From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ronnie Sahlberg Subject: [PATCH 1/2] sequencer.c: check for lock failure and bail early in fast_forward_to Date: Tue, 15 Apr 2014 16:46:47 -0700 Message-ID: <1397605608-12128-2-git-send-email-sahlberg@google.com> References: <1397605608-12128-1-git-send-email-sahlberg@google.com> Cc: mhagger@alum.mit.edu, Ronnie Sahlberg To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Wed Apr 16 01:47:11 2014 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 1WaD4H-0001Uy-7A for gcvg-git-2@plane.gmane.org; Wed, 16 Apr 2014 01:47:09 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751134AbaDOXqy (ORCPT ); Tue, 15 Apr 2014 19:46:54 -0400 Received: from mail-vc0-f201.google.com ([209.85.220.201]:50298 "EHLO mail-vc0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099AbaDOXqw (ORCPT ); Tue, 15 Apr 2014 19:46:52 -0400 Received: by mail-vc0-f201.google.com with SMTP id ik5so1517687vcb.2 for ; Tue, 15 Apr 2014 16:46:51 -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=vZoskFuQd1vKG/IR+wDe38jYNg0nOUQg0MDmpX+dXW8=; b=QiQKopQf7ELiUCfQC7jkc249M5/VeVQdECLeNN/jbF3LYvPJYOpA9u4aNqaKb+vsEv vuMF72hIi7IY84Q/PeOfy6491fP1s7QW7w6HGWXSwJqce8jwD5PdAQQuLGyE6xgY3OA0 ot9tGMd6t++o6njX2YeNkCjOpMOoXSFw3Zfyj0leJuah50PB7WLQp7vEjZh2IlbYIBIP Cgdq448+6TmdkhJroykAET7E4xweck9N6Fli8xsUiW0a7atg9Bx5h33y7/HmcgFVxbgF IrqK1o8sPw3QWNghx1djLomrlXvWFugk1PmY0k9DSP1Iq2ZHqi33W5O2t4CuvfOl+lQf U0yQ== 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=vZoskFuQd1vKG/IR+wDe38jYNg0nOUQg0MDmpX+dXW8=; b=XritqSV38DtxKqzQutazkMsfsXbxdog+1ehSCBKrBkk08ui2pxs17h7UbPpXigSvxl A0J28KMOd1pLZyCr8g6GSxAZeka7RYZnRonpDS/EZb2Xx/Ay6A3G4KQ2nAY5vegDJcNZ qNOHeKsPd/2HFG4QFPBZsiiKzFL0KaPfsvS7Hlf1QG4TMDRkY0Gg5S4YLp6GDwfQCbpu jtF6vy8qN+0Ly7lFcq0NXA09MWC2VorQOQeG8NUO6a5ZUzddueLXp6d34QIbCSt22BId kzpkjARwII1Xa8cUb/8yUGffjYmdasGuE+VrKeiSrsYHVrOGDDNqgPUm66rMSuAoF4K8 twJQ== X-Gm-Message-State: ALoCoQmhKH82HGJZz6TuFwo36w2y2dQ/v5Z63D+0J4/+2QFHa8C0JGCA2XM3ftwAPWMNH+mYK2534nTMiRXnLkdC7mUGeZ6ePekMsERyJBLb365vLm/fKtSQN6MGbBazubzuVHdMXeflt6Zoz3GvL1yb0lA7VDPe9cgob7VZMrT0SgvqdhIEBvdccyF16Be6LW37ESUWW22D X-Received: by 10.224.95.9 with SMTP id b9mr680677qan.2.1397605611753; Tue, 15 Apr 2014 16:46:51 -0700 (PDT) Received: from corp2gmr1-1.hot.corp.google.com (corp2gmr1-1.hot.corp.google.com [172.24.189.92]) by gmr-mx.google.com with ESMTPS id r61si2916738yhf.1.2014.04.15.16.46.51 for (version=TLSv1.1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 15 Apr 2014 16:46:51 -0700 (PDT) Received: from sahlberg1.mtv.corp.google.com (sahlberg1.mtv.corp.google.com [172.27.69.52]) by corp2gmr1-1.hot.corp.google.com (Postfix) with ESMTP id 95B4C31C1D6; Tue, 15 Apr 2014 16:46:51 -0700 (PDT) Received: by sahlberg1.mtv.corp.google.com (Postfix, from userid 177442) id 5616EE099E; Tue, 15 Apr 2014 16:46:51 -0700 (PDT) X-Mailer: git-send-email 1.9.1.503.ge4c3920.dirty In-Reply-To: <1397605608-12128-1-git-send-email-sahlberg@google.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Change fast_forward_to() to check if locking the ref failed, print a nice error message and bail out early. The old code did not check if ref_lock was NULL and relied on the fact that the write_ref_sha1() would safely detect this condition and set the return variable ret to indicate an error. While that is safe, it makes the code harder to read for two reasons: * Inconsistency. Almost all other places we do check the lock for NULL explicitely, so the naive reader is confused "why don't we check here". * And relying on write_ref_sha1() to detect and return an error for when a previous lock_any_ref_for_update() feels obfuscated. This change should not change any functionality or logic aside from adding an extra error message when this condition is triggered. (write_ref_sha1() returns an error silently for this condition) Signed-off-by: Ronnie Sahlberg --- sequencer.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/sequencer.c b/sequencer.c index bde5f04..6aa3b50 100644 --- a/sequencer.c +++ b/sequencer.c @@ -281,8 +281,15 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from, exit(1); /* the callee should have complained already */ ref_lock = lock_any_ref_for_update("HEAD", unborn ? null_sha1 : from, 0, NULL); + if (!ref_lock) { + ret = error(_("Failed to lock HEAD during fast_forward_to")); + goto leave; + } + strbuf_addf(&sb, "%s: fast-forward", action_name(opts)); ret = write_ref_sha1(ref_lock, to, sb.buf); + +leave: strbuf_release(&sb); return ret; } -- 1.9.1.503.ge4c3920.dirty