[PATCH BlueZ v2 1/2] hciemu: Fix silently dropping packet if writev return -EAGAIN

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

The code has been silently dropping packets due to lack of buffer
since hciemu design is single threaded it cannot do partial writes
or flushes to force the buffer to be consumed and give space to the
next chunk, so in order to fix this the code will now attempt to
detect if a socket runs out of space and automatically bump the
buffer with use of SO_SNDBUF.
---
 emulator/hciemu.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/emulator/hciemu.c b/emulator/hciemu.c
index 8c73a07eede0..01a8e80b727e 100644
--- a/emulator/hciemu.c
+++ b/emulator/hciemu.c
@@ -118,8 +118,35 @@ static void writev_callback(const struct iovec *iov, int iovlen,
 	fd = g_io_channel_unix_get_fd(channel);
 
 	written = writev(fd, iov, iovlen);
-	if (written < 0)
-		return;
+	if (written < 0) {
+		ssize_t ret;
+		int size, data_len;
+		socklen_t len = sizeof(size);
+		int i;
+
+		if (errno != EAGAIN)
+			return;
+
+		data_len = 0;
+
+		for (i = 0; i < iovlen; i++)
+			data_len += iov[i].iov_len;
+
+		/* Automatically bump the send buffer size if the data to be
+		 * sent is larger than the current buffer size. This is needed
+		 * for btdev which doesn't flush the socket buffer until all
+		 * data has been sent.
+		 */
+		ret = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &size, &len);
+		if (!ret) {
+			size += data_len;
+			setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &size, len);
+		}
+
+		written = writev(fd, iov, iovlen);
+		if (written < 0)
+			return;
+	}
 }
 
 static gboolean receive_bthost(GIOChannel *channel, GIOCondition condition,
-- 
2.52.0