From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id D16175A0278 for ; Thu, 22 Feb 2024 06:56:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202312; t=1708581366; bh=BBhpy5yXb9jdJU4BCihqGRwipW+cj2hG9AczC1ZaHm8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gg3MIk+UeVhll2TEvJ00VzkOblLGEsXXcuLUH4X0wn2ul+8W1We2Gb9nJmohS5X9/ NKexaLlQnIFqqZLQPGBs6FlqO5/ZJn/wwvyqIzIwvfAYv4DlgeoBuETukZYwzyISyC s4L3Y5YJe5507OH1NYdaWsT73YDDXlFsVjkc+wJTpuD9ak5ZP5f8QuyXqD9rWpXSmi i3wO1DJNTnPOlHVuVdyB619iFwW5IY9jMfXV2a3y9KvVrOU+8ITLM4GR0JS4DaHRQR tHOGttEuI2+pK/rUaMlnIiY7cY0BIpKXX5490x/vpRjnMEVkBRANhBOUthAMKldJVK GNlefk9jyIaJA== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4TgMny2rC9z4wqM; Thu, 22 Feb 2024 16:56:06 +1100 (AEDT) From: David Gibson To: passt-dev@passt.top, Stefano Brivio , Laurent Vivier Subject: [PATCH 3/6] util: Add write_remainder() helper Date: Thu, 22 Feb 2024 16:55:59 +1100 Message-ID: <20240222055602.1872516-4-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240222055602.1872516-1-david@gibson.dropbear.id.au> References: <20240222055602.1872516-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: F5N7OWTLC4DEO5KDN2J56BNCXGZEDICS X-Message-ID-Hash: F5N7OWTLC4DEO5KDN2J56BNCXGZEDICS X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: We have several places where we want to write(2) a buffer or buffers and we do (or should) handle sort write()s by retrying until everything is successfully written. Add a helper for this in util.c. This version has some differences from the typical write_all() function. First, take an IO vector rather than a single buffer, because that will be useful for some of our cases. Second, allow it to take an parameter to skip the first n bytes of the given buffers. This will be usefl for some of the cases we want, and also falls out quite naturally from the implementation. Signed-off-by: David Gibson --- util.c | 32 ++++++++++++++++++++++++++++++++ util.h | 1 + 2 files changed, 33 insertions(+) diff --git a/util.c b/util.c index fb6a0430..a475f2b5 100644 --- a/util.c +++ b/util.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -597,3 +598,34 @@ size_t iov_offset(const struct iovec *iov, size_t n, size_t *offset) return i; } + +/* write_remainder() - write the tail of an IO vector to an fd + * @fd: File descriptor + * @iov: IO vector + * @iovcnt: Number of entries in @iov + * @skip: Number of bytes of the vector to skip writing + * + * Return: 0 on success, -1 on error (with errno set) + * + * #syscalls write writev + */ +int write_remainder(int fd, const struct iovec *iov, int iovcnt, size_t skip) +{ + int i; + + while ((i = iov_offset(iov, iovcnt, &skip)) < iovcnt) { + ssize_t rc; + + if (skip) + rc = write(fd, (char *)iov[i].iov_base + skip, + iov[i].iov_len - skip); + else + rc = writev(fd, &iov[i], iovcnt - i); + + if (rc < 0) + return -1; + skip += rc; + } + + return 0; +} diff --git a/util.h b/util.h index 62fad6fe..ee380f55 100644 --- a/util.h +++ b/util.h @@ -230,6 +230,7 @@ int __daemon(int pidfile_fd, int devnull_fd); int fls(unsigned long x); int write_file(const char *path, const char *buf); size_t iov_offset(const struct iovec *iov, size_t n, size_t *offset); +int write_remainder(int fd, const struct iovec *iov, int iovcnt, size_t skip); /** * mod_sub() - Modular arithmetic subtraction -- 2.43.2