* [PATCH] gdb: add a file event mask parameter to add_file_handler
@ 2022-08-19 17:46 Patrick Monnerat via Gdb-patches
2022-08-23 19:09 ` Tom Tromey
0 siblings, 1 reply; 7+ messages in thread
From: Patrick Monnerat via Gdb-patches @ 2022-08-19 17:46 UTC (permalink / raw)
To: gdb-patches
Tcl/Tk (used as the Insight GUI) delegates event handling to gdb and
requires file events monitoring to be masked with READ/WRITE/EXCEPTION
flags.
Currently, gdb only uses read events, but an unused and incomplete
provision exists for such flags.
This patch adds an event mask parameter to add_file_handler, allowing
to monitor non-read file events. Its value is always given as ored-in gdb
flags, whether effectively using poll or select. This parameter defaults to
GDB_READABLE | GDB_EXCEPTION, resulting in no change for existing calls.
To unify the semantics between select and poll, POLLRDHUP
(HANGUP-sensitiveness) is also included in read events on platforms
supporting it. This is the only change in this patch that may affect
bare gdb.
This patch benefits to Insight: the latter itself does not use non-read
file events. However these must be supported for Tcl/Tk internals.
It should be noted that gdb does not support write events on the mingw
platform but checks this condition with gdb_assert. This patch does not
change this.
Flags GDB_READABLE, GDB_WRITABLE and GDB_EXCEPTION are now made globally
available through the inclusion of event-loop.h.
---
gdbsupport/event-loop.cc | 40 ++++++++++++++++++++++------------------
gdbsupport/event-loop.h | 11 +++++++++--
2 files changed, 31 insertions(+), 20 deletions(-)
diff --git a/gdbsupport/event-loop.cc b/gdbsupport/event-loop.cc
index 941885529f1..b4797ae04b8 100644
--- a/gdbsupport/event-loop.cc
+++ b/gdbsupport/event-loop.cc
@@ -28,6 +28,11 @@
#elif defined (HAVE_SYS_POLL_H)
#include <sys/poll.h>
#endif
+#if defined(POLLRDHUP)
+#define POLL_HANGUP POLLRDHUP
+#else
+#define POLL_HANGUP 0
+#endif
#endif
#include <sys/types.h>
@@ -40,13 +45,6 @@
debug_event_loop_kind debug_event_loop;
-/* Tell create_file_handler what events we are interested in.
- This is used by the select version of the event loop. */
-
-#define GDB_READABLE (1<<1)
-#define GDB_WRITABLE (1<<2)
-#define GDB_EXCEPTION (1<<3)
-
/* Information about each file descriptor we register with the event
loop. */
@@ -269,8 +267,11 @@ gdb_do_one_event (int mstimeout)
void
add_file_handler (int fd, handler_func *proc, gdb_client_data client_data,
- std::string &&name, bool is_ui)
+ std::string &&name, bool is_ui, int mask)
{
+ if (fd < 0 || (mask & (GDB_READABLE | GDB_WRITABLE | GDB_EXCEPTION)) == 0)
+ return;
+
#ifdef HAVE_POLL
if (use_poll)
{
@@ -282,25 +283,28 @@ add_file_handler (int fd, handler_func *proc, gdb_client_data client_data,
On m68k-motorola-sysv, tty's are not stream-based and not
`poll'able. */
fds.fd = fd;
- fds.events = POLLIN;
+ fds.events = 0;
+ if (mask & GDB_READABLE)
+ fds.events |= POLLIN | POLL_HANGUP;
+ if (mask & GDB_WRITABLE)
+ fds.events |= POLLOUT;
+ if (mask & GDB_EXCEPTION)
+ fds.events |= POLLPRI;
if (poll (&fds, 1, 0) == 1 && (fds.revents & POLLNVAL))
use_poll = false;
+ else
+ create_file_handler (fd, fds.events, proc, client_data,
+ std::move (name), is_ui);
}
- if (use_poll)
- {
- create_file_handler (fd, POLLIN, proc, client_data, std::move (name),
- is_ui);
- }
- else
+ if (!use_poll)
#endif /* HAVE_POLL */
- create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION,
- proc, client_data, std::move (name), is_ui);
+ create_file_handler (fd, mask, proc, client_data, std::move (name), is_ui);
}
/* Helper for add_file_handler.
For the poll case, MASK is a combination (OR) of POLLIN,
- POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM, POLLWRBAND:
+ POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM, POLLWRBAND, POLLRDHUP:
these are the events we are interested in. If any of them occurs,
proc should be called.
diff --git a/gdbsupport/event-loop.h b/gdbsupport/event-loop.h
index c82493e9bdf..8c1f831af27 100644
--- a/gdbsupport/event-loop.h
+++ b/gdbsupport/event-loop.h
@@ -70,11 +70,17 @@
Corollary tasks are the creation and deletion of event sources. */
+/* Tell add_file_handler what events we are interested in. */
+
+#define GDB_READABLE (1<<1)
+#define GDB_WRITABLE (1<<2)
+#define GDB_EXCEPTION (1<<3)
+
typedef void *gdb_client_data;
typedef void (handler_func) (int, gdb_client_data);
typedef void (timer_handler_func) (gdb_client_data);
-/* Exported functions from event-loop.c */
+/* Exported functions from event-loop.cc */
extern int gdb_do_one_event (int mstimeout = -1);
extern void delete_file_handler (int fd);
@@ -90,7 +96,8 @@ extern void delete_file_handler (int fd);
extern void add_file_handler (int fd, handler_func *proc,
gdb_client_data client_data,
- std::string &&name, bool is_ui = false);
+ std::string &&name, bool is_ui = false,
+ int mask = GDB_READABLE | GDB_EXCEPTION);
extern int create_timer (int milliseconds,
timer_handler_func *proc,
--
2.37.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] gdb: add a file event mask parameter to add_file_handler
2022-08-19 17:46 [PATCH] gdb: add a file event mask parameter to add_file_handler Patrick Monnerat via Gdb-patches
@ 2022-08-23 19:09 ` Tom Tromey
2022-08-24 15:26 ` Patrick Monnerat via Gdb-patches
0 siblings, 1 reply; 7+ messages in thread
From: Tom Tromey @ 2022-08-23 19:09 UTC (permalink / raw)
To: Patrick Monnerat via Gdb-patches
>>>>> "Patrick" == Patrick Monnerat via Gdb-patches <gdb-patches@sourceware.org> writes:
Thanks for the patch.
Patrick> +#if defined(POLLRDHUP)
Space before the '('.
Patrick> void
Patrick> add_file_handler (int fd, handler_func *proc, gdb_client_data client_data,
Patrick> - std::string &&name, bool is_ui)
Patrick> + std::string &&name, bool is_ui, int mask)
Patrick> {
Patrick> + if (fd < 0 || (mask & (GDB_READABLE | GDB_WRITABLE | GDB_EXCEPTION)) == 0)
Patrick> + return;
Is there ever a situation where this can happen and it is not a bug in
the caller? I am wondering if this ought to be an assert instead.
Patrick> +/* Tell add_file_handler what events we are interested in. */
Patrick> +
Patrick> +#define GDB_READABLE (1<<1)
Patrick> +#define GDB_WRITABLE (1<<2)
Patrick> +#define GDB_EXCEPTION (1<<3)
I tend to think it would be better to use enum_flags here.
Tom
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] gdb: add a file event mask parameter to add_file_handler
2022-08-23 19:09 ` Tom Tromey
@ 2022-08-24 15:26 ` Patrick Monnerat via Gdb-patches
2022-08-24 17:26 ` Tom Tromey
0 siblings, 1 reply; 7+ messages in thread
From: Patrick Monnerat via Gdb-patches @ 2022-08-24 15:26 UTC (permalink / raw)
To: Tom Tromey, Patrick Monnerat via Gdb-patches
On 8/23/22 21:09, Tom Tromey wrote:
>>>>>> "Patrick" == Patrick Monnerat via Gdb-patches <gdb-patches@sourceware.org> writes:
> Thanks for the patch.
>
> Patrick> +#if defined(POLLRDHUP)
>
> Space before the '('.
Sure: my bad !
> Patrick> void
> Patrick> add_file_handler (int fd, handler_func *proc, gdb_client_data client_data,
> Patrick> - std::string &&name, bool is_ui)
> Patrick> + std::string &&name, bool is_ui, int mask)
> Patrick> {
> Patrick> + if (fd < 0 || (mask & (GDB_READABLE | GDB_WRITABLE | GDB_EXCEPTION)) == 0)
> Patrick> + return;
>
> Is there ever a situation where this can happen and it is not a bug in
> the caller? I am wondering if this ought to be an assert instead.
Yes. In Insight, command input from stdin is disabled by setting
main_ui->input_fd to -1. A later call to register_file_handler from
async_enable_stdin causes add_file_handler to be called with fd = -1.
Maybe I should add a comment for this.
>
> Patrick> +/* Tell add_file_handler what events we are interested in. */
> Patrick> +
> Patrick> +#define GDB_READABLE (1<<1)
> Patrick> +#define GDB_WRITABLE (1<<2)
> Patrick> +#define GDB_EXCEPTION (1<<3)
>
> I tend to think it would be better to use enum_flags here.
I thought so too and did try to use enum_flags! Unfortunately the same
int field (file_handler::mask) stores either these bits in case of
select use, or a poll mask as defined by the system when poll is used.
We then have a type conflict: it can be resolved but is rather
cumbersome (a simple cast would be awful). Your opinion?
Thanks for the review.
Patrick
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] gdb: add a file event mask parameter to add_file_handler
2022-08-24 15:26 ` Patrick Monnerat via Gdb-patches
@ 2022-08-24 17:26 ` Tom Tromey
2022-08-30 17:34 ` Tom Tromey via Gdb-patches
0 siblings, 1 reply; 7+ messages in thread
From: Tom Tromey @ 2022-08-24 17:26 UTC (permalink / raw)
To: Patrick Monnerat; +Cc: Tom Tromey, Patrick Monnerat via Gdb-patches
>> Is there ever a situation where this can happen and it is not a bug in
>> the caller? I am wondering if this ought to be an assert instead.
Patrick> Yes. In Insight, command input from stdin is disabled by setting
main_ui-> input_fd to -1. A later call to register_file_handler from
Patrick> async_enable_stdin causes add_file_handler to be called with fd =
Patrick> -1. Maybe I should add a comment for this.
I took this same approach in my DAP implementation, which is why I
changed gdb to always call the 'ui' methods to manipulate the event
handlers. In my patch I then change these methods to check for the -1
case.
I can submit this bit separately next week.
Or you can do it, it's trivial.
Patrick> I thought so too and did try to use enum_flags! Unfortunately the same
Patrick> int field (file_handler::mask) stores either these bits in case of
Patrick> select use, or a poll mask as defined by the system when poll is used.
Ok, I see.
Tom
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] gdb: add a file event mask parameter to add_file_handler
2022-08-24 17:26 ` Tom Tromey
@ 2022-08-30 17:34 ` Tom Tromey via Gdb-patches
2022-08-31 10:47 ` Patrick Monnerat via Gdb-patches
0 siblings, 1 reply; 7+ messages in thread
From: Tom Tromey via Gdb-patches @ 2022-08-30 17:34 UTC (permalink / raw)
To: Tom Tromey; +Cc: Patrick Monnerat via Gdb-patches
Patrick> Yes. In Insight, command input from stdin is disabled by setting
Patrick> main_ui->input_fd to -1. A later call to register_file_handler from
Patrick> async_enable_stdin causes add_file_handler to be called with fd =
Patrick> -1. Maybe I should add a comment for this.
Tom> I took this same approach in my DAP implementation, which is why I
Tom> changed gdb to always call the 'ui' methods to manipulate the event
Tom> handlers. In my patch I then change these methods to check for the -1
Tom> case.
Tom> I can submit this bit separately next week.
Tom> Or you can do it, it's trivial.
What do you think of this?
Tom
commit 73d104a6fc246f0cd7d42a4ed1c009304fb55327
Author: Tom Tromey <tromey@adacore.com>
Date: Tue Aug 30 11:30:13 2022 -0600
Let ui::input_fd be -1
This changes gdb so that, if ui::input_fd is set to -1, then it will
not be registered with the event loop. This is useful for the DAP
support code I wrote, but as it turns out to also be useful to
Insight, it seems best to check it in separately.
diff --git a/gdb/event-top.c b/gdb/event-top.c
index 02b3786320f..4547d614522 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -533,8 +533,9 @@ stdin_event_handler (int error, gdb_client_data client_data)
void
ui::register_file_handler ()
{
- add_file_handler (input_fd, stdin_event_handler, this,
- string_printf ("ui-%d", num), true);
+ if (input_fd != -1)
+ add_file_handler (input_fd, stdin_event_handler, this,
+ string_printf ("ui-%d", num), true);
}
/* See top.h. */
@@ -542,7 +543,8 @@ ui::register_file_handler ()
void
ui::unregister_file_handler ()
{
- delete_file_handler (input_fd);
+ if (input_fd != -1)
+ delete_file_handler (input_fd);
}
/* Re-enable stdin after the end of an execution command in
diff --git a/gdb/top.h b/gdb/top.h
index 5c1db84b2ce..9ea07262c39 100644
--- a/gdb/top.h
+++ b/gdb/top.h
@@ -118,7 +118,8 @@ struct ui
FILE *errstream;
/* The file descriptor for the input stream, so that we can register
- it with the event loop. */
+ it with the event loop. This can be set to -1 to prevent this
+ registration. */
int input_fd;
/* Whether ISATTY returns true on input_fd. Cached here because
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] gdb: add a file event mask parameter to add_file_handler
2022-08-30 17:34 ` Tom Tromey via Gdb-patches
@ 2022-08-31 10:47 ` Patrick Monnerat via Gdb-patches
2022-08-31 16:51 ` Tom Tromey via Gdb-patches
0 siblings, 1 reply; 7+ messages in thread
From: Patrick Monnerat via Gdb-patches @ 2022-08-31 10:47 UTC (permalink / raw)
To: Tom Tromey; +Cc: Patrick Monnerat via Gdb-patches
On 8/30/22 19:34, Tom Tromey wrote:
> Patrick> Yes. In Insight, command input from stdin is disabled by setting
> Patrick> main_ui->input_fd to -1. A later call to register_file_handler from
> Patrick> async_enable_stdin causes add_file_handler to be called with fd =
> Patrick> -1. Maybe I should add a comment for this.
>
> Tom> I took this same approach in my DAP implementation, which is why I
> Tom> changed gdb to always call the 'ui' methods to manipulate the event
> Tom> handlers. In my patch I then change these methods to check for the -1
> Tom> case.
>
> Tom> I can submit this bit separately next week.
> Tom> Or you can do it, it's trivial.
>
> What do you think of this?
This is great! I applied your changes to Insight and dropped the fd<0
test in add_file_handler with total success.
I'll soon submit version 2 of my patch with the fd<0 test removed, and
an updated test for mask==0 (this case should call delete_file_handler).
This would have to be pushed after your patch, of course!
Thanks a lot.
Patrick
> Tom
>
> commit 73d104a6fc246f0cd7d42a4ed1c009304fb55327
> Author: Tom Tromey <tromey@adacore.com>
> Date: Tue Aug 30 11:30:13 2022 -0600
>
> Let ui::input_fd be -1
>
> This changes gdb so that, if ui::input_fd is set to -1, then it will
> not be registered with the event loop. This is useful for the DAP
> support code I wrote, but as it turns out to also be useful to
> Insight, it seems best to check it in separately.
>
> diff --git a/gdb/event-top.c b/gdb/event-top.c
> index 02b3786320f..4547d614522 100644
> --- a/gdb/event-top.c
> +++ b/gdb/event-top.c
> @@ -533,8 +533,9 @@ stdin_event_handler (int error, gdb_client_data client_data)
> void
> ui::register_file_handler ()
> {
> - add_file_handler (input_fd, stdin_event_handler, this,
> - string_printf ("ui-%d", num), true);
> + if (input_fd != -1)
> + add_file_handler (input_fd, stdin_event_handler, this,
> + string_printf ("ui-%d", num), true);
> }
>
> /* See top.h. */
> @@ -542,7 +543,8 @@ ui::register_file_handler ()
> void
> ui::unregister_file_handler ()
> {
> - delete_file_handler (input_fd);
> + if (input_fd != -1)
> + delete_file_handler (input_fd);
> }
>
> /* Re-enable stdin after the end of an execution command in
> diff --git a/gdb/top.h b/gdb/top.h
> index 5c1db84b2ce..9ea07262c39 100644
> --- a/gdb/top.h
> +++ b/gdb/top.h
> @@ -118,7 +118,8 @@ struct ui
> FILE *errstream;
>
> /* The file descriptor for the input stream, so that we can register
> - it with the event loop. */
> + it with the event loop. This can be set to -1 to prevent this
> + registration. */
> int input_fd;
>
> /* Whether ISATTY returns true on input_fd. Cached here because
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] gdb: add a file event mask parameter to add_file_handler
2022-08-31 10:47 ` Patrick Monnerat via Gdb-patches
@ 2022-08-31 16:51 ` Tom Tromey via Gdb-patches
0 siblings, 0 replies; 7+ messages in thread
From: Tom Tromey via Gdb-patches @ 2022-08-31 16:51 UTC (permalink / raw)
To: Patrick Monnerat; +Cc: Patrick Monnerat via Gdb-patches, Tom Tromey
Patrick> This is great! I applied your changes to Insight and dropped the fd<0
Patrick> test in add_file_handler with total success.
Patrick> I'll soon submit version 2 of my patch with the fd<0 test removed, and
Patrick> an updated test for mask==0 (this case should call
Patrick> delete_file_handler).
Patrick> This would have to be pushed after your patch, of course!
Patrick> Thanks a lot.
No problem, and thanks for trying it out.
I'm going to check it in now.
Tom
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-08-31 16:52 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2022-08-19 17:46 [PATCH] gdb: add a file event mask parameter to add_file_handler Patrick Monnerat via Gdb-patches
2022-08-23 19:09 ` Tom Tromey
2022-08-24 15:26 ` Patrick Monnerat via Gdb-patches
2022-08-24 17:26 ` Tom Tromey
2022-08-30 17:34 ` Tom Tromey via Gdb-patches
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