On Wed, Aug 10, 2016 at 03:04:00PM +0200, larsxschnei...@gmail.com wrote:

> From: Lars Schneider <larsxschnei...@gmail.com>
> packet_write() has two shortcomings. First, it uses format_packet() which
> lets the caller only send string data via "%s". That means it cannot be
> used for arbitrary data that may contain NULs. Second, it will always
> die on error.
> Add packet_write_gently() which writes arbitrary data and returns `0` for
> success and `-1` for an error.

So now we have packet_write() and packet_write_gently(), but they differ
in more than just whether they are gentle. That seems like a weird

Should we either be picking a new name (e.g., packet_write_mem() or
something), or migrating packet_write() to packet_write_fmt()?

> diff --git a/pkt-line.c b/pkt-line.c
> index e6b8410..4f25748 100644
> --- a/pkt-line.c
> +++ b/pkt-line.c
> @@ -3,6 +3,7 @@
>  #include "run-command.h"
>  char packet_buffer[LARGE_PACKET_MAX];
> +char packet_write_buffer[LARGE_PACKET_MAX];

Should this be static? I.e., are random other bits of the code allowed
to write into it (I guess not because it's not declared in pkt-line.h).

> +int packet_write_gently(const int fd_out, const char *buf, size_t size)
> +{
> +     if (size > PKTLINE_DATA_MAXLEN)
> +             return -1;
> +     packet_trace(buf, size, 1);
> +     memmove(packet_write_buffer + 4, buf, size);

It looks like this iteration drops the idea of callers using a
LARGE_PACKET_MAX buffer and only filling it at "buf+4" with
PKTLINE_DATA_MAXLEN bytes (which is fine).

I wonder if we still need PKTLINE_DATA_MAXLEN, or of it is just
obscuring things. The magic number "4" still appears separately here,
and it actually makes it harder to see that things are correct.  I.e.,

  if (size > sizeof(packet_write_buffer) - 4)
        return -1;
  memmove(packet_write_buffer + 4, buf, size);

is more obviously correct, because you do not have to wonder about the
relationship between the size of your buffer and the macro.

It might still be worth having PKTLINE_DATA_MAXLEN public, though, if
callers use it to size their input to packet_write_gently().

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