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allow qemu_iovec_from_buffer() to specify offset from which to start copying

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Similar to
 qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
                   int c, size_t bytes);
the new prototype is:
 qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,
                     const void *buf, size_t bytes);

The processing starts at offset bytes within qiov.

This way, we may copy a bounce buffer directly to
a middle of qiov.

This is exactly the same function as iov_from_buf() from
iov.c, so use the existing implementation and rename it
to qemu_iovec_from_buf() to be shorter and to match the
utility function.

As with utility implementation, we now assert that the
offset is inside actual iovec.  Nothing changed for
current callers, because `offset' parameter is new.

While at it, stop using "bounce-qiov" in block/qcow2.c
and copy decrypted data directly from cluster_data
instead of recreating a temp qiov for doing that.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Michael Tokarev 2012-06-07 20:17:55 +04:00
parent 3d9b49254f
commit 03396148bc
7 changed files with 16 additions and 28 deletions
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16
cutils.c
View file

@ -245,20 +245,10 @@ void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf)
}
}
void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count)
size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,
const void *buf, size_t bytes)
{
const uint8_t *p = (const uint8_t *)buf;
size_t copy;
int i;
for (i = 0; i < qiov->niov && count; ++i) {
copy = count;
if (copy > qiov->iov[i].iov_len)
copy = qiov->iov[i].iov_len;
memcpy(qiov->iov[i].iov_base, p, copy);
p += copy;
count -= copy;
}
return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes);
}
size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,