Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Sat, Jul 24, 2021 at 8:21 AM Juhee Kang <claudiajkang@gmail.com> wrote:
>
> The current behavior of 'tracex7' doesn't consist with other bpf samples
> tracex{1..6}. Other samples do not require any argument to run with, but
> tracex7 should be run with btrfs device argument. (it should be executed
> with test_override_return.sh)
>
> Currently, tracex7 doesn't have any description about how to run this
> program and raises an unexpected error. And this result might be
> confusing since users might not have a hunch about how to run this
> program.
>
>     // Current behavior
>     # ./tracex7
>     sh: 1: Syntax error: word unexpected (expecting ")")
>     // Fixed behavior
>     # ./tracex7
>     ERROR: Run with the btrfs device argument!
>
> In order to fix this error, this commit adds logic to report a message
> and exit when running this program with a missing argument.
>
> Additionally in test_override_return.sh, there is a problem with
> multiple directory(tmpmnt) creation. So in this commit adds a line with
> removing the directory with every execution.
>
> Signed-off-by: Juhee Kang <claudiajkang@gmail.com>
> ---
>  samples/bpf/test_override_return.sh | 1 +
>  samples/bpf/tracex7_user.c          | 5 +++++
>  2 files changed, 6 insertions(+)
>
> diff --git a/samples/bpf/test_override_return.sh b/samples/bpf/test_override_return.sh
> index e68b9ee6814b..6480b55502c7 100755
> --- a/samples/bpf/test_override_return.sh
> +++ b/samples/bpf/test_override_return.sh
> @@ -1,5 +1,6 @@
>  #!/bin/bash
>
> +rm -rf tmpmnt

Do we need -rf or -r would do?

>  rm -f testfile.img
>  dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1
>  DEVICE=$(losetup --show -f testfile.img)
> diff --git a/samples/bpf/tracex7_user.c b/samples/bpf/tracex7_user.c
> index fdcd6580dd73..8be7ce18d3ba 100644
> --- a/samples/bpf/tracex7_user.c
> +++ b/samples/bpf/tracex7_user.c
> @@ -14,6 +14,11 @@ int main(int argc, char **argv)
>         int ret = 0;
>         FILE *f;
>
> +       if (!argv[1]) {
> +               fprintf(stderr, "ERROR: Run with the btrfs device argument!\n");
> +               return 0;
> +       }
> +
>         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
>         obj = bpf_object__open_file(filename, NULL);
>         if (libbpf_get_error(obj)) {
> --
> 2.27.0
>