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Re: [PATCH v9 09/14] pkt-line: add packet_write_gently()

From
Junio C Hamano <gitster@pobox.com>
Date
Oct 4, 2016, 19:33 UTC
Message-ID
<xmqqd1jfucwo.fsf@gitster.mtv.corp.google.com>
In-Reply-To
<20161004125947.67104-10-larsxschneider@gmail.com>
larsxschneider@gmail.com writes:
Show 31 quoted lines
> From: Lars Schneider <larsxschneider@gmail.com>
>
> packet_write_fmt_gently() 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.
>
> Add packet_write_gently() which writes arbitrary data and does not die
> in case of an error. The function is used by other pkt-line functions in
> a subsequent patch.
>
> Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  pkt-line.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/pkt-line.c b/pkt-line.c
> index 286eb09..3fd4dc0 100644
> --- a/pkt-line.c
> +++ b/pkt-line.c
> @@ -171,6 +171,22 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
>  	return status;
>  }
>  
> +static int packet_write_gently(const int fd_out, const char *buf, size_t size)
> +{
> +	static char packet_write_buffer[LARGE_PACKET_MAX];
> +	const size_t packet_size = size + 4;
> +
> +	if (packet_size > sizeof(packet_write_buffer))
> +		return error("packet write failed - data exceeds max packet size");

Hmph, in the previous round, this used to be "is the size larger than sizeof(..) - 4?", which avoided integer overflow issue rather nicely and more idiomatic. If size is near the size_t's max, packet_size may wrap around to become very small, and we won't hit this error, will we?

Show 11 quoted lines
> +	packet_trace(buf, size, 1);
> +	set_packet_header(packet_write_buffer, packet_size);
> +	memcpy(packet_write_buffer + 4, buf, size);
> +	if (write_in_full(fd_out, packet_write_buffer, packet_size) == packet_size)
> +		return 0;
> +	return error("packet write failed");
> +}
> +
>  void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
>  {
>  	va_list args;
Previous: larsxschneider@gmail.comNext: Lars Schneider
Message 6 of 28 in “Git filter protocol”
  1. 00/14 Git filter protocollarsxschneider@gmail.com, Oct 4, 2016
  2. 02/14 convert: modernize testslarsxschneider@gmail.com, Oct 4, 2016
  3. 06/14 pkt-line: extract set_packet_header()larsxschneider@gmail.com, Oct 4, 2016
  4. 07/14 pkt-line: add packet_write_fmt_gently()larsxschneider@gmail.com, Oct 4, 2016
  5. 09/14 pkt-line: add packet_write_gently()larsxschneider@gmail.com, Oct 4, 2016
  6. Junio C HamanoOct 4, 2016
  7. Lars SchneiderOct 5, 2016
  8. Junio C HamanoOct 6, 2016
  9. 11/14 convert: make apply_filter() adhere to standard Git error handlinglarsxschneider@gmail.com, Oct 4, 2016
  10. 10/14 pkt-line: add functions to read/write flush terminated packet streamslarsxschneider@gmail.com, Oct 4, 2016
  11. Junio C HamanoOct 4, 2016
  12. Junio C HamanoOct 4, 2016
  13. Lars SchneiderOct 5, 2016
  14. 12/14 convert: prepare filter.<driver>.process optionlarsxschneider@gmail.com, Oct 4, 2016
  15. 13/14 convert: add filter.<driver>.process optionlarsxschneider@gmail.com, Oct 4, 2016
  16. 01/14 convert: quote filter names in error messageslarsxschneider@gmail.com, Oct 4, 2016
  17. 08/14 pkt-line: add packet_flush_gently()larsxschneider@gmail.com, Oct 4, 2016
  18. 14/14 contrib/long-running-filter: add long running filter examplelarsxschneider@gmail.com, Oct 4, 2016
  19. 04/14 run-command: add wait_on_exitlarsxschneider@gmail.com, Oct 4, 2016
  20. Junio C HamanoOct 4, 2016
  21. Lars SchneiderOct 5, 2016
  22. Junio C HamanoOct 5, 2016
  23. Johannes SchindelinOct 6, 2016
  24. Lars SchneiderOct 6, 2016
  25. Junio C HamanoOct 6, 2016
  26. 03/14 run-command: move check_pipe() from write_or_die to run_commandlarsxschneider@gmail.com, Oct 4, 2016
  27. 05/14 pkt-line: rename packet_write() to packet_write_fmt()larsxschneider@gmail.com, Oct 4, 2016
  28. Jakub NarębskiOct 5, 2016

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