Bug 1171208 - Fix null-terminating chunks in ChunkedJSONWriteFunc. (r=mstange)

tools/profiler/ProfileJSONWriter.cpp

@@ -12,6 +12,7 @@ ChunkedJSONWriteFunc::Write(const char* aStr)
 {
   MOZ_ASSERT(mChunkPtr >= mChunkList.back().get() && mChunkPtr <= mChunkEnd);
   MOZ_ASSERT(mChunkEnd >= mChunkList.back().get() + mChunkLengths.back());
+  MOZ_ASSERT(*mChunkPtr == '\0');
 
   size_t len = strlen(aStr);
 
@@ -20,17 +21,18 @@ ChunkedJSONWriteFunc::Write(const char* aStr)
   // than a chunk, allocate its own chunk.
   char* newPtr;
   if (len >= kChunkSize) {
-    AllocChunk(len);
+    AllocChunk(len + 1);
     newPtr = mChunkPtr + len;
   } else {
     newPtr = mChunkPtr + len;
-    if (newPtr > mChunkEnd) {
+    if (newPtr >= mChunkEnd) {
       AllocChunk(kChunkSize);
       newPtr = mChunkPtr + len;
     }
   }
 
   memcpy(mChunkPtr, aStr, len);
+  *newPtr = '\0';
   mChunkPtr = newPtr;
   mChunkLengths.back() += len;
 }
@@ -62,6 +64,7 @@ ChunkedJSONWriteFunc::AllocChunk(size_t aChunkSize)
   mozilla::UniquePtr<char[]> newChunk = mozilla::MakeUnique<char[]>(aChunkSize);
   mChunkPtr = newChunk.get();
   mChunkEnd = mChunkPtr + aChunkSize;
+  *mChunkPtr = '\0';
   MOZ_ALWAYS_TRUE(mChunkLengths.append(0));
   MOZ_ALWAYS_TRUE(mChunkList.append(mozilla::Move(newChunk)));
 }