export iov_send_recv() and use it in iov_send() and iov_recv()

Rename do_sendv_recvv() to iov_send_recv(), change its last arg
(do_send) from int to bool, export it in iov.h, and made the two
callers of it (iov_send() and iov_recv()) to be trivial #defines
just adding 5th arg.

iov_send_recv() will be used later.
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

cutils.c

@@ -376,9 +376,9 @@ int qemu_parse_fd(const char *param)
     return fd;
 }
 
-static ssize_t do_sendv_recvv(int sockfd, struct iovec *iov,
-                          size_t offset, size_t bytes,
-                          int do_sendv)
+ssize_t iov_send_recv(int sockfd, struct iovec *iov,
+                      size_t offset, size_t bytes,
+                      bool do_sendv)
 {
     int iovlen;
     ssize_t ret;
@@ -458,14 +458,3 @@ static ssize_t do_sendv_recvv(int sockfd, struct iovec *iov,
     last_iov->iov_len += diff;
     return ret;
 }
-
-ssize_t iov_recv(int sockfd, struct iovec *iov, size_t offset, size_t bytes)
-{
-    return do_sendv_recvv(sockfd, iov, offset, bytes, 0);
-}
-
-ssize_t iov_send(int sockfd, struct iovec *iov, size_t offset, size_t bytes)
-{
-    return do_sendv_recvv(sockfd, iov, offset, bytes, 1);
-}
-

iov.h

@@ -60,7 +60,7 @@ size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
  * `offset' bytes in the beginning of iovec buffer are skipped and
  * next `bytes' bytes are used, which must be within data of iovec.
  *
- *   r = iov_send(sockfd, iov, offset, bytes);
+ *   r = iov_send_recv(sockfd, iov, offset, bytes, true);
  *
  * is logically equivalent to
  *
@@ -69,8 +69,12 @@ size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
  *   r = send(sockfd, buf, bytes, 0);
  *   free(buf);
  */
-ssize_t iov_recv(int sockfd, struct iovec *iov, size_t offset, size_t bytes);
-ssize_t iov_send(int sockfd, struct iovec *iov, size_t offset, size_t bytes);
+ssize_t iov_send_recv(int sockfd, struct iovec *iov,
+                      size_t offset, size_t bytes, bool do_send);
+#define iov_recv(sockfd, iov, offset, bytes) \
+  iov_send_recv(sockfd, iov, offset, bytes, false)
+#define iov_send(sockfd, iov, offset, bytes) \
+  iov_send_recv(sockfd, iov, offset, bytes, true)
 
 /**
  * Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements