| // 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 <algorithm> |
| #include <cstdlib> |
| #include <cstring> |
| #include <map> |
| #include <vector> |
| |
| // The OpenType Font File |
| // http://www.microsoft.com/opentype/otspec/otff.htm |
| |
| #define F(name, capname) \ |
| namespace ots { \ |
| bool ots_##name##_parse(OpenTypeFile *f, const uint8_t *d, size_t l); \ |
| bool ots_##name##_should_serialise(OpenTypeFile *f); \ |
| bool ots_##name##_serialise(OTSStream *s, OpenTypeFile *f); \ |
| void ots_##name##_free(OpenTypeFile *f); \ |
| } |
| // TODO(yusukes): change these function names to follow Chromium coding rule. |
| FOR_EACH_TABLE_TYPE |
| #undef F |
| |
| namespace { |
| |
| bool g_debug_output = true; |
| |
| struct OpenTypeTable { |
| uint32_t tag; |
| uint32_t chksum; |
| uint32_t offset; |
| uint32_t length; |
| }; |
| |
| // Round a value up to the nearest multiple of 4. Note that this can overflow |
| // and return zero. |
| template<typename T> T Round4(T value) { |
| return (value + 3) & ~3; |
| } |
| |
| uint32_t Tag(const char *tag_str) { |
| uint32_t ret; |
| std::memcpy(&ret, tag_str, 4); |
| return ret; |
| } |
| |
| 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 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; |
| } |
| }; |
| |
| const struct { |
| uint32_t 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[] = { |
| { Tag("maxp"), ots::ots_maxp_parse, ots::ots_maxp_serialise, |
| ots::ots_maxp_should_serialise, ots::ots_maxp_free, true }, |
| { Tag("head"), ots::ots_head_parse, ots::ots_head_serialise, |
| ots::ots_head_should_serialise, ots::ots_head_free, true }, |
| { Tag("OS/2"), ots::ots_os2_parse, ots::ots_os2_serialise, |
| ots::ots_os2_should_serialise, ots::ots_os2_free, true }, |
| { Tag("cmap"), ots::ots_cmap_parse, ots::ots_cmap_serialise, |
| ots::ots_cmap_should_serialise, ots::ots_cmap_free, true }, |
| { Tag("hhea"), ots::ots_hhea_parse, ots::ots_hhea_serialise, |
| ots::ots_hhea_should_serialise, ots::ots_hhea_free, true }, |
| { Tag("hmtx"), ots::ots_hmtx_parse, ots::ots_hmtx_serialise, |
| ots::ots_hmtx_should_serialise, ots::ots_hmtx_free, true }, |
| { Tag("name"), ots::ots_name_parse, ots::ots_name_serialise, |
| ots::ots_name_should_serialise, ots::ots_name_free, true }, |
| { Tag("post"), ots::ots_post_parse, ots::ots_post_serialise, |
| ots::ots_post_should_serialise, ots::ots_post_free, true }, |
| { Tag("loca"), ots::ots_loca_parse, ots::ots_loca_serialise, |
| ots::ots_loca_should_serialise, ots::ots_loca_free, false }, |
| { Tag("glyf"), ots::ots_glyf_parse, ots::ots_glyf_serialise, |
| ots::ots_glyf_should_serialise, ots::ots_glyf_free, false }, |
| { Tag("CFF "), ots::ots_cff_parse, ots::ots_cff_serialise, |
| ots::ots_cff_should_serialise, ots::ots_cff_free, false }, |
| { Tag("VDMX"), ots::ots_vdmx_parse, ots::ots_vdmx_serialise, |
| ots::ots_vdmx_should_serialise, ots::ots_vdmx_free, false }, |
| { Tag("hdmx"), ots::ots_hdmx_parse, ots::ots_hdmx_serialise, |
| ots::ots_hdmx_should_serialise, ots::ots_hdmx_free, false }, |
| { Tag("gasp"), ots::ots_gasp_parse, ots::ots_gasp_serialise, |
| ots::ots_gasp_should_serialise, ots::ots_gasp_free, false }, |
| { Tag("cvt "), ots::ots_cvt_parse, ots::ots_cvt_serialise, |
| ots::ots_cvt_should_serialise, ots::ots_cvt_free, false }, |
| { Tag("fpgm"), ots::ots_fpgm_parse, ots::ots_fpgm_serialise, |
| ots::ots_fpgm_should_serialise, ots::ots_fpgm_free, false }, |
| { Tag("prep"), ots::ots_prep_parse, ots::ots_prep_serialise, |
| ots::ots_prep_should_serialise, ots::ots_prep_free, false }, |
| { Tag("LTSH"), ots::ots_ltsh_parse, ots::ots_ltsh_serialise, |
| ots::ots_ltsh_should_serialise, ots::ots_ltsh_free, false }, |
| { Tag("VORG"), ots::ots_vorg_parse, ots::ots_vorg_serialise, |
| ots::ots_vorg_should_serialise, ots::ots_vorg_free, false }, |
| // TODO(yusukes): Support GDEF, GPOS, GSUB, kern, mort, base, and jstf tables. |
| { 0, NULL, NULL, NULL, NULL, false }, |
| }; |
| |
| bool DoProcess(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 ((header->version != Tag("\x00\x01\x00\x00")) && |
| // OpenType fonts with CFF data have 'OTTO' tag. |
| (header->version != Tag("OTTO")) && |
| // Older Mac fonts might have 'true' or 'typ1' tag. |
| (header->version != Tag("true")) && (header->version != Tag("typ1"))) { |
| 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(); |
| } |
| |
| tables.push_back(table); |
| } |
| |
| const size_t data_offset = file.offset(); |
| |
| 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(); |
| } |
| // since we required that the file be < 1GB in length, and that the table |
| // length is < 1GB, the following addtion doesn't overflow |
| const uint32_t end_byte = Round4(tables[i].offset + tables[i].length); |
| if (!end_byte || end_byte > length) { |
| 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, 1 /* start */)); |
| overlap_checker.push_back( |
| std::make_pair(tables[i].offset + tables[i].length, 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(); |
| } |
| } |
| |
| for (unsigned i = 0; ; ++i) { |
| if (table_parsers[i].parse == NULL) break; |
| |
| const std::map<uint32_t, OpenTypeTable>::const_iterator it |
| = table_map.find(table_parsers[i].tag); |
| |
| if (it == table_map.end()) { |
| if (table_parsers[i].required) { |
| return OTS_FAILURE(); |
| } |
| continue; |
| } |
| |
| if (!table_parsers[i].parse( |
| header, data + it->second.offset, it->second.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 are 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++; |
| } |
| } |
| |
| 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; |
| out.tag = table_parsers[i].tag; |
| out.offset = output->Tell(); |
| |
| output->ResetChecksum(); |
| if (table_parsers[i].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 { |
| |
| void DisableDebugOutput() { |
| g_debug_output = false; |
| } |
| |
| bool Process(OTSStream *output, const uint8_t *data, size_t length) { |
| OpenTypeFile header; |
| const bool result = DoProcess(&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 |