Re: Problem with scatter/gather IO

[Leon Romanovsky <leon@xxxxxxx>]

On Wed, Jul 13, 2011 at 14:54, Randi Botse <nightdecoder@xxxxxxxxx> wrote:
>
> Hi,
>
> I will read/write file with readv() and writev(), I have problem to
> use that since the struct iovec will be a variable-length array, if i
> have code.
>
> struct foo {
>    unsigned char data[100];
>    unsigned char another_data[28];
> };
> unsigned len;
> ....
>
> /* calculate len */
> /* use len as array's member size */
> struct iovec iov[len];
> printf("len is: %i\n", len);
> readv(fd, iov, len);
>
> I got: BAD ADDRESS, and if I remove the printf() then I will get
> INVALID ARGUMENT. What the possible problem with that?
>
> Thanks,
> --

Did you try "man readv" ?
You didn't initialized iovec struct.
http://pubs.opengroup.org/onlinepubs/009695399/functions/readv.html

--
Leon Romanovsky | Independent Linux Consultant
        www.leon.nu | leon@xxxxxxx
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