[Spice-devel] [PATCH spice-streaming-agent v2 1/2] Move reading stream messages into a function

[Christophe de Dinechin]

> On 22 Feb 2018, at 18:41, Lukáš Hrázký <lhrazky at redhat.com> wrote:
> 
> Signed-off-by: Lukáš Hrázký <lhrazky at redhat.com>
> ---
> src/spice-streaming-agent.cpp | 31 +++++++++++++++++++++----------
> 1 file changed, 21 insertions(+), 10 deletions(-)
> 
> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
> index aeee5d3..20ac1f4 100644
> --- a/src/spice-streaming-agent.cpp
> +++ b/src/spice-streaming-agent.cpp
> @@ -79,6 +79,24 @@ static int have_something_to_read(int timeout)
>     return 0;
> }
> 
> +static void read_all(void *msg, size_t len)
> +{
> +    size_t len_read = 0;
> +
> +    while (len_read < len) {
> +        ssize_t n = read(streamfd, (uint8_t *) msg + len_read, len - len_read);

What about removing read_len, and decrementing len instead of incrementing read_len? (also need to increment the pointer, obviously)


> +
> +        if (n < 0) {
> +            if (errno == EINTR) {
> +                continue;
> +            }
> +            throw std::runtime_error("Reading message from device failed: " +
> +                                     std::string(strerror(errno)));

If this goes in before my own series, I will use that as an excuse to create the IOError and ReadError classes, and avoid all this duplication of strerror(errno) and string concatenation that bloats the code :-)

> +        }
> +        len_read += n;
> +    }
> +}
> +
> static void handle_stream_start_stop(uint32_t len)
> {
>     uint8_t msg[256];
> @@ -87,11 +105,8 @@ static void handle_stream_start_stop(uint32_t len)
>         throw std::runtime_error("msg size (" + std::to_string(len) + ") is too long "
>                                  "(longer than " + std::to_string(sizeof(msg)) + ")");
>     }
> -    int n = read(streamfd, &msg, len);
> -    if (n != len) {
> -        throw std::runtime_error("read command from device FAILED -- read " + std::to_string(n) +
> -                                 " expected " + std::to_string(len));
> -    }
> +
> +    read_all(msg, len);
>     streaming_requested = (msg[0] != 0); /* num_codecs */
>     syslog(LOG_INFO, "GOT START_STOP message -- request to %s streaming\n",
>            streaming_requested ? "START" : "STOP");
> @@ -108,12 +123,8 @@ static void handle_stream_capabilities(uint32_t len)
>     if (len > sizeof(caps)) {
>         throw std::runtime_error("capability message too long");
>     }
> -    int n = read(streamfd, caps, len);
> -    if (n != len) {
> -        throw std::runtime_error("read command from device FAILED -- read " + std::to_string(n) +
> -                                 " expected " + std::to_string(len));
> -    }
> 
> +    read_all(caps, len);
>     // we currently do not support extensions so just reply so
>     StreamDevHeader hdr = {
>         STREAM_DEVICE_PROTOCOL,
> -- 
> 2.16.1
> 
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