\n",
type,
this_index);
for (unsigned i = 0; i < subTable.len; i++)
{
unsigned subtable_index = c.graph.index_for_offset (this_index, &subTable[i]);
@ -149,8 +108,6 @@ struct Lookup : public OT::Lookup
unsigned lookup_index,
unsigned subtable_index)
{
printf(" Promoting subtable %u in lookup %u to extension.\n", subtable_index, lookup_index);
unsigned type = lookupType;
unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
unsigned start = c.buffer.length;
@ -165,9 +122,6 @@ struct Lookup : public OT::Lookup
extension->extensionLookupType = type;
extension->extensionOffset = 0;
unsigned type_prime = extension->extensionLookupType;
printf("Assigned type %d to extension\n", type_prime);
unsigned ext_index = c.graph.new_node (&c.buffer.arrayZ[start],
&c.buffer.arrayZ[end]);
if (ext_index == (unsigned) -1) return false;
@ -176,12 +130,9 @@ struct Lookup : public OT::Lookup
for (auto& l : lookup_vertex.obj.real_links.writer ())
{
if (l.objidx == subtable_index)
{
// Change lookup to point at the extension.
printf(" Changing %d to %d\n", l.objidx, ext_index);
l.objidx = ext_index;
}
}
// Make extension point at the subtable.
auto& ext_vertex = c.graph.vertices_[ext_index];
@ -213,6 +164,73 @@ struct Lookup : public OT::Lookup
}
};
template <typename T>
struct LookupList : public OT::LookupList<T>
{
bool sanitize (const graph_t::vertex_t& vertex) const
{
int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
if (vertex_len < OT::LookupList<T>::min_size) return false;
return vertex_len >= OT::LookupList<T>::item_size * this->len;
}
};
struct GSTAR : public OT::GSUBGPOS
{
static GSTAR* graph_to_gstar (graph_t& graph)
{
const auto& r = graph.root ();
GSTAR* gstar = (GSTAR*) r.obj.head;
if (!gstar->sanitize (r))
return nullptr;
return gstar;
}
const void* get_lookup_list_field_offset () const
{
switch (u.version.major) {
case 1: return &(u.version1.lookupList);
#ifndef HB_NO_BORING_EXPANSION
case 2: return &(u.version2.lookupList);
#endif
default: return 0;
}
}
bool sanitize (const graph_t::vertex_t& vertex)
{
int64_t len = vertex.obj.tail - vertex.obj.head;
// Only need access to fields in min_size
return len >= OT::GSUBGPOS::min_size;
}
void find_lookups (graph_t& graph,
hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
{
// TODO: template on types, based on gstar version.
unsigned lookup_list_idx = graph.index_for_offset (graph.root_idx (),
get_lookup_list_field_offset());
const LookupList<SmallTypes>* lookupList =
(const LookupList<SmallTypes>*) graph.object (lookup_list_idx).head;
if (!lookupList->sanitize (graph.vertices_[lookup_list_idx]))
return;
for (unsigned i = 0; i < lookupList->len; i++)
{
unsigned lookup_idx = graph.index_for_offset (lookup_list_idx, &(lookupList->arrayZ[i]));
Lookup* lookup = (Lookup*) graph.object (lookup_idx).head;
if (!lookup->sanitize (graph.vertices_[lookup_idx])) continue;
lookups.set (lookup_idx, lookup);
}
}
};
}
#endif /* GRAPH_GSUBGPOS_GRAPH_HH */

1
src/graph/serialize.hh
View File

@ -205,7 +205,6 @@ inline hb_blob_t* serialize (const graph_t& graph)
{
hb_vector_t<char> buffer;
size_t size = graph.total_size_in_bytes ();
printf("Expected graph size: %lu.\n", size);
if (!buffer.alloc (size)) {
DEBUG_MSG (SUBSET_REPACK, nullptr, "Unable to allocate output buffer.");
return nullptr;

22
src/hb-repacker.hh
View File

@ -41,8 +41,12 @@ using graph::graph_t;
* docs/repacker.md
*/
/*
* Analyze the lookups in a GSUB/GPOS table and decide if any should be promoted
* to extension lookups.
*/
static inline
bool _make_extensions (graph::make_extension_context_t& ext_context)
bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context)
{
// TODO: Move this into graph or gsubgpos graph?
for (auto p : ext_context.lookups.iter ())
@ -50,6 +54,7 @@ bool _make_extensions (graph::make_extension_context_t& ext_context)
if (!p.second->make_extension (ext_context, p.first))
return false;
}
return true;
}
@ -169,11 +174,8 @@ inline hb_blob_t*
hb_resolve_overflows (const T& packed,
hb_tag_t table_tag,
unsigned max_rounds = 20) {
printf("Resolving overflows!\n");
graph_t sorted_graph (packed);
sorted_graph.sort_shortest_distance ();
printf("Initial graph size: %lu.\n",
sorted_graph.total_size_in_bytes ());
bool will_overflow = graph::will_overflow (sorted_graph);
if (!will_overflow)
@ -181,16 +183,18 @@ hb_resolve_overflows (const T& packed,
return graph::serialize (sorted_graph);
}
graph::make_extension_context_t ext_context (table_tag, sorted_graph);
if (ext_context.in_error ())
return nullptr;
hb_vector_t<char> extension_buffer; // Needs to live until serialization is done.
if ((table_tag == HB_OT_TAG_GPOS
|| table_tag == HB_OT_TAG_GSUB)
&& will_overflow)
{
if (!_make_extensions (ext_context)) {
printf("make extensions failed.\n");
graph::make_extension_context_t ext_context (table_tag, sorted_graph, extension_buffer);
if (ext_context.in_error ())
return nullptr;
if (1 && !_promote_extensions_if_needed (ext_context)) {
DEBUG_MSG (SUBSET_REPACK, nullptr, "Extensions promotion failed.");
return nullptr;
}