Improve sync handling for -Ojob/-Otarget and recursion.

If we are not going to sync a command line then dump any collected output
first to preserve ordering.  Do some code cleanup:
  * Move the handle init to a separate function.
  * Move the temp file truncation to the output function.
  * Remember whether we sync in a variable for readability.
  * Handle EINTR and short writes in child_out().
  * Always call sync_output() in case output_sync was changed due to error.

1 files changed, 10 insertions, 0 deletions

diff --git a/tests/scripts/features/output-sync b/tests/scripts/features/output-sync
index c8ff2911..a1560adb 100644
--- a/tests/scripts/features/output-sync
+++ b/tests/scripts/features/output-sync
@@ -244,5 +244,15 @@ foo: end
 # Remove temporary directories and contents.
 output_sync_clean();
 
+# Ensure recursion doesn't mis-order or double-print output
+run_make_test(qq!
+all:
+\t\@echo foo
+\t\@+echo bar
+!,
+              '-j -Ojob', "foo\nbar\n");
+
+run_make_test(undef, '-j -Otarget', "foo\nbar\n");
+
 # This tells the test driver that the perl test script executed properly.
 1;