Re: [dpdk-dev] [PATCH] eal/bsd: reinitialize optind and optreset to 1

[Tiwei Bie <btw@mail.ustc.edu.cn>]

On Wed, Oct 14, 2015 at 06:19:33PM +0800, Tiwei Bie wrote:
> On Wed, Oct 14, 2015 at 10:31:28AM +0100, Bruce Richardson wrote:
> > On Wed, Oct 14, 2015 at 10:28:44AM +0800, Tiwei Bie wrote:
> > > On Tue, Oct 13, 2015 at 05:14:38PM +0000, Don Provan wrote:
> > > > Actually, this is a good opportunity to fix a bug that's been in this code forever: it shouldn't be resetting optind to some arbitrary value: it should be saving optind (and optarg and optopt) at the beginning, initializing optind to 1 before calling getopt_long(), then restoring all the values after. (And, from what you're saying, optreset should be handled the same as optind.)
> > > > 
> > > 
> > > It is designed to have DPDK's parameters specified in the front of the
> > > cmd line and terminated by '--'. Or at least, you should put DPDK's
> > > parameters together and terminate them by '--'. And 1 or 0 are not some
> > > arbitrary values. They are used to put the index back to the beginning
> > > of the new argv[] array.
> > > 
> > > > This avoids broken behavior if rte_eal_init() is called by code that's in the middle of using getopt() to parse its own unrelated argc/argv parameters. 
> > > > 
> > > 
> > > We shouldn't mix up DPDK's parameters and application's parameters.
> > > And we should group them using '--'.
> > > 
> > > Best,
> > > Tiwei Bie
> > 
> > While true, that does not prevent us from implementing Don's suggestion, as it
> > should fix the bug you are looking at with your original patch, and also allow
> > additional use-cases for applications at no extra cost.
> > 
> 
> As I understand it, what Don wants is something like this:
> 
> int main(int argc, char **argv)
> {
> 	int ret;
> 	int ch;
> 
> 	while ((ch = getopt(argc, argv, "whateveroptions:d")) != -1) {
> 		switch (ch) {
> 		case 'd':
> 			/* rte_eal_init() will be called */
> 			ret = dpdk_init(argc, argv);
> 			argc -= ret;
> 			argv += ret;
> 			break;
> 		case 'w':
> 			......
> 		}
> 	}
> 
> 	argc -= optind;
> 	argv += optind;
> 
> 	......
> }
> 
> static int
> dpdk_init(int argc, char **argv)
> {
> 	int ret;
> 
> 	ret = rte_eal_init(argc, argv);
> 	if (ret < 0)
> 		FATAL_ERROR("Could not initialise EAL (%d)", ret);
> 
> 	......
> 
> 	return (ret);
> }
> 
> And the current code should work correctly if DPDK's parameters are
> put together and terminated by '--':
> 
> $ ./demo -whatever -d -c f -n 2 -- -option -s hello
> 

eal_log_level_parse() needs to be reworked to make the code work correctly.

> The only limitation is that the return value of rte_eal_init() must
> be returned to the code which is using getopt() to parse argc/argv.
> 
> And I'm very willing to rework my patch to get rid of this limitation.
> 

I'm considering updating optind to make it point to the option after
'--' before eal_parse_args() returns, and eal_parse_args() will return
0 to avoid breaking the current applications which use the return value
of rte_eal_init() to update argc/argv.

Any comments? Thanks! :-)

Best regards,
Tiwei Bie

> Best regards,
> Tiwei Bie
> 
> > /Bruce
> > 
> > > 
> > > > -don provan
> > > > dprovan@bivio.net
> > > > 
> > > > -----Original Message-----
> > > > From: Tiwei Bie [mailto:btw@mail.ustc.edu.cn] 
> > > > Sent: Tuesday, October 13, 2015 1:54 AM
> > > > To: dev@dpdk.org
> > > > Subject: [dpdk-dev] [PATCH] eal/bsd: reinitialize optind and optreset to 1
> > > > 
> > > > The variable optind must be reinitialized to 1 in order to skip over argv[0] on FreeBSD. Because getopt() on FreeBSD will return -1 when it meets an argument which doesn't start with '-'.
> > > > 
> > > > The variable optreset is provided on FreeBSD to indicate the additional set of calls to getopt(). So, also reinitialize it to 1.
> > > > 
> > > > Signed-off-by: Tiwei Bie <btw@mail.ustc.edu.cn>
> > > > ---
> > > >  lib/librte_eal/bsdapp/eal/eal.c | 6 ++++--
> > > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/lib/librte_eal/bsdapp/eal/eal.c b/lib/librte_eal/bsdapp/eal/eal.c index 1b6f705..35feaee 100644
> > > > --- a/lib/librte_eal/bsdapp/eal/eal.c
> > > > +++ b/lib/librte_eal/bsdapp/eal/eal.c
> > > > @@ -334,7 +334,8 @@ eal_log_level_parse(int argc, char **argv)
> > > >  			break;
> > > >  	}
> > > >  
> > > > -	optind = 0; /* reset getopt lib */
> > > > +	optind = 1; /* reset getopt lib */
> > > > +	optreset = 1;
> > > >  }
> > > >  
> > > >  /* Parse the argument given in the command line of the application */ @@ -403,7 +404,8 @@ eal_parse_args(int argc, char **argv)
> > > >  	if (optind >= 0)
> > > >  		argv[optind-1] = prgname;
> > > >  	ret = optind-1;
> > > > -	optind = 0; /* reset getopt lib */
> > > > +	optind = 1; /* reset getopt lib */
> > > > +	optreset = 1;
> > > >  	return ret;
> > > >  }
> > > >  
> > > > --
> > > > 2.6.0
> > > > 
> > > > 
> > > > 
> > >