From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Beller Subject: Re: [PATCH v4 01/44] wrapper: implement xopen() Date: Sun, 28 Jun 2015 22:04:02 -0700 Message-ID: References: <1435500366-31700-1-git-send-email-pyokagan@gmail.com> <1435500366-31700-2-git-send-email-pyokagan@gmail.com> <5590CE10.3020104@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Paul Tan , "git@vger.kernel.org" , Johannes Schindelin To: =?UTF-8?Q?Torsten_B=C3=B6gershausen?= X-From: git-owner@vger.kernel.org Mon Jun 29 07:04:09 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 1Z9REm-0002n6-MA for gcvg-git-2@plane.gmane.org; Mon, 29 Jun 2015 07:04:09 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753022AbbF2FEE convert rfc822-to-quoted-printable (ORCPT ); Mon, 29 Jun 2015 01:04:04 -0400 Received: from mail-yk0-f174.google.com ([209.85.160.174]:32768 "EHLO mail-yk0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750992AbbF2FED convert rfc822-to-8bit (ORCPT ); Mon, 29 Jun 2015 01:04:03 -0400 Received: by ykdt186 with SMTP id t186so105448026ykd.0 for ; Sun, 28 Jun 2015 22:04:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=Bw8e3uF28/cdEdxvCMCdA0bblEbgDS1BAPEf0+obtYU=; b=cidf1XYUleP4EP/ewKUaYkn69/8f9prhjo5rXM8aEG+8dfe1+F1MJgOAGmiz+unWkf 4uZmRBNFGK2C0nhcXXh3ZKWQE2itvNsp22ttusX4KERvO4ECwnptf0FEvpaQFiMoBJRf bOCDer5P/WvYLAlmaMo/eQhG2kQrnZiLpCRJ5uLVTEpfj0yrgZba0+b5Ya/juUXqFWiF k+g4/m201StQvUft4XdI2lOiNphf+q2AuvMaJvugppGkTmYPYxPWQ/dqYOBr6C/xFA4K /deRzUn4dSnvLk55omD8dZvbzW7YMBrikjhCmeVkzx5l89/yjW87czvM9DaYZSnnACxH 70XQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=Bw8e3uF28/cdEdxvCMCdA0bblEbgDS1BAPEf0+obtYU=; b=SEhR1rJwDtjK0iqf3pTPPSubwe2zHrbmok7jA6+/CAPcs9F9xRYgDmf3NcBRn+r9n2 Y9QAUqqFlvl3hXvYbfI5FvynUCGwkXOOuvDvUvbe83f0imB2sIbU5aZWQirKUKeTZsUN Db30MJ4F6LG/EcvXUbR7Qt46UiRVu0f3KLeQ6riAiwCf9fKCHq+ehmJaF/LcWkdly00H +ENJKDTc2rjSnRea4vLeZnsrUIpYZNjyMDcKoGk42Gb4xw3K9qExPe3qvtD4gL4dZIof gexU+zGUNyJXgCzlYLdev7Nl/tVY78q0y/Mksy5KdWZng06xrevOrHB/kNqbgNRAI8+h h+fA== X-Gm-Message-State: ALoCoQkSJVHtfmj+YQUJCQGg8bZeVtKugj09vX92F/CkMYjyTS6HtNqgzWC2Pl6TmAE2Q6fdhSHx X-Received: by 10.13.238.71 with SMTP id x68mr17252758ywe.129.1435554242492; Sun, 28 Jun 2015 22:04:02 -0700 (PDT) Received: by 10.37.4.80 with HTTP; Sun, 28 Jun 2015 22:04:02 -0700 (PDT) In-Reply-To: <5590CE10.3020104@web.de> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Sun, Jun 28, 2015 at 9:48 PM, Torsten B=C3=B6gershausen wrote: > On 06/28/2015 04:05 PM, Paul Tan wrote: >> >> A common usage pattern of open() is to check if it was successful, a= nd >> die() if it was not: >> >> int fd =3D open(path, O_WRONLY | O_CREAT, 0777); >> if (fd < 0) >> die_errno(_("Could not open '%s' for writing."), pat= h); >> >> Implement a wrapper function xopen() that does the above so that we = can >> save a few lines of code, and make the die() messages consistent. >> >> Helped-by: Torsten B=C3=B6gershausen >> Helped-by: Jeff King >> Signed-off-by: Paul Tan >> --- >> git-compat-util.h | 1 + >> wrapper.c | 25 +++++++++++++++++++++++++ >> 2 files changed, 26 insertions(+) >> >> diff --git a/git-compat-util.h b/git-compat-util.h >> index c6d391f..e168dfd 100644 >> --- a/git-compat-util.h >> +++ b/git-compat-util.h >> @@ -717,6 +717,7 @@ extern void *xrealloc(void *ptr, size_t size); >> extern void *xcalloc(size_t nmemb, size_t size); >> extern void *xmmap(void *start, size_t length, int prot, int flags= , int >> fd, off_t offset); >> extern void *xmmap_gently(void *start, size_t length, int prot, in= t >> flags, int fd, off_t offset); >> +extern int xopen(const char *path, int flags, ...); >> extern ssize_t xread(int fd, void *buf, size_t len); >> extern ssize_t xwrite(int fd, const void *buf, size_t len); >> extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset)= ; >> diff --git a/wrapper.c b/wrapper.c >> index ff49807..7e13ae0 100644 >> --- a/wrapper.c >> +++ b/wrapper.c >> @@ -189,6 +189,31 @@ void *xcalloc(size_t nmemb, size_t size) >> # endif >> #endif >> +/** >> + * xopen() is the same as open(), but it die()s if the open() fails= =2E >> + */ >> +int xopen(const char *path, int oflag, ...) >> +{ >> + mode_t mode =3D 0; >> + va_list ap; >> + >> + va_start(ap, oflag); >> + if (oflag & O_CREAT) >> + mode =3D va_arg(ap, mode_t); >> + va_end(ap); >> + >> + assert(path); >> + > > 2 remarks: > - I don't know if and why we need the assert() here (but don't know i= f we > have a strategie in Git for assert()) Yeah I think we usually do if (!assertion) die("BUG: assertion not met"); > - Having xopen() with 2 or 3 parameter is good, but the current may n= eed > some tweaks for better portability: > > int xopen(const char *path, int oflag, ...) > { > mode_t mode =3D 0; > if (oflag & O_CREAT) { > va_list ap; > va_start(ap, oflag); > mode =3D va_arg(ap, int); > va_end(ap); > > } > > See e.g. > > why va_arg(ap, int) should be used: > > > + > + /* va_arg() can only take fully promoted types, and m= ode_t > + * sometimes is smaller than an int, so we should alw= ays > pass > + * int to it, and not mode_t. Not doing so would may = result > in > + * a compile-time warning and run-time error. We asum= e that > it > + * is never bigger than an int, which holds in practi= se. */ > + mode =3D va_arg(l, int); > + > >