Revert of Update OTS to revision 6d2e08b (patchset #1 id:1 of https://codereview.chromium.org/1062093002/)

Reason for revert:
This CL caused many tests fail on uninit read errors reported by MSan

BUG=474597

Original issue's description:
> Update OTS to revision 6d2e08b
>
> This brings in a bugfix of checksum calculation that caused assertion
> failure on debug builds.
>
> BUG=464780
>
> Committed: https://crrev.com/3a672fe050438bc787af3f9bb652048291558c6c
> Cr-Commit-Position: refs/heads/master@{#324023}

TBR=bashi@chromium.org,ksakamoto@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=464780

Review URL: https://codereview.chromium.org/1064913002

Cr-Commit-Position: refs/heads/master@{#324046}

9 files changed, 131 insertions, 125 deletions

diff --git a/third_party/ots/README.chromium b/third_party/ots/README.chromium
index befc3aa..ffe584d 100644
--- a/third_party/ots/README.chromium
+++ b/third_party/ots/README.chromium
@@ -1,9 +1,8 @@
 Name: OTS
 URL: https://github.com/khaledhosny/ots.git
-Version: 6d2e08bdc56d6739d48f5e59594669616f6b8b9d
+Version: 4d011721c2eadd4e649326f8d164423db060d85e
 Security Critical: yes
 License: BSD
 
 Local Modifications:
 - src/woff2.cc: Changed include path to brotli/dec/decode.h.
-- BUILD.gn: Added.
diff --git a/third_party/ots/include/opentype-sanitiser.h b/third_party/ots/include/opentype-sanitiser.h
index 285a438..1c445ae 100644
--- a/third_party/ots/include/opentype-sanitiser.h
+++ b/third_party/ots/include/opentype-sanitiser.h
@@ -29,9 +29,6 @@ typedef unsigned __int64 uint64_t;
 #include <cstddef>
 #include <cstring>
 
-#define OTS_TAG(c1,c2,c3,c4) ((uint32_t)((((uint8_t)(c1))<<24)|(((uint8_t)(c2))<<16)|(((uint8_t)(c3))<<8)|((uint8_t)(c4))))
-#define OTS_UNTAG(tag)       ((uint8_t)((tag)>>24)), ((uint8_t)((tag)>>16)), ((uint8_t)((tag)>>8)), ((uint8_t)(tag))
-
 namespace ots {
 
 // -----------------------------------------------------------------------------
@@ -40,7 +37,9 @@ namespace ots {
 // -----------------------------------------------------------------------------
 class OTSStream {
  public:
-  OTSStream() : chksum_(0) {}
+  OTSStream() {
+    ResetChecksum();
+  }
 
   virtual ~OTSStream() {}
 
@@ -52,15 +51,20 @@ class OTSStream {
 
     const size_t orig_length = length;
     size_t offset = 0;
+    if (chksum_buffer_offset_) {
+      const size_t l =
+        std::min(length, static_cast<size_t>(4) - chksum_buffer_offset_);
+      std::memcpy(chksum_buffer_ + chksum_buffer_offset_, data, l);
+      chksum_buffer_offset_ += l;
+      offset += l;
+      length -= l;
+    }
 
-    size_t chksum_offset = Tell() & 3;
-    if (chksum_offset) {
-      const size_t l = std::min(length, static_cast<size_t>(4) - chksum_offset);
-      uint32_t tmp = 0;
-      std::memcpy(reinterpret_cast<uint8_t *>(&tmp) + chksum_offset, data, l);
+    if (chksum_buffer_offset_ == 4) {
+      uint32_t tmp;
+      std::memcpy(&tmp, chksum_buffer_, 4);
       chksum_ += ntohl(tmp);
-      length -= l;
-      offset += l;
+      chksum_buffer_offset_ = 0;
     }
 
     while (length >= 4) {
@@ -73,11 +77,11 @@ class OTSStream {
     }
 
     if (length) {
+      if (chksum_buffer_offset_ != 0) return false;  // not reached
       if (length > 4) return false;  // not reached
-      uint32_t tmp = 0;
-      std::memcpy(&tmp,
-                  reinterpret_cast<const uint8_t*>(data) + offset, length);
-      chksum_ += ntohl(tmp);
+      std::memcpy(chksum_buffer_,
+             reinterpret_cast<const uint8_t*>(data) + offset, length);
+      chksum_buffer_offset_ = length;
     }
 
     return WriteRaw(data, orig_length);
@@ -138,16 +142,41 @@ class OTSStream {
   }
 
   void ResetChecksum() {
-    assert((Tell() & 3) == 0);
     chksum_ = 0;
+    chksum_buffer_offset_ = 0;
   }
 
   uint32_t chksum() const {
+    assert(chksum_buffer_offset_ == 0);
     return chksum_;
   }
 
+  struct ChecksumState {
+    uint32_t chksum;
+    uint8_t chksum_buffer[4];
+    unsigned chksum_buffer_offset;
+  };
+
+  ChecksumState SaveChecksumState() const {
+    ChecksumState s;
+    s.chksum = chksum_;
+    s.chksum_buffer_offset = chksum_buffer_offset_;
+    std::memcpy(s.chksum_buffer, chksum_buffer_, 4);
+
+    return s;
+  }
+
+  void RestoreChecksum(const ChecksumState &s) {
+    assert(chksum_buffer_offset_ == 0);
+    chksum_ += s.chksum;
+    chksum_buffer_offset_ = s.chksum_buffer_offset;
+    std::memcpy(chksum_buffer_, s.chksum_buffer, 4);
+  }
+
  protected:
   uint32_t chksum_;
+  uint8_t chksum_buffer_[4];
+  unsigned chksum_buffer_offset_;
 };
 
 #ifdef __GCC__
@@ -189,6 +218,9 @@ class OTSContext {
     virtual TableAction GetTableAction(uint32_t tag) { return ots::TABLE_ACTION_DEFAULT; }
 };
 
+// For backward compatibility - remove once Chrome switches over to the new API.
+bool Process(OTSStream *output, const uint8_t *input, size_t length);
+
 }  // namespace ots
 
 #endif  // OPENTYPE_SANITISER_H_
diff --git a/third_party/ots/src/cmap.cc b/third_party/ots/src/cmap.cc
index a238300..b1bf5fd 100644
--- a/third_party/ots/src/cmap.cc
+++ b/third_party/ots/src/cmap.cc
@@ -1023,6 +1023,10 @@ bool ots_cmap_serialise(OTSStream *out, OpenTypeFile *file) {
   }
 
   const off_t table_end = out->Tell();
+  // We might have hanging bytes from the above's checksum which the OTSStream
+  // then merges into the table of offsets.
+  OTSStream::ChecksumState saved_checksum = out->SaveChecksumState();
+  out->ResetChecksum();
 
   // Now seek back and write the table of offsets
   if (!out->Seek(record_offset)) {
@@ -1088,6 +1092,7 @@ bool ots_cmap_serialise(OTSStream *out, OpenTypeFile *file) {
   if (!out->Seek(table_end)) {
     return OTS_FAILURE();
   }
+  out->RestoreChecksum(saved_checksum);
 
   return true;
 }
diff --git a/third_party/ots/src/os2.cc b/third_party/ots/src/os2.cc
index 3c0d1fd..915877e 100644
--- a/third_party/ots/src/os2.cc
+++ b/third_party/ots/src/os2.cc
@@ -2,9 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <string>
-
 #include "os2.h"
+
 #include "head.h"
 
 // OS/2 - OS/2 and Windows Metrics
@@ -36,29 +35,26 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
       !table.ReadS16(&os2->strikeout_size) ||
       !table.ReadS16(&os2->strikeout_position) ||
       !table.ReadS16(&os2->family_class)) {
-    return OTS_FAILURE_MSG("Error reading basic table elements");
+    return OTS_FAILURE_MSG("Failed toi read basic os2 elements");
   }
 
-  if (os2->version > 5) {
-    return OTS_FAILURE_MSG("Unsupported table version: %u", os2->version);
+  if (os2->version > 4) {
+    return OTS_FAILURE_MSG("os2 version too high %d", os2->version);
   }
 
-  // Follow WPF Font Selection Model's advice.
-  if (1 <= os2->weight_class && os2->weight_class <= 9) {
-    OTS_WARNING("Bad usWeightClass: %u, changing it to: %u", os2->weight_class, os2->weight_class * 100);
-    os2->weight_class *= 100;
+  // Some linux fonts (e.g., Kedage-t.ttf and LucidaSansDemiOblique.ttf) have
+  // weird weight/width classes. Overwrite them with FW_NORMAL/1/9.
+  if (os2->weight_class < 100 ||
+      os2->weight_class > 900 ||
+      os2->weight_class % 100) {
+    OTS_WARNING("bad weight: %u", os2->weight_class);
+    os2->weight_class = 400;  // FW_NORMAL
   }
-  // Ditto.
-  if (os2->weight_class > 999) {
-    OTS_WARNING("Bad usWeightClass: %u, changing it to: %d", os2->weight_class, 999);
-    os2->weight_class = 999;
-  }
-
   if (os2->width_class < 1) {
-    OTS_WARNING("Bad usWidthClass: %u, changing it to: %d", os2->width_class, 1);
+    OTS_WARNING("bad width: %u", os2->width_class);
     os2->width_class = 1;
   } else if (os2->width_class > 9) {
-    OTS_WARNING("Bad usWidthClass: %u, changing it to: %d", os2->width_class, 9);
+    OTS_WARNING("bad width: %u", os2->width_class);
     os2->width_class = 9;
   }
 
@@ -77,34 +73,30 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
   // mask reserved bits. use only 0..3, 8, 9 bits.
   os2->type &= 0x30f;
 
-#define SET_TO_ZERO(a, b)                                     \
-  if (os2->b < 0) {                                           \
-    OTS_WARNING("Bad " a ": %d, setting it to zero", os2->b); \
-    os2->b = 0;                                               \
-  }
-
-  SET_TO_ZERO("ySubscriptXSize", subscript_x_size);
-  SET_TO_ZERO("ySubscriptYSize", subscript_y_size);
-  SET_TO_ZERO("ySuperscriptXSize", superscript_x_size);
-  SET_TO_ZERO("ySuperscriptYSize", superscript_y_size);
-  SET_TO_ZERO("yStrikeoutSize", strikeout_size);
-#undef SET_TO_ZERO
-
-  static std::string panose_strings[10] = {
-    "bFamilyType",
-    "bSerifStyle",
-    "bWeight",
-    "bProportion",
-    "bContrast",
-    "bStrokeVariation",
-    "bArmStyle",
-    "bLetterform",
-    "bMidline",
-    "bXHeight",
-  };
+  if (os2->subscript_x_size < 0) {
+    OTS_WARNING("bad subscript_x_size: %d", os2->subscript_x_size);
+    os2->subscript_x_size = 0;
+  }
+  if (os2->subscript_y_size < 0) {
+    OTS_WARNING("bad subscript_y_size: %d", os2->subscript_y_size);
+    os2->subscript_y_size = 0;
+  }
+  if (os2->superscript_x_size < 0) {
+    OTS_WARNING("bad superscript_x_size: %d", os2->superscript_x_size);
+    os2->superscript_x_size = 0;
+  }
+  if (os2->superscript_y_size < 0) {
+    OTS_WARNING("bad superscript_y_size: %d", os2->superscript_y_size);
+    os2->superscript_y_size = 0;
+  }
+  if (os2->strikeout_size < 0) {
+    OTS_WARNING("bad strikeout_size: %d", os2->strikeout_size);
+    os2->strikeout_size = 0;
+  }
+
   for (unsigned i = 0; i < 10; ++i) {
     if (!table.ReadU8(&os2->panose[i])) {
-      return OTS_FAILURE_MSG("Error reading PANOSE %s", panose_strings[i].c_str());
+      return OTS_FAILURE_MSG("Failed to read panose in os2 table");
     }
   }
 
@@ -121,7 +113,7 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
       !table.ReadS16(&os2->typo_linegap) ||
       !table.ReadU16(&os2->win_ascent) ||
       !table.ReadU16(&os2->win_descent)) {
-    return OTS_FAILURE_MSG("Error reading more basic table fields");
+    return OTS_FAILURE_MSG("Failed to read more basic os2 fields");
   }
 
   // If bit 6 is set, then bits 0 and 5 must be clear.
@@ -132,7 +124,7 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
   // the settings of bits 0 and 1 must be reflected in the macStyle bits
   // in the 'head' table.
   if (!file->head) {
-    return OTS_FAILURE_MSG("Needed head table is missing from the font");
+    return OTS_FAILURE_MSG("Head table missing from font as needed by os2 table");
   }
   if ((os2->selection & 0x1) &&
       !(file->head->mac_style & 0x2)) {
@@ -156,7 +148,7 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
   if ((os2->version < 4) &&
       (os2->selection & 0x300)) {
     // bit 8 and 9 must be unset in OS/2 table versions less than 4.
-    return OTS_FAILURE_MSG("Version %d incompatible with selection %d", os2->version, os2->selection);
+    return OTS_FAILURE_MSG("OS2 version %d incompatible with selection %d", os2->version, os2->selection);
   }
 
   // mask reserved bits. use only 0..9 bits.
@@ -206,7 +198,7 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
       !table.ReadU16(&os2->default_char) ||
       !table.ReadU16(&os2->break_char) ||
       !table.ReadU16(&os2->max_context)) {
-    return OTS_FAILURE_MSG("Failed to read version 2-specific fields");
+    return OTS_FAILURE_MSG("Failed to read os2 version 2 information");
   }
 
   if (os2->x_height < 0) {
@@ -218,26 +210,6 @@ bool ots_os2_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
     os2->cap_height = 0;
   }
 
-  if (os2->version < 5) {
-    // http://www.microsoft.com/typography/otspec/os2ver4.htm
-    return true;
-  }
-
-  if (!table.ReadU16(&os2->lower_optical_pointsize) ||
-      !table.ReadU16(&os2->upper_optical_pointsize)) {
-    return OTS_FAILURE_MSG("Failed to read version 5-specific fields");
-  }
-
-  if (os2->lower_optical_pointsize > 0xFFFE) {
-    OTS_WARNING("'usLowerOpticalPointSize' is bigger than 0xFFFE: %d", os2->lower_optical_pointsize);
-    os2->lower_optical_pointsize = 0xFFFE;
-  }
-
-  if (os2->upper_optical_pointsize < 2) {
-    OTS_WARNING("'usUpperOpticalPointSize' is lower than 2: %d", os2->upper_optical_pointsize);
-    os2->upper_optical_pointsize = 2;
-  }
-
   return true;
 }
 
@@ -286,7 +258,7 @@ bool ots_os2_serialise(OTSStream *out, OpenTypeFile *file) {
       !out->WriteS16(os2->typo_linegap) ||
       !out->WriteU16(os2->win_ascent) ||
       !out->WriteU16(os2->win_descent)) {
-    return OTS_FAILURE_MSG("Failed to write version 1-specific fields");
+    return OTS_FAILURE_MSG("Failed to write os2 version 1 information");
   }
 
   if (os2->version < 1) {
@@ -307,16 +279,7 @@ bool ots_os2_serialise(OTSStream *out, OpenTypeFile *file) {
       !out->WriteU16(os2->default_char) ||
       !out->WriteU16(os2->break_char) ||
       !out->WriteU16(os2->max_context)) {
-    return OTS_FAILURE_MSG("Failed to write version 2-specific fields");
-  }
-
-  if (os2->version < 2) {
-    return true;
-  }
-
-  if (!out->WriteU16(os2->lower_optical_pointsize) ||
-      !out->WriteU16(os2->upper_optical_pointsize)) {
-    return OTS_FAILURE_MSG("Failed to write version 5-specific fields");
+    return OTS_FAILURE_MSG("Failed to write os2 version 2 information");
   }
 
   return true;
diff --git a/third_party/ots/src/os2.h b/third_party/ots/src/os2.h
index 01511c5..9e0fc34 100644
--- a/third_party/ots/src/os2.h
+++ b/third_party/ots/src/os2.h
@@ -47,8 +47,6 @@ struct OpenTypeOS2 {
   uint16_t default_char;
   uint16_t break_char;
   uint16_t max_context;
-  uint16_t lower_optical_pointsize;
-  uint16_t upper_optical_pointsize;
 };
 
 }  // namespace ots
diff --git a/third_party/ots/src/ots.cc b/third_party/ots/src/ots.cc
index 28d0285d..5ba8dd9 100644
--- a/third_party/ots/src/ots.cc
+++ b/third_party/ots/src/ots.cc
@@ -24,7 +24,6 @@ namespace {
 // Generate a message with or without a table tag, when 'header' is the OpenTypeFile pointer
 #define OTS_FAILURE_MSG_TAG(msg_,tag_) OTS_FAILURE_MSG_TAG_(header, msg_, tag_)
 #define OTS_FAILURE_MSG_HDR(msg_)      OTS_FAILURE_MSG_(header, msg_)
-#define OTS_WARNING_MSG_HDR(msg_)      OTS_WARNING_MSG_(header, msg_)
 
 
 struct OpenTypeTable {
@@ -473,7 +472,7 @@ bool ProcessGeneric(ots::OpenTypeFile *header, uint32_t signature,
       const uint32_t this_tag = ntohl(tables[i].tag);
       const uint32_t prev_tag = ntohl(tables[i - 1].tag);
       if (this_tag <= prev_tag) {
-        OTS_WARNING_MSG_HDR("Table directory is not correctly ordered");
+        return OTS_FAILURE_MSG_HDR("table directory not correctly ordered");
       }
     }
 
@@ -819,4 +818,10 @@ bool OTSContext::Process(OTSStream *output,
   return result;
 }
 
+// For backward compatibility
+bool Process(OTSStream *output, const uint8_t *data, size_t length) {
+  static OTSContext context;
+  return context.Process(output, data, length);
+}
+
 }  // namespace ots
diff --git a/third_party/ots/src/woff2.cc b/third_party/ots/src/woff2.cc
index 5a79598..b244aec 100644
--- a/third_party/ots/src/woff2.cc
+++ b/third_party/ots/src/woff2.cc
@@ -45,7 +45,7 @@ const size_t kCompositeGlyphBegin = 10;
 
 // Note that the byte order is big-endian, not the same as ots.cc
 #define TAG(a, b, c, d) ((a << 24) | (b << 16) | (c << 8) | d)
-#define UNTAG(t)         (t >> 24),  (t >> 16),  (t >> 8), (t >> 0)
+#define CHR(t)           (t >> 24),  (t >> 16),  (t >> 8), (t >> 0)
 
 const unsigned int kWoff2FlagsTransform = 1 << 5;
 
@@ -772,6 +772,17 @@ bool FixChecksums(const std::vector<Table>& tables, uint8_t* dst) {
   return true;
 }
 
+bool Woff2Uncompress(uint8_t* dst_buf, size_t dst_size,
+    const uint8_t* src_buf, size_t src_size) {
+  size_t uncompressed_size = dst_size;
+  int ok = BrotliDecompressBuffer(src_size, src_buf,
+                                  &uncompressed_size, dst_buf);
+  if (!ok || uncompressed_size != dst_size) {
+    return OTS_FAILURE();
+  }
+  return true;
+}
+
 bool ReadTableDirectory(ots::OpenTypeFile* file,
     ots::Buffer* buffer, std::vector<Table>* tables,
     size_t num_tables) {
@@ -801,16 +812,12 @@ bool ReadTableDirectory(ots::OpenTypeFile* file,
     }
     uint32_t dst_length;
     if (!ReadBase128(buffer, &dst_length)) {
-      return OTS_FAILURE_MSG("Failed to read 'origLength' for table '%c%c%c%c'", UNTAG(tag));
+      return OTS_FAILURE_MSG("Failed to read 'origLength' for table '%c%c%c%c'", CHR(tag));
     }
     uint32_t transform_length = dst_length;
     if ((flags & kWoff2FlagsTransform) != 0) {
       if (!ReadBase128(buffer, &transform_length)) {
-        return OTS_FAILURE_MSG("Failed to read 'transformLength' for table '%c%c%c%c'", UNTAG(tag));
-      }
-
-      if (tag == TAG('l', 'o', 'c', 'a') && transform_length != 0) {
-        return OTS_FAILURE_MSG("The 'transformLength' of 'loca' table must be zero: %d", transform_length);
+        return OTS_FAILURE_MSG("Failed to read 'transformLength' for table '%c%c%c%c'", CHR(tag));
       }
     }
     // Disallow huge numbers (> 1GB) for sanity.
@@ -1013,16 +1020,13 @@ bool ConvertWOFF2ToSFNT(ots::OpenTypeFile* file,
   if (total_size > 30 * 1024 * 1024) {
     return OTS_FAILURE();
   }
-  size_t uncompressed_size = static_cast<size_t>(total_size);
-  uncompressed_buf.resize(uncompressed_size);
-  const uint8_t* compressed_buf = data + compressed_offset;
-  if (!BrotliDecompressBuffer(compressed_length, compressed_buf,
-                              &uncompressed_size, &uncompressed_buf[0])) {
+  const size_t total_size_size_t = static_cast<size_t>(total_size);
+  uncompressed_buf.resize(total_size_size_t);
+  const uint8_t* src_buf = data + compressed_offset;
+  if (!Woff2Uncompress(&uncompressed_buf[0], total_size_size_t,
+      src_buf, compressed_length)) {
     return OTS_FAILURE_MSG("Failed to uncompress font data");
   }
-  if (uncompressed_size != static_cast<size_t>(total_size)) {
-    return OTS_FAILURE_MSG("Decompressed font data size does not match the sum of 'origLength' and 'transformLength'");
-  }
   transform_buf = &uncompressed_buf[0];
 
   for (uint16_t i = 0; i < num_tables; ++i) {
@@ -1043,7 +1047,7 @@ bool ConvertWOFF2ToSFNT(ots::OpenTypeFile* file,
     } else {
       if (!ReconstructTransformed(file, tables, table->tag,
             transform_buf, transform_length, result, result_length)) {
-        return OTS_FAILURE_MSG("Failed to reconstruct '%c%c%c%c' table", UNTAG(table->tag));
+        return OTS_FAILURE_MSG("Failed to reconstruct '%c%c%c%c' table", CHR(table->tag));
       }
     }
 
diff --git a/third_party/ots/test/ot-sanitise.cc b/third_party/ots/test/ot-sanitise.cc
index 3204ce4..2d4526a 100644
--- a/third_party/ots/test/ot-sanitise.cc
+++ b/third_party/ots/test/ot-sanitise.cc
@@ -49,18 +49,18 @@ class Context: public ots::OTSContext {
   }
 
   virtual ots::TableAction GetTableAction(uint32_t tag) {
+#define TAG(a, b, c, d) ((a) << 24 | (b) << 16 | (c) << 8 | (d))
     switch (tag) {
-      case OTS_TAG('S','i','l','f'):
-      case OTS_TAG('S','i','l','l'):
-      case OTS_TAG('G','l','o','c'):
-      case OTS_TAG('G','l','a','t'):
-      case OTS_TAG('F','e','a','t'):
-      case OTS_TAG('C','B','D','T'):
-      case OTS_TAG('C','B','L','C'):
+      case TAG('S','i','l','f'):
+      case TAG('S','i','l','l'):
+      case TAG('G','l','o','c'):
+      case TAG('G','l','a','t'):
+      case TAG('F','e','a','t'):
         return ots::TABLE_ACTION_PASSTHRU;
       default:
         return ots::TABLE_ACTION_DEFAULT;
     }
+#undef TAG
   }
 };
 
diff --git a/third_party/ots/test/side-by-side.cc b/third_party/ots/test/side-by-side.cc
index 8565bfe..9034a7c 100644
--- a/third_party/ots/test/side-by-side.cc
+++ b/third_party/ots/test/side-by-side.cc
@@ -20,7 +20,7 @@
 namespace {
 
 void DumpBitmap(const FT_Bitmap *bitmap) {
-  for (unsigned int i = 0; i < bitmap->rows * bitmap->width; ++i) {
+  for (int i = 0; i < bitmap->rows * bitmap->width; ++i) {
     if (bitmap->buffer[i] > 192) {
       std::fprintf(stderr, "#");
     } else if (bitmap->buffer[i] > 128) {
@@ -44,7 +44,7 @@ int CompareBitmaps(const FT_Bitmap *orig, const FT_Bitmap *trans) {
 
   if (orig->width == trans->width &&
       orig->rows == trans->rows) {
-    for (unsigned int i = 0; i < orig->rows * orig->width; ++i) {
+    for (int i = 0; i < orig->rows * orig->width; ++i) {
       if (orig->buffer[i] != trans->buffer[i]) {
         std::fprintf(stderr, "bitmap data doesn't match!\n");
         ret = 1;