[PATCH 2/3] Don't set terminal flags twice in a row

Pedro Alves
2017-11-02T15:12:18Z

I find this odd 'set flags twice' ancient code and comment annoyingly
distracting. It may well be that the reason for the double-set was
simply a copy/paste mistake, and that we've been doing this for
decades [1] for no good reason. Let's just get rid of it, and if we
find a real reason, add it back with a comment explaining why it's
necessary.

[1] This double-set was already in gdb 2.4 / 1988, the oldest release
we have sources for, and imported in git. From 'git show 7b4ac7e1ed2c
inflow.c':

+void
+terminal_inferior ()
+{
+ if (terminal_is_ours) /* && inferior_thisrun_terminal == 0) */
+ {
+ fcntl (0, F_SETFL, tflags_inferior);
+ fcntl (0, F_SETFL, tflags_inferior);

The "is there a reason" comment was added in 1993, by:

commit a88797b5eadf31e21804bc820429028bf708fbcd
Author: Fred Fish <fnf@specifix.com>
AuthorDate: Thu Aug 5 01:33:45 1993 +0000

gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>

* inflow.c (child_terminal_inferior, child_terminal_ours_1): No
longer set flags twice in row.
---
gdb/inflow.c | 9 ---------
1 file changed, 9 deletions(-)

diff --git a/gdb/inflow.c b/gdb/inflow.c
index a96d4fc..d46d693 100644
--- a/gdb/inflow.c
+++ b/gdb/inflow.c
@@ -244,10 +244,6 @@ child_terminal_inferior (struct target_ops *self)
int result;

#ifdef F_GETFL
- /* Is there a reason this is being done twice? It happens both
- places we use F_SETFL, so I'm inclined to think perhaps there
- is some reason, however perverse. Perhaps not though... */
- result = fcntl (0, F_SETFL, tinfo->tflags);
result = fcntl (0, F_SETFL, tinfo->tflags);
OOPSY ("fcntl F_SETFL");
#endif
@@ -403,11 +399,6 @@ child_terminal_ours_1 (int output_only)

#ifdef F_GETFL
tinfo->tflags = fcntl (0, F_GETFL, 0);
-
- /* Is there a reason this is being done twice? It happens both
- places we use F_SETFL, so I'm inclined to think perhaps there
- is some reason, however perverse. Perhaps not though... */
- result = fcntl (0, F_SETFL, our_terminal_info.tflags);
result = fcntl (0, F_SETFL, our_terminal_info.tflags);
#endif
}
--
2.5.5