iov: Helper macro to construct iovs covering existing variables or fields

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>

1 files changed, 3 insertions, 0 deletions

diff --git a/iov.h b/iov.h
index 6058af7..5668ca5 100644
--- a/iov.h
+++ b/iov.h
@@ -18,6 +18,9 @@
 #include <unistd.h>
 #include <string.h>
 
+#define IOV_OF_LVALUE(lval) \
+	(struct iovec){ .iov_base = &(lval), .iov_len = sizeof(lval) }
+
 size_t iov_skip_bytes(const struct iovec *iov, size_t n,
 		      size_t skip, size_t *offset);
 size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,