From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Beller Subject: [PATCH 4/8] strbuf: add strbuf_read_once to read without blocking Date: Mon, 28 Sep 2015 16:14:02 -0700 Message-ID: <1443482046-25569-5-git-send-email-sbeller@google.com> References: <1443482046-25569-1-git-send-email-sbeller@google.com> Cc: Stefan Beller , ramsay@ramsayjones.plus.com, jacob.keller@gmail.com, peff@peff.net, gitster@pobox.com, jrnieder@gmail.com, johannes.schindelin@gmail.com, Jens.Lehmann@web.de, ericsunshine@gmail.com To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Tue Sep 29 01:14:46 2015 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Zghd4-0007Kf-7L for gcvg-git-2@plane.gmane.org; Tue, 29 Sep 2015 01:14:42 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753844AbbI1XOc (ORCPT ); Mon, 28 Sep 2015 19:14:32 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:36494 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753726AbbI1XO3 (ORCPT ); Mon, 28 Sep 2015 19:14:29 -0400 Received: by pablk4 with SMTP id lk4so89756507pab.3 for ; Mon, 28 Sep 2015 16:14:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=GH9txRb3DbeQDZH5Qtj6oHzO/Jm8xOKM5uTWKeU7Pxg=; b=prKxDuRC3FC5zevHTJTVFSNutyXMT1awo4G4N3s4YYzwm7+/9+wVmLjY6891ySwO9D LfAVsCBvmH9OXBrRoUwbjlhhL3PiD9sKdfsFNoGcetuHsvagRI0mNRoC5YyWfjQEZFwg QqkMoG9dj8sblddyRmKK26DM3Nnd2pnB4Qgihad08X+psFrsanMtS+g5HRdZlG1JatVq U+xG0RFL7DDplXLSK5jVYaag8hVhnvNtGynryz5TZ63/eX/BjtBtDEgYIewlRZcAqMA+ HPiYvgf1z8g9i6bsW85L1ssa10imOYTgcLFGjToz3U1vjqf1wr93LWy4bkOJ7AsUcGFD /0+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=GH9txRb3DbeQDZH5Qtj6oHzO/Jm8xOKM5uTWKeU7Pxg=; b=VDIAJyqrievK6YEgVE1q6Zret2cnsFP0UA9H+hsUSVfAQcRHUWdfaVXrxhG070YP/F gNohEMZrp+bd05SSah8T6oPcyBCaVKFs0CVJKwvjg0OgjhhlsVD8BT28eNopDvPSbR3R HTBhknPDma23qXTFk57slcVNq1aQg86tr2HqA8BVz5WVOYbPTd640jk94rCtTidTMH/N AVyE9fsvV6NE+eJ0orbbVR75S7Jw72WXjZOZOuzzBrN4HGnIBkk6lTCIo7EZ3qnwMPhC Nd9udZhhDJPX2fx2RmBSQYKeFc+nxjMcyuHQnsAGqWS9gD6Hxwlr7BEIrL1OYRJXX1fw jaqQ== X-Gm-Message-State: ALoCoQlapxWLSoS3H+cQRYAG5NSmkpyhANNF6Y0a8R+LpODWDKLQmFQiwyOmepcOUpKiEa31BGgV X-Received: by 10.68.237.161 with SMTP id vd1mr28526850pbc.168.1443482066067; Mon, 28 Sep 2015 16:14:26 -0700 (PDT) Received: from localhost ([2620:0:1000:5b00:79ce:7412:e4be:3e39]) by smtp.gmail.com with ESMTPSA id df2sm21588629pad.19.2015.09.28.16.14.25 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 28 Sep 2015 16:14:25 -0700 (PDT) X-Mailer: git-send-email 2.5.0.273.g6fa2560.dirty In-Reply-To: <1443482046-25569-1-git-send-email-sbeller@google.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: The new call will read from a file descriptor into a strbuf once. The underlying call xread_nonblock is meant to execute without blocking if the file descriptor is set to O_NONBLOCK. It is a bug to call strbuf_read_once on a file descriptor which would block. Signed-off-by: Stefan Beller Signed-off-by: Junio C Hamano --- strbuf.c | 11 +++++++++++ strbuf.h | 9 +++++++++ 2 files changed, 20 insertions(+) diff --git a/strbuf.c b/strbuf.c index cce5eed..35e71b8 100644 --- a/strbuf.c +++ b/strbuf.c @@ -384,6 +384,17 @@ ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint) return sb->len - oldlen; } +ssize_t strbuf_read_once(struct strbuf *sb, int fd, size_t hint) +{ + ssize_t cnt; + + strbuf_grow(sb, hint ? hint : 8192); + cnt = xread_nonblock(fd, sb->buf + sb->len, sb->alloc - sb->len - 1); + if (cnt > 0) + strbuf_setlen(sb, sb->len + cnt); + return cnt; +} + #define STRBUF_MAXLINK (2*PATH_MAX) int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint) diff --git a/strbuf.h b/strbuf.h index aef2794..ea69665 100644 --- a/strbuf.h +++ b/strbuf.h @@ -367,6 +367,15 @@ extern size_t strbuf_fread(struct strbuf *, size_t, FILE *); extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint); /** + * Read from a file descriptor that is marked as O_NONBLOCK without + * blocking. Returns the number of new bytes appended to the sb. + * Negative return value signals there was an error returned from + * underlying read(2), in which case the caller should check errno. + * e.g. errno == EAGAIN when the read may have blocked. + */ +extern ssize_t strbuf_read_once(struct strbuf *, int fd, size_t hint); + +/** * Read the contents of a file, specified by its path. The third argument * can be used to give a hint about the file size, to avoid reallocs. */ -- 2.5.0.273.g6fa2560.dirty