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Make it much more understandable, add a missing
iov_cnt argument (number of iovs in the iov), and
add comments to it.
The new implementation has been extensively tested
by splitting a large buffer into many small
randomly-sized chunks, sending it over socket to
another, slow process and verifying the receiving
data is the same.
Also add a unit test for iov_send_recv(), sending/
receiving data between two processes over a socketpair
using random vectors and random sizes.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
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Rename arguments and use size_t for sizes instead of int,
from
int
qemu_sendv(int sockfd, struct iovec *iov,
int len, int iov_offset)
to
ssize_t
iov_send(int sockfd, struct iovec *iov,
size_t offset, size_t bytes)
The main motivation was to make it clear that length
and offset are in _bytes_, not in iov elements: it was
very confusing before, because all standard functions
which deals with iovecs expects number of iovs, not
bytes, even the fact that struct iovec has iov_len and
iov_ prefix does not help. With "bytes" and "offset",
especially since they're now size_t, it is much more
explicit. Also change the return type to be ssize_t
instead of int.
This also changes it to match other iov-related functons,
but not _quite_: there's still no argument indicating
where iovec ends, ie, no iov_cnt parameter as used
in iov_size() and friends. If will be added in subsequent
patch/rewrite.
All callers of qemu_sendv() and qemu_recvv() and
related, like qemu_co_sendv() and qemu_co_recvv(),
were checked to verify that it is safe to use unsigned
datatype instead of int.
Note that the order of arguments is changed to: offset
and bytes (len and iov_offset) are swapped with each
other. This is to make them consistent with very similar
functions from qemu_iovec family, where offset always
follows qiov, to mean the place in it to start from.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
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