From e8ce6767b14704acf54b3f567b301bfbe46b3dc8 Mon Sep 17 00:00:00 2001
From: jsteemann <jan@arangodb.com>
Date: Mon, 4 Jul 2016 14:59:50 +0200
Subject: [PATCH] fix double precision loss in VelocyPack parser

---
 3rdParty/velocypack/src/Parser.cpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/3rdParty/velocypack/src/Parser.cpp b/3rdParty/velocypack/src/Parser.cpp
index 9574b92490..1b11060341 100644
--- a/3rdParty/velocypack/src/Parser.cpp
+++ b/3rdParty/velocypack/src/Parser.cpp
@@ -28,6 +28,8 @@
 #include "velocypack/Parser.h"
 #include "asm-functions.h"
 
+#include <cstdlib>
+
 using namespace arangodb::velocypack;
 
 // The following function does the actual parse. It gets bytes
@@ -121,6 +123,7 @@ int Parser::skipWhiteSpace(char const* err) {
 
 // parses a number value
 void Parser::parseNumber() {
+  size_t startPos = _pos;
   ParsedNumber numberValue;
   bool negative = false;
   int i = consume();
@@ -191,7 +194,10 @@ void Parser::parseNumber() {
   }
   if (i != 'e' && i != 'E') {
     unconsume();
-    _b->addDouble(fractionalPart);
+    // use conventional atof() conversion here, to avoid precision loss
+    // when interpreting and multiplying the single digits of the input stream
+    // _b->addDouble(fractionalPart);
+    _b->addDouble(atof(reinterpret_cast<char const*>(_start) + startPos));
     return;
   }
   i = getOneOrThrow("Incomplete number");
@@ -214,7 +220,10 @@ void Parser::parseNumber() {
   if (std::isnan(fractionalPart) || !std::isfinite(fractionalPart)) {
     throw Exception(Exception::NumberOutOfRange);
   }
-  _b->addDouble(fractionalPart);
+  // use conventional atof() conversion here, to avoid precision loss
+  // when interpreting and multiplying the single digits of the input stream
+  // _b->addDouble(fractionalPart);
+  _b->addDouble(atof(reinterpret_cast<char const*>(_start) + startPos));
 }
 
 void Parser::parseString() {