On Sat, Nov 19, 2022 at 09:36:14AM +0000, manish.mishra wrote:
> MSG_PEEK reads from the peek of channel, The data is treated as
> unread and the next read shall still return this data. This
> support is currently added only for socket class. Extra parameter
> 'flags' is added to io_readv calls to pass extra read flags like
> MSG_PEEK.
>
> Suggested-by: Daniel P. Berrangé <berra...@redhat.com
> Signed-off-by: manish.mishra <manish.mis...@nutanix.com>
> ---
> chardev/char-socket.c | 4 +-
> include/io/channel.h | 83 +++++++++++++++++++++++++++++
> io/channel-buffer.c | 1 +
> io/channel-command.c | 1 +
> io/channel-file.c | 1 +
> io/channel-null.c | 1 +
> io/channel-socket.c | 16 +++++-
> io/channel-tls.c | 1 +
> io/channel-websock.c | 1 +
> io/channel.c | 73 +++++++++++++++++++++++--
> migration/channel-block.c | 1 +
> scsi/qemu-pr-helper.c | 2 +-
> tests/qtest/tpm-emu.c | 2 +-
> tests/unit/test-io-channel-socket.c | 1 +
> util/vhost-user-server.c | 2 +-
> 15 files changed, 179 insertions(+), 11 deletions(-)
> diff --git a/io/channel-socket.c b/io/channel-socket.c
> index b76dca9cc1..a06b24766d 100644
> --- a/io/channel-socket.c
> +++ b/io/channel-socket.c
> @@ -406,6 +406,8 @@ qio_channel_socket_accept(QIOChannelSocket *ioc,
> }
> #endif /* WIN32 */
>
> + qio_channel_set_feature(QIO_CHANNEL(cioc),
> QIO_CHANNEL_FEATURE_READ_MSG_PEEK);
> +
This covers the incoming server side socket.
This also needs to be set in outgoing client side socket in
qio_channel_socket_connect_async
> @@ -705,7 +718,6 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
> }
> #endif /* WIN32 */
>
> -
> #ifdef QEMU_MSG_ZEROCOPY
> static int qio_channel_socket_flush(QIOChannel *ioc,
> Error **errp)
Please remove this unrelated whitespace change.
> @@ -109,6 +117,37 @@ int qio_channel_readv_all_eof(QIOChannel *ioc,
> return qio_channel_readv_full_all_eof(ioc, iov, niov, NULL, NULL, errp);
> }
>
> +int qio_channel_readv_peek_all_eof(QIOChannel *ioc,
> + const struct iovec *iov,
> + size_t niov,
> + Error **errp)
> +{
> + ssize_t len = 0;
> + ssize_t total = iov_size(iov, niov);
> +
> + while (len < total) {
> + len = qio_channel_readv_full(ioc, iov, niov, NULL,
> + NULL, QIO_CHANNEL_READ_FLAG_MSG_PEEK,
> errp);
> +
> + if (len == QIO_CHANNEL_ERR_BLOCK) {
> + if (qemu_in_coroutine()) {
> + qio_channel_yield(ioc, G_IO_IN);
> + } else {
> + qio_channel_wait(ioc, G_IO_IN);
> + }
> + continue;
> + }
> + if (len == 0) {
> + return 0;
> + }
> + if (len < 0) {
> + return -1;
> + }
> + }
This will busy wait burning CPU where there is a read > 0 and < total.
With regards,
Daniel
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