Fix parsing of "-Infinity" when the "-" and "Infinity" are split across multiple calls.

Add several additional test cases for partial parsing of infinity values.

json_tokener.c

@@ -763,7 +763,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
           printbuf_memappend_fast(tok->pb, case_start, case_len);
 
 	// Check for -Infinity
-	if (tok->pb->buf[0] == '-' && case_len == 1 &&
+	if (tok->pb->buf[0] == '-' && case_len <= 1 &&
 	    (c == 'i' || c == 'I'))
 	{
 		state = json_tokener_state_inf;

tests/test_parse.c

@@ -197,6 +197,40 @@ struct incremental_step {
 	{ "null",              4, 4, json_tokener_continue, 1 },
 	{ "null",              5, 4, json_tokener_success, 1 },
 
+	{ "Infinity",          9, 8, json_tokener_success, 1 },
+	{ "infinity",          9, 8, json_tokener_success, 1 },
+	{ "-infinity",        10, 9, json_tokener_success, 1 },
+	{ "infinity",          9, 0, json_tokener_error_parse_unexpected, 3 },
+	{ "-infinity",        10, 1, json_tokener_error_parse_unexpected, 3 },
+
+	{ "inf",               3, 3, json_tokener_continue, 0 },
+	{ "inity",             6, 5, json_tokener_success, 1 },
+	{ "-inf",              4, 4, json_tokener_continue, 0 },
+	{ "inity",             6, 5, json_tokener_success, 1 },
+
+	{ "i",                 1, 1, json_tokener_continue, 0 },
+	{ "n",                 1, 1, json_tokener_continue, 0 },
+	{ "f",                 1, 1, json_tokener_continue, 0 },
+	{ "i",                 1, 1, json_tokener_continue, 0 },
+	{ "n",                 1, 1, json_tokener_continue, 0 },
+	{ "i",                 1, 1, json_tokener_continue, 0 },
+	{ "t",                 1, 1, json_tokener_continue, 0 },
+	{ "y",                 1, 1, json_tokener_continue, 0 },
+	{ "",                  1, 0, json_tokener_success, 1 },
+
+	{ "-",                 1, 1, json_tokener_continue, 0 },
+	{ "inf",               3, 3, json_tokener_continue, 0 },
+	{ "ini",               3, 3, json_tokener_continue, 0 },
+	{ "ty",                3, 2, json_tokener_success, 1 },
+
+	{ "-",                 1, 1, json_tokener_continue, 0 },
+	{ "i",                 1, 1, json_tokener_continue, 0 },
+	{ "nfini",             5, 5, json_tokener_continue, 0 },
+	{ "ty",                3, 2, json_tokener_success, 1 },
+
+	{ "-i",                2, 2, json_tokener_continue, 0 },
+	{ "nfinity",           8, 7, json_tokener_success, 1 },
+
 	/* offset=1 because "n" is the start of "null".  hmm... */
 	{ "noodle",            7, 1, json_tokener_error_parse_null, 1 },
 	/* offset=2 because "na" is the start of "nan".  hmm... */