From: Bo You <byou@fb.com>
Date: Mon, 27 Jun 2016 16:17:21 +0000 (-0700)
Subject: Folly parseJson doesn't handle minInt properly
X-Git-Tag: 2016.07.26~113
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6dbd5d0641f727d50995921e2dd188b67caf2bd0;p=folly.git

Folly parseJson doesn't handle minInt properly

Summary:
Right now in ##parseNumber## in ##folly/json.cpp##, when a negative number is provided, both the minus sign and the digits are stored in the variable ##integral##: https://fburl.com/362938516.

This causes problem when the exact min int is provided (-9223372036854775808). Because now ##integral.size()## equals 20 (including the minus sign), which is greater than ##maxIntLen## (which is 19). We need to handle negatives separately to get the correct result.

Reviewed By: yfeldblum

Differential Revision: D3479054

fbshipit-source-id: 15c782962a5f5ee845a2a18f2145c7695ec2d546
---

diff --git a/folly/json.cpp b/folly/json.cpp
index 86600fd5..f4607efd 100644
--- a/folly/json.cpp
+++ b/folly/json.cpp
@@ -512,9 +512,9 @@ dynamic parseNumber(Input& in) {
   auto const wasE = *in == 'e' || *in == 'E';
 
   constexpr const char* maxInt = "9223372036854775807";
-  constexpr const char* minInt = "9223372036854775808";
+  constexpr const char* minInt = "-9223372036854775808";
   constexpr auto maxIntLen = constexpr_strlen(maxInt);
-
+  constexpr auto minIntLen = constexpr_strlen(minInt);
 
   if (*in != '.' && !wasE && in.getOpts().parse_numbers_as_strings) {
     return integral;
@@ -522,8 +522,8 @@ dynamic parseNumber(Input& in) {
 
   if (*in != '.' && !wasE) {
     if (LIKELY(!in.getOpts().double_fallback || integral.size() < maxIntLen) ||
-         (integral.size() == maxIntLen &&
-           (integral <= maxInt || (integral == minInt && negative)))) {
+        (!negative && integral.size() == maxIntLen && integral <= maxInt) ||
+        (negative && integral.size() == minIntLen && integral <= minInt)) {
       auto val = to<int64_t>(integral);
       in.skipWhitespace();
       return val;
diff --git a/folly/test/JsonTest.cpp b/folly/test/JsonTest.cpp
index a9bca3ba..e6820f7f 100644
--- a/folly/test/JsonTest.cpp
+++ b/folly/test/JsonTest.cpp
@@ -395,6 +395,9 @@ TEST(Json, ParseDoubleFallback) {
   EXPECT_EQ(847605071342477612345678900000.0,
       parseJson("{\"a\":847605071342477612345678912345}",
         opts).items().begin()->second.asDouble());
+  EXPECT_EQ(
+      toJson(parseJson(R"({"a":-9223372036854775808})", opts)),
+      R"({"a":-9223372036854775808})");
 }
 
 TEST(Json, ParseNumbersAsStrings) {