Re: [Qemu-devel] [PATCH v2 4/7] io: pass a struct iovec into qio_channel_websock_encode

[Eric Blake <eblake@redhat.com>]

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On 10/11/2017 05:09 AM, Daniel P. Berrange wrote:
> Instead of requiring use of another Buffer, pass a struct iovec
> into qio_channel_websock_encode, which gives callers more
> flexibility in how they process data.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

> +static void qio_channel_websock_encode(QIOChannelWebsock *ioc,
> +                                       uint8_t opcode,
> +                                       const struct iovec *iov,
> +                                       size_t niov,
> +                                       size_t size)
>  {
>      size_t header_size;
> +    size_t i;
>      union {
>          char buf[QIO_CHANNEL_WEBSOCK_HEADER_LEN_64_BIT];
>          QIOChannelWebsockHeader ws;

Is it worth adding assert(size <= iov_size(iov, niov)) near the top,

> +    trace_qio_channel_websock_encode(ioc, opcode, header_size, size);
> +    buffer_reserve(&ioc->encoutput, header_size + size);
> +    buffer_append(&ioc->encoutput, header.buf, header_size);
> +    for (i = 0; i < niov && size != 0; i++) {
> +        size_t want = iov[i].iov_len;
> +        if (want > size) {
> +            want = size;
> +        }
> +        buffer_append(&ioc->encoutput, iov[i].iov_base, want);
> +        size -= want;
> +    }

so we don't have to worry about a huge size causing us to buffer_reserve
far too much space?

Doesn't affect my R-b, though.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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