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

[Lukáš Hrázký]

On Thu, 2018-02-22 at 18:56 +0100, Christophe de Dinechin wrote:
> > 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)

That's a possibility, I just followed the structure of write_all()...

> > +
> > +        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 :-)

No problem...

> > +        }
> > +        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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> 
>