libfuse: support zero copy writes in lowlevel interface

Add new ->write_buf() method to low level interface.  This
allows passig a generic buffer, either containing a memory buffer
or a file descriptor.  This allows implementing zero copy writes.

Add fuse_session_receive_buf() and fuse_session_process_buf()
which may be used in event loop implementations to replace
fuse_chan_recv() and fuse_session_process() respectively.

1 files changed, 9 insertions, 2 deletions

diff --git a/lib/fuse_loop.c b/lib/fuse_loop.c
index 104c5d4..b7b4ca4 100644
--- a/lib/fuse_loop.c
+++ b/lib/fuse_loop.c
@@ -25,12 +25,19 @@ int fuse_session_loop(struct fuse_session *se)
 
 	while (!fuse_session_exited(se)) {
 		struct fuse_chan *tmpch = ch;
-		res = fuse_chan_recv(&tmpch, buf, bufsize);
+		struct fuse_buf fbuf = {
+			.mem = buf,
+			.size = bufsize,
+		};
+
+		res = fuse_session_receive_buf(se, &fbuf, &tmpch);
+
 		if (res == -EINTR)
 			continue;
 		if (res <= 0)
 			break;
-		fuse_session_process(se, buf, res, tmpch);
+
+		fuse_session_process_buf(se, &fbuf, tmpch);
 	}
 
 	free(buf);