third_party/ots/src/post.cc

   1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "post.h"
   6
   7 #include "maxp.h"
   8
   9 // post - PostScript
  10 // http://www.microsoft.com/typography/otspec/post.htm
  11
  12 #define TABLE_NAME "post"
  13
  14 namespace ots {
  15
  16 bool ots_post_parse(Font *font, const uint8_t *data, size_t length) {
  17   Buffer table(data, length);
  18
  19   OpenTypePOST *post = new OpenTypePOST;
  20   font->post = post;
  21
  22   if (!table.ReadU32(&post->version) ||
  23       !table.ReadU32(&post->italic_angle) ||
  24       !table.ReadS16(&post->underline) ||
  25       !table.ReadS16(&post->underline_thickness) ||
  26       !table.ReadU32(&post->is_fixed_pitch)) {
  27     return OTS_FAILURE_MSG("Failed to read post header");
  28   }
  29
  30   if (post->underline_thickness < 0) {
  31     post->underline_thickness = 1;
  32   }
  33
  34   if (post->version == 0x00010000) {
  35     return true;
  36   } else if (post->version == 0x00030000) {
  37     return true;
  38   } else if (post->version != 0x00020000) {
  39     // 0x00025000 is deprecated. We don't accept it.
  40     return OTS_FAILURE_MSG("Bad post version %x", post->version);
  41   }
  42
  43   // We have a version 2 table with a list of Pascal strings at the end
  44
  45   // We don't care about the memory usage fields. We'll set all these to zero
  46   // when serialising
  47   if (!table.Skip(16)) {
  48     return OTS_FAILURE_MSG("Failed to skip memory usage in post table");
  49   }
  50
  51   uint16_t num_glyphs = 0;
  52   if (!table.ReadU16(&num_glyphs)) {
  53     return OTS_FAILURE_MSG("Failed to read number of glyphs");
  54   }
  55
  56   if (!font->maxp) {
  57     return OTS_FAILURE_MSG("No maxp table required by post table");
  58   }
  59
  60   if (num_glyphs == 0) {
  61     if (font->maxp->num_glyphs > 258) {
  62       return OTS_FAILURE_MSG("Can't have no glyphs in the post table if there are more than 256 glyphs in the font");
  63     }
  64     OTS_WARNING("table version is 1, but no glyf names are found");
  65     // workaround for fonts in http://www.fontsquirrel.com/fontface
  66     // (e.g., yataghan.ttf).
  67     post->version = 0x00010000;
  68     return true;
  69   }
  70
  71   if (num_glyphs != font->maxp->num_glyphs) {
  72     // Note: Fixedsys500c.ttf seems to have inconsistent num_glyphs values.
  73     return OTS_FAILURE_MSG("Bad number of glyphs in post table %d", num_glyphs);
  74   }
  75
  76   post->glyph_name_index.resize(num_glyphs);
  77   for (unsigned i = 0; i < num_glyphs; ++i) {
  78     if (!table.ReadU16(&post->glyph_name_index[i])) {
  79       return OTS_FAILURE_MSG("Failed to read post information for glyph %d", i);
  80     }
  81     // Note: A strict interpretation of the specification requires name indexes
  82     // are less than 32768. This, however, excludes fonts like unifont.ttf
  83     // which cover all of unicode.
  84   }
  85
  86   // Now we have an array of Pascal strings. We have to check that they are all
  87   // valid and read them in.
  88   const size_t strings_offset = table.offset();
  89   const uint8_t *strings = data + strings_offset;
  90   const uint8_t *strings_end = data + length;
  91
  92   for (;;) {
  93     if (strings == strings_end) break;
  94     const unsigned string_length = *strings;
  95     if (strings + 1 + string_length > strings_end) {
  96       return OTS_FAILURE_MSG("Bad string length %d", string_length);
  97     }
  98     if (std::memchr(strings + 1, '\0', string_length)) {
  99       return OTS_FAILURE_MSG("Bad string of length %d", string_length);
 100     }
 101     post->names.push_back(
 102         std::string(reinterpret_cast<const char*>(strings + 1), string_length));
 103     strings += 1 + string_length;
 104   }
 105   const unsigned num_strings = post->names.size();
 106
 107   // check that all the references are within bounds
 108   for (unsigned i = 0; i < num_glyphs; ++i) {
 109     unsigned offset = post->glyph_name_index[i];
 110     if (offset < 258) {
 111       continue;
 112     }
 113
 114     offset -= 258;
 115     if (offset >= num_strings) {
 116       return OTS_FAILURE_MSG("Bad string index %d", offset);
 117     }
 118   }
 119
 120   return true;
 121 }
 122
 123 bool ots_post_should_serialise(Font *font) {
 124   return font->post != NULL;
 125 }
 126
 127 bool ots_post_serialise(OTSStream *out, Font *font) {
 128   const OpenTypePOST *post = font->post;
 129
 130   // OpenType with CFF glyphs must have v3 post table.
 131   if (font->post && font->cff && font->post->version != 0x00030000) {
 132     return OTS_FAILURE_MSG("Bad post version %x", post->version);
 133   }
 134
 135   if (!out->WriteU32(post->version) ||
 136       !out->WriteU32(post->italic_angle) ||
 137       !out->WriteS16(post->underline) ||
 138       !out->WriteS16(post->underline_thickness) ||
 139       !out->WriteU32(post->is_fixed_pitch) ||
 140       !out->WriteU32(0) ||
 141       !out->WriteU32(0) ||
 142       !out->WriteU32(0) ||
 143       !out->WriteU32(0)) {
 144     return OTS_FAILURE_MSG("Failed to write post header");
 145   }
 146
 147   if (post->version != 0x00020000) {
 148     return true;  // v1.0 and v3.0 does not have glyph names.
 149   }
 150
 151   const uint16_t num_indexes =
 152       static_cast<uint16_t>(post->glyph_name_index.size());
 153   if (num_indexes != post->glyph_name_index.size() ||
 154       !out->WriteU16(num_indexes)) {
 155     return OTS_FAILURE_MSG("Failed to write number of indices");
 156   }
 157
 158   for (uint16_t i = 0; i < num_indexes; ++i) {
 159     if (!out->WriteU16(post->glyph_name_index[i])) {
 160       return OTS_FAILURE_MSG("Failed to write name index %d", i);
 161     }
 162   }
 163
 164   // Now we just have to write out the strings in the correct order
 165   for (unsigned i = 0; i < post->names.size(); ++i) {
 166     const std::string& s = post->names[i];
 167     const uint8_t string_length = static_cast<uint8_t>(s.size());
 168     if (string_length != s.size() ||
 169         !out->Write(&string_length, 1)) {
 170       return OTS_FAILURE_MSG("Failed to write string %d", i);
 171     }
 172     // Some ttf fonts (e.g., frank.ttf on Windows Vista) have zero-length name.
 173     // We allow them.
 174     if (string_length > 0 && !out->Write(s.data(), string_length)) {
 175       return OTS_FAILURE_MSG("Failed to write string length for string %d", i);
 176     }
 177   }
 178
 179   return true;
 180 }
 181
 182 void ots_post_reuse(Font *font, Font *other) {
 183   font->post = other->post;
 184   font->post_reused = true;
 185 }
 186
 187 void ots_post_free(Font *font) {
 188   delete font->post;
 189 }
 190
 191 }  // namespace ots
 192
 193 #undef TABLE_NAME