Re: [PATCH v2 1/8] test-pkt-line: add unpack-sideband subcommand

[Stefan Beller <sbeller@google.com>]

On Wed, Jun 13, 2018 at 2:39 PM Brandon Williams <bmwill@google.com> wrote:
>
> Add an 'unpack-sideband' subcommand to the test-pkt-line helper to
> enable unpacking packet line data sent multiplexed using a sideband.
>
> Signed-off-by: Brandon Williams <bmwill@google.com>
> ---
>  t/helper/test-pkt-line.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
>
> diff --git a/t/helper/test-pkt-line.c b/t/helper/test-pkt-line.c
> index 0f19e53c7..2a55ffff1 100644
> --- a/t/helper/test-pkt-line.c
> +++ b/t/helper/test-pkt-line.c
> @@ -1,3 +1,4 @@
> +#include "cache.h"
>  #include "pkt-line.h"
>
>  static void pack_line(const char *line)
> @@ -48,6 +49,40 @@ static void unpack(void)
>         }
>  }
>
> +static void unpack_sideband(void)
> +{
> +       struct packet_reader reader;
> +       packet_reader_init(&reader, 0, NULL, 0,
> +                          PACKET_READ_GENTLE_ON_EOF |
> +                          PACKET_READ_CHOMP_NEWLINE);
> +
> +       while (packet_reader_read(&reader) != PACKET_READ_EOF) {
> +               int band;
> +               int fd;
> +
> +               switch (reader.status) {
> +               case PACKET_READ_EOF:
> +                       break;
> +               case PACKET_READ_NORMAL:
> +                       band = reader.line[0] & 0xff;
> +                       if (band == 1)
> +                               fd = 1;
> +                       else
> +                               fd = 2;
> +
> +                       write_or_die(fd, reader.line+1, reader.pktlen-1);

white space around + and - ?

> +
> +                       if (band == 3)
> +                               die("sind-band error");

s/sind/side/ ?

What values for band are possible?
e.g. band==4 would also just write to fd=1;
but I suspect we don't want that, yet.

So maybe

    band = reader.line[0] & 0xff;
    if (band < 1 || band > 2)
        die("unexpected side band %d", band)
    fd = band;

instead?