_frontend/cli.py: Clear stdout/stderr fd flags at startup
This fixes #929
diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index 02ca52e..f500f89 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -9,6 +9,7 @@
from .._exceptions import BstError, LoadError, AppError
from .._versions import BST_FORMAT_VERSION
from .complete import main_bashcomplete, complete_path, CompleteUnhandled
+import fcntl
##################################################################
@@ -170,6 +171,13 @@
def override_main(self, args=None, prog_name=None, complete_var=None,
standalone_mode=True, **extra):
+ # Clear file status flags, if stdout/stderr is open in non-blocking
+ # mode for some reason then this can cause BlockingIOError errors
+ # when trying to write to the file.
+ #
+ fcntl.fcntl(sys.stdout.fileno(), fcntl.F_SETFL, 0)
+ fcntl.fcntl(sys.stderr.fileno(), fcntl.F_SETFL, 0)
+
# Hook for the Bash completion. This only activates if the Bash
# completion is actually enabled, otherwise this is quite a fast
# noop.
