netdev - Re: [PATCH iproute2-next 1/8] iplink: Return from function instead of calling exit()

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Date:   Tue, 20 Feb 2018 14:36:47 -0800
From:   Roopa Prabhu <roopa@...ulusnetworks.com>
To:     David Ahern <dsahern@...il.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        Serhey Popovych <serhe.popovych@...il.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCH iproute2-next 1/8] iplink: Return from function instead of
 calling exit()

On Tue, Feb 20, 2018 at 12:49 PM, David Ahern <dsahern@...il.com> wrote:
> On 2/20/18 1:44 PM, Roopa Prabhu wrote:
>> On Tue, Feb 20, 2018 at 12:33 PM, Stephen Hemminger
>> <stephen@...workplumber.org> wrote:
>>> On Tue, 20 Feb 2018 13:27:21 -0700
>>> David Ahern <dsahern@...il.com> wrote:
>>>
>>>> On 2/20/18 1:17 PM, Serhey Popovych wrote:
>>>>> Stephen Hemminger wrote:
>>>>>> On Tue, 20 Feb 2018 21:39:51 +0200
>>>>>> Serhey Popovych <serhe.popovych@...il.com> wrote:
>>>>>>
>>>>>>> Signed-off-by: Serhey Popovych <serhe.popovych@...il.com>
>>>>>>> ---
>>>>>>>  ip/iplink.c |   12 ++++++------
>>>>>>>  1 file changed, 6 insertions(+), 6 deletions(-)
>>>>>>>
>>>>>>> diff --git a/ip/iplink.c b/ip/iplink.c
>>>>>>> index 74c377c..a2c8108 100644
>>>>>>> --- a/ip/iplink.c
>>>>>>> +++ b/ip/iplink.c
>>>>>>> @@ -653,7 +653,7 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
>>>>>>>                   NEXT_ARG();
>>>>>>>                   if (xdp_parse(&argc, &argv, req, dev_index,
>>>>>>>                                 generic, drv, offload))
>>>>>>> -                         exit(-1);
>>>>>>> +                         return -1;
>>>>>>>           } else if (strcmp(*argv, "netns") == 0) {
>>>>>>>                   NEXT_ARG();
>>>>>>>                   if (netns != -1)
>>>>>>> @@ -972,12 +972,12 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
>>>>>>>           if (!dev) {
>>>>>>>                   fprintf(stderr,
>>>>>>>                           "Not enough information: \"dev\" argument is required.\n");
>>>>>>> -                 exit(-1);
>>>>>>> +                 return -1;
>>>>>>>           }
>>>>>>>           if (cmd == RTM_NEWLINK && index) {
>>>>>>>                   fprintf(stderr,
>>>>>>>                           "index can be used only when creating devices.\n");
>>>>>>> -                 exit(-1);
>>>>>>> +                 return -1;
>>>>>>>           }
>>>>>>>
>>>>>>>           req.i.ifi_index = ll_name_to_index(dev);
>>>>>>> @@ -1392,7 +1392,7 @@ static int do_set(int argc, char **argv)
>>>>>>>   if (!dev) {
>>>>>>>           fprintf(stderr,
>>>>>>>                   "Not enough of information: \"dev\" argument is required.\n");
>>>>>>> -         exit(-1);
>>>>>>> +         return -1;
>>>>>>>   }
>>>>>>>
>>>>>>>   if (newaddr || newbrd) {
>>>>>>> @@ -1553,7 +1553,7 @@ static int iplink_afstats(int argc, char **argv)
>>>>>>>                   fprintf(stderr,
>>>>>>>                           "Command \"%s\" is unknown, try \"ip link help\".\n",
>>>>>>>                           *argv);
>>>>>>> -                 exit(-1);
>>>>>>> +                 return -1;
>>>>>>>           }
>>>>>>>
>>>>>>>           argv++; argc--;
>>>>>>> @@ -1648,5 +1648,5 @@ int do_iplink(int argc, char **argv)
>>>>>>>
>>>>>>>   fprintf(stderr, "Command \"%s\" is unknown, try \"ip link help\".\n",
>>>>>>>           *argv);
>>>>>>> - exit(-1);
>>>>>>> + return -1;
>>>>>>>  }
>>>>>>
>>>>>> Not sure I like this. If given bad input in batch it is better to stop and exit
>>>>>> rather than continuing with more bad data.
>>>>>
>>>>> When preparing this change I think in opposite direction: we want to
>>>>> continue batch mode if single line is broken.
>>>>>
>>>>
>>>> batch mode needs to stop on the line that fails. That said, batch still
>>>> fails with the /exit/return/ change
>>>>
>>>> $ cat /tmp/ip.batch
>>>> li sh
>>>> li foo
>>>> li add veth1 type veth peer name veth2
>>>>
>>>> Current command
>>>> $ ip -batch /tmp/ip.batch
>>>> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode
>>>> DEFAULT group default qlen 1000
>>>>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>>>>
>>>> <link list snipped>
>>>> Command "foo" is unknown, try "ip link help".
>>>> $ echo $?
>>>> 255
>>>>
>>>> $ ip/ip -batch /tmp/ip.batch
>>>> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode
>>>> DEFAULT group default qlen 1000
>>>>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>>>> <link list snipped>
>>>> Command "foo" is unknown, try "ip link help".
>>>> Command failed /tmp/ip.batch:2
>>>> dsa@...ny:~/iproute2/iproute2-next.git$ echo $?
>>>> 1
>>>>
>>>> I like that better because it tells me the line that fails.
>>>
>>> Normally ip batch will exit on errors.
>>> The question is what about -force?
>>
>> on -force, it needs to continue.
>>
>
>
> It does.
>
> $ ip/ip -batch /tmp/ip.batch -force
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode
> DEFAULT group default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> <snipped>
> Command "foo" is unknown, try "ip link help".
> Command failed /tmp/ip.batch:2
> RTNETLINK answers: Operation not permitted
> Command failed /tmp/ip.batch:3
>
> Which is an improvement over today where it just exits - ignoring the force.

cool :).

some other iproute2 commands have also received patches to continue on
-force over the last few years.