1// Copyright 2013 Google Inc. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14//
15// Font management utilities
16
17#include "./font.h"
18
19#include <algorithm>
20
21#include "./buffer.h"
22#include "./port.h"
23#include "./store_bytes.h"
24#include "./table_tags.h"
25
26namespace woff2 {
27
28Font::Table* Font::FindTable(uint32_t tag) {
29  std::map<uint32_t, Font::Table>::iterator it = tables.find(tag);
30  return it == tables.end() ? 0 : &it->second;
31}
32
33const Font::Table* Font::FindTable(uint32_t tag) const {
34  std::map<uint32_t, Font::Table>::const_iterator it = tables.find(tag);
35  return it == tables.end() ? 0 : &it->second;
36}
37
38bool ReadFont(const uint8_t* data, size_t len, Font* font) {
39  Buffer file(data, len);
40
41  // We don't care about the search_range, entry_selector and range_shift
42  // fields, they will always be computed upon writing the font.
43  if (!file.ReadU32(&font->flavor) ||
44      !file.ReadU16(&font->num_tables) ||
45      !file.Skip(6)) {
46    return FONT_COMPRESSION_FAILURE();
47  }
48
49  std::map<uint32_t, uint32_t> intervals;
50  for (uint16_t i = 0; i < font->num_tables; ++i) {
51    Font::Table table;
52    if (!file.ReadU32(&table.tag) ||
53        !file.ReadU32(&table.checksum) ||
54        !file.ReadU32(&table.offset) ||
55        !file.ReadU32(&table.length)) {
56      return FONT_COMPRESSION_FAILURE();
57    }
58    if ((table.offset & 3) != 0 ||
59        table.length > len ||
60        len - table.length < table.offset) {
61      return FONT_COMPRESSION_FAILURE();
62    }
63    intervals[table.offset] = table.length;
64    table.data = data + table.offset;
65    if (font->tables.find(table.tag) != font->tables.end()) {
66      return FONT_COMPRESSION_FAILURE();
67    }
68    font->tables[table.tag] = table;
69  }
70
71  // Check that tables are non-overlapping.
72  uint32_t last_offset = 12UL + 16UL * font->num_tables;
73  for (const auto& i : intervals) {
74    if (i.first < last_offset || i.first + i.second < i.first) {
75      return FONT_COMPRESSION_FAILURE();
76    }
77    last_offset = i.first + i.second;
78  }
79  return true;
80}
81
82size_t FontFileSize(const Font& font) {
83  size_t max_offset = 12ULL + 16ULL * font.num_tables;
84  for (const auto& i : font.tables) {
85    const Font::Table& table = i.second;
86    size_t padding_size = (4 - (table.length & 3)) & 3;
87    size_t end_offset = (padding_size + table.offset) + table.length;
88    max_offset = std::max(max_offset, end_offset);
89  }
90  return max_offset;
91}
92
93bool WriteFont(const Font& font, uint8_t* dst, size_t dst_size) {
94  if (dst_size < 12ULL + 16ULL * font.num_tables) {
95    return FONT_COMPRESSION_FAILURE();
96  }
97  size_t offset = 0;
98  StoreU32(font.flavor, &offset, dst);
99  Store16(font.num_tables, &offset, dst);
100  uint16_t max_pow2 = font.num_tables ? Log2Floor(font.num_tables) : 0;
101  uint16_t search_range = max_pow2 ? 1 << (max_pow2 + 4) : 0;
102  uint16_t range_shift = (font.num_tables << 4) - search_range;
103  Store16(search_range, &offset, dst);
104  Store16(max_pow2, &offset, dst);
105  Store16(range_shift, &offset, dst);
106  for (const auto& i : font.tables) {
107    const Font::Table& table = i.second;
108    StoreU32(table.tag, &offset, dst);
109    StoreU32(table.checksum, &offset, dst);
110    StoreU32(table.offset, &offset, dst);
111    StoreU32(table.length, &offset, dst);
112    if (table.offset + table.length < table.offset ||
113        dst_size < table.offset + table.length) {
114      return FONT_COMPRESSION_FAILURE();
115    }
116    memcpy(dst + table.offset, table.data, table.length);
117    size_t padding_size = (4 - (table.length & 3)) & 3;
118    if (table.offset + table.length + padding_size < padding_size ||
119        dst_size < table.offset + table.length + padding_size) {
120      return FONT_COMPRESSION_FAILURE();
121    }
122    memset(dst + table.offset + table.length, 0, padding_size);
123  }
124  return true;
125}
126
127int NumGlyphs(const Font& font) {
128  const Font::Table* head_table = font.FindTable(kHeadTableTag);
129  const Font::Table* loca_table = font.FindTable(kLocaTableTag);
130  if (head_table == NULL || loca_table == NULL || head_table->length < 52) {
131    return 0;
132  }
133  int index_fmt = head_table->data[51];
134  return (loca_table->length / (index_fmt == 0 ? 2 : 4)) - 1;
135}
136
137bool GetGlyphData(const Font& font, int glyph_index,
138                  const uint8_t** glyph_data, size_t* glyph_size) {
139  if (glyph_index < 0) {
140    return FONT_COMPRESSION_FAILURE();
141  }
142  const Font::Table* head_table = font.FindTable(kHeadTableTag);
143  const Font::Table* loca_table = font.FindTable(kLocaTableTag);
144  const Font::Table* glyf_table = font.FindTable(kGlyfTableTag);
145  if (head_table == NULL || loca_table == NULL || glyf_table == NULL ||
146      head_table->length < 52) {
147    return FONT_COMPRESSION_FAILURE();
148  }
149  int index_fmt = head_table->data[51];
150  Buffer loca_buf(loca_table->data, loca_table->length);
151  if (index_fmt == 0) {
152    uint16_t offset1, offset2;
153    if (!loca_buf.Skip(2 * glyph_index) ||
154        !loca_buf.ReadU16(&offset1) ||
155        !loca_buf.ReadU16(&offset2) ||
156        offset2 < offset1 ||
157        2 * offset2 > glyf_table->length) {
158      return FONT_COMPRESSION_FAILURE();
159    }
160    *glyph_data = glyf_table->data + 2 * offset1;
161    *glyph_size = 2 * (offset2 - offset1);
162  } else {
163    uint32_t offset1, offset2;
164    if (!loca_buf.Skip(4 * glyph_index) ||
165        !loca_buf.ReadU32(&offset1) ||
166        !loca_buf.ReadU32(&offset2) ||
167        offset2 < offset1 ||
168        offset2 > glyf_table->length) {
169      return FONT_COMPRESSION_FAILURE();
170    }
171    *glyph_data = glyf_table->data + offset1;
172    *glyph_size = offset2 - offset1;
173  }
174  return true;
175}
176
177bool RemoveDigitalSignature(Font* font) {
178  std::map<uint32_t, Font::Table>::iterator it =
179      font->tables.find(kDsigTableTag);
180  if (it != font->tables.end()) {
181    font->tables.erase(it);
182    font->num_tables = font->tables.size();
183  }
184  return true;
185}
186
187} // namespace woff2
188