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

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Date:   Tue, 20 Feb 2018 13:49:10 -0700
From:   David Ahern <dsahern@...il.com>
To:     Roopa Prabhu <roopa@...ulusnetworks.com>,
        Stephen Hemminger <stephen@...workplumber.org>
Cc:     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 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.