diff -r 000000000000 -r 6474c204b198 gfx/ots/src/metrics.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/ots/src/metrics.cc	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,186 @@
+// Copyright (c) 2011 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 "metrics.h"
+
+#include "head.h"
+#include "maxp.h"
+
+// OpenType horizontal and vertical common header format
+// http://www.microsoft.com/typography/otspec/hhea.htm
+// http://www.microsoft.com/typography/otspec/vhea.htm
+
+#define TABLE_NAME "metrics" // XXX: use individual table names
+
+namespace ots {
+
+bool ParseMetricsHeader(OpenTypeFile *file, Buffer *table,
+                        OpenTypeMetricsHeader *header) {
+  if (!table->ReadS16(&header->ascent) ||
+      !table->ReadS16(&header->descent) ||
+      !table->ReadS16(&header->linegap) ||
+      !table->ReadU16(&header->adv_width_max) ||
+      !table->ReadS16(&header->min_sb1) ||
+      !table->ReadS16(&header->min_sb2) ||
+      !table->ReadS16(&header->max_extent) ||
+      !table->ReadS16(&header->caret_slope_rise) ||
+      !table->ReadS16(&header->caret_slope_run) ||
+      !table->ReadS16(&header->caret_offset)) {
+    return OTS_FAILURE_MSG("Failed to read metrics header");
+  }
+
+  if (header->ascent < 0) {
+    OTS_WARNING("bad ascent: %d", header->ascent);
+    header->ascent = 0;
+  }
+  if (header->linegap < 0) {
+    OTS_WARNING("bad linegap: %d", header->linegap);
+    header->linegap = 0;
+  }
+
+  if (!file->head) {
+    return OTS_FAILURE_MSG("Missing head font table");
+  }
+
+  // if the font is non-slanted, caret_offset should be zero.
+  if (!(file->head->mac_style & 2) &&
+      (header->caret_offset != 0)) {
+    OTS_WARNING("bad caret offset: %d", header->caret_offset);
+    header->caret_offset = 0;
+  }
+
+  // skip the reserved bytes
+  if (!table->Skip(8)) {
+    return OTS_FAILURE_MSG("Failed to skip reserverd bytes");
+  }
+
+  int16_t data_format;
+  if (!table->ReadS16(&data_format)) {
+    return OTS_FAILURE_MSG("Failed to read data format");
+  }
+  if (data_format) {
+    return OTS_FAILURE_MSG("Bad data format %d", data_format);
+  }
+
+  if (!table->ReadU16(&header->num_metrics)) {
+    return OTS_FAILURE_MSG("Failed to read number of metrics");
+  }
+
+  if (!file->maxp) {
+    return OTS_FAILURE_MSG("Missing maxp font table");
+  }
+
+  if (header->num_metrics > file->maxp->num_glyphs) {
+    return OTS_FAILURE_MSG("Bad number of metrics %d", header->num_metrics);
+  }
+
+  return true;
+}
+
+bool SerialiseMetricsHeader(const ots::OpenTypeFile *file,
+                            OTSStream *out,
+                            const OpenTypeMetricsHeader *header) {
+  if (!out->WriteU32(header->version) ||
+      !out->WriteS16(header->ascent) ||
+      !out->WriteS16(header->descent) ||
+      !out->WriteS16(header->linegap) ||
+      !out->WriteU16(header->adv_width_max) ||
+      !out->WriteS16(header->min_sb1) ||
+      !out->WriteS16(header->min_sb2) ||
+      !out->WriteS16(header->max_extent) ||
+      !out->WriteS16(header->caret_slope_rise) ||
+      !out->WriteS16(header->caret_slope_run) ||
+      !out->WriteS16(header->caret_offset) ||
+      !out->WriteR64(0) ||  // reserved
+      !out->WriteS16(0) ||  // metric data format
+      !out->WriteU16(header->num_metrics)) {
+    return OTS_FAILURE_MSG("Failed to write metrics");
+  }
+
+  return true;
+}
+
+bool ParseMetricsTable(const ots::OpenTypeFile *file,
+                       Buffer *table,
+                       const uint16_t num_glyphs,
+                       const OpenTypeMetricsHeader *header,
+                       OpenTypeMetricsTable *metrics) {
+  // |num_metrics| is a uint16_t, so it's bounded < 65536. This limits that
+  // amount of memory that we'll allocate for this to a sane amount.
+  const unsigned num_metrics = header->num_metrics;
+
+  if (num_metrics > num_glyphs) {
+    return OTS_FAILURE_MSG("Bad number of metrics %d", num_metrics);
+  }
+  if (!num_metrics) {
+    return OTS_FAILURE_MSG("No metrics!");
+  }
+  const unsigned num_sbs = num_glyphs - num_metrics;
+
+  metrics->entries.reserve(num_metrics);
+  for (unsigned i = 0; i < num_metrics; ++i) {
+    uint16_t adv = 0;
+    int16_t sb = 0;
+    if (!table->ReadU16(&adv) || !table->ReadS16(&sb)) {
+      return OTS_FAILURE_MSG("Failed to read metric %d", i);
+    }
+
+    // Since so many fonts don't have proper value on |adv| and |sb|,
+    // we should not call ots_failure() here. For example, about 20% of fonts
+    // in http://www.princexml.com/fonts/ (200+ fonts) fails these tests.
+    if (adv > header->adv_width_max) {
+      OTS_WARNING("bad adv: %u > %u", adv, header->adv_width_max);
+      adv = header->adv_width_max;
+    }
+
+    if (sb < header->min_sb1) {
+      OTS_WARNING("bad sb: %d < %d", sb, header->min_sb1);
+      sb = header->min_sb1;
+    }
+
+    metrics->entries.push_back(std::make_pair(adv, sb));
+  }
+
+  metrics->sbs.reserve(num_sbs);
+  for (unsigned i = 0; i < num_sbs; ++i) {
+    int16_t sb;
+    if (!table->ReadS16(&sb)) {
+      // Some Japanese fonts (e.g., mona.ttf) fail this test.
+      return OTS_FAILURE_MSG("Failed to read side bearing %d", i + num_metrics);
+    }
+
+    if (sb < header->min_sb1) {
+      // The same as above. Three fonts in http://www.fontsquirrel.com/fontface
+      // (e.g., Notice2Std.otf) have weird lsb values.
+      OTS_WARNING("bad lsb: %d < %d", sb, header->min_sb1);
+      sb = header->min_sb1;
+    }
+
+    metrics->sbs.push_back(sb);
+  }
+
+  return true;
+}
+
+bool SerialiseMetricsTable(const ots::OpenTypeFile *file,
+                           OTSStream *out,
+                           const OpenTypeMetricsTable *metrics) {
+  for (unsigned i = 0; i < metrics->entries.size(); ++i) {
+    if (!out->WriteU16(metrics->entries[i].first) ||
+        !out->WriteS16(metrics->entries[i].second)) {
+      return OTS_FAILURE_MSG("Failed to write metric %d", i);
+    }
+  }
+
+  for (unsigned i = 0; i < metrics->sbs.size(); ++i) {
+    if (!out->WriteS16(metrics->sbs[i])) {
+      return OTS_FAILURE_MSG("Failed to write side bearing %ld", i + metrics->entries.size());
+    }
+  }
+
+  return true;
+}
+
+}  // namespace ots
+