From da7c2c0ee90104524ed98a2370af0ea70a0f6d0d Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Mon, 11 Mar 2019 16:21:27 -0400
Subject: [PATCH] Fix json serialization for {x | -1 < x < 1} (fixes #308)

JSON serialization was preserving the value as presented, but JSON
doesn't accept decimal values without a 0 before the decimal point.
---
 ChangeLog            |  5 +++++
 libqpdf/QPDF_Real.cc | 25 ++++++++++++++++++++++++-
 libtests/json.cc     |  6 +++++-
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 62c20948..9f33d4cf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-03-11  Jay Berkenbilt  <ejb@ql.org>
+
+	* JSON serialization: add missing leading 0 to decimal values
+	between -1 and 1. Fixes #308.
+
 2019-02-01  Jay Berkenbilt  <ejb@ql.org>
 
 	* 8.4.0: release
diff --git a/libqpdf/QPDF_Real.cc b/libqpdf/QPDF_Real.cc
index b28c2f70..b4c8283f 100644
--- a/libqpdf/QPDF_Real.cc
+++ b/libqpdf/QPDF_Real.cc
@@ -25,7 +25,30 @@ QPDF_Real::unparse()
 JSON
 QPDF_Real::getJSON()
 {
-    return JSON::makeNumber(this->val);
+    // While PDF allows .x or -.x, JSON does not. Rather than
+    // convering from string to double and back, just handle this as a
+    // special case for JSON.
+    std::string result;
+    if (this->val.length() == 0)
+    {
+        // Can't really happen...
+        result = "0";
+    }
+    else if (this->val.at(0) == '.')
+    {
+        result = "0" + this->val;
+    }
+    else if ((this->val.length() >= 2) &&
+             (this->val.at(0) == '-') &&
+             (this->val.at(1) == '.'))
+    {
+        result = "-0." + this->val.substr(2);
+    }
+    else
+    {
+        result = this->val;
+    }
+    return JSON::makeNumber(result);
 }
 
 QPDFObject::object_type_e
diff --git a/libtests/json.cc b/libtests/json.cc
index 1a9123ad..e3086c18 100644
--- a/libtests/json.cc
+++ b/libtests/json.cc
@@ -3,7 +3,7 @@
 #include <iostream>
 #include <assert.h>
 
-static void check(JSON& j, std::string const& exp)
+static void check(JSON const& j, std::string const& exp)
 {
     if (exp != j.unparse())
     {
@@ -69,6 +69,10 @@ static void test_main()
           "  ],\n"
           "  \"yes\": false\n"
           "}");
+    check(QPDFObjectHandle::newReal("0.12").getJSON(), "0.12");
+    check(QPDFObjectHandle::newReal(".34").getJSON(), "0.34");
+    check(QPDFObjectHandle::newReal("-0.56").getJSON(), "-0.56");
+    check(QPDFObjectHandle::newReal("-.78").getJSON(), "-0.78");
 }
 
 static void check_schema(JSON& obj, JSON& schema, bool exp,