From: Eric Haszlakiewicz <erh+git@nimenees.com>
Date: Sun, 9 Jul 2017 22:04:18 +0000 (-0700)
Subject: Fix bad usage of strncat introduces in 1a94c70.  Pointed out by @rouault in PR #331.
X-Git-Tag: json-c-0.13-20171207~79
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7b7a76e161a2b727e68ce26c32c2fb3467682840;p=thirdparty%2Fjson-c.git

Fix bad usage of strncat introduces in 1a94c70.  Pointed out by @rouault in PR #331.
---

diff --git a/json_object.c b/json_object.c
index 3f6298e2..2abf4df5 100644
--- a/json_object.c
+++ b/json_object.c
@@ -774,12 +774,11 @@ static int json_object_double_to_json_string_format(struct json_object* jso,
 		if (!format)
 			format = std_format;
 		size = snprintf(buf, sizeof(buf), format, jso->o.c_double);
-		if (modf(jso->o.c_double, &dummy) == 0)
+		if (modf(jso->o.c_double, &dummy) == 0  && size >= 0 && size < (int)sizeof(buf) - 2)
 		{
 			// Ensure it looks like a float, even if snprintf didn't.
-			strncat(buf, ".0", sizeof(buf) - 1);
-			if (size >= 0)
-				size += 2; // yes, even if strncat ran out of room
+			strcat(buf, ".0");
+			size += 2;
 		}
 	}
 	// although unlikely, snprintf can fail