input: stream_set_blocking(): libuv impl

- Create a private libuv loop instead of re-using uv_default_loop(), to
  avoid conflict[1] with existing watcher(s) on the fd.
- Expose the global "input" fd as a getter instead of a mutable global.

[1] .deps/build/src/libuv/src/unix/core.c:833:
      uv__io_stop: Assertion `loop->watchers[w->fd] == w' failed.

1 files changed, 12 insertions, 8 deletions

diff --git a/src/nvim/os/stream.c b/src/nvim/os/stream.c
index 35cb41081d..0c448872c3 100644
--- a/src/nvim/os/stream.c
+++ b/src/nvim/os/stream.c
@@ -14,13 +14,17 @@
 /// @return `0` on success, or `-errno` on failure.
 int stream_set_blocking(int fd, bool blocking)
 {
-  int flags = fcntl(fd, F_GETFL, 0);
-  int err = 0;
-  if (!blocking && !(flags & O_NONBLOCK)) {
-    err = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
-  } else if (blocking && (flags & O_NONBLOCK)) {
-    err = fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
-  }
-  return err == -1 ? -errno : 0;
+  // Private loop to avoid conflict with existing watcher(s):
+  //    uv__io_stop: Assertion `loop->watchers[w->fd] == w' failed.
+  uv_loop_t loop;
+  uv_pipe_t stream;
+  uv_loop_init(&loop);
+  uv_pipe_init(&loop, &stream, 0);
+  uv_pipe_open(&stream, fd);
+  int retval = uv_stream_set_blocking((uv_stream_t *)&stream, blocking);
+  uv_close((uv_handle_t *)&stream, NULL);
+  uv_run(&loop, UV_RUN_NOWAIT);  // not necessary, but couldn't hurt.
+  uv_loop_close(&loop);
+  return retval;
 }