unix/file: Don't raise OSError(EINVAL) on sys.stdin/out/err.flush().

sys.stdout.flush() is needed on CPython to flush the output, and the change
in this commit makes such an expression also work on MicroPython (although
MicroPython doesn't actual need to do any flushing).

1 files changed, 7 insertions, 0 deletions

diff --git a/ports/unix/file.c b/ports/unix/file.c
index 0fe4f9878..ed05fe733 100644
--- a/ports/unix/file.c
+++ b/ports/unix/file.c
@@ -126,6 +126,13 @@ STATIC mp_uint_t fdfile_ioctl(mp_obj_t o_in, mp_uint_t request, uintptr_t arg, i
             int ret = fsync(o->fd);
             MP_THREAD_GIL_ENTER();
             if (ret == -1) {
+                if (errno == EINVAL
+                    && (o->fd == STDIN_FILENO || o->fd == STDOUT_FILENO || o->fd == STDERR_FILENO)) {
+                    // fsync(stdin/stdout/stderr) may fail with EINVAL, but don't propagate that
+                    // error out.  Because data is not buffered by us, and stdin/out/err.flush()
+                    // should just be a no-op.
+                    return 0;
+                }
                 *errcode = errno;
                 return MP_STREAM_ERROR;
             }