Add fsetxattr(), fremovexattr(), open_by_handle_at(), and "virtiofsd demo"

Mostly assorted fixes, a new FDGET operation (get a copy of the
target file descriptor via pidfd_getfd()) and a new "FD" flag that
means we have to do that on direct tag reference.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/demo/fsetxattr.c b/demo/fsetxattr.c
new file mode 100644
index 0000000..6ee423a
--- /dev/null
+++ b/demo/fsetxattr.c
@@ -0,0 +1,11 @@
+#include <sys/stat.h>
+#include <sys/xattr.h>
+#include <fcntl.h>
+#include <string.h>
+
+int main(int argc, char **argv)
+{
+	int fd = open(argv[1], O_RDONLY);
+
+	return fsetxattr(fd, argv[2], argv[3], strlen(argv[3]) + 1, 0);
+}