Fix buffer printing in json value to string

src/ripple/json/impl/json_writer.cpp

@@ -77,55 +77,21 @@ std::string valueToString ( UInt value )
     return current;
 }
 
-std::string valueToString ( double value )
+std::string valueToString( double value )
 {
+    // Allocate a buffer that is more than large enough to store the 16 digits of
+    // precision requested below.
     char buffer[32];
-#if defined(_MSC_VER) && defined(__STDC_SECURE_LIB__) // Use secure version with visual studio 2005 to avoid warning. 
-    sprintf_s (buffer, sizeof (buffer), "%#f", value);
+    // Print into the buffer. We need not request the alternative representation
+    // that always has a decimal point because JSON doesn't distingish the
+    // concepts of reals and integers.
+#if defined(_MSC_VER) && defined(__STDC_SECURE_LIB__) // Use secure version with visual studio 2005 to avoid warning.
+    sprintf_s(buffer, sizeof(buffer), "%.16g", value);
 #else
-    sprintf (buffer, "%#f", value);
+    snprintf(buffer, sizeof(buffer), "%.16g", value);
 #endif
-    char* ch = buffer + strlen (buffer) - 1;
-
-    if (*ch != '0') return buffer; // nothing to truncate, so save time
-
-    while (ch > buffer && *ch == '0')
-    {
-        --ch;
-    }
-
-    char* last_nonzero = ch;
-
-    while (ch >= buffer)
-    {
-        switch (*ch)
-        {
-        case '0':
-        case '1':
-        case '2':
-        case '3':
-        case '4':
-        case '5':
-        case '6':
-        case '7':
-        case '8':
-        case '9':
-            --ch;
-            continue;
-
-        case '.':
-            // Truncate zeroes to save bytes in output, but keep one.
-            * (last_nonzero + 2) = '\0';
-            return buffer;
-
-        default:
-            return buffer;
-        }
-    }
-
     return buffer;
-}
-
+} 
 
 std::string valueToString ( bool value )
 {