From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Beller Subject: [PATCHv7 4/8] strbuf: add strbuf_read_once to read without blocking Date: Mon, 12 Oct 2015 11:47:17 -0700 Message-ID: <1444675641-14866-5-git-send-email-sbeller@google.com> References: <1444675641-14866-1-git-send-email-sbeller@google.com> Cc: git@vger.kernel.org, Stefan Beller To: gitster@pobox.com X-From: git-owner@vger.kernel.org Mon Oct 12 20:47:55 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 1Zli8Y-0006Ox-QM for gcvg-git-2@plane.gmane.org; Mon, 12 Oct 2015 20:47:55 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752591AbbJLSrw (ORCPT ); Mon, 12 Oct 2015 14:47:52 -0400 Received: from mail-pa0-f49.google.com ([209.85.220.49]:34717 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400AbbJLSrb (ORCPT ); Mon, 12 Oct 2015 14:47:31 -0400 Received: by padhy16 with SMTP id hy16so160546056pad.1 for ; Mon, 12 Oct 2015 11:47:31 -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=UCvrp32jCnbalAYlwSiCdEhpXBl/+3kWMwAt/SFGKcc=; b=pMOpS/DEAjMO0CFakRrpFuSFt3D8s6wqHIYmJIEc38IwsGljbnh62+CNBbUZJ902n7 3jjQig0+WOO75VOs1n9BPb8/kwTokTpr4WxyWH/WV8nSFHYnK/rD5S6MHhI30pRhuPQ8 sMFK9u8cspFlTzCYHvtjhwKLNwiXbpPNsAhVvjwOKsMV2NSw8Yp87xDsPuujp66G1Xty R1ogV80lK4FddzC+k1THxSWMsIcjAWlBCw5CjyJvSCkI/iwmfojfeTS9sOMW8Khddaoh OIRQLrnFHYeibABEGR5RkRj+G6iyEUDsOLVatnswiUJI1GQJhdrz5YU+xqp4Sr2YgQcD MU7Q== 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=UCvrp32jCnbalAYlwSiCdEhpXBl/+3kWMwAt/SFGKcc=; b=MH8mjECK2lSlBBV1VdyQ2FLhMyjft5jk8QLJcyd3pbeDtEZkwEsspUV5Xv7FNnRTQa y1+Qs/M04VAh0Icr037n5IdeQ+HgiQjFI5ZzyDwBW1icj1pIzSihD6OrSOqiAiGr1MKd z6njfStl63XQSbe1c/1F2DrETq0T+C/7cMoRiBY3n/wnZ/dmH5Cdf0SLpkHlG3cRZ8gY b/uaC+uXQijuxdz5W1EpiZExCDX9Jy2Q3VCLOP/3n6ZJKGRwuDleq9AYzz29wcbHMcQ1 x+acbvlxOOep0LamfcvdpFoZIBoqNze6zP5Hy12asXhq1jd/gcnxNX9Rq3BnDelatZZt /WCg== X-Gm-Message-State: ALoCoQnowPSwc8bx+YlIKi556Ku2tKLBNsinCpYkLYd27N0XORA+aeRZ19N6y1/zKhY82WiBnQBU X-Received: by 10.66.250.197 with SMTP id ze5mr36291808pac.50.1444675650986; Mon, 12 Oct 2015 11:47:30 -0700 (PDT) Received: from localhost ([2620:0:1000:5b00:5950:8bdc:8939:e460]) by smtp.gmail.com with ESMTPSA id qy5sm19712315pbb.16.2015.10.12.11.47.30 (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 12 Oct 2015 11:47:30 -0700 (PDT) X-Mailer: git-send-email 2.5.0.268.g453a26a In-Reply-To: <1444675641-14866-1-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. */ -- 2.5.0.268.g453a26a