Updating to new OTS repo from https://github.com/khaledhosny/ots.git

src/loca.cc

 // 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 "loca.h"
 
 #include "head.h"
 #include "maxp.h"
 
 // loca - Index to Location
-// http://www.microsoft.com/opentype/otspec/loca.htm
+// http://www.microsoft.com/typography/otspec/loca.htm
+
+#define TABLE_NAME "loca"
 
 namespace ots {
 
 bool ots_loca_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
   Buffer table(data, length);
 
   // We can't do anything useful in validating this data except to ensure that
   // the values are monotonically increasing.
 
   OpenTypeLOCA *loca = new OpenTypeLOCA;
   file->loca = loca;
 
   if (!file->maxp || !file->head) {
-    return OTS_FAILURE();
+    return OTS_FAILURE_MSG("maxp or head tables missing from font, needed by loca");
   }
 
   const unsigned num_glyphs = file->maxp->num_glyphs;
   unsigned last_offset = 0;
   loca->offsets.resize(num_glyphs + 1);
   // maxp->num_glyphs is uint16_t, thus the addition never overflows.
 
   if (file->head->index_to_loc_format == 0) {
     // Note that the <= here (and below) is correct. There is one more offset
     // than the number of glyphs in order to give the length of the final
     // glyph.
     for (unsigned i = 0; i <= num_glyphs; ++i) {
       uint16_t offset = 0;
       if (!table.ReadU16(&offset)) {
-        return OTS_FAILURE();
+        return OTS_FAILURE_MSG("Failed to read offset for glyph %d", i);
       }
       if (offset < last_offset) {
-        return OTS_FAILURE();
+        return OTS_FAILURE_MSG("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
       }
       last_offset = offset;
       loca->offsets[i] = offset * 2;
     }
   } else {
     for (unsigned i = 0; i <= num_glyphs; ++i) {
       uint32_t offset = 0;
       if (!table.ReadU32(&offset)) {
-        return OTS_FAILURE();
+        return OTS_FAILURE_MSG("Failed to read offset for glyph %d", i);
       }
       if (offset < last_offset) {
-        return OTS_FAILURE();
+        return OTS_FAILURE_MSG("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
       }
       last_offset = offset;
       loca->offsets[i] = offset;
     }
   }
 
   return true;
 }
 
 bool ots_loca_should_serialise(OpenTypeFile *file) {
   return file->loca != NULL;
 }
 
 bool ots_loca_serialise(OTSStream *out, OpenTypeFile *file) {
   const OpenTypeLOCA *loca = file->loca;
   const OpenTypeHEAD *head = file->head;
 
   if (!head) {
-    return OTS_FAILURE();
+    return OTS_FAILURE_MSG("Missing head table in font needed by loca");
   }
 
   if (head->index_to_loc_format == 0) {
     for (unsigned i = 0; i < loca->offsets.size(); ++i) {
       const uint16_t offset = static_cast<uint16_t>(loca->offsets[i] >> 1);
       if ((offset != (loca->offsets[i] >> 1)) ||
           !out->WriteU16(offset)) {
-        return OTS_FAILURE();
+        return OTS_FAILURE_MSG("Failed to write glyph offset for glyph %d", i);
       }
     }
   } else {
     for (unsigned i = 0; i < loca->offsets.size(); ++i) {
       if (!out->WriteU32(loca->offsets[i])) {
-        return OTS_FAILURE();
+        return OTS_FAILURE_MSG("Failed to write glyph offset for glyph %d", i);
       }
     }
   }
 
   return true;
 }
 
 void ots_loca_free(OpenTypeFile *file) {
   delete file->loca;
 }
 
 }  // namespace ots
+
+#undef TABLE_NAME