* [PATCH] tui-out: don't "inherit" redirect from CLI
@ 2010-08-30 9:29 Paul Bolle
2010-08-30 11:29 ` Pedro Alves
0 siblings, 1 reply; 3+ messages in thread
From: Paul Bolle @ 2010-08-30 9:29 UTC (permalink / raw)
To: gdb-patches
Since revision 1.17 tui_ui_out_impl "inherits" from cli_ui_out_impl (ie,
it starts as a copy of that struct). tui_ui_out_impl.redirect is never
redefined after that so it points to cli_redirect(). (Before revision
1.17 it was NULL.)
As a consequence, uo_redirect() will actually try to redirect if passed
a tui_ui_out_impl. That will probably crash gdb (as
tui_ui_out_impl->data->stream and tui_ui_out_impl->data->original_stream
don't exist).
So set tui_ui_out_impl.redirect to NULL after "inheriting".
(Just something I noticed while trying to understand the ui code.)
---
gdb/ChangeLog | 5 +++++
gdb/tui/tui-out.c | 1 +
2 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5d81848..1beb8fc 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2010-08-30 Paul Bolle <pebolle@tiscali.nl>
+
+ * tui/tui-out.c (_initialize_tui_out): Don't "inherit" redirect from
+ CLI.
+
2010-08-28 Jan Kratochvil <jan.kratochvil@redhat.com>
Code cleanup.
diff --git a/gdb/tui/tui-out.c b/gdb/tui/tui-out.c
index 8cd6b88..1e8ef74 100644
--- a/gdb/tui/tui-out.c
+++ b/gdb/tui/tui-out.c
@@ -178,4 +178,5 @@ _initialize_tui_out (void)
tui_ui_out_impl.field_string = tui_field_string;
tui_ui_out_impl.field_fmt = tui_field_fmt;
tui_ui_out_impl.text = tui_text;
+ tui_ui_out_impl.redirect = NULL;
}
--
1.7.2.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tui-out: don't "inherit" redirect from CLI
2010-08-30 9:29 [PATCH] tui-out: don't "inherit" redirect from CLI Paul Bolle
@ 2010-08-30 11:29 ` Pedro Alves
2010-08-30 11:49 ` Paul Bolle
0 siblings, 1 reply; 3+ messages in thread
From: Pedro Alves @ 2010-08-30 11:29 UTC (permalink / raw)
To: gdb-patches; +Cc: Paul Bolle
On Monday 30 August 2010 10:29:10, Paul Bolle wrote:
> Since revision 1.17 tui_ui_out_impl "inherits" from cli_ui_out_impl (ie,
> it starts as a copy of that struct). tui_ui_out_impl.redirect is never
> redefined after that so it points to cli_redirect(). (Before revision
> 1.17 it was NULL.)
That was the main reason that tui_ui_out_impl was made to inherit
cli_ui_out_impl in the first place.
See <http://sourceware.org/ml/gdb-patches/2010-04/msg00540.html>.
> As a consequence, uo_redirect() will actually try to redirect if passed
> a tui_ui_out_impl. That will probably crash gdb (as
> tui_ui_out_impl->data->stream and tui_ui_out_impl->data->original_stream
> don't exist).
Yes they do exist, because tui_ui_out_data "inherits" cli_ui_out_data.
See:
struct tui_ui_out_data
{
struct cli_ui_out_data base;
^^^^^^^^^^^^^^^^^^^^^^^^^^^
int line;
int start_of_line;
};
typedef struct tui_ui_out_data tui_out_data;
"base" is the first field of tui_ui_out_data, so you can
pass a pointer to a tui_ui_out_data to a function that expects
a cli_ui_out_data pointer. This is legal, and a common idiom on C,
as means to implementing "is-a" inheritance.
>
> So set tui_ui_out_impl.redirect to NULL after "inheriting".
Nope, sorry, this isn't correct.
> (Just something I noticed while trying to understand the ui code.)
--
Pedro Alves
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tui-out: don't "inherit" redirect from CLI
2010-08-30 11:29 ` Pedro Alves
@ 2010-08-30 11:49 ` Paul Bolle
0 siblings, 0 replies; 3+ messages in thread
From: Paul Bolle @ 2010-08-30 11:49 UTC (permalink / raw)
To: Pedro Alves; +Cc: gdb-patches
On Mon, 2010-08-30 at 12:29 +0100, Pedro Alves wrote:
> That was the main reason that tui_ui_out_impl was made to inherit
> cli_ui_out_impl in the first place.
> See <http://sourceware.org/ml/gdb-patches/2010-04/msg00540.html>.
Missed that one, obviously. (My excuse could be that the commit message
doesn't seem to mention that reason.)
> [...] tui_ui_out_data "inherits" cli_ui_out_data.
> See:
>
> struct tui_ui_out_data
> {
> struct cli_ui_out_data base;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> int line;
> int start_of_line;
> };
> typedef struct tui_ui_out_data tui_out_data;
>
> "base" is the first field of tui_ui_out_data, so you can
> pass a pointer to a tui_ui_out_data to a function that expects
> a cli_ui_out_data pointer. This is legal, and a common idiom on C,
> as means to implementing "is-a" inheritance.
Thanks for taking the time to explain this to me. Maybe next time I'll
recognize the idiom.
Paul
^ permalink raw reply [flat|nested] 3+ messages in thread
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2010-08-30 11:29 ` Pedro Alves
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