From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47910) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a69NB-0004Iy-GC for qemu-devel@nongnu.org; Mon, 07 Dec 2015 22:55:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a69N8-0003UY-6q for qemu-devel@nongnu.org; Mon, 07 Dec 2015 22:55:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46678) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a69N8-0003Tm-0J for qemu-devel@nongnu.org; Mon, 07 Dec 2015 22:55:26 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 91E9BC0B7A29 for ; Tue, 8 Dec 2015 03:55:25 +0000 (UTC) From: Eric Blake Date: Mon, 7 Dec 2015 20:54:51 -0700 Message-Id: <1449546921-6378-2-git-send-email-eblake@redhat.com> In-Reply-To: <1449546921-6378-1-git-send-email-eblake@redhat.com> References: <1449546921-6378-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v7 01/31] qobject: Document more shortcomings in our number handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: armbru@redhat.com, Luiz Capitulino We've already documented that our JSON parsing is locale dependent; but we should also document that our JSON output has the same problem. Additionally, JSON requires finite values (you have to upgrade to JSON5 to get support for Inf or NaN), and our output risks truncating floating point numbers to the point of losing significant precision. Sadly, this series is not going to be the one that addresses these problems. Fix some trailing whitespace I noticed in the vicinity. Signed-off-by: Eric Blake --- v7: new patch --- qobject/json-parser.c | 4 +++- qobject/qjson.c | 8 +++++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/qobject/json-parser.c b/qobject/json-parser.c index 3c5d35d..6ab98a7 100644 --- a/qobject/json-parser.c +++ b/qobject/json-parser.c @@ -1,5 +1,5 @@ /* - * JSON Parser + * JSON Parser * * Copyright IBM, Corp. 2009 * @@ -519,6 +519,8 @@ static QObject *parse_literal(JSONParserContext *ctxt) } case JSON_FLOAT: /* FIXME dependent on locale */ + /* FIXME our lexer matches RFC7159 in forbidding Inf or NaN, + * but those might be useful extensions beyond JSON */ return QOBJECT(qfloat_from_double(strtod(token->str, NULL))); default: abort(); diff --git a/qobject/qjson.c b/qobject/qjson.c index a3e6a7c..41d9d65 100644 --- a/qobject/qjson.c +++ b/qobject/qjson.c @@ -237,6 +237,12 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent) char buffer[1024]; int len; + /* FIXME: snprintf() is locale dependent; but JSON requires + * numbers to be formatted as if in the C locale. */ + /* FIXME: This risks printing Inf or NaN, which are not valid + * JSON values. */ + /* FIXME: the default precision of %f may be insufficient to + * tell this number apart from others. */ len = snprintf(buffer, sizeof(buffer), "%f", qfloat_get_double(val)); while (len > 0 && buffer[len - 1] == '0') { len--; @@ -247,7 +253,7 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent) } else { buffer[len] = 0; } - + qstring_append(str, buffer); break; } -- 2.4.3