Issue json-c#103: allow Infinity and -Infinity to be parsed.

config.h.in

@@ -3,6 +3,10 @@
 /* Define if .gnu.warning accepts long strings. */
 #undef HAS_GNU_WARNING_LONG
 
+/* Define to 1 if you have the declaration of `INFINITY', and to 0 if you
+   don't. */
+#undef HAVE_DECL_INFINITY
+
 /* Define to 1 if you have the declaration of `isinf', and to 0 if you don't.
    */
 #undef HAVE_DECL_ISINF

configure.ac

@@ -29,6 +29,7 @@ AC_FUNC_MEMCMP
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 AC_CHECK_FUNCS(strcasecmp strdup strerror snprintf vsnprintf vasprintf open vsyslog strncasecmp setlocale)
+AC_CHECK_DECLS([INFINITY], [], [], [[#include <math.h>]])
 AC_CHECK_DECLS([nan], [], [], [[#include <math.h>]])
 AC_CHECK_DECLS([isnan], [], [], [[#include <math.h>]])
 AC_CHECK_DECLS([isinf], [], [], [[#include <math.h>]])

json_tokener.c

@@ -57,6 +57,8 @@
 
 static const char json_null_str[] = "null";
 static const int json_null_str_len = sizeof(json_null_str) - 1;
+static const char json_inf_str[] = "Infinity";
+static const int json_inf_str_len = sizeof(json_inf_str) - 1;
 static const char json_nan_str[] = "NaN";
 static const int json_nan_str_len = sizeof(json_nan_str) - 1;
 static const char json_true_str[] = "true";
@@ -275,6 +277,12 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
 	saved_state = json_tokener_state_array;
 	current = json_object_new_array();
 	break;
+      case 'I':
+      case 'i':
+	state = json_tokener_state_inf;
+	printbuf_reset(tok->pb);
+	tok->st_pos = 0;
+	goto redo_char;
       case 'N':
       case 'n':
 	state = json_tokener_state_null; // or NaN
@@ -332,7 +340,41 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
       tok->depth--;
       goto redo_char;
 
-    case json_tokener_state_null:
+    case json_tokener_state_inf: /* aka starts with 'i' */
+      {
+	int size;
+	int size_inf;
+	int is_negative = 0;
+
+	printbuf_memappend_fast(tok->pb, &c, 1);
+	size = json_min(tok->st_pos+1, json_null_str_len);
+	size_inf = json_min(tok->st_pos+1, json_inf_str_len);
+	char *infbuf = tok->pb->buf;
+	if (*infbuf == '-')
+	{
+		infbuf++;
+		is_negative = 1;
+	}
+	if ((!(tok->flags & JSON_TOKENER_STRICT) &&
+	          strncasecmp(json_inf_str, infbuf, size_inf) == 0) ||
+	         (strncmp(json_inf_str, infbuf, size_inf) == 0)
+	        )
+	{
+		if (tok->st_pos == json_inf_str_len)
+		{
+			current = json_object_new_double(is_negative ? -INFINITY : INFINITY); 
+			saved_state = json_tokener_state_finish;
+			state = json_tokener_state_eatws;
+			goto redo_char;
+		}
+	} else {
+		tok->err = json_tokener_error_parse_unexpected;
+		goto out;
+	}
+	tok->st_pos++;
+      }
+      break;
+    case json_tokener_state_null: /* aka starts with 'n' */
       {
 	int size;
 	int size_nan;
@@ -628,6 +670,14 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
 	}
         if (case_len>0)
           printbuf_memappend_fast(tok->pb, case_start, case_len);
+
+	// Check for -Infinity
+	if (tok->pb->buf[0] == '-' && case_len == 1 &&
+	    (c == 'i' || c == 'I'))
+	{
+		state = json_tokener_state_inf;
+		goto redo_char;
+	}
       }
       {
 	int64_t num64;

json_tokener.h

@@ -60,7 +60,8 @@ enum json_tokener_state {
   json_tokener_state_object_value_add,
   json_tokener_state_object_sep,
   json_tokener_state_array_after_sep,
-  json_tokener_state_object_field_start_after_sep
+  json_tokener_state_object_field_start_after_sep,
+  json_tokener_state_inf
 };
 
 struct json_tokener_srec

math_compat.h

@@ -21,4 +21,8 @@
 #error This platform does not have nan()
 #endif
 
+#ifndef HAVE_DECL_INFINITY
+#error This platform does not have INFINITY
+#endif
+
 #endif

tests/test_parse.c

@@ -51,6 +51,34 @@ static void test_basic_parse()
 	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
 	json_object_put(new_obj);
 
+	new_obj = json_tokener_parse("-NaN"); /* non-sensical, returns null */
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
+	new_obj = json_tokener_parse("Inf"); /* must use full string, returns null */
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
+	new_obj = json_tokener_parse("inf"); /* must use full string, returns null */
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
+	new_obj = json_tokener_parse("Infinity");
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
+	new_obj = json_tokener_parse("infinity");
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
+	new_obj = json_tokener_parse("-Infinity");
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
+	new_obj = json_tokener_parse("-infinity");
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
 	new_obj = json_tokener_parse("True");
 	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
 	json_object_put(new_obj);

tests/test_parse.expected

@@ -4,6 +4,13 @@ new_obj.to_string()="foo"
 new_obj.to_string()="ABC"
 new_obj.to_string()=null
 new_obj.to_string()=NaN
+new_obj.to_string()=null
+new_obj.to_string()=null
+new_obj.to_string()=null
+new_obj.to_string()=Infinity
+new_obj.to_string()=Infinity
+new_obj.to_string()=-Infinity
+new_obj.to_string()=-Infinity
 new_obj.to_string()=true
 new_obj.to_string()=12
 new_obj.to_string()=12.3