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linux-nat: Eliminate custom target_terminal_{inferior,ours}, stop using set_sigint_trap

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This patch gets rid of linux-nat.c's custom
target_terminal_inferior/target_terminal_ours implementations.

The only remaining reason those overrides exist is to install
clear_sigint_trap in order to pass Ctrl-C/SIGINT to the inferior
process in case the inferior is not sharing GDB's terminal (and
target_wait was called without TARGET_WNOHANG).

However, I think that's better handled by QUIT / target_pass_ctrlc
nowadays.  Going that route avoids the issue with set_sigint_trap only
looking at the current inferior to know whether to override SIGINT or
not, which doesn't really work correctly with multi-inferior in the
picture.  Also centralizing on a single SIGINT handler as much as
possible seems better considering a future multi-target world.

Tested on x86-64 GNU/Linux.

gdb/ChangeLog:
2018-01-30  Pedro Alves  <palves@redhat.com>

	* linux-nat.c (wait_for_signal): New function.
	(wait_lwp, linux_nat_wait_1): Use it instead of calling sigsuspend
	directly.
	(async_terminal_is_ours)
	(linux_nat_terminal_inferior, linux_nat_terminal_ours): Delete.
	(linux_nat_add_target): Don't override
	to_terminal_inferior/to_terminal_ours.
This commit is contained in:
Pedro Alves 2018-01-30 14:23:51 +00:00
parent 040b4a9eb8
commit 9c3a5d9319
2 changed files with 36 additions and 52 deletions
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10
gdb/ChangeLog
View File

@ -1,3 +1,13 @@
2018-01-30 Pedro Alves <palves@redhat.com>
* linux-nat.c (wait_for_signal): New function.
(wait_lwp, linux_nat_wait_1): Use it instead of calling sigsuspend
directly.
(async_terminal_is_ours)
(linux_nat_terminal_inferior, linux_nat_terminal_ours): Delete.
(linux_nat_add_target): Don't override
to_terminal_inferior/to_terminal_ours.
2018-01-29 Sergio Durigan Junior <sergiodj@redhat.com>
* remote.c (remote_follow_fork): Don't call "detach_inferior".

78
gdb/linux-nat.c
View File

@ -2152,6 +2152,30 @@ linux_handle_extended_wait (struct lwp_info *lp, int status)
_("unknown ptrace event %d"), event);
}
/* Suspend waiting for a signal. We're mostly interested in
SIGCHLD/SIGINT. */
static void
wait_for_signal ()
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog, "linux-nat: about to sigsuspend\n");
sigsuspend (&suspend_mask);
/* If the quit flag is set, it means that the user pressed Ctrl-C
and we're debugging a process that is running on a separate
terminal, so we must forward the Ctrl-C to the inferior. (If the
inferior is sharing GDB's terminal, then the Ctrl-C reaches the
inferior directly.) We must do this here because functions that
need to block waiting for a signal loop forever until there's an
event to report before returning back to the event loop. */
if (!target_terminal::is_ours ())
{
if (check_quit_flag ())
target_pass_ctrlc ();
}
}
/* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
exited. */
@ -2217,10 +2241,7 @@ wait_lwp (struct lwp_info *lp)
linux_nat_wait_1 and there if we get called my_waitpid gets called
again before it gets to sigsuspend so we can safely let the handlers
get executed here. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog, "WL: about to sigsuspend\n");
sigsuspend (&suspend_mask);
wait_for_signal ();
}
restore_child_signals_mask (&prev_mask);
@ -3404,9 +3425,7 @@ linux_nat_wait_1 (struct target_ops *ops,
gdb_assert (lp == NULL);
/* Block until we get an event reported with SIGCHLD. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog, "LNW: about to sigsuspend\n");
sigsuspend (&suspend_mask);
wait_for_signal ();
}
gdb_assert (lp);
@ -4429,49 +4448,6 @@ linux_nat_supports_disable_randomization (struct target_ops *self)
#endif
}
static int async_terminal_is_ours = 1;
/* target_terminal_inferior implementation.
This is a wrapper around child_terminal_inferior to add async support. */
static void
linux_nat_terminal_inferior (struct target_ops *self)
{
child_terminal_inferior (self);
/* Calls to target_terminal_*() are meant to be idempotent. */
if (!async_terminal_is_ours)
return;
async_terminal_is_ours = 0;
set_sigint_trap ();
}
/* target_terminal::ours implementation.
This is a wrapper around child_terminal_ours to add async support (and
implement the target_terminal::ours vs target_terminal::ours_for_output
distinction). child_terminal_ours is currently no different than
child_terminal_ours_for_output.
We leave target_terminal::ours_for_output alone, leaving it to
child_terminal_ours_for_output. */
static void
linux_nat_terminal_ours (struct target_ops *self)
{
/* GDB should never give the terminal to the inferior if the
inferior is running in the background (run&, continue&, etc.),
but claiming it sure should. */
child_terminal_ours (self);
if (async_terminal_is_ours)
return;
clear_sigint_trap ();
async_terminal_is_ours = 1;
}
/* SIGCHLD handler that serves two purposes: In non-stop/async mode,
so we notice when any child changes state, and notify the
event-loop; it allows us to use sigsuspend in linux_nat_wait_1
@ -4820,8 +4796,6 @@ linux_nat_add_target (struct target_ops *t)
t->to_supports_non_stop = linux_nat_supports_non_stop;
t->to_always_non_stop_p = linux_nat_always_non_stop_p;
t->to_async = linux_nat_async;
t->to_terminal_inferior = linux_nat_terminal_inferior;
t->to_terminal_ours = linux_nat_terminal_ours;
super_close = t->to_close;
t->to_close = linux_nat_close;