Re: [PATCH v3 1/8] test-pkt-line: add unpack-sideband subcommand

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Jun 22, 2018, 21:12 UTC
Message-ID: <20180622211236.GH12013@aiede.svl.corp.google.com>
In-Reply-To: <20180620213235.10952-2-bmwill@google.com>

Hi,

Brandon Williams wrote:

Show 7 quoted lines

> 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 | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)

Neat. It appears that this writes sideband channel 1 (packfile data) to stdout, sideband channel 2 (progress) to stderr, and sideband channel 3 (errors) cause the helper to fail. It would have been nice if a comment or the commit message said that, but it's no reason to reroll --- the code is clear enough.

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> --- 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"

I think this is for write_or_die. Makes sense (well, in the same way as any of the other functions that ended up in cache.h instead of a more thought-through place do).

The old #includes were problematic, since the caller cannot count on git-compat-util.h to be the first include of pkt-line.h. See Documentation/CodingGuidelines "The first #include" for more on this subject.

[...]

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> +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;

reader.line[0] is a char. This promotes it to an 'int' and then ANDs against 0xff, which would ensure it is a positive value. In other words, this does the same thing as

	band = (int) (unsigned char) reader.line[0];

but more concisely.

More importantly, it matches what recv_sideband does.  Good.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>

Thanks.