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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.h"
// The OpenType Font File
// http://www.microsoft.com/typography/otspec/cmap.htm
namespace {
bool g_debug_output = true;
bool g_enable_woff2 = false;
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;
}
uint32_t Tag(const char *tag_str) {
uint32_t ret;
std::memcpy(&ret, tag_str, 4);
return ret;
}
struct OutputTable {
uint32_t tag;
size_t offset;
size_t length;
uint32_t chksum;
static bool SortByTag(const OutputTable& a, const OutputTable& b) {
const uint32_t atag = ntohl(a.tag);
const uint32_t btag = ntohl(b.tag);
return atag < btag;
}
};
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 {
const char* tag;
bool (*parse)(ots::OpenTypeFile *otf, const uint8_t *data, size_t length);
bool (*serialise)(ots::OTSStream *out, ots::OpenTypeFile *file);
bool (*should_serialise)(ots::OpenTypeFile *file);
void (*free)(ots::OpenTypeFile *file);
bool required;
} table_parsers[] = {
{ "maxp", ots::ots_maxp_parse, ots::ots_maxp_serialise,
ots::ots_maxp_should_serialise, ots::ots_maxp_free, true },
{ "head", ots::ots_head_parse, ots::ots_head_serialise,
ots::ots_head_should_serialise, ots::ots_head_free, true },
{ "OS/2", ots::ots_os2_parse, ots::ots_os2_serialise,
ots::ots_os2_should_serialise, ots::ots_os2_free, true },
{ "cmap", ots::ots_cmap_parse, ots::ots_cmap_serialise,
ots::ots_cmap_should_serialise, ots::ots_cmap_free, true },
{ "hhea", ots::ots_hhea_parse, ots::ots_hhea_serialise,
ots::ots_hhea_should_serialise, ots::ots_hhea_free, true },
{ "hmtx", ots::ots_hmtx_parse, ots::ots_hmtx_serialise,
ots::ots_hmtx_should_serialise, ots::ots_hmtx_free, true },
{ "name", ots::ots_name_parse, ots::ots_name_serialise,
ots::ots_name_should_serialise, ots::ots_name_free, true },
{ "post", ots::ots_post_parse, ots::ots_post_serialise,
ots::ots_post_should_serialise, ots::ots_post_free, true },
{ "loca", ots::ots_loca_parse, ots::ots_loca_serialise,
ots::ots_loca_should_serialise, ots::ots_loca_free, false },
{ "glyf", ots::ots_glyf_parse, ots::ots_glyf_serialise,
ots::ots_glyf_should_serialise, ots::ots_glyf_free, false },
{ "CFF ", ots::ots_cff_parse, ots::ots_cff_serialise,
ots::ots_cff_should_serialise, ots::ots_cff_free, false },
{ "VDMX", ots::ots_vdmx_parse, ots::ots_vdmx_serialise,
ots::ots_vdmx_should_serialise, ots::ots_vdmx_free, false },
{ "hdmx", ots::ots_hdmx_parse, ots::ots_hdmx_serialise,
ots::ots_hdmx_should_serialise, ots::ots_hdmx_free, false },
{ "gasp", ots::ots_gasp_parse, ots::ots_gasp_serialise,
ots::ots_gasp_should_serialise, ots::ots_gasp_free, false },
{ "cvt ", ots::ots_cvt_parse, ots::ots_cvt_serialise,
ots::ots_cvt_should_serialise, ots::ots_cvt_free, false },
{ "fpgm", ots::ots_fpgm_parse, ots::ots_fpgm_serialise,
ots::ots_fpgm_should_serialise, ots::ots_fpgm_free, false },
{ "prep", ots::ots_prep_parse, ots::ots_prep_serialise,
ots::ots_prep_should_serialise, ots::ots_prep_free, false },
{ "LTSH", ots::ots_ltsh_parse, ots::ots_ltsh_serialise,
ots::ots_ltsh_should_serialise, ots::ots_ltsh_free, false },
{ "VORG", ots::ots_vorg_parse, ots::ots_vorg_serialise,
ots::ots_vorg_should_serialise, ots::ots_vorg_free, false },
{ "kern", ots::ots_kern_parse, ots::ots_kern_serialise,
ots::ots_kern_should_serialise, ots::ots_kern_free, false },
// We need to parse GDEF table in advance of parsing GSUB/GPOS tables
// because they could refer GDEF table.
{ "GDEF", ots::ots_gdef_parse, ots::ots_gdef_serialise,
ots::ots_gdef_should_serialise, ots::ots_gdef_free, false },
{ "GPOS", ots::ots_gpos_parse, ots::ots_gpos_serialise,
ots::ots_gpos_should_serialise, ots::ots_gpos_free, false },
{ "GSUB", ots::ots_gsub_parse, ots::ots_gsub_serialise,
ots::ots_gsub_should_serialise, ots::ots_gsub_free, false },
{ "vhea", ots::ots_vhea_parse, ots::ots_vhea_serialise,
ots::ots_vhea_should_serialise, ots::ots_vhea_free, false },
{ "vmtx", ots::ots_vmtx_parse, ots::ots_vmtx_serialise,
ots::ots_vmtx_should_serialise, ots::ots_vmtx_free, false },
// TODO(bashi): Support mort, base, and jstf tables.
{ 0, NULL, NULL, NULL, NULL, false },
};
bool ProcessGeneric(ots::OpenTypeFile *header,
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::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();
}
if (!file.ReadTag(&header->version)) {
return OTS_FAILURE();
}
if (!ots::IsValidVersionTag(header->version)) {
return OTS_FAILURE();
}
if (!file.ReadU16(&header->num_tables) ||
!file.ReadU16(&header->search_range) ||
!file.ReadU16(&header->entry_selector) ||
!file.ReadU16(&header->range_shift)) {
return OTS_FAILURE();
}
// 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 (header->num_tables >= 4096 || header->num_tables < 1) {
return OTS_FAILURE();
}
unsigned max_pow2 = 0;
while (1u << (max_pow2 + 1) <= header->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 (header->search_range != expected_search_range) {
OTS_WARNING("bad search range");
header->search_range = expected_search_range; // Fix the value.
}
// entry_selector is Log2(maximum power of 2 <= numTables)
if (header->entry_selector != max_pow2) {
return OTS_FAILURE();
}
// 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 > header->search_range by construction of search_range.
const uint32_t expected_range_shift
= 16 * header->num_tables - header->search_range;
if (header->range_shift != expected_range_shift) {
OTS_WARNING("bad range shift");
header->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 < header->num_tables; ++i) {
OpenTypeTable table;
if (!file.ReadTag(&table.tag) ||
!file.ReadU32(&table.chksum) ||
!file.ReadU32(&table.offset) ||
!file.ReadU32(&table.length)) {
return OTS_FAILURE();
}
table.uncompressed_length = table.length;
tables.push_back(table);
}
return ProcessGeneric(header, header->version, output, data, length,
tables, file);
}
bool ProcessWOFF(ots::OpenTypeFile *header,
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();
}
uint32_t woff_tag;
if (!file.ReadTag(&woff_tag)) {
return OTS_FAILURE();
}
if (woff_tag != Tag("wOFF")) {
return OTS_FAILURE();
}
if (!file.ReadTag(&header->version)) {
return OTS_FAILURE();
}
if (!ots::IsValidVersionTag(header->version)) {
return OTS_FAILURE();
}
header->search_range = 0;
header->entry_selector = 0;
header->range_shift = 0;
uint32_t reported_length;
if (!file.ReadU32(&reported_length) || length != reported_length) {
return OTS_FAILURE();
}
if (!file.ReadU16(&header->num_tables) || !header->num_tables) {
return OTS_FAILURE();
}
uint16_t reserved_value;
if (!file.ReadU16(&reserved_value) || reserved_value) {
return OTS_FAILURE();
}
uint32_t reported_total_sfnt_size;
if (!file.ReadU32(&reported_total_sfnt_size)) {
return OTS_FAILURE();
}
// We don't care about these fields of the header:
// uint16_t major_version, minor_version
if (!file.Skip(2 * 2)) {
return OTS_FAILURE();
}
// 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();
}
if (meta_offset) {
if (meta_offset >= length || length - meta_offset < meta_length) {
return OTS_FAILURE();
}
}
// 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();
}
if (priv_offset) {
if (priv_offset >= length || length - priv_offset < priv_length) {
return OTS_FAILURE();
}
}
// 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 * header->num_tables;
for (unsigned i = 0; i < header->num_tables; ++i) {
OpenTypeTable table;
if (!file.ReadTag(&table.tag) ||
!file.ReadU32(&table.offset) ||
!file.ReadU32(&table.length) ||
!file.ReadU32(&table.uncompressed_length) ||
!file.ReadU32(&table.chksum)) {
return OTS_FAILURE();
}
total_sfnt_size += ots::Round4(table.uncompressed_length);
if (total_sfnt_size > std::numeric_limits<uint32_t>::max()) {
return OTS_FAILURE();
}
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();
}
// Table data must follow immediately after the header.
if (tables[first_index].offset != ots::Round4(file.offset())) {
return OTS_FAILURE();
}
if (tables[last_index].offset >= length ||
length - tables[last_index].offset < tables[last_index].length) {
return OTS_FAILURE();
}
// 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();
}
if (meta_offset) {
if (block_end != meta_offset) {
return OTS_FAILURE();
}
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();
}
}
if (priv_offset) {
if (block_end != priv_offset) {
return OTS_FAILURE();
}
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();
}
}
if (block_end != ots::Round4(length)) {
return OTS_FAILURE();
}
return ProcessGeneric(header, woff_tag, output, data, length, tables, file);
}
bool ProcessWOFF2(ots::OpenTypeFile *header,
ots::OTSStream *output, const uint8_t *data, size_t length) {
size_t decompressed_size = ots::ComputeWOFF2FinalSize(data, length);
if (decompressed_size == 0) {
return OTS_FAILURE();
}
// decompressed font must be <= 30MB
if (decompressed_size > 30 * 1024 * 1024) {
return OTS_FAILURE();
}
std::vector<uint8_t> decompressed_buffer(decompressed_size);
if (!ots::ConvertWOFF2ToTTF(&decompressed_buffer[0], decompressed_size,
data, length)) {
return OTS_FAILURE();
}
return ProcessTTF(header, output, &decompressed_buffer[0], decompressed_size);
}
bool ProcessGeneric(ots::OpenTypeFile *header, uint32_t signature,
ots::OTSStream *output,
const uint8_t *data, size_t length,
const std::vector<OpenTypeTable>& tables,
ots::Buffer& file) {
const size_t data_offset = file.offset();
uint32_t uncompressed_sum = 0;
for (unsigned i = 0; i < header->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 = ntohl(tables[i].tag);
const uint32_t prev_tag = ntohl(tables[i - 1].tag);
if (this_tag <= prev_tag) {
return OTS_FAILURE();
}
}
// all tag names must be built from printable ASCII characters
if (!CheckTag(tables[i].tag)) {
return OTS_FAILURE();
}
// tables must be 4-byte aligned
if (tables[i].offset & 3) {
return OTS_FAILURE();
}
// and must be within the file
if (tables[i].offset < data_offset || tables[i].offset >= length) {
return OTS_FAILURE();
}
// disallow all tables with a zero length
if (tables[i].length < 1) {
// Note: malayalam.ttf has zero length CVT table...
return OTS_FAILURE();
}
// disallow all tables with a length > 1GB
if (tables[i].length > 1024 * 1024 * 1024) {
return OTS_FAILURE();
}
// disallow tables where the uncompressed size is < the compressed size.
if (tables[i].uncompressed_length < tables[i].length) {
return OTS_FAILURE();
}
if (tables[i].uncompressed_length > tables[i].length) {
// We'll probably be decompressing this table.
// disallow all tables which uncompress to > 30 MB
if (tables[i].uncompressed_length > 30 * 1024 * 1024) {
return OTS_FAILURE();
}
if (uncompressed_sum + tables[i].uncompressed_length < uncompressed_sum) {
return OTS_FAILURE();
}
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 == Tag("wOFF")) {
end_byte = ots::Round4(end_byte);
}
if (!end_byte || end_byte > length) {
return OTS_FAILURE();
}
}
// All decompressed tables uncompressed must be <= 30MB.
if (uncompressed_sum > 30 * 1024 * 1024) {
return OTS_FAILURE();
}
std::map<uint32_t, OpenTypeTable> table_map;
for (unsigned i = 0; i < header->num_tables; ++i) {
table_map[tables[i].tag] = tables[i];
}
// check that the tables are not overlapping.
std::vector<std::pair<uint32_t, uint8_t> > overlap_checker;
for (unsigned i = 0; i < header->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();
}
}
Arena arena;
for (unsigned i = 0; ; ++i) {
if (table_parsers[i].parse == NULL) break;
const std::map<uint32_t, OpenTypeTable>::const_iterator it
= table_map.find(Tag(table_parsers[i].tag));
if (it == table_map.end()) {
if (table_parsers[i].required) {
return OTS_FAILURE();
}
continue;
}
const uint8_t* table_data;
size_t table_length;
if (it->second.uncompressed_length != it->second.length) {
// compressed table. Need to uncompress into memory first.
table_length = it->second.uncompressed_length;
table_data = arena.Allocate(table_length);
uLongf dest_len = table_length;
int r = uncompress((Bytef*) table_data, &dest_len,
data + it->second.offset, it->second.length);
if (r != Z_OK || dest_len != table_length) {
return OTS_FAILURE();
}
} else {
// uncompressed table. We can process directly from memory.
table_data = data + it->second.offset;
table_length = it->second.length;
}
if (!table_parsers[i].parse(header, table_data, table_length)) {
return OTS_FAILURE();
}
}
if (header->cff) {
// font with PostScript glyph
if (header->version != Tag("OTTO")) {
return OTS_FAILURE();
}
if (header->glyf || header->loca) {
// mixing outline formats is not recommended
return OTS_FAILURE();
}
} else {
if (!header->glyf || !header->loca) {
// No TrueType glyph found.
// Note: bitmap-only fonts are not supported.
return OTS_FAILURE();
}
}
unsigned num_output_tables = 0;
for (unsigned i = 0; ; ++i) {
if (table_parsers[i].parse == NULL) {
break;
}
if (table_parsers[i].should_serialise(header)) {
num_output_tables++;
}
}
unsigned max_pow2 = 0;
while (1u << (max_pow2 + 1) <= num_output_tables) {
max_pow2++;
}
const uint16_t output_search_range = (1u << max_pow2) << 4;
output->ResetChecksum();
if (!output->WriteTag(header->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();
}
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();
}
std::vector<OutputTable> out_tables;
size_t head_table_offset = 0;
for (unsigned i = 0; ; ++i) {
if (table_parsers[i].parse == NULL) {
break;
}
if (!table_parsers[i].should_serialise(header)) {
continue;
}
OutputTable out;
uint32_t tag = Tag(table_parsers[i].tag);
out.tag = tag;
out.offset = output->Tell();
output->ResetChecksum();
if (tag == Tag("head")) {
head_table_offset = out.offset;
}
if (!table_parsers[i].serialise(output, header)) {
return OTS_FAILURE();
}
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();
}
out.length = end_offset - out.offset;
// align tables to four bytes
if (!output->Pad((4 - (end_offset & 3)) % 4)) {
return OTS_FAILURE();
}
out.chksum = output->chksum();
out_tables.push_back(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(), OutputTable::SortByTag);
if (!output->Seek(table_record_offset)) {
return OTS_FAILURE();
}
output->ResetChecksum();
uint32_t tables_chksum = 0;
for (unsigned i = 0; i < out_tables.size(); ++i) {
if (!output->WriteTag(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();
}
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(); // not reached.
}
if (!output->Seek(head_table_offset + 8)) {
return OTS_FAILURE();
}
if (!output->WriteU32(chksum_magic)) {
return OTS_FAILURE();
}
if (!output->Seek(end_of_file)) {
return OTS_FAILURE();
}
return true;
}
} // namespace
namespace ots {
bool IsValidVersionTag(uint32_t tag) {
return tag == Tag("\x00\x01\x00\x00") ||
// OpenType fonts with CFF data have 'OTTO' tag.
tag == Tag("OTTO") ||
// Older Mac fonts might have 'true' or 'typ1' tag.
tag == Tag("true") ||
tag == Tag("typ1");
}
void DisableDebugOutput() {
g_debug_output = false;
}
void EnableWOFF2() {
g_enable_woff2 = true;
}
bool Process(OTSStream *output, const uint8_t *data, size_t length) {
OpenTypeFile header;
if (length < 4) {
return OTS_FAILURE();
}
bool result;
if (data[0] == 'w' && data[1] == 'O' && data[2] == 'F' && data[3] == 'F') {
result = ProcessWOFF(&header, output, data, length);
} else if (g_enable_woff2 &&
data[0] == 'w' && data[1] == 'O' && data[2] == 'F' &&
data[3] == '2') {
result = ProcessWOFF2(&header, output, data, length);
} else {
result = ProcessTTF(&header, output, data, length);
}
for (unsigned i = 0; ; ++i) {
if (table_parsers[i].parse == NULL) break;
table_parsers[i].free(&header);
}
return result;
}
#if !defined(_MSC_VER) && defined(OTS_DEBUG)
bool Failure(const char *f, int l, const char *fn) {
if (g_debug_output) {
std::fprintf(stderr, "ERROR at %s:%d (%s)\n", f, l, fn);
std::fflush(stderr);
}
return false;
}
void Warning(const char *f, int l, const char *format, ...) {
if (g_debug_output) {
std::fprintf(stderr, "WARNING at %s:%d: ", f, l);
std::va_list va;
va_start(va, format);
std::vfprintf(stderr, format, va);
va_end(va);
std::fprintf(stderr, "\n");
std::fflush(stderr);
}
}
#endif
} // namespace ots
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