From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id YRRqCmgqM2Ps6wAAWB0awg (envelope-from ) for ; Tue, 27 Sep 2022 12:52:56 -0400 Received: by simark.ca (Postfix, from userid 112) id 13EA01E112; Tue, 27 Sep 2022 12:52:56 -0400 (EDT) Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=lists.lttng.org header.i=@lists.lttng.org header.a=rsa-sha256 header.s=default header.b=B8Om69KG; dkim-atps=neutral X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 Received: from lists.lttng.org (lists.lttng.org [167.114.26.123]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 550091E0D5 for ; Tue, 27 Sep 2022 12:52:55 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1664297574; bh=UdMYpsM6ZQlYUly/HVA28qKeKGkqlrAxvX3p+Uiohyk=; h=To:Date:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:Cc:From; b=B8Om69KGZt+u8vmgRRQkMdYxX/JLaCe/9kqtg4NLzHk+g8xcV1/NV9Unzjy5v/pnv 8lBeqS4d3DhWTxOxJovk57JLPNpVlkntpUz1GI+0GFBsc3+xkpURWsEzHrVGhqGYDe 1fa9pQxy/CQaOn9ucw1hLDisFP1D6ur58CA6J12Yp1NadLe2VD+UDX4cCGvY1Jndka svhMvgH6XZjcJFi8YY4D0GkNaXbHPxJ1FjZFiIGQOSEv1RyuDm2B+b2gLc4qm9jA2m dubxIhu1/cVb3MU23z/MeXDCzJS6KALW6Ynm54VnGJBAXe2396DBp8z1c+tAbsCrnR eSCb+sAZe9n+g== Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4McQfZ5XJ0z261X; Tue, 27 Sep 2022 12:52:54 -0400 (EDT) Received: from smtpout.efficios.com (smtpout.efficios.com [IPv6:2607:5300:203:5aae::31e5]) by lists.lttng.org (Postfix) with ESMTPS id 4McQfY707nz25xv for ; Tue, 27 Sep 2022 12:52:53 -0400 (EDT) Received: from localhost.localdomain (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4McQfR2GTXzNy5; Tue, 27 Sep 2022 12:52:47 -0400 (EDT) To: jgalar@efficios.com Date: Tue, 27 Sep 2022 12:52:42 -0400 Message-Id: <20220927165242.644594-1-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Subject: [lttng-dev] [PATCH lttng-tools 1/1] Fix: Handle empty string in lttng_event_field_value_string_create_with_size X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Mathieu Desnoyers via lttng-dev Reply-To: Mathieu Desnoyers Cc: lttng-dev@lists.lttng.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" When using the event notification capture API, empty strings are represented by a NULL pointer with a size=0 in the msgpack object. The NULL pointer is unexpected, which triggers an assertion in lttng_event_field_value_string_create_with_size. Fix this by duplicating an empty string ("") when a size=0 is encountered. This ensures that users of the API don't end up with an unexpected NULL pointer. Indeed, the sample program notif-app.c in the LTTng website documentation does not expect a NULL pointer. Signed-off-by: Mathieu Desnoyers Change-Id: I7c3a839dbbeeb95a1b3bf6ddc3205a2f6b4538e3 --- src/common/event-field-value.cpp | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/src/common/event-field-value.cpp b/src/common/event-field-value.cpp index 8017fd081..fa9e97018 100644 --- a/src/common/event-field-value.cpp +++ b/src/common/event-field-value.cpp @@ -183,8 +183,17 @@ struct lttng_event_field_value *lttng_event_field_value_string_create_with_size( goto error; } - LTTNG_ASSERT(val); - field_val->val = strndup(val, size); + if (size) { + LTTNG_ASSERT(val); + field_val->val = strndup(val, size); + } else { + /* + * User code (e.g. notif-app.c on lttng.org/docs) do not expect + * a NULL string pointer. Populate with an empty string when + * length is 0. + */ + field_val->val = strdup(""); + } if (!field_val->val) { goto error; } -- 2.25.1 _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev