Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1151 insertions, 0 deletions

diff --git a/gfx/ots/src/ots.cc b/gfx/ots/src/ots.cc
new file mode 100644
index 0000000000..73b1d235cf
--- /dev/null
+++ b/gfx/ots/src/ots.cc
@@ -0,0 +1,1151 @@
+// Copyright (c) 2009-2017 The OTS 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 "ots.h"
+
+#include <sys/types.h>
+#include <zlib.h>
+
+#include <algorithm>
+#include <cstdlib>
+#include <cstring>
+#include <limits>
+#include <map>
+#include <vector>
+
+#include "../RLBoxWOFF2Host.h"
+
+// The OpenType Font File
+// http://www.microsoft.com/typography/otspec/otff.htm
+
+#include "avar.h"
+#include "cff.h"
+#include "cmap.h"
+#include "colr.h"
+#include "cpal.h"
+#include "cvar.h"
+#include "cvt.h"
+#include "fpgm.h"
+#include "fvar.h"
+#include "gasp.h"
+#include "gdef.h"
+#include "glyf.h"
+#include "gpos.h"
+#include "gsub.h"
+#include "gvar.h"
+#include "hdmx.h"
+#include "head.h"
+#include "hhea.h"
+#include "hmtx.h"
+#include "hvar.h"
+#include "kern.h"
+#include "loca.h"
+#include "ltsh.h"
+#include "math_.h"
+#include "maxp.h"
+#include "mvar.h"
+#include "name.h"
+#include "os2.h"
+#include "ots.h"
+#include "post.h"
+#include "prep.h"
+#include "stat.h"
+#include "vdmx.h"
+#include "vhea.h"
+#include "vmtx.h"
+#include "vorg.h"
+#include "vvar.h"
+
+// Graphite tables
+#ifdef OTS_GRAPHITE
+#include "feat.h"
+#include "glat.h"
+#include "gloc.h"
+#include "sile.h"
+#include "silf.h"
+#include "sill.h"
+#endif
+
+namespace ots {
+
+struct Arena {
+ public:
+  ~Arena() {
+    for (auto& hunk : hunks_) {
+      delete[] hunk;
+    }
+  }
+
+  uint8_t* Allocate(size_t length) {
+    uint8_t* p = new uint8_t[length];
+    hunks_.push_back(p);
+    return p;
+  }
+
+ private:
+  std::vector<uint8_t*> hunks_;
+};
+
+bool CheckTag(uint32_t tag_value) {
+  for (unsigned i = 0; i < 4; ++i) {
+    const uint32_t check = tag_value & 0xff;
+    if (check < 32 || check > 126) {
+      return false;  // non-ASCII character found.
+    }
+    tag_value >>= 8;
+  }
+  return true;
+}
+
+}; // namespace ots
+
+namespace {
+
+#define OTS_MSG_TAG_(level,otf_,msg_,tag_) \
+  (OTS_MESSAGE_(level,otf_,"%c%c%c%c: %s", OTS_UNTAG(tag_), msg_), false)
+
+// Generate a message with or without a table tag, when 'header' is the FontFile pointer
+#define OTS_FAILURE_MSG_TAG(msg_,tag_) OTS_MSG_TAG_(0, header, msg_, tag_)
+#define OTS_FAILURE_MSG_HDR(...)       OTS_FAILURE_MSG_(header, __VA_ARGS__)
+#define OTS_WARNING_MSG_HDR(...)       OTS_WARNING_MSG_(header, __VA_ARGS__)
+
+
+const struct {
+  uint32_t tag;
+  bool required;
+} supported_tables[] = {
+  { OTS_TAG_MAXP, true },
+  { OTS_TAG_HEAD, true },
+  { OTS_TAG_OS2,  true },
+  { OTS_TAG_CMAP, true },
+  { OTS_TAG_HHEA, true },
+  { OTS_TAG_HMTX, true },
+  { OTS_TAG_NAME, true },
+  { OTS_TAG_POST, true },
+  { OTS_TAG_LOCA, false },
+  { OTS_TAG_GLYF, false },
+  { OTS_TAG_CFF,  false },
+  { OTS_TAG_VDMX, false },
+  { OTS_TAG_HDMX, false },
+  { OTS_TAG_GASP, false },
+  { OTS_TAG_CVT,  false },
+  { OTS_TAG_FPGM, false },
+  { OTS_TAG_PREP, false },
+  { OTS_TAG_LTSH, false },
+  { OTS_TAG_VORG, false },
+  { OTS_TAG_KERN, false },
+  // We need to parse fvar table before other tables that may need to know
+  // the number of variation axes (if any)
+  { OTS_TAG_FVAR, false },
+  { OTS_TAG_AVAR, false },
+  { OTS_TAG_CVAR, false },
+  { OTS_TAG_GVAR, false },
+  { OTS_TAG_HVAR, false },
+  { OTS_TAG_MVAR, false },
+  { OTS_TAG_STAT, false },
+  { OTS_TAG_VVAR, false },
+  { OTS_TAG_CFF2, false },
+  // Color font tables.
+  // We need to parse CPAL before COLR so that the number of palette entries
+  // is known; and these tables follow fvar because COLR may use variations.
+  { OTS_TAG_CPAL, false },
+  { OTS_TAG_COLR, false },
+  // We need to parse GDEF table in advance of parsing GSUB/GPOS tables
+  // because they could refer GDEF table.
+  { OTS_TAG_GDEF, false },
+  { OTS_TAG_GPOS, false },
+  { OTS_TAG_GSUB, false },
+  { OTS_TAG_VHEA, false },
+  { OTS_TAG_VMTX, false },
+  { OTS_TAG_MATH, false },
+  // Graphite tables
+#ifdef OTS_GRAPHITE
+  { OTS_TAG_GLOC, false },
+  { OTS_TAG_GLAT, false },
+  { OTS_TAG_FEAT, false },
+  { OTS_TAG_SILF, false },
+  { OTS_TAG_SILE, false },
+  { OTS_TAG_SILL, false },
+#endif
+  { 0, false },
+};
+
+bool ValidateVersionTag(ots::Font *font) {
+  switch (font->version) {
+    case 0x000010000:
+    case OTS_TAG('O','T','T','O'):
+      return true;
+    case OTS_TAG('t','r','u','e'):
+      font->version = 0x000010000;
+      return true;
+    default:
+      return false;
+  }
+}
+
+bool ProcessGeneric(ots::FontFile *header,
+                    ots::Font *font,
+                    uint32_t signature,
+                    ots::OTSStream *output,
+                    const uint8_t *data, size_t length,
+                    const std::vector<ots::TableEntry>& tables,
+                    ots::Buffer& file);
+
+bool ProcessTTF(ots::FontFile *header,
+                ots::Font *font,
+                ots::OTSStream *output, const uint8_t *data, size_t length,
+                uint32_t offset = 0) {
+  ots::Buffer file(data + offset, length - offset);
+
+  if (offset > length) {
+    return OTS_FAILURE_MSG_HDR("offset beyond end of file");
+  }
+
+  // we disallow all files > 1GB in size for sanity.
+  if (length > 1024 * 1024 * 1024) {
+    return OTS_FAILURE_MSG_HDR("file exceeds 1GB");
+  }
+
+  if (!file.ReadU32(&font->version)) {
+    return OTS_FAILURE_MSG_HDR("error reading sfntVersion");
+  }
+  if (!ValidateVersionTag(font)) {
+    return OTS_FAILURE_MSG_HDR("invalid sfntVersion: %d", font->version);
+  }
+
+  if (!file.ReadU16(&font->num_tables) ||
+      !file.ReadU16(&font->search_range) ||
+      !file.ReadU16(&font->entry_selector) ||
+      !file.ReadU16(&font->range_shift)) {
+    return OTS_FAILURE_MSG_HDR("error reading table directory search header");
+  }
+
+  // search_range is (Maximum power of 2 <= numTables) x 16. Thus, to avoid
+  // overflow num_tables is, at most, 2^16 / 16 = 2^12
+  if (font->num_tables >= 4096 || font->num_tables < 1) {
+    return OTS_FAILURE_MSG_HDR("excessive (or zero) number of tables");
+  }
+
+  unsigned max_pow2 = 0;
+  while (1u << (max_pow2 + 1) <= font->num_tables) {
+    max_pow2++;
+  }
+  const uint16_t expected_search_range = (1u << max_pow2) << 4;
+
+  // Don't call ots_failure() here since ~25% of fonts (250+ fonts) in
+  // http://www.princexml.com/fonts/ have unexpected search_range value.
+  if (font->search_range != expected_search_range) {
+    OTS_WARNING_MSG_HDR("bad table directory searchRange");
+    font->search_range = expected_search_range;  // Fix the value.
+  }
+
+  // entry_selector is Log2(maximum power of 2 <= numTables)
+  if (font->entry_selector != max_pow2) {
+    OTS_WARNING_MSG_HDR("bad table directory entrySelector");
+    font->entry_selector = max_pow2;  // Fix the value.
+  }
+
+  // range_shift is NumTables x 16-searchRange. We know that 16*num_tables
+  // doesn't over flow because we range checked it above. Also, we know that
+  // it's > font->search_range by construction of search_range.
+  const uint16_t expected_range_shift =
+      16 * font->num_tables - font->search_range;
+  if (font->range_shift != expected_range_shift) {
+    OTS_WARNING_MSG_HDR("bad table directory rangeShift");
+    font->range_shift = expected_range_shift;  // the same as above.
+  }
+
+  // Next up is the list of tables.
+  std::vector<ots::TableEntry> tables;
+
+  for (unsigned i = 0; i < font->num_tables; ++i) {
+    ots::TableEntry table;
+    if (!file.ReadU32(&table.tag) ||
+        !file.ReadU32(&table.chksum) ||
+        !file.ReadU32(&table.offset) ||
+        !file.ReadU32(&table.length)) {
+      return OTS_FAILURE_MSG_HDR("error reading table directory");
+    }
+
+    table.uncompressed_length = table.length;
+    tables.push_back(table);
+  }
+
+  return ProcessGeneric(header, font, font->version, output, data, length,
+                        tables, file);
+}
+
+bool ProcessTTC(ots::FontFile *header,
+                ots::OTSStream *output,
+                const uint8_t *data,
+                size_t length,
+                uint32_t index) {
+  ots::Buffer file(data, length);
+
+  // we disallow all files > 1GB in size for sanity.
+  if (length > 1024 * 1024 * 1024) {
+    return OTS_FAILURE_MSG_HDR("file exceeds 1GB");
+  }
+
+  uint32_t ttc_tag;
+  if (!file.ReadU32(&ttc_tag)) {
+    return OTS_FAILURE_MSG_HDR("Error reading TTC tag");
+  }
+  if (ttc_tag != OTS_TAG('t','t','c','f')) {
+    return OTS_FAILURE_MSG_HDR("Invalid TTC tag");
+  }
+
+  uint32_t ttc_version;
+  if (!file.ReadU32(&ttc_version)) {
+    return OTS_FAILURE_MSG_HDR("Error reading TTC version");
+  }
+  if (ttc_version != 0x00010000 && ttc_version != 0x00020000) {
+    return OTS_FAILURE_MSG_HDR("Invalid TTC version");
+  }
+
+  uint32_t num_fonts;
+  if (!file.ReadU32(&num_fonts)) {
+    return OTS_FAILURE_MSG_HDR("Error reading number of TTC fonts");
+  }
+  // Limit the allowed number of subfonts to have same memory allocation.
+  if (num_fonts > 0x10000) {
+    return OTS_FAILURE_MSG_HDR("Too many fonts in TTC");
+  }
+
+  std::vector<uint32_t> offsets(num_fonts);
+  for (unsigned i = 0; i < num_fonts; i++) {
+    if (!file.ReadU32(&offsets[i])) {
+      return OTS_FAILURE_MSG_HDR("Error reading offset to OffsetTable");
+    }
+  }
+
+  if (ttc_version == 0x00020000) {
+    // We don't care about these fields of the header:
+    // uint32_t dsig_tag, dsig_length, dsig_offset
+    if (!file.Skip(3 * 4)) {
+      return OTS_FAILURE_MSG_HDR("Error reading DSIG offset and length in TTC font");
+    }
+  }
+
+  if (index == static_cast<uint32_t>(-1)) {
+    if (!output->WriteU32(ttc_tag) ||
+        !output->WriteU32(0x00010000) ||
+        !output->WriteU32(num_fonts) ||
+        !output->Seek((3 + num_fonts) * 4)) {
+      return OTS_FAILURE_MSG_HDR("Error writing output");
+    }
+
+    // Keep references to the fonts processed in the loop below, as we need
+    // them for reused tables.
+    std::vector<ots::Font> fonts(num_fonts, ots::Font(header));
+
+    for (unsigned i = 0; i < num_fonts; i++) {
+      uint32_t out_offset = output->Tell();
+      if (!output->Seek((3 + i) * 4) ||
+          !output->WriteU32(out_offset) ||
+          !output->Seek(out_offset)) {
+        return OTS_FAILURE_MSG_HDR("Error writing output");
+      }
+      if (!ProcessTTF(header, &fonts[i], output, data, length, offsets[i])) {
+        return false;
+      }
+    }
+
+    return true;
+  } else {
+    if (index >= num_fonts) {
+      return OTS_FAILURE_MSG_HDR("Requested font index is bigger than the number of fonts in the TTC file");
+    }
+
+    ots::Font font(header);
+    return ProcessTTF(header, &font, output, data, length, offsets[index]);
+  }
+}
+
+bool ProcessWOFF(ots::FontFile *header,
+                 ots::Font *font,
+                 ots::OTSStream *output, const uint8_t *data, size_t length) {
+  ots::Buffer file(data, length);
+
+  // we disallow all files > 1GB in size for sanity.
+  if (length > 1024 * 1024 * 1024) {
+    return OTS_FAILURE_MSG_HDR("file exceeds 1GB");
+  }
+
+  uint32_t woff_tag;
+  if (!file.ReadU32(&woff_tag)) {
+    return OTS_FAILURE_MSG_HDR("error reading WOFF marker");
+  }
+
+  if (woff_tag != OTS_TAG('w','O','F','F')) {
+    return OTS_FAILURE_MSG_HDR("invalid WOFF marker");
+  }
+
+  if (!file.ReadU32(&font->version)) {
+    return OTS_FAILURE_MSG_HDR("error reading sfntVersion");
+  }
+  if (!ValidateVersionTag(font)) {
+    return OTS_FAILURE_MSG_HDR("invalid sfntVersion: %d", font->version);
+  }
+
+  uint32_t reported_length;
+  if (!file.ReadU32(&reported_length) || length != reported_length) {
+    return OTS_FAILURE_MSG_HDR("incorrect file size in WOFF header");
+  }
+
+  if (!file.ReadU16(&font->num_tables) || !font->num_tables) {
+    return OTS_FAILURE_MSG_HDR("error reading number of tables");
+  }
+
+  uint16_t reserved_value;
+  if (!file.ReadU16(&reserved_value) || reserved_value) {
+    return OTS_FAILURE_MSG_HDR("error in reserved field of WOFF header");
+  }
+
+  uint32_t reported_total_sfnt_size;
+  if (!file.ReadU32(&reported_total_sfnt_size)) {
+    return OTS_FAILURE_MSG_HDR("error reading total sfnt size");
+  }
+
+  // We don't care about these fields of the header:
+  //   uint16_t major_version, minor_version
+  if (!file.Skip(2 * 2)) {
+    return OTS_FAILURE_MSG_HDR("Failed to read 'majorVersion' or 'minorVersion'");
+  }
+
+  // Checks metadata block size.
+  uint32_t meta_offset;
+  uint32_t meta_length;
+  uint32_t meta_length_orig;
+  if (!file.ReadU32(&meta_offset) ||
+      !file.ReadU32(&meta_length) ||
+      !file.ReadU32(&meta_length_orig)) {
+    return OTS_FAILURE_MSG_HDR("Failed to read header metadata block fields");
+  }
+  if (meta_offset) {
+    if (meta_offset >= length || length - meta_offset < meta_length) {
+      return OTS_FAILURE_MSG_HDR("Invalid metadata block offset or length");
+    }
+  }
+
+  // Checks private data block size.
+  uint32_t priv_offset;
+  uint32_t priv_length;
+  if (!file.ReadU32(&priv_offset) ||
+      !file.ReadU32(&priv_length)) {
+    return OTS_FAILURE_MSG_HDR("Failed to read header private block fields");
+  }
+  if (priv_offset) {
+    if (priv_offset >= length || length - priv_offset < priv_length) {
+      return OTS_FAILURE_MSG_HDR("Invalid private block offset or length");
+    }
+  }
+
+  // Next up is the list of tables.
+  std::vector<ots::TableEntry> tables;
+
+  uint32_t first_index = 0;
+  uint32_t last_index = 0;
+  // Size of sfnt header plus size of table records.
+  uint64_t total_sfnt_size = 12 + 16 * font->num_tables;
+  for (unsigned i = 0; i < font->num_tables; ++i) {
+    ots::TableEntry table;
+    if (!file.ReadU32(&table.tag) ||
+        !file.ReadU32(&table.offset) ||
+        !file.ReadU32(&table.length) ||
+        !file.ReadU32(&table.uncompressed_length) ||
+        !file.ReadU32(&table.chksum)) {
+      return OTS_FAILURE_MSG_HDR("error reading table directory");
+    }
+
+    total_sfnt_size += ots::Round4(table.uncompressed_length);
+    if (total_sfnt_size > std::numeric_limits<uint32_t>::max()) {
+      return OTS_FAILURE_MSG_HDR("sfnt size overflow");
+    }
+    tables.push_back(table);
+    if (i == 0 || tables[first_index].offset > table.offset)
+      first_index = i;
+    if (i == 0 || tables[last_index].offset < table.offset)
+      last_index = i;
+  }
+
+  if (reported_total_sfnt_size != total_sfnt_size) {
+    return OTS_FAILURE_MSG_HDR("uncompressed sfnt size mismatch");
+  }
+
+  // Table data must follow immediately after the header.
+  if (tables[first_index].offset != ots::Round4(file.offset())) {
+    return OTS_FAILURE_MSG_HDR("junk before tables in WOFF file");
+  }
+
+  if (tables[last_index].offset >= length ||
+      length - tables[last_index].offset < tables[last_index].length) {
+    return OTS_FAILURE_MSG_HDR("invalid table location/size");
+  }
+  // Blocks must follow immediately after the previous block.
+  // (Except for padding with a maximum of three null bytes)
+  uint64_t block_end = ots::Round4(
+      static_cast<uint64_t>(tables[last_index].offset) +
+      static_cast<uint64_t>(tables[last_index].length));
+  if (block_end > std::numeric_limits<uint32_t>::max()) {
+    return OTS_FAILURE_MSG_HDR("invalid table location/size");
+  }
+  if (meta_offset) {
+    if (block_end != meta_offset) {
+      return OTS_FAILURE_MSG_HDR("Invalid metadata block offset");
+    }
+    block_end = ots::Round4(static_cast<uint64_t>(meta_offset) +
+                            static_cast<uint64_t>(meta_length));
+    if (block_end > std::numeric_limits<uint32_t>::max()) {
+      return OTS_FAILURE_MSG_HDR("Invalid metadata block length");
+    }
+  }
+  if (priv_offset) {
+    if (block_end != priv_offset) {
+      return OTS_FAILURE_MSG_HDR("Invalid private block offset");
+    }
+    block_end = ots::Round4(static_cast<uint64_t>(priv_offset) +
+                            static_cast<uint64_t>(priv_length));
+    if (block_end > std::numeric_limits<uint32_t>::max()) {
+      return OTS_FAILURE_MSG_HDR("Invalid private block length");
+    }
+  }
+  if (block_end != ots::Round4(length)) {
+    return OTS_FAILURE_MSG_HDR("File length mismatch (trailing junk?)");
+  }
+
+  return ProcessGeneric(header, font, woff_tag, output, data, length, tables, file);
+}
+
+bool ProcessWOFF2(ots::FontFile* header, ots::OTSStream* output,
+                  const uint8_t* data, size_t length, uint32_t index) {
+  return RLBoxProcessWOFF2(header, output, data, length, index, ProcessTTC, ProcessTTF);
+}
+
+ots::TableAction GetTableAction(const ots::FontFile *header, uint32_t tag) {
+  ots::TableAction action = header->context->GetTableAction(tag);
+
+  if (action == ots::TABLE_ACTION_DEFAULT) {
+    action = ots::TABLE_ACTION_DROP;
+
+    for (unsigned i = 0; ; ++i) {
+      if (supported_tables[i].tag == 0) break;
+
+      if (supported_tables[i].tag == tag) {
+        action = ots::TABLE_ACTION_SANITIZE;
+        break;
+      }
+    }
+  }
+
+  assert(action != ots::TABLE_ACTION_DEFAULT); // Should never return this.
+  return action;
+}
+
+bool GetTableData(const uint8_t *data,
+                  const ots::TableEntry& table,
+                  ots::Arena &arena,
+                  size_t *table_length,
+                  const uint8_t **table_data) {
+  if (table.uncompressed_length != table.length) {
+    // Compressed table. Need to uncompress into memory first.
+    *table_length = table.uncompressed_length;
+    *table_data = arena.Allocate(*table_length);
+    uLongf dest_len = *table_length;
+    int r = uncompress((Bytef*) *table_data, &dest_len,
+                       data + table.offset, table.length);
+    if (r != Z_OK || dest_len != *table_length) {
+      return false;
+    }
+  } else {
+    // Uncompressed table. We can process directly from memory.
+    *table_data = data + table.offset;
+    *table_length = table.length;
+  }
+
+  return true;
+}
+
+bool ProcessGeneric(ots::FontFile *header,
+                    ots::Font *font,
+                    uint32_t signature,
+                    ots::OTSStream *output,
+                    const uint8_t *data, size_t length,
+                    const std::vector<ots::TableEntry>& tables,
+                    ots::Buffer& file) {
+  const size_t data_offset = file.offset();
+
+  uint32_t uncompressed_sum = 0;
+
+  for (unsigned i = 0; i < font->num_tables; ++i) {
+    // the tables must be sorted by tag (when taken as big-endian numbers).
+    // This also remove the possibility of duplicate tables.
+    if (i) {
+      const uint32_t this_tag = tables[i].tag;
+      const uint32_t prev_tag = tables[i - 1].tag;
+      if (this_tag <= prev_tag) {
+        OTS_WARNING_MSG_HDR("Table directory is not correctly ordered");
+      }
+    }
+
+    // all tag names must be built from printable ASCII characters
+    if (!ots::CheckTag(tables[i].tag)) {
+      OTS_WARNING_MSG_HDR("Invalid table tag: 0x%X", tables[i].tag);
+    }
+
+    // tables must be 4-byte aligned
+    if (tables[i].offset & 3) {
+      return OTS_FAILURE_MSG_TAG("misaligned table", tables[i].tag);
+    }
+
+    // and must be within the file
+    if (tables[i].offset < data_offset || tables[i].offset >= length) {
+      return OTS_FAILURE_MSG_TAG("invalid table offset", tables[i].tag);
+    }
+    // disallow all tables with a zero length
+    if (tables[i].length < 1) {
+      // Note: malayalam.ttf has zero length CVT table...
+      return OTS_FAILURE_MSG_TAG("zero-length table", tables[i].tag);
+    }
+    // disallow all tables with a length > 1GB
+    if (tables[i].length > 1024 * 1024 * 1024) {
+      return OTS_FAILURE_MSG_TAG("table length exceeds 1GB", tables[i].tag);
+    }
+    // disallow tables where the uncompressed size is < the compressed size.
+    if (tables[i].uncompressed_length < tables[i].length) {
+      return OTS_FAILURE_MSG_TAG("invalid compressed table", tables[i].tag);
+    }
+    if (tables[i].uncompressed_length > tables[i].length) {
+      // We'll probably be decompressing this table.
+
+      // disallow all tables which decompress to > OTS_MAX_DECOMPRESSED_TABLE_SIZE
+      if (tables[i].uncompressed_length > OTS_MAX_DECOMPRESSED_TABLE_SIZE) {
+        return OTS_FAILURE_MSG_HDR("%c%c%c%c: decompressed table length exceeds %gMB",
+                                   OTS_UNTAG(tables[i].tag),
+                                   OTS_MAX_DECOMPRESSED_TABLE_SIZE / (1024.0 * 1024.0));        
+      }
+      if (uncompressed_sum + tables[i].uncompressed_length < uncompressed_sum) {
+        return OTS_FAILURE_MSG_TAG("overflow of decompressed sum", tables[i].tag);
+      }
+
+      uncompressed_sum += tables[i].uncompressed_length;
+    }
+    // since we required that the file be < 1GB in length, and that the table
+    // length is < 1GB, the following addtion doesn't overflow
+    uint32_t end_byte = tables[i].offset + tables[i].length;
+    // Tables in the WOFF file must be aligned 4-byte boundary.
+    if (signature == OTS_TAG('w','O','F','F')) {
+        end_byte = ots::Round4(end_byte);
+    }
+    if (!end_byte || end_byte > length) {
+      return OTS_FAILURE_MSG_TAG("table overruns end of file", tables[i].tag);
+    }
+  }
+
+  // All decompressed tables decompressed must be <= OTS_MAX_DECOMPRESSED_FILE_SIZE.
+  if (uncompressed_sum > OTS_MAX_DECOMPRESSED_FILE_SIZE) {
+    return OTS_FAILURE_MSG_HDR("decompressed sum exceeds %gMB",
+                               OTS_MAX_DECOMPRESSED_FILE_SIZE / (1024.0 * 1024.0));        
+  }
+
+  if (uncompressed_sum > output->size()) {
+    return OTS_FAILURE_MSG_HDR("decompressed sum exceeds output size (%gMB)", output->size() / (1024.0 * 1024.0));
+  }
+
+  // check that the tables are not overlapping.
+  std::vector<std::pair<uint32_t, uint8_t> > overlap_checker;
+  for (unsigned i = 0; i < font->num_tables; ++i) {
+    overlap_checker.push_back(
+        std::make_pair(tables[i].offset, static_cast<uint8_t>(1) /* start */));
+    overlap_checker.push_back(
+        std::make_pair(tables[i].offset + tables[i].length,
+                       static_cast<uint8_t>(0) /* end */));
+  }
+  std::sort(overlap_checker.begin(), overlap_checker.end());
+  int overlap_count = 0;
+  for (unsigned i = 0; i < overlap_checker.size(); ++i) {
+    overlap_count += (overlap_checker[i].second ? 1 : -1);
+    if (overlap_count > 1) {
+      return OTS_FAILURE_MSG_HDR("overlapping tables");
+    }
+  }
+
+  std::map<uint32_t, ots::TableEntry> table_map;
+  for (unsigned i = 0; i < font->num_tables; ++i) {
+    table_map[tables[i].tag] = tables[i];
+  }
+
+  ots::Arena arena;
+  // Parse known tables first as we need to parse them in specific order.
+  for (unsigned i = 0; ; ++i) {
+    if (supported_tables[i].tag == 0) break;
+
+    uint32_t tag = supported_tables[i].tag;
+    const auto &it = table_map.find(tag);
+    if (it == table_map.cend()) {
+      if (supported_tables[i].required) {
+        return OTS_FAILURE_MSG_TAG("missing required table", tag);
+      }
+    } else {
+      if (!font->ParseTable(it->second, data, arena)) {
+        return OTS_FAILURE_MSG_TAG("Failed to parse table", tag);
+      }
+    }
+  }
+
+  // Then parse any tables left.
+  for (const auto &table_entry : tables) {
+    if (!font->GetTable(table_entry.tag)) {
+      if (!font->ParseTable(table_entry, data, arena)) {
+        return OTS_FAILURE_MSG_TAG("Failed to parse table", table_entry.tag);
+      }
+    }
+  }
+
+#ifdef OTS_SYNTHESIZE_MISSING_GVAR
+  // If there was an fvar table but no gvar, synthesize an empty gvar to avoid
+  // issues with rasterizers (e.g. Core Text) that assume it must be present.
+  if (font->GetTable(OTS_TAG_FVAR) && !font->GetTable(OTS_TAG_GVAR)) {
+    ots::TableEntry table_entry{ OTS_TAG_GVAR, 0, 0, 0, 0 };
+    const auto &it = font->file->tables.find(table_entry);
+    if (it != font->file->tables.end()) {
+      table_map[OTS_TAG_GVAR] = table_entry;
+      font->AddTable(table_entry, it->second);
+    } else {
+      ots::OpenTypeGVAR *gvar = new ots::OpenTypeGVAR(font, OTS_TAG_GVAR);
+      if (gvar->InitEmpty()) {
+        table_map[OTS_TAG_GVAR] = table_entry;
+        font->AddTable(table_entry, gvar);
+      } else {
+        delete gvar;
+      }
+    }
+  }
+#endif
+
+  ots::Table *glyf = font->GetTable(OTS_TAG_GLYF);
+  ots::Table *loca = font->GetTable(OTS_TAG_LOCA);
+  ots::Table *cff  = font->GetTable(OTS_TAG_CFF);
+  ots::Table *cff2 = font->GetTable(OTS_TAG_CFF2);
+
+  if (glyf && loca) {
+    if (font->version != 0x000010000) {
+      OTS_WARNING_MSG_HDR("wrong sfntVersion for glyph data");
+      font->version = 0x000010000;
+    }
+    if (cff)
+       cff->Drop("font contains both CFF and glyf/loca tables");
+    if (cff2)
+       cff2->Drop("font contains both CFF and glyf/loca tables");
+  } else if (cff || cff2) {
+    if (font->version != OTS_TAG('O','T','T','O')) {
+      OTS_WARNING_MSG_HDR("wrong sfntVersion for glyph data");
+      font->version = OTS_TAG('O','T','T','O');
+    }
+    if (glyf)
+       glyf->Drop("font contains both CFF and glyf tables");
+    if (loca)
+       loca->Drop("font contains both CFF and loca tables");
+  } else if (font->GetTable(OTS_TAG('C','B','D','T')) &&
+             font->GetTable(OTS_TAG('C','B','L','C'))) {
+      // We don't sanitize bitmap tables, but don’t reject bitmap-only fonts if
+      // we are asked to pass them thru.
+  } else {
+      return OTS_FAILURE_MSG_HDR("no supported glyph data table(s) present");
+  }
+
+  uint16_t num_output_tables = 0;
+  for (const auto &it : table_map) {
+    ots::Table *table = font->GetTable(it.first);
+    if (table)
+      num_output_tables++;
+  }
+
+  uint16_t max_pow2 = 0;
+  while (1u << (max_pow2 + 1) <= num_output_tables) {
+    max_pow2++;
+  }
+  const uint16_t output_search_range = (1u << max_pow2) << 4;
+
+  // most of the errors here are highly unlikely - they'd only occur if the
+  // output stream returns a failure, e.g. lack of space to write
+  output->ResetChecksum();
+  if (!output->WriteU32(font->version) ||
+      !output->WriteU16(num_output_tables) ||
+      !output->WriteU16(output_search_range) ||
+      !output->WriteU16(max_pow2) ||
+      !output->WriteU16((num_output_tables << 4) - output_search_range)) {
+    return OTS_FAILURE_MSG_HDR("error writing output");
+  }
+  const uint32_t offset_table_chksum = output->chksum();
+
+  const size_t table_record_offset = output->Tell();
+  if (!output->Pad(16 * num_output_tables)) {
+    return OTS_FAILURE_MSG_HDR("error writing output");
+  }
+
+  std::vector<ots::TableEntry> out_tables;
+
+  size_t head_table_offset = 0;
+  for (const auto &it : table_map) {
+    uint32_t input_offset = it.second.offset;
+    const auto &ot = header->table_entries.find(input_offset);
+    if (ot != header->table_entries.end()) {
+      ots::TableEntry out = ot->second;
+      if (out.tag == OTS_TAG('h','e','a','d')) {
+        head_table_offset = out.offset;
+      }
+      out_tables.push_back(out);
+    } else {
+      ots::TableEntry out;
+      out.tag = it.first;
+      out.offset = output->Tell();
+
+      if (out.tag == OTS_TAG('h','e','a','d')) {
+        head_table_offset = out.offset;
+      }
+
+      ots::Table *table = font->GetTable(out.tag);
+      if (table) {
+        output->ResetChecksum();
+        if (!table->Serialize(output)) {
+          return OTS_FAILURE_MSG_TAG("Failed to serialize table", out.tag);
+        }
+
+        const size_t end_offset = output->Tell();
+        if (end_offset <= out.offset) {
+          // paranoid check. |end_offset| is supposed to be greater than the offset,
+          // as long as the Tell() interface is implemented correctly.
+          return OTS_FAILURE_MSG_TAG("Table is empty or have -ve size", out.tag);
+        }
+        out.length = end_offset - out.offset;
+
+        // align tables to four bytes
+        if (!output->Pad((4 - (end_offset & 3)) % 4)) {
+          return OTS_FAILURE_MSG_TAG("Failed to pad table to 4 bytes", out.tag);
+        }
+        out.chksum = output->chksum();
+        out_tables.push_back(out);
+        header->table_entries[input_offset] = out;
+      }
+    }
+  }
+
+  const size_t end_of_file = output->Tell();
+
+  // Need to sort the output tables for inclusion in the file
+  std::sort(out_tables.begin(), out_tables.end());
+  if (!output->Seek(table_record_offset)) {
+    return OTS_FAILURE_MSG_HDR("error writing output");
+  }
+
+  output->ResetChecksum();
+  uint32_t tables_chksum = 0;
+  for (unsigned i = 0; i < out_tables.size(); ++i) {
+    if (!output->WriteU32(out_tables[i].tag) ||
+        !output->WriteU32(out_tables[i].chksum) ||
+        !output->WriteU32(out_tables[i].offset) ||
+        !output->WriteU32(out_tables[i].length)) {
+      return OTS_FAILURE_MSG_HDR("error writing output");
+    }
+    tables_chksum += out_tables[i].chksum;
+  }
+  const uint32_t table_record_chksum = output->chksum();
+
+  // http://www.microsoft.com/typography/otspec/otff.htm
+  const uint32_t file_chksum
+      = offset_table_chksum + tables_chksum + table_record_chksum;
+  const uint32_t chksum_magic = static_cast<uint32_t>(0xb1b0afba) - file_chksum;
+
+  // seek into the 'head' table and write in the checksum magic value
+  if (!head_table_offset) {
+    return OTS_FAILURE_MSG_HDR("internal error!");
+  }
+  if (!output->Seek(head_table_offset + 8)) {
+    return OTS_FAILURE_MSG_HDR("error writing output");
+  }
+  if (!output->WriteU32(chksum_magic)) {
+    return OTS_FAILURE_MSG_HDR("error writing output");
+  }
+
+  if (!output->Seek(end_of_file)) {
+    return OTS_FAILURE_MSG_HDR("error writing output");
+  }
+
+  return true;
+}
+
+bool IsGraphiteTag(uint32_t tag) {
+  if (tag == OTS_TAG_FEAT ||
+      tag == OTS_TAG_GLAT ||
+      tag == OTS_TAG_GLOC ||
+      tag == OTS_TAG_SILE ||
+      tag == OTS_TAG_SILF ||
+      tag == OTS_TAG_SILL) {
+    return true;
+  }
+  return false;
+}
+
+bool IsVariationsTag(uint32_t tag) {
+  if (tag == OTS_TAG_AVAR ||
+      tag == OTS_TAG_CVAR ||
+      tag == OTS_TAG_FVAR ||
+      tag == OTS_TAG_GVAR ||
+      tag == OTS_TAG_HVAR ||
+      tag == OTS_TAG_MVAR ||
+      tag == OTS_TAG_STAT ||
+      tag == OTS_TAG_VVAR) {
+    return true;
+  }
+  return false;
+}
+
+}  // namespace
+
+namespace ots {
+
+FontFile::~FontFile() {
+  for (const auto& it : tables) {
+    delete it.second;
+  }
+  tables.clear();
+}
+
+bool Font::ParseTable(const TableEntry& table_entry, const uint8_t* data,
+                      Arena &arena) {
+  uint32_t tag = table_entry.tag;
+  TableAction action = GetTableAction(file, tag);
+  if (action == TABLE_ACTION_DROP) {
+    return true;
+  }
+
+  const auto &it = file->tables.find(table_entry);
+  if (it != file->tables.end()) {
+    m_tables[tag] = it->second;
+    return true;
+  }
+
+  Table *table = NULL;
+  bool ret = false;
+
+  if (action == TABLE_ACTION_PASSTHRU) {
+    table = new TablePassthru(this, tag);
+  } else {
+    switch (tag) {
+      case OTS_TAG_AVAR: table = new OpenTypeAVAR(this, tag); break;
+      case OTS_TAG_CFF:  table = new OpenTypeCFF(this,  tag); break;
+      case OTS_TAG_CFF2: table = new OpenTypeCFF2(this, tag); break;
+      case OTS_TAG_CMAP: table = new OpenTypeCMAP(this, tag); break;
+      case OTS_TAG_COLR: table = new OpenTypeCOLR(this, tag); break;
+      case OTS_TAG_CPAL: table = new OpenTypeCPAL(this, tag); break;
+      case OTS_TAG_CVAR: table = new OpenTypeCVAR(this, tag); break;
+      case OTS_TAG_CVT:  table = new OpenTypeCVT(this,  tag); break;
+      case OTS_TAG_FPGM: table = new OpenTypeFPGM(this, tag); break;
+      case OTS_TAG_FVAR: table = new OpenTypeFVAR(this, tag); break;
+      case OTS_TAG_GASP: table = new OpenTypeGASP(this, tag); break;
+      case OTS_TAG_GDEF: table = new OpenTypeGDEF(this, tag); break;
+      case OTS_TAG_GLYF: table = new OpenTypeGLYF(this, tag); break;
+      case OTS_TAG_GPOS: table = new OpenTypeGPOS(this, tag); break;
+      case OTS_TAG_GSUB: table = new OpenTypeGSUB(this, tag); break;
+      case OTS_TAG_GVAR: table = new OpenTypeGVAR(this, tag); break;
+      case OTS_TAG_HDMX: table = new OpenTypeHDMX(this, tag); break;
+      case OTS_TAG_HEAD: table = new OpenTypeHEAD(this, tag); break;
+      case OTS_TAG_HHEA: table = new OpenTypeHHEA(this, tag); break;
+      case OTS_TAG_HMTX: table = new OpenTypeHMTX(this, tag); break;
+      case OTS_TAG_HVAR: table = new OpenTypeHVAR(this, tag); break;
+      case OTS_TAG_KERN: table = new OpenTypeKERN(this, tag); break;
+      case OTS_TAG_LOCA: table = new OpenTypeLOCA(this, tag); break;
+      case OTS_TAG_LTSH: table = new OpenTypeLTSH(this, tag); break;
+      case OTS_TAG_MATH: table = new OpenTypeMATH(this, tag); break;
+      case OTS_TAG_MAXP: table = new OpenTypeMAXP(this, tag); break;
+      case OTS_TAG_MVAR: table = new OpenTypeMVAR(this, tag); break;
+      case OTS_TAG_NAME: table = new OpenTypeNAME(this, tag); break;
+      case OTS_TAG_OS2:  table = new OpenTypeOS2(this,  tag); break;
+      case OTS_TAG_POST: table = new OpenTypePOST(this, tag); break;
+      case OTS_TAG_PREP: table = new OpenTypePREP(this, tag); break;
+      case OTS_TAG_STAT: table = new OpenTypeSTAT(this, tag); break;
+      case OTS_TAG_VDMX: table = new OpenTypeVDMX(this, tag); break;
+      case OTS_TAG_VHEA: table = new OpenTypeVHEA(this, tag); break;
+      case OTS_TAG_VMTX: table = new OpenTypeVMTX(this, tag); break;
+      case OTS_TAG_VORG: table = new OpenTypeVORG(this, tag); break;
+      case OTS_TAG_VVAR: table = new OpenTypeVVAR(this, tag); break;
+      // Graphite tables
+#ifdef OTS_GRAPHITE
+      case OTS_TAG_FEAT: table = new OpenTypeFEAT(this, tag); break;
+      case OTS_TAG_GLAT: table = new OpenTypeGLAT(this, tag); break;
+      case OTS_TAG_GLOC: table = new OpenTypeGLOC(this, tag); break;
+      case OTS_TAG_SILE: table = new OpenTypeSILE(this, tag); break;
+      case OTS_TAG_SILF: table = new OpenTypeSILF(this, tag); break;
+      case OTS_TAG_SILL: table = new OpenTypeSILL(this, tag); break;
+#endif
+      default: break;
+    }
+  }
+
+  if (table) {
+    const uint8_t* table_data;
+    size_t table_length;
+
+    ret = GetTableData(data, table_entry, arena, &table_length, &table_data);
+    if (ret) {
+      ret = table->Parse(table_data, table_length);
+      if (ret)
+        AddTable(table_entry, table);
+    }
+  }
+
+  if (!ret)
+    delete table;
+
+  return ret;
+}
+
+Table* Font::GetTable(uint32_t tag) const {
+  const auto &it = m_tables.find(tag);
+  if (it != m_tables.end() && it->second && it->second->ShouldSerialize())
+    return it->second;
+  return NULL;
+}
+
+Table* Font::GetTypedTable(uint32_t tag) const {
+  Table* t = GetTable(tag);
+  if (t && t->Type() == tag)
+    return t;
+  return NULL;
+}
+
+void Font::AddTable(TableEntry entry, Table* table) {
+  // Attempting to add a duplicate table would be an error; this should only
+  // be used to add a table that does not already exist.
+  assert(m_tables.find(table->Tag()) == m_tables.end());
+  m_tables[table->Tag()] = table;
+  file->tables[entry] = table;
+}
+
+void Font::DropGraphite() {
+  file->context->Message(0, "Dropping all Graphite tables");
+  for (const std::pair<uint32_t, Table*> entry : m_tables) {
+    if (IsGraphiteTag(entry.first)) {
+      entry.second->Drop("Discarding Graphite table");
+    }
+  }
+}
+
+void Font::DropVariations() {
+  file->context->Message(0, "Dropping all Variation tables");
+  for (const std::pair<uint32_t, Table*> entry : m_tables) {
+    if (IsVariationsTag(entry.first)) {
+      entry.second->Drop("Discarding Variations table");
+    }
+  }
+}
+
+bool Table::ShouldSerialize() {
+  return m_shouldSerialize;
+}
+
+void Table::Message(int level, const char *format, va_list va) {
+  char msg[206] = { OTS_UNTAG(m_tag), ':', ' ' };
+  std::vsnprintf(msg + 6, 200, format, va);
+  m_font->file->context->Message(level, msg);
+}
+
+bool Table::Error(const char *format, ...) {
+  va_list va;
+  va_start(va, format);
+  Message(0, format, va);
+  va_end(va);
+
+  return false;
+}
+
+bool Table::Warning(const char *format, ...) {
+  va_list va;
+  va_start(va, format);
+  Message(1, format, va);
+  va_end(va);
+
+  return true;
+}
+
+bool Table::Drop(const char *format, ...) {
+  m_shouldSerialize = false;
+
+  va_list va;
+  va_start(va, format);
+  Message(0, format, va);
+  m_font->file->context->Message(0, "Table discarded");
+  va_end(va);
+
+  return true;
+}
+
+bool Table::DropGraphite(const char *format, ...) {
+  va_list va;
+  va_start(va, format);
+  Message(0, format, va);
+  va_end(va);
+
+  m_font->DropGraphite();
+  if (IsGraphiteTag(m_tag))
+      Drop("Discarding Graphite table");
+
+  return true;
+}
+
+bool Table::DropVariations(const char *format, ...) {
+  va_list va;
+  va_start(va, format);
+  Message(0, format, va);
+  va_end(va);
+
+  m_font->DropVariations();
+  if (IsVariationsTag(m_tag))
+      Drop("Discarding Variations table");
+
+  return true;
+}
+
+bool TablePassthru::Parse(const uint8_t *data, size_t length) {
+  m_data = data;
+  m_length = length;
+  return true;
+}
+
+bool TablePassthru::Serialize(OTSStream *out) {
+    if (!out->Write(m_data, m_length)) {
+    return Error("Failed to write table");
+  }
+
+  return true;
+}
+
+bool OTSContext::Process(OTSStream *output,
+                         const uint8_t *data,
+                         size_t length,
+                         uint32_t index) {
+  FontFile header;
+  Font font(&header);
+  header.context = this;
+
+  if (length < 4) {
+    return OTS_FAILURE_MSG_(&header, "file less than 4 bytes");
+  }
+
+  bool result;
+  if (data[0] == 'w' && data[1] == 'O' && data[2] == 'F' && data[3] == 'F') {
+    result = ProcessWOFF(&header, &font, output, data, length);
+  } else if (data[0] == 'w' && data[1] == 'O' && data[2] == 'F' && data[3] == '2') {
+    result = ProcessWOFF2(&header, output, data, length, index);
+  } else if (data[0] == 't' && data[1] == 't' && data[2] == 'c' && data[3] == 'f') {
+    result = ProcessTTC(&header, output, data, length, index);
+  } else {
+    result = ProcessTTF(&header, &font, output, data, length);
+  }
+
+  return result;
+}
+
+}  // namespace ots