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gdb/remote-fileio.c: Eliminate custom SIGINT signal handler

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... and fix Ctrl-C races.

The current remote-fileio.c SIGINT/EINTR code can lose Ctrl-C --
there's a period where SIG_IGN is installed as signal handler, for
example.

Since:

 - remote.c no longer installs a custom SIGINT handler;

 - The current remote-fileio.c SIGINT handler is basically the same as
   the default SIGINT handler (event-top.c:handle_sigint), in
   principle, except that instead of setting the quit flag, it sets a
   separate flag.

I think we should be able to completely remove the remote-fileio.c
SIGINT handler, and centralize on the quit flag, thus fixing the
Ctrl-C race.

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

	* remote-fileio.c (remote_fio_ctrl_c_flag, remote_fio_sa)
	(remote_fio_osa)
	(remote_fio_ofunc, remote_fileio_sig_init, remote_fileio_sig_set)
	(remote_fileio_sig_exit, remote_fileio_ctrl_c_signal_handler):
	Delete.
	(remote_fileio_o_quit_handler): New global.
	(remote_fileio_quit_handler): New function.
	(remote_fileio_reply): Check the quit flag instead of the custom
	'remote_fio_ctrl_c_flag' flag.  Restore the quit handler instead
	of changing the SIGINT handler.
	(do_remote_fileio_request): Override the quit handler instead of
	changing the SIGINT handler.
This commit is contained in:
Pedro Alves 2016-06-01 16:34:49 +01:00
parent 315f180f2f
commit bb7c96deb1
2 changed files with 35 additions and 60 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
gdb/ChangeLog
View file

@ -1,3 +1,18 @@
2016-06-01 Pedro Alves <palves@redhat.com>
* remote-fileio.c (remote_fio_ctrl_c_flag, remote_fio_sa)
(remote_fio_osa)
(remote_fio_ofunc, remote_fileio_sig_init, remote_fileio_sig_set)
(remote_fileio_sig_exit, remote_fileio_ctrl_c_signal_handler):
Delete.
(remote_fileio_o_quit_handler): New global.
(remote_fileio_quit_handler): New function.
(remote_fileio_reply): Check the quit flag instead of the custom
'remote_fio_ctrl_c_flag' flag. Restore the quit handler instead
of changing the SIGINT handler.
(do_remote_fileio_request): Override the quit handler instead of
changing the SIGINT handler.
2016-06-01 Nick Clifton <nickc@redhat.com>
* common/common-utils.c (xmalloc_failed): New function. Provided

80
gdb/remote-fileio.c
View file

@ -298,66 +298,25 @@ remote_fileio_to_fio_timeval (struct timeval *tv, struct fio_timeval *ftv)
remote_fileio_to_fio_long (tv->tv_usec, ftv->ftv_usec);
}
static int remote_fio_ctrl_c_flag = 0;
/* The quit handler originally installed. */
static quit_handler_ftype *remote_fileio_o_quit_handler;
#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
static struct sigaction remote_fio_sa;
static struct sigaction remote_fio_osa;
#else
static void (*remote_fio_ofunc)(int);
#endif
/* What to do on a QUIT call while handling a file I/O request. We
throw a quit exception, which is caught by remote_fileio_request
and translated to an EINTR reply back to the target. */
static void
remote_fileio_sig_init (void)
remote_fileio_quit_handler (void)
{
#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
remote_fio_sa.sa_handler = SIG_IGN;
sigemptyset (&remote_fio_sa.sa_mask);
remote_fio_sa.sa_flags = 0;
sigaction (SIGINT, &remote_fio_sa, &remote_fio_osa);
#else
remote_fio_ofunc = signal (SIGINT, SIG_IGN);
#endif
}
static void
remote_fileio_sig_set (void (*sigint_func)(int))
{
#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
remote_fio_sa.sa_handler = sigint_func;
sigemptyset (&remote_fio_sa.sa_mask);
remote_fio_sa.sa_flags = 0;
sigaction (SIGINT, &remote_fio_sa, NULL);
#else
signal (SIGINT, sigint_func);
#endif
}
static void
remote_fileio_sig_exit (void)
{
#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
sigaction (SIGINT, &remote_fio_osa, NULL);
#else
signal (SIGINT, remote_fio_ofunc);
#endif
}
static void
remote_fileio_ctrl_c_signal_handler (int signo)
{
remote_fileio_sig_set (remote_fileio_ctrl_c_signal_handler);
remote_fio_ctrl_c_flag = 1;
/* Wake up interruptible_select. */
quit_serial_event_set ();
quit ();
}
static void
remote_fileio_reply (int retcode, int error)
{
char buf[32];
int ctrl_c = check_quit_flag ();
remote_fileio_sig_set (SIG_IGN);
strcpy (buf, "F");
if (retcode < 0)
{
@ -365,9 +324,9 @@ remote_fileio_reply (int retcode, int error)
retcode = -retcode;
}
sprintf (buf + strlen (buf), "%x", retcode);
if (error || remote_fio_ctrl_c_flag)
if (error || ctrl_c)
{
if (error && remote_fio_ctrl_c_flag)
if (error && ctrl_c)
error = FILEIO_EINTR;
if (error < 0)
{
@ -375,11 +334,10 @@ remote_fileio_reply (int retcode, int error)
error = -error;
}
sprintf (buf + strlen (buf), ",%x", error);
if (remote_fio_ctrl_c_flag)
if (ctrl_c)
strcat (buf, ",C");
}
remote_fio_ctrl_c_flag = 0;
remote_fileio_sig_set (remote_fileio_ctrl_c_signal_handler);
quit_handler = remote_fileio_o_quit_handler;
putpkt (buf);
}
@ -1166,7 +1124,7 @@ do_remote_fileio_request (struct ui_out *uiout, void *buf_arg)
char *c;
int idx;
remote_fileio_sig_set (remote_fileio_ctrl_c_signal_handler);
quit_handler = remote_fileio_quit_handler;
c = strchr (++buf, ',');
if (c)
@ -1213,20 +1171,22 @@ remote_fileio_request (char *buf, int ctrlc_pending_p)
{
int ex;
remote_fileio_sig_init ();
/* Save the previous quit handler, so we can restore it. No need
for a cleanup since we catch all exceptions below. Note that the
quit handler is also restored by remote_fileio_reply just before
pushing a packet. */
remote_fileio_o_quit_handler = quit_handler;
if (ctrlc_pending_p)
{
/* If the target hasn't responded to the Ctrl-C sent
asynchronously earlier, take this opportunity to send the
Ctrl-C synchronously. */
remote_fio_ctrl_c_flag = 1;
set_quit_flag ();
remote_fileio_reply (-1, FILEIO_EINTR);
}
else
{
remote_fio_ctrl_c_flag = 0;
ex = catch_exceptions (current_uiout,
do_remote_fileio_request, (void *)buf,
RETURN_MASK_ALL);
@ -1243,7 +1203,7 @@ remote_fileio_request (char *buf, int ctrlc_pending_p)
}
}
remote_fileio_sig_exit ();
quit_handler = remote_fileio_o_quit_handler;
}