OTS: Adds more layout common table supports....

src/layout.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "layout.h"
 
+#include <vector>
+
+#include "gdef.h"
+
 // OpenType Layout Common Table Formats
 // http://www.microsoft.com/typography/otspec/chapter2.htm
 
 namespace {
 
+// The 'DFLT' tag of script table.
+const uint32_t kScriptTableTagDflt = 0x44464c54;
+// The value which represents there is no required feature index.
+const uint16_t kNoRequiredFeatureIndexDefined = 0xFFFF;
+// The lookup flag bit which indicates existence of MarkFilteringSet.
+const uint16_t kUseMarkFilteringSetBit = 0x0010;
+// The mask for MarkAttachmentType.
+const uint16_t kMarkAttachmentTypeMask = 0xFF00;
+// The maximum type number of format for device tables.
+const uint16_t kMaxDeltaFormatType = 3;
+
+struct ScriptRecord {
+  uint32_t tag;
+  uint16_t offset;
+};
+
+struct LangSysRecord {
+  uint32_t tag;
+  uint16_t offset;
+};
+
+struct FeatureRecord {
+  uint32_t tag;
+  uint16_t offset;
+};
+
+bool ParseLangSysTable(ots::Buffer *subtable, const uint32_t tag,
+                       const uint16_t num_features) {
+  uint16_t offset_lookup_order = 0;
+  uint16_t req_feature_index = 0;
+  uint16_t feature_count = 0;
+  if (!subtable->ReadU16(&offset_lookup_order) ||
+      !subtable->ReadU16(&req_feature_index) ||
+      !subtable->ReadU16(&feature_count)) {
+    return OTS_FAILURE();
+  }
+  // |offset_lookup_order| is reserved and should be NULL.
+  if (offset_lookup_order != 0) {
+    OTS_FAILURE();

[Yusuke Sato, 2011/02/04 06:12:52]

return is missing.

[bashi, 2011/02/07 01:17:07]

Done.

+  }
+  if (req_feature_index != kNoRequiredFeatureIndexDefined &&
+      req_feature_index >= num_features) {
+    return OTS_FAILURE();
+  }
+  if (feature_count > num_features) {
+    return OTS_FAILURE();
+  }
+
+  for (unsigned i = 0; i < feature_count; ++i) {
+    uint16_t feature_index = 0;
+    if (!subtable->ReadU16(&feature_index)) {
+      return OTS_FAILURE();
+    }
+    if (feature_index >= num_features) {
+      return OTS_FAILURE();
+    }
+  }
+  return true;
+}
+
+bool ParseScriptTable(const uint8_t *data, const size_t length,
+                      const uint32_t tag, const uint16_t num_features) {
+  ots::Buffer subtable(data, length);
+
+  uint16_t offset_default_lang_sys = 0;
+  uint16_t lang_sys_count = 0;
+  if (!subtable.ReadU16(&offset_default_lang_sys) ||
+      !subtable.ReadU16(&lang_sys_count)) {
+    return OTS_FAILURE();
+  }
+
+  // The spec requires a script table for 'DFLT' tag must contain non-NULL
+  // |offset_default_lang_sys| and |lang_sys_count| == 0
+  if (tag == kScriptTableTagDflt &&
+      (offset_default_lang_sys == 0 || lang_sys_count != 0)) {
+    OTS_WARNING("DFLT table doesn't satisfy the spec.");
+    OTS_FAILURE();

[Yusuke Sato, 2011/02/04 06:12:52]

ditto. please grep your change again.

[bashi, 2011/02/07 01:17:07]

Done.

+  }
+
+  const unsigned lang_sys_record_end = static_cast<unsigned>(4) +
+      lang_sys_count * 6;
+  std::vector<LangSysRecord> lang_sys_records;
+  lang_sys_records.resize(lang_sys_count);
+  uint32_t last_tag = 0;
+  for (unsigned i = 0; i < lang_sys_count; ++i) {
+    if (!subtable.ReadU32(&lang_sys_records[i].tag) ||
+        !subtable.ReadU16(&lang_sys_records[i].offset)) {
+      return OTS_FAILURE();
+    }
+    // The record array must store the records alphabetically by tag
+    if (last_tag != 0 && last_tag > lang_sys_records[i].tag) {
+      return OTS_FAILURE();
+    }
+    if (lang_sys_records[i].offset < lang_sys_record_end ||
+        lang_sys_records[i].offset >= length) {
+      return OTS_FAILURE();
+    }
+    last_tag = lang_sys_records[i].tag;
+  }
+
+  // Check lang sys tables
+  for (unsigned i = 0; i < lang_sys_count; ++i) {
+    subtable.set_offset(lang_sys_records[i].offset);
+    if (!ParseLangSysTable(&subtable, lang_sys_records[i].tag, num_features)) {
+      return OTS_FAILURE();
+    }
+  }
+
+  return true;
+}
+
+bool ParseFeatureTable(const uint8_t *data, const size_t length,
+                       const uint16_t num_lookups) {
+  ots::Buffer subtable(data, length);
+
+  uint16_t offset_feature_params = 0;
+  uint16_t lookup_count = 0;
+  if (!subtable.ReadU16(&offset_feature_params) ||
+      !subtable.ReadU16(&lookup_count)) {
+    return OTS_FAILURE();
+  }
+
+  const unsigned feature_table_end = static_cast<unsigned>(4) +
+      num_lookups * 2;
+  // |offset_feature_params| is generally set to NULL.
+  if (offset_feature_params != 0 &&
+      (offset_feature_params < feature_table_end ||
+       offset_feature_params >= length)) {
+    return OTS_FAILURE();
+  }
+
+  for (unsigned i = 0; i < lookup_count; ++i) {
+    uint16_t lookup_index = 0;
+    if (!subtable.ReadU16(&lookup_index)) {
+      return OTS_FAILURE();
+    }
+    // lookup index starts with 0.
+    if (lookup_index >= num_lookups) {
+      return OTS_FAILURE();
+    }
+  }
+  return true;
+}
+
+bool LookupTypeParserLess(const ots::LookupTypeParser& parser,
+                          const uint16_t type) {
+  return parser.type < type;
+}
+
+bool ParseLookupTable(ots::OpenTypeFile *file, const uint8_t *data,
+                      const size_t length, const size_t num_types,
+                      const ots::LookupTypeParser* parsers) {
+  ots::Buffer subtable(data, length);
+
+  uint16_t lookup_type = 0;
+  uint16_t lookup_flag = 0;
+  uint16_t subtable_count = 0;
+  if (!subtable.ReadU16(&lookup_type) ||
+      !subtable.ReadU16(&lookup_flag) ||
+      !subtable.ReadU16(&subtable_count)) {
+    return OTS_FAILURE();
+  }
+
+  if (lookup_type == 0 || lookup_type > num_types) {
+    return OTS_FAILURE();
+  }
+
+  // Check lookup flags.
+  if (lookup_flag & kMarkAttachmentTypeMask &&

[Yusuke Sato, 2011/02/04 06:12:52]

I slightly prefer:

if ((lookup_flag & kMarkAttachmentTypeMask) &&

since the operator precedence of bitwise-AND is sometimes confusing (higher than
&& but lower than ==, as you should know.)

[bashi, 2011/02/07 01:17:07]

Done.

+      (!file->gdef || !file->gdef->has_mark_attachment_class_def)) {
+    return OTS_FAILURE();
+  }
+  bool use_mark_filtering_set = false;
+  if (lookup_flag & kUseMarkFilteringSetBit) {
+    if (!file->gdef || !file->gdef->has_mark_glyph_sets_def) {
+      return OTS_FAILURE();
+    }
+    use_mark_filtering_set = true;
+  }
+
+  std::vector<uint16_t> subtables;
+  subtables.reserve(subtable_count);
+  // If the |kUseMarkFilteringSetBit| of |lookup_flag| is set,
+  // extra 2 bytes will follow after subtable offset array.
+  const unsigned lookup_table_end =
+      static_cast<unsigned>(use_mark_filtering_set ? 8 : 6) +
+      subtable_count * 2;
+  for (unsigned i = 0; i < subtable_count; ++i) {
+    if (!subtable.ReadU16(&subtables[i])) {
+      return OTS_FAILURE();
+    }
+    if (subtables[i] < lookup_table_end || subtables[i] >= length) {
+      return OTS_FAILURE();
+    }
+  }
+
+  if (use_mark_filtering_set) {
+    uint16_t mark_filtering_set = 0;
+    if (!subtable.ReadU16(&mark_filtering_set)) {
+      return OTS_FAILURE();
+    }
+    if (file->gdef->num_mark_glyph_sets == 0 ||
+        mark_filtering_set >= file->gdef->num_mark_glyph_sets) {
+      return OTS_FAILURE();
+    }
+  }
+
+  // Parse lookup subtables for this lookup type.
+  for (unsigned i = 0; i < subtable_count; ++i) {
+    const ots::LookupTypeParser *parser =
+        std::lower_bound(parsers, parsers + num_types, lookup_type,
+                         LookupTypeParserLess);
+    if (parser == parsers + num_types || parser->type != lookup_type ||
+        !parser->parse) {
+      return OTS_FAILURE();
+    }
+    if (!parser->parse(file, data + subtables[i], length - subtables[i])) {
+      return OTS_FAILURE();
+    }
+  }
+  return true;
+}
+
 bool ParseClassDefFormat1(const uint8_t *data, size_t length,
                           const uint16_t num_glyphs,
                           const uint16_t num_classes) {
   ots::Buffer subtable(data, length);
 
   // Skip format field.
   if (!subtable.Skip(2)) {
     return OTS_FAILURE();
   }
 
@@ skipping 58 matching lines @@
       return OTS_FAILURE();
     }
     if (start > end || (last_end && start <= last_end)) {
       OTS_WARNING("glyph range is overlapping.");
       return OTS_FAILURE();
     }
     if (class_value == 0 || class_value > num_classes) {
       OTS_WARNING("bad class value: %u", class_value);
       return OTS_FAILURE();
     }
+    last_end = end;
   }
 
   return true;
 }
 
 bool ParseCoverageFormat1(const uint8_t *data, size_t length,
                           const uint16_t num_glyphs) {
   ots::Buffer subtable(data, length);
 
   // Skip format field.
@@ skipping 29 matching lines @@
 
   // Skip format field.
   if (!subtable.Skip(2)) {
     return OTS_FAILURE();
   }
 
   uint16_t range_count = 0;
   if (!subtable.ReadU16(&range_count)) {
     return OTS_FAILURE();
   }
-  if (range_count >= num_glyphs) {
+  if (range_count > num_glyphs) {
     OTS_WARNING("bad range count: %u", range_count);
     return OTS_FAILURE();
   }
   uint16_t last_end = 0;
+  uint16_t last_start_coverage_index = 0;
   for (unsigned i = 0; i < range_count; ++i) {
     uint16_t start = 0;
     uint16_t end = 0;
     uint16_t start_coverage_index = 0;
     if (!subtable.ReadU16(&start) ||
         !subtable.ReadU16(&end) ||
         !subtable.ReadU16(&start_coverage_index)) {
       return OTS_FAILURE();
     }
     if (start > end || (last_end && start <= last_end)) {
       OTS_WARNING("glyph range is overlapping.");
       return OTS_FAILURE();
     }
+    if (start_coverage_index != last_start_coverage_index) {
+      OTS_WARNING("bad start coverage index.");
+      return OTS_FAILURE();
+    }
+    last_end = end;
+    last_start_coverage_index += end - start + 1;
   }
 
   return true;
 }
 
 }  // namespace
 
 namespace ots {
 
+// Parsing ScriptListTable requires number of features so we need to
+// parse FeatureListTable before calling this function.
+bool ParseScriptListTable(const uint8_t *data, const size_t length,
+                          const uint16_t num_features) {
+  Buffer subtable(data, length);
+
+  uint16_t script_count = 0;
+  if (!subtable.ReadU16(&script_count)) {
+    return OTS_FAILURE();
+  }
+
+  const unsigned script_record_end = static_cast<unsigned>(2) +
+      script_count * 6;
+  std::vector<ScriptRecord> script_list;
+  script_list.reserve(script_count);
+  uint32_t last_tag = 0;
+  for (unsigned i = 0; i < script_count; ++i) {
+    if (!subtable.ReadU32(&script_list[i].tag) ||
+        !subtable.ReadU16(&script_list[i].offset)) {
+      return OTS_FAILURE();
+    }
+    // Script tags should be arranged alphabetically by tag
+    if (last_tag != 0 && last_tag > script_list[i].tag) {
+      return OTS_FAILURE();
+    }
+    last_tag = script_list[i].tag;
+    if (script_list[i].offset < script_record_end ||
+        script_list[i].offset >= length) {
+      return OTS_FAILURE();
+    }
+  }
+
+  // Check script records.
+  for (unsigned i = 0; i < script_count; ++i) {
+    if (!ParseScriptTable(data + script_list[i].offset,
+                          length - script_list[i].offset,
+                          script_list[i].tag, num_features)) {
+      return OTS_FAILURE();
+    }
+  }
+
+  return true;
+}
+
+// Parsing FeatureListTable requires number of lookups so we need to parse
+// LookupListTable before calling this function.
+bool ParseFeatureListTable(const uint8_t *data, const size_t length,
+                           const uint16_t num_lookups,
+                           uint16_t* num_features) {
+  Buffer subtable(data, length);
+
+  uint16_t feature_count = 0;
+  if (!subtable.ReadU16(&feature_count)) {
+    return OTS_FAILURE();
+  }
+
+  std::vector<FeatureRecord> feature_records;
+  feature_records.resize(feature_count);
+  const unsigned feature_record_end = static_cast<unsigned>(2) +
+      feature_count * 6;
+  uint32_t last_tag = 0;
+  for (unsigned i = 0; i < feature_count; ++i) {
+    if (!subtable.ReadU32(&feature_records[i].tag) ||
+        !subtable.ReadU16(&feature_records[i].offset)) {
+      return OTS_FAILURE();
+    }
+    // Feature record array should be arranged alphabetically by tag
+    if (last_tag != 0 && last_tag > feature_records[i].tag) {
+      return OTS_FAILURE();
+    }
+    last_tag = feature_records[i].tag;
+    if (feature_records[i].offset < feature_record_end ||
+        feature_records[i].offset >= length) {
+      return OTS_FAILURE();
+    }
+  }
+
+  for (unsigned i = 0; i < feature_count; ++i) {
+    if (!ParseFeatureTable(data + feature_records[i].offset,
+                           length - feature_records[i].offset, num_lookups)) {
+      return OTS_FAILURE();
+    }
+  }
+  *num_features = feature_count;
+  return true;
+}
+
+// For parsing GPOS/GSUB tables, this function should be called at first to
+// obtain the number of lookups because parsing FeatureTableList requires
+// the number.
+bool ParseLookupListTable(OpenTypeFile *file, const uint8_t *data,
+                          const size_t length, const size_t num_types,
+                          const LookupTypeParser* parsers,
+                          uint16_t *num_lookups) {
+  Buffer subtable(data, length);
+
+  if (!subtable.ReadU16(num_lookups)) {
+    return OTS_FAILURE();
+  }
+
+  std::vector<uint16_t> lookups;
+  lookups.reserve(*num_lookups);
+  const unsigned lookup_end = static_cast<unsigned>(2) +
+      (*num_lookups) * 2;
+  for (unsigned i = 0; i < *num_lookups; ++i) {
+    if (!subtable.ReadU16(&lookups[i])) {
+      return OTS_FAILURE();
+    }
+    if (lookups[i] < lookup_end || lookups[i] >= length) {
+      return OTS_FAILURE();
+    }
+  }
+
+  for (unsigned i = 0; i < *num_lookups; ++i) {
+    if (!ParseLookupTable(file, data + lookups[i], length - lookups[i],
+                          num_types, parsers)) {
+      return OTS_FAILURE();
+    }
+  }
+
+  return true;
+}
+
 bool ParseClassDefTable(const uint8_t *data, size_t length,
                         const uint16_t num_glyphs,
                         const uint16_t num_classes) {
   Buffer subtable(data, length);
 
   uint16_t format = 0;
   if (!subtable.ReadU16(&format)) {
     return OTS_FAILURE();
   }
   if (format == 1) {
@@ skipping 15 matching lines @@
   }
   if (format == 1) {
     return ParseCoverageFormat1(data, length, num_glyphs);
   } else if (format == 2) {
     return ParseCoverageFormat2(data, length, num_glyphs);
   }
 
   return OTS_FAILURE();
 }
 
+bool ParseDeviceTable(const uint8_t *data, size_t length) {
+  Buffer subtable(data, length);
+
+  uint16_t start_size = 0;
+  uint16_t end_size = 0;
+  uint16_t delta_format = 0;
+  if (!subtable.ReadU16(&start_size) ||
+      !subtable.ReadU16(&end_size) ||
+      !subtable.ReadU16(&delta_format)) {
+    return OTS_FAILURE();
+  }
+  if (start_size > end_size) {
+    OTS_WARNING("bad size range: %u > %u", start_size, end_size);
+    return OTS_FAILURE();
+  }
+  if (delta_format == 0 || delta_format > kMaxDeltaFormatType) {
+    OTS_WARNING("bad delta format: %u", delta_format);
+    return OTS_FAILURE();
+  }
+  // The number of delta values per uint16. The device table should contain
+  // at least |num_units| * 2 bytes compressed data.
+  const unsigned num_units = (end_size - start_size) /
+      (1 << (4 - delta_format)) + 1;
+  // Just skip |num_units| * 2 bytes since the compressed data could take
+  // arbitrary values.
+  if (!subtable.Skip(num_units * 2)) {
+    return OTS_FAILURE();
+  }
+  return true;
+}
+
 }  // namespace ots