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// Copyright (c) 2009 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 "ots.h"

#include <sys/types.h>
#include <zlib.h>

#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <limits>
#include <map>
#include <vector>

#include "woff2_dec.h"

// The OpenType Font File
// http://www.microsoft.com/typography/otspec/cmap.htm

namespace {

// Generate a message with or without a table tag, when 'header' is the OpenTypeFile pointer
#define OTS_FAILURE_MSG_TAG(msg_,tag_) OTS_FAILURE_MSG_TAG_(header, msg_, tag_)
#define OTS_FAILURE_MSG_HDR(msg_)      OTS_FAILURE_MSG_(header, msg_)
#define OTS_WARNING_MSG_HDR(msg_)      OTS_WARNING_MSG_(header, msg_)


struct OpenTypeTable {
  uint32_t tag;
  uint32_t chksum;
  uint32_t offset;
  uint32_t length;
  uint32_t uncompressed_length;
};

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;
}

struct Arena {
 public:
  ~Arena() {
    for (std::vector<uint8_t*>::iterator
         i = hunks_.begin(); i != hunks_.end(); ++i) {
      delete[] *i;
    }
  }

  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_;
};

const struct {
  uint32_t tag;
  bool (*parse)(ots::Font *font, const uint8_t *data, size_t length);
  bool (*serialise)(ots::OTSStream *out, ots::Font *font);
  bool (*should_serialise)(ots::Font *font);
  void (*reuse)(ots::Font *font, ots::Font *other);
  bool required;
} table_parsers[] = {
  { OTS_TAG('m','a','x','p'), ots::ots_maxp_parse, ots::ots_maxp_serialise,
    ots::ots_maxp_should_serialise, ots::ots_maxp_reuse, true },
  { OTS_TAG('h','e','a','d'), ots::ots_head_parse, ots::ots_head_serialise,
    ots::ots_head_should_serialise, ots::ots_head_reuse, true },
  { OTS_TAG('O','S','/','2'), ots::ots_os2_parse, ots::ots_os2_serialise,
    ots::ots_os2_should_serialise, ots::ots_os2_reuse, true },
  { OTS_TAG('c','m','a','p'), ots::ots_cmap_parse, ots::ots_cmap_serialise,
    ots::ots_cmap_should_serialise, ots::ots_cmap_reuse, true },
  { OTS_TAG('h','h','e','a'), ots::ots_hhea_parse, ots::ots_hhea_serialise,
    ots::ots_hhea_should_serialise, ots::ots_hhea_reuse, true },
  { OTS_TAG('h','m','t','x'), ots::ots_hmtx_parse, ots::ots_hmtx_serialise,
    ots::ots_hmtx_should_serialise, ots::ots_hmtx_reuse, true },
  { OTS_TAG('n','a','m','e'), ots::ots_name_parse, ots::ots_name_serialise,
    ots::ots_name_should_serialise, ots::ots_name_reuse, true },
  { OTS_TAG('p','o','s','t'), ots::ots_post_parse, ots::ots_post_serialise,
    ots::ots_post_should_serialise, ots::ots_post_reuse, true },
  { OTS_TAG('l','o','c','a'), ots::ots_loca_parse, ots::ots_loca_serialise,
    ots::ots_loca_should_serialise, ots::ots_loca_reuse, false },
  { OTS_TAG('g','l','y','f'), ots::ots_glyf_parse, ots::ots_glyf_serialise,
    ots::ots_glyf_should_serialise, ots::ots_glyf_reuse, false },
  { OTS_TAG('C','F','F',' '), ots::ots_cff_parse, ots::ots_cff_serialise,
    ots::ots_cff_should_serialise, ots::ots_cff_reuse, false },
  { OTS_TAG('V','D','M','X'), ots::ots_vdmx_parse, ots::ots_vdmx_serialise,
    ots::ots_vdmx_should_serialise, ots::ots_vdmx_reuse, false },
  { OTS_TAG('h','d','m','x'), ots::ots_hdmx_parse, ots::ots_hdmx_serialise,
    ots::ots_hdmx_should_serialise, ots::ots_hdmx_reuse, false },
  { OTS_TAG('g','a','s','p'), ots::ots_gasp_parse, ots::ots_gasp_serialise,
    ots::ots_gasp_should_serialise, ots::ots_gasp_reuse, false },
  { OTS_TAG('c','v','t',' '), ots::ots_cvt_parse, ots::ots_cvt_serialise,
    ots::ots_cvt_should_serialise, ots::ots_cvt_reuse, false },
  { OTS_TAG('f','p','g','m'), ots::ots_fpgm_parse, ots::ots_fpgm_serialise,
    ots::ots_fpgm_should_serialise, ots::ots_fpgm_reuse, false },
  { OTS_TAG('p','r','e','p'), ots::ots_prep_parse, ots::ots_prep_serialise,
    ots::ots_prep_should_serialise, ots::ots_prep_reuse, false },
  { OTS_TAG('L','T','S','H'), ots::ots_ltsh_parse, ots::ots_ltsh_serialise,
    ots::ots_ltsh_should_serialise, ots::ots_ltsh_reuse, false },
  { OTS_TAG('V','O','R','G'), ots::ots_vorg_parse, ots::ots_vorg_serialise,
    ots::ots_vorg_should_serialise, ots::ots_vorg_reuse, false },
  { OTS_TAG('k','e','r','n'), ots::ots_kern_parse, ots::ots_kern_serialise,
    ots::ots_kern_should_serialise, ots::ots_kern_reuse, false },
  // We need to parse GDEF table in advance of parsing GSUB/GPOS tables
  // because they could refer GDEF table.
  { OTS_TAG('G','D','E','F'), ots::ots_gdef_parse, ots::ots_gdef_serialise,
    ots::ots_gdef_should_serialise, ots::ots_gdef_reuse, false },
  { OTS_TAG('G','P','O','S'), ots::ots_gpos_parse, ots::ots_gpos_serialise,
    ots::ots_gpos_should_serialise, ots::ots_gpos_reuse, false },
  { OTS_TAG('G','S','U','B'), ots::ots_gsub_parse, ots::ots_gsub_serialise,
    ots::ots_gsub_should_serialise, ots::ots_gsub_reuse, false },
  { OTS_TAG('v','h','e','a'), ots::ots_vhea_parse, ots::ots_vhea_serialise,
    ots::ots_vhea_should_serialise, ots::ots_vhea_reuse, false },
  { OTS_TAG('v','m','t','x'), ots::ots_vmtx_parse, ots::ots_vmtx_serialise,
    ots::ots_vmtx_should_serialise, ots::ots_vmtx_reuse, false },
  { OTS_TAG('M','A','T','H'), ots::ots_math_parse, ots::ots_math_serialise,
    ots::ots_math_should_serialise, ots::ots_math_reuse, false },
  { 0, NULL, NULL, NULL, NULL, false },
};

bool ProcessGeneric(ots::OpenTypeFile *header,
                    ots::Font *font,
                    uint32_t signature,
                    ots::OTSStream *output,
                    const uint8_t *data, size_t length,
                    const std::vector<OpenTypeTable>& tables,
                    ots::Buffer& file);

bool ProcessTTF(ots::OpenTypeFile *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 version tag");
  }
  if (!ots::IsValidVersionTag(font->version)) {
      return OTS_FAILURE_MSG_HDR("invalid version tag");
  }

  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 search range");
    font->search_range = expected_search_range;  // Fix the value.
  }

  // entry_selector is Log2(maximum power of 2 <= numTables)
  if (font->entry_selector != max_pow2) {
    return OTS_FAILURE_MSG_HDR("incorrect entrySelector for table directory");
  }

  // 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 range shift");
    font->range_shift = expected_range_shift;  // the same as above.
  }

  // Next up is the list of tables.
  std::vector<OpenTypeTable> tables;

  for (unsigned i = 0; i < font->num_tables; ++i) {
    OpenTypeTable 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::OpenTypeFile *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::OpenTypeFile *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 version tag");
  }
  if (!ots::IsValidVersionTag(font->version)) {
    return OTS_FAILURE_MSG_HDR("invalid version tag");
  }

  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<OpenTypeTable> 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) {
    OpenTypeTable 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 (