From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [RFC 2/4] eal: enable experimental dlopen()-based
 secondary process support
Date: Fri, 19 May 2017 10:39:48 -0700
Message-ID: <20170519103948.4d829353@xeon-e3>
References: <1495211986-15177-1-git-send-email-anatoly.burakov@intel.com>
 <1495211986-15177-3-git-send-email-anatoly.burakov@intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: dev@dpdk.org
To: Anatoly Burakov <anatoly.burakov@intel.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-pf0-f173.google.com (mail-pf0-f173.google.com
 [209.85.192.173]) by dpdk.org (Postfix) with ESMTP id 4238E107A
 for <dev@dpdk.org>; Fri, 19 May 2017 19:39:56 +0200 (CEST)
Received: by mail-pf0-f173.google.com with SMTP id n23so42935626pfb.2
 for <dev@dpdk.org>; Fri, 19 May 2017 10:39:56 -0700 (PDT)
In-Reply-To: <1495211986-15177-3-git-send-email-anatoly.burakov@intel.com>
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Fri, 19 May 2017 17:39:44 +0100
Anatoly Burakov <anatoly.burakov@intel.com> wrote:

> This new forked secondary dlopen()'s the original secondary process
> binary and runs main() again. In the meantime, the original secondary
> process waits until this new forked secondary dies, and exits.


You don't have to use a lock file. Just using a pipe for process
standard input and detecting close on process exit is often simpler.

> +static
> +const char *get_run_dir(void) {
> +	const char *dir = "/var/run";
> +	const char *home_dir = getenv("HOME");
> +
> +	if (getuid() != 0 && home_dir != NULL)
> +		dir = home_dir;
> +	return dir;
> +}
> +
> +static
> +void get_rand_str(char *str, int sz) {
> +	char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
> +	for (int i = 0; i < sz - 1; i++) {
> +		// this does not give us *true* randomness but it's good enough
> +		int idx = rand() % sizeof(charset);
> +		str[i] = charset[idx];
> +	}
> +	str[sz - 1] = '\0';
> +}
> +
> +/* we need to know its length */
> +static
> +int get_lock_file_path(char *str, int sz) {
> +	char rand_str[16];
> +
> +	get_rand_str(rand_str, 16);
> +
> +	return snprintf(str, sz, LOCKFILE_PATH_FMT, get_run_dir(),
> +	                internal_config.hugefile_prefix, rand_str);
> +}
> +

Why reinvent all the stuff in mkstemp and friends?

Also don't use C++ style comments in DPDK code.