Re: [Qemu-devel] [PATCH v4 2/8] Add socket_writev_buffer function

[Eric Blake <eblake@redhat.com>]

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On 03/21/2013 12:34 PM, Orit Wasserman wrote:
> Signed-off-by: Orit Wasserman <owasserm@redhat.com>
> ---
>  savevm.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/savevm.c b/savevm.c
> index 35c8d1e..6608b6e 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -39,6 +39,7 @@
>  #include "qmp-commands.h"
>  #include "trace.h"
>  #include "qemu/bitops.h"
> +#include "qemu/iov.h"
>  
>  #define SELF_ANNOUNCE_ROUNDS 5
>  
> @@ -171,6 +172,19 @@ static void coroutine_fn yield_until_fd_readable(int fd)
>      qemu_coroutine_yield();
>  }
>  
> +static int socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt)

Returning int...

> +{
> +    QEMUFileSocket *s = opaque;
> +    ssize_t len;
> +    ssize_t size = iov_size(iov, iovcnt);
> +
> +    len = iov_send(s->fd, iov, iovcnt, 0, size);
> +    if (len < size) {
> +        len = -socket_error();
> +    }
> +    return len;

...but len is an ssize_t.  If we send an iov with 2 gigabytes of data,
this can wrap around to a negative int even though we send a positive
amount of data.  Why not make the callback be typed to return ssize_t
from the beginning (affects patch 1/8)?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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