In the vhost-user code we have a number of places where we need to locate
a particular header within the guest-supplied IO vector. We need to work
out which buffer the header is in, and verify that it's contiguous and
aligned as we need. At the moment this is open-coded, but introduce a
helper to make this more straightforward.
We add a new datatype 'struct iov_tail' representing an IO vector from
which we've logically consumed some number of headers. The IOV_PULL_HEADER
macro consumes a new header from the vector, returning a pointer and
updating the iov_tail.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
it was needed by a draft version of vhost-user, it is not needed
anymore.
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Laurent's recent changes mean we use IO vectors much more heavily in the
TCP code. In many of those cases, and few others around the code base,
individual iovs of these vectors are constructed to exactly cover existing
variables or fields. We can make initializing such iovs shorter and
clearer with a macro for the purpose.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
As pointed out in review, the documentation comments for iov_skip_bytes()
are more confusing than they should be. Reword them, including updating
parameter names, to make it clearer.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Several of the IOV functions in iov.c, and also tap_send_frames_passt()
needs to determine which buffer element a byte offset into an IO vector
lies in. Split this out into a helper function iov_skip_bytes().
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Introduce functions to copy to/from a buffer from/to an iovec array,
to compute data length in in bytes of an iovec and to copy memory from
an iovec to another.
iov_from_buf(), iov_to_buf(), iov_size(), iov_copy().
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Message-ID: <20240217150725.661467-2-lvivier@redhat.com>
[dwg: Small changes to suppress cppcheck warnings]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
