iov: add iov_cpy

Add API to copy part of iovec safely.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/iov.h b/iov.h
index a73569f94e..34c8ec9faa 100644
--- a/iov.h
+++ b/iov.h
@@ -86,3 +86,12 @@ ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
  */
 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
                  FILE *fp, const char *prefix, size_t limit);
+
+/*
+ * Partial copy of vector from iov to dst_iov (data is not copied).
+ * dst_iov overlaps iov at a specified offset.
+ * size of dst_iov is at most bytes. dst vector count is returned.
+ */
+unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
+                 const struct iovec *iov, unsigned int iov_cnt,
+                 size_t offset, size_t bytes);