From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id D7866A00C4; Fri, 29 Jul 2022 18:03:25 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 342B242C46; Fri, 29 Jul 2022 18:03:17 +0200 (CEST) Received: from office2.cesnet.cz (office2.cesnet.cz [195.113.144.244]) by mails.dpdk.org (Postfix) with ESMTP id 217A842C05 for ; Fri, 29 Jul 2022 09:19:15 +0200 (CEST) Received: from dpdk-test8.liberouter.org (rt-tmc-kou.liberouter.org [195.113.172.126]) (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 office2.cesnet.cz (Postfix) with ESMTPSA id DB99840006E; Fri, 29 Jul 2022 09:19:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cesnet.cz; s=office2-2020; t=1659079154; bh=RAJzHFS3EQkQbwg5eobqWAt9P7/eF7rSZS+/AN6Ya5o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dJaEL/Nq55qjd+7lRtgeyZYqxYRlC0WznIBx11Wp724QBPFXUaGvI0gPUPH2xe582 3D2ka/rZDPC5hGnmqQtNg3yoCqT9ydrwrpY5/RpOW+9MJNdCreeeD/t1xMbODpKNzf /ME6FNxgz5hJs+6izJKcI17kjCwpFOm1COBvnD9zSYA8sveOiro4WKwIi+ya6ynvEy YPfqcOr6F2k34RC0Cc7Ys1DGUCvgza0F+4oCckPmuglrV1CmfoBt8H/PY12W7DmIc/ /RTBTGdK8mlomSksCwWYotc+tAEIBmwFRjJ0Ocw+CiRV2w3jnBgjYot+P6y3gP/CoG j9x6Lu/m0uUnA== From: =?UTF-8?q?M=C3=A1rio=20Kuka?= To: kuka@cesnet.cz Cc: dev@dpdk.org, mdr@ashroe.eu, reshma.pattan@intel.com, stephen@networkplumber.org Subject: [PATCH v2 2/2] pcapng: check if writev() returns a partial write Date: Fri, 29 Jul 2022 09:18:41 +0200 Message-Id: <20220729071841.18198-3-kuka@cesnet.cz> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220729071841.18198-1-kuka@cesnet.cz> References: <20220725152811.409447-1-kuka@cesnet.cz> <20220729071841.18198-1-kuka@cesnet.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Fri, 29 Jul 2022 18:03:14 +0200 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org The result from wrtiev() is not checked. When writev() returns a partial write, the output file will not contain all packets from the pkts buffer and some packets may be partially written, which is undesirable behavior. To avoid this problem, we have to check the number of bytes returned from the writev(), and if we get a partial write, we need to call the writev() function again on any ivo buffers that were not written or were written partially. Fixes: 8d23ce8f5ee9 ("pcapng: add new library for writing pcapng files") Cc: stephen@networkplumber.org Signed-off-by: Mário Kuka --- lib/pcapng/rte_pcapng.c | 67 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 65 insertions(+), 2 deletions(-) diff --git a/lib/pcapng/rte_pcapng.c b/lib/pcapng/rte_pcapng.c index e41cf909e1..7c1136337c 100644 --- a/lib/pcapng/rte_pcapng.c +++ b/lib/pcapng/rte_pcapng.c @@ -551,6 +551,69 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue, return NULL; } +/* + * Update iov after writev() has returned written. We must find how many iov + * buffers (from beginning) have been written. The first buffer that was not + * written fully is to be updated accordingly. + * + * Returns offset of buffer that was not written fully. + */ +static int +pcapng_update_iov(struct iovec *iov, const int count, size_t written) +{ + int i; + + for (i = 0; written > 0 && i < count; ++i) { + if (written < iov[i].iov_len) { + /* found buffer that was not written fully */ + iov[i].iov_base = RTE_PTR_ADD(iov[i].iov_base, written); + iov[i].iov_len -= written; + + return i; + } + + written -= iov[i].iov_len; + } + + return count; +} + +/* + * Writes all iovcnt buffers of data described by iov to the file associated with + * the file descriptor fd. + */ +static ssize_t +pcapng_writev(int fd, struct iovec *iov, const int count) +{ + size_t total = 0; + int at = 0; + + while (at < count) { + /* + * Note: writev() can return the following on a write request: + * Complete: + * written = [sum of all iov.iov_len] + * Partial: + * written < [sum of all iov.iov_len] + * Deferred: + * written = -1, errno = [EAGAIN] + * + * Partial and deferred writes are only possible with O_NONBLOCK set. + * + * If we get a partial result, we have to call the writev() again on any ivo buffers + * that have not been fully written. + */ + ssize_t written = writev(fd, &iov[at], count - at); + if (unlikely(written < 0)) + return written; + + total += written; + at += pcapng_update_iov(&iov[at], count - at, written); + } + + return total; +} + /* Write pre-formatted packets to file. */ ssize_t rte_pcapng_write_packets(rte_pcapng_t *self, @@ -577,7 +640,7 @@ rte_pcapng_write_packets(rte_pcapng_t *self, * Note: this assumes that max segments per mbuf < IOV_MAX */ if (unlikely(cnt + m->nb_segs >= IOV_MAX)) { - ret = writev(self->outfd, iov, cnt); + ret = pcapng_writev(self->outfd, iov, cnt); if (unlikely(ret < 0)) { rte_errno = errno; return -1; @@ -598,7 +661,7 @@ rte_pcapng_write_packets(rte_pcapng_t *self, } while ((m = m->next)); } - ret = writev(self->outfd, iov, cnt); + ret = pcapng_writev(self->outfd, iov, cnt); if (unlikely(ret < 0)) { rte_errno = errno; return -1; -- 2.31.1