From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: [PATCH 10/22] libxc: suspend: Fix suspend event
 channel locking
Date: Tue, 18 Mar 2014 09:44:27 +0100
Message-ID: <20140318084426.GA16621@aepfle.de>
References: <1395063006-6671-1-git-send-email-ian.jackson@eu.citrix.com>
	<1395063006-6671-11-git-send-email-ian.jackson@eu.citrix.com>
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To: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Shriram Rajagopalan <rshriram@cs.ubc.ca>, Lai Jiangshan <laijs@cn.fujitsu.com>, xen-devel@lists.xensource.com, Ian Campbell <Ian.Campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

On Mon, Mar 17, Ian Jackson wrote:

> +#define SUSPEND_FILE_BUFLEN (sizeof(SUSPEND_LOCK_FILE) + 10)
> +
> +static void get_suspend_file(char buf[SUSPEND_FILE_BUFLEN], int domid)
>  {
> -    int fd, rc;
> -    mode_t mask;
> -    char buf[128];
> -    char suspend_file[256];
> -
> -    snprintf(suspend_file, sizeof(suspend_file), "%s_%d_lock.d",
> -	    SUSPEND_LOCK_FILE, domid);
> -    mask = umask(022);
> -    fd = open(suspend_file, O_CREAT | O_EXCL | O_RDWR, 0666);
> -    if (fd < 0)
> -    {
> -        ERROR("Can't create lock file for suspend event channel %s\n",
> -		suspend_file);
> -        return -EINVAL;
> +    snprintf(buf, sizeof(buf), SUSPEND_LOCK_FILE, domid);
> +}

This fails with newer gcc, such as gcc-4.8:

xc_suspend.c: In function 'get_suspend_file':
xc_suspend.c:39:25: error: argument to 'sizeof' in 'snprintf' call is the same expression as the destination; did you mean to provide an explicit length? [-Werror=sizeof-pointer-memaccess]
     snprintf(buf, sizeof(buf), SUSPEND_LOCK_FILE, domid);
                         ^
cc1: all warnings being treated as errors

Olaf