patches and low-level development discussion
 help / color / mirror / code / Atom feed
From: Cole Helbling <cole.e.helbling@outlook.com>
To: Alyssa Ross <hi@alyssa.is>, devel@spectrum-os.org
Subject: Re: [PATCH wayland] Support virtio_wl display sockets
Date: Wed, 08 Jul 2020 08:43:54 -0700	[thread overview]
Message-ID: <SJ0PR03MB5581479F3388047230F36EB3B3670@SJ0PR03MB5581.namprd03.prod.outlook.com> (raw)
In-Reply-To: <20200708151600.10607-1-hi@alyssa.is>

Alyssa Ross <hi@alyssa.is> writes:

>  src/connection.c       |   4 +
>  src/meson.build        |  16 +-
>  src/virtio_wl.c        | 344 +++++++++++++++++++++++
>  src/virtio_wl.h        |  23 ++
>  src/wayland-os.c       |  23 ++
>  src/wayland-os.h       |   3 +
>  src/wayland-server.c   |  20 +-
>  src/wayland-shm.c      |  24 +-
>  tests/meson.build      |   1 +
>  tests/virtio_wl-test.c | 615 +++++++++++++++++++++++++++++++++++++++++
>  10 files changed, 1064 insertions(+), 9 deletions(-)
>  create mode 100644 src/virtio_wl.c
>  create mode 100644 src/virtio_wl.h
>  create mode 100644 tests/virtio_wl-test.c
>
> diff --git a/src/virtio_wl.c b/src/virtio_wl.c
> new file mode 100644
> index 0000000..a1ee8ee
> --- /dev/null
> +++ b/src/virtio_wl.c

(snip)

> +static size_t
> +fdbuf_to_cmsg(struct msghdr *msg, const int *buf, size_t buflen)
> +{
> +	// Check msg->msg_control is long enough to fit at least one fd.
> +	if (msg->msg_controllen < CMSG_SPACE(sizeof(int))) {
> +
> +		// If there's at least one fd in buf, set MSG_CTRUNC.
> +		size_t i = 0;
> +		while (i < buflen && !(msg->msg_flags & MSG_CTRUNC))
> +			if (buf[i++] != -1)
> +				msg->msg_flags |= MSG_CTRUNC;
> +
> +		return 0;
> +	}
> +
> +	// cmsg(3):
> +	// > When initializing a buffer that will contain a series of cmsghdr
> +        // > structures (e.g., to be sent with sendmsg(2)), that buffer should
> +        // > first be zero-initialized to en‐ sure the correct operation of
> +        // > CMSG_NXTHDR().

This comment looks weird -- both the misalignment (tabs vs spaces, it
seems) and "en- sure" (probably reflow mistake).

> +	memset(msg->msg_control, 0, msg->msg_controllen);
> +
> +	// Set up the cmsg.
> +	struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
> +	cmsg->cmsg_level = SOL_SOCKET;
> +	cmsg->cmsg_type = SCM_RIGHTS;
> +
> +	// Copy as many fds as fit into cmsg.
> +	size_t len = 0;
> +	for (size_t i = 0; i < buflen; i++) {
> +		if (buf[i] == -1)
> +			continue;
> +
> +		if (CMSG_LEN((len + 1) * sizeof(int)) > msg->msg_controllen) {
> +			msg->msg_flags |= MSG_CTRUNC;
> +			break;
> +		}
> +
> +		memcpy(CMSG_DATA(cmsg) + sizeof(int) * len, &buf[i], sizeof(int));
> +		len++;
> +	}
> +
> +	cmsg->cmsg_len = CMSG_LEN(len * sizeof(int));
> +	return len;
> +}

I can't comment on the code itself, as I'm unfamiliar with both Wayland
and C. :D

Cole

  reply	other threads:[~2020-07-08 15:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-08 15:16 Alyssa Ross
2020-07-08 15:43 ` Cole Helbling [this message]
2020-07-08 21:07 ` [PATCH wayland v2] " Alyssa Ross
2020-07-26  6:03 ` [PATCH wayland v3] " Alyssa Ross
2020-07-27 18:37   ` Cole Helbling

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=SJ0PR03MB5581479F3388047230F36EB3B3670@SJ0PR03MB5581.namprd03.prod.outlook.com \
    --to=cole.e.helbling@outlook.com \
    --cc=devel@spectrum-os.org \
    --cc=hi@alyssa.is \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://spectrum-os.org/git/crosvm
	https://spectrum-os.org/git/doc
	https://spectrum-os.org/git/mktuntap
	https://spectrum-os.org/git/nixpkgs
	https://spectrum-os.org/git/spectrum
	https://spectrum-os.org/git/ucspi-vsock
	https://spectrum-os.org/git/www

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).