posix: fall back to send if sendmsg is unavailable for ipc and tcp

This will be slower, as each vector element has to be sent in a single
system call, but for platforms that lack sendmsg it will at least work.

1 files changed, 15 insertions, 14 deletions

diff --git a/src/platform/posix/posix_ipcconn.c b/src/platform/posix/posix_ipcconn.c
index 72fe660b..b3376815 100644
--- a/src/platform/posix/posix_ipcconn.c
+++ b/src/platform/posix/posix_ipcconn.c
@@ -39,22 +39,18 @@ ipc_dowrite(ipc_conn *c)
 	}
 
 	while ((aio = nni_list_first(&c->writeq)) != NULL) {
-		unsigned      i;
-		int           n;
-		int           niov;
-		unsigned      naiov;
-		nni_iov      *aiov;
-		struct msghdr hdr;
-		struct iovec  iovec[16];
+		int      n;
+		unsigned naiov;
+		nni_iov *aiov;
 
-		memset(&hdr, 0, sizeof(hdr));
 		nni_aio_get_iov(aio, &naiov, &aiov);
+		NNI_ASSERT(naiov <= NNI_AIO_MAX_IOV);
 
-		if (naiov > NNI_NUM_ELEMENTS(iovec)) {
-			nni_aio_list_remove(aio);
-			nni_aio_finish_error(aio, NNG_EINVAL);
-			continue;
-		}
+#ifdef NNG_HAVE_SENDMSG
+		struct msghdr hdr = { 0 };
+		struct iovec  iovec[NNI_AIO_MAX_IOV];
+		int           niov;
+		unsigned      i;
 
 		for (niov = 0, i = 0; i < naiov; i++) {
 			if (aiov[i].iov_len > 0) {
@@ -67,7 +63,12 @@ ipc_dowrite(ipc_conn *c)
 		hdr.msg_iovlen = niov;
 		hdr.msg_iov    = iovec;
 
-		if ((n = sendmsg(fd, &hdr, MSG_NOSIGNAL)) < 0) {
+		n = sendmsg(fd, &hdr, MSG_NOSIGNAL);
+#else
+		// We have to send a bit at a time.
+		n = send(fd, aiov[0].iov_buf, aiov[0].iov_len, MSG_NOSIGNAL);
+#endif
+		if (n < 0) {
 			switch (errno) {
 			case EINTR:
 				continue;