The Tor Browser: comparison gfx/ots/src/kern.cc

--1:000000000000
+:0c42a67a498f
+// 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 "kern.h"
+// kern - Kerning
+// http://www.microsoft.com/typography/otspec/kern.htm
+#define TABLE_NAME "kern"
+#define DROP_THIS_TABLE \
+do { \
+delete file->kern; \
+file->kern = 0; \
+OTS_FAILURE_MSG("Table discarded"); \
+} while (0)
+namespace ots {
+bool ots_kern_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
+Buffer table(data, length);
+OpenTypeKERN *kern = new OpenTypeKERN;
+file->kern = kern;
+uint16_t num_tables = 0;
+if (!table.ReadU16(&kern->version) ||
+!table.ReadU16(&num_tables)) {
+return OTS_FAILURE_MSG("Failed to read kern header");
+}
+if (kern->version > 0) {
+DROP_THIS_TABLE;
+return true;
+}
+if (num_tables == 0) {
+OTS_WARNING("num_tables is zero");
+DROP_THIS_TABLE;
+return true;
+}
+kern->subtables.reserve(num_tables);
+for (unsigned i = 0; i < num_tables; ++i) {
+OpenTypeKERNFormat0 subtable;
+uint16_t sub_length = 0;
+if (!table.ReadU16(&subtable.version) ||
+!table.ReadU16(&sub_length)) {
+return OTS_FAILURE_MSG("Failed to read kern subtable %d header", i);
+}
+if (subtable.version > 0) {
+OTS_WARNING("Bad subtable version: %d", subtable.version);
+continue;
+}
+const size_t current_offset = table.offset();
+if (current_offset - 4 + sub_length > length) {
+return OTS_FAILURE_MSG("Bad kern subtable %d offset %ld", i, current_offset);
+}
+if (!table.ReadU16(&subtable.coverage)) {
+return OTS_FAILURE_MSG("Cailed to read kern subtable %d coverage", i);
+}
+if (!(subtable.coverage & 0x1)) {
+OTS_WARNING(
+"We don't support vertical data as the renderer doesn't support it.");
+continue;
+}
+if (subtable.coverage & 0xF0) {
+OTS_WARNING("Reserved fields should zero-filled.");
+DROP_THIS_TABLE;
+return true;
+}
+const uint32_t format = (subtable.coverage & 0xFF00) >> 8;
+if (format != 0) {
+OTS_WARNING("Format %d is not supported.", format);
+continue;
+}
+// Parse the format 0 field.
+uint16_t num_pairs = 0;
+if (!table.ReadU16(&num_pairs) ||
+!table.ReadU16(&subtable.search_range) ||
+!table.ReadU16(&subtable.entry_selector) ||
+!table.ReadU16(&subtable.range_shift)) {
+return OTS_FAILURE_MSG("Failed to read kern subtable %d format 0 fields", i);
+}
+if (!num_pairs) {
+OTS_WARNING("Zero length subtable is found.");
+DROP_THIS_TABLE;
+return true;
+}
+// Sanity checks for search_range, entry_selector, and range_shift. See the
+// comment in ots.cc for details.
+const size_t kFormat0PairSize = 6;  // left, right, and value. 2 bytes each.
+if (num_pairs > (65536 / kFormat0PairSize)) {
+// Some fonts (e.g. calibri.ttf, pykes_peak_zero.ttf) have pairs >= 10923.
+OTS_WARNING("Too large subtable.");
+DROP_THIS_TABLE;
+return true;
+}
+unsigned max_pow2 = 0;
+while (1u << (max_pow2 + 1) <= num_pairs) {
+++max_pow2;
+}
+const uint16_t expected_search_range = (1u << max_pow2) * kFormat0PairSize;
+if (subtable.search_range != expected_search_range) {
+OTS_WARNING("bad search range");
+subtable.search_range = expected_search_range;
+}
+if (subtable.entry_selector != max_pow2) {
+return OTS_FAILURE_MSG("Bad subtable %d entry selector %d", i, subtable.entry_selector);
+}
+const uint32_t expected_range_shift
+= kFormat0PairSize * num_pairs - subtable.search_range;
+if (subtable.range_shift != expected_range_shift) {
+OTS_WARNING("bad range shift");
+subtable.range_shift = expected_range_shift;
+}
+// Read kerning pairs.
+subtable.pairs.reserve(num_pairs);
+uint32_t last_pair = 0;
+for (unsigned j = 0; j < num_pairs; ++j) {
+OpenTypeKERNFormat0Pair kerning_pair;
+if (!table.ReadU16(&kerning_pair.left) ||
+!table.ReadU16(&kerning_pair.right) ||
+!table.ReadS16(&kerning_pair.value)) {
+return OTS_FAILURE_MSG("Failed to read subtable %d kerning pair %d", i, j);
+}
+const uint32_t current_pair
+= (kerning_pair.left << 16) + kerning_pair.right;
+if (j != 0 && current_pair <= last_pair) {
+OTS_WARNING("Kerning pairs are not sorted.");
+// Many free fonts don't follow this rule, so we don't call OTS_FAILURE
+// in order to support these fonts.
+DROP_THIS_TABLE;
+return true;
+}
+last_pair = current_pair;
+subtable.pairs.push_back(kerning_pair);
+}
+kern->subtables.push_back(subtable);
+}
+if (!kern->subtables.size()) {
+OTS_WARNING("All subtables are removed.");
+DROP_THIS_TABLE;
+return true;
+}
+return true;
+}
+bool ots_kern_should_serialise(OpenTypeFile *file) {
+if (!file->glyf) return false;  // this table is not for CFF fonts.
+return file->kern != NULL;
+}
+bool ots_kern_serialise(OTSStream *out, OpenTypeFile *file) {
+const OpenTypeKERN *kern = file->kern;
+if (!out->WriteU16(kern->version) ||
+!out->WriteU16(kern->subtables.size())) {
+return OTS_FAILURE_MSG("Can't write kern table header");
+}
+for (unsigned i = 0; i < kern->subtables.size(); ++i) {
+const uint16_t length = 14 + (6 * kern->subtables[i].pairs.size());
+if (!out->WriteU16(kern->subtables[i].version) ||
+!out->WriteU16(length) ||
+!out->WriteU16(kern->subtables[i].coverage) ||
+!out->WriteU16(kern->subtables[i].pairs.size()) ||
+!out->WriteU16(kern->subtables[i].search_range) ||
+!out->WriteU16(kern->subtables[i].entry_selector) ||
+!out->WriteU16(kern->subtables[i].range_shift)) {
+return OTS_FAILURE_MSG("Failed to write kern subtable %d", i);
+}
+for (unsigned j = 0; j < kern->subtables[i].pairs.size(); ++j) {
+if (!out->WriteU16(kern->subtables[i].pairs[j].left) ||
+!out->WriteU16(kern->subtables[i].pairs[j].right) ||
+!out->WriteS16(kern->subtables[i].pairs[j].value)) {
+return OTS_FAILURE_MSG("Failed to write kern pair %d for subtable %d", j, i);
+}
+}
+}
+return true;
+}
+void ots_kern_free(OpenTypeFile *file) {
+delete file->kern;
+}
+}  // namespace ots

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comparison: gfx/ots/src/kern.cc

gfx/ots/src/kern.cc