From bb7c96deb1a14ef7e8b51d5339a65a8064515c78 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Wed, 1 Jun 2016 16:34:49 +0100 Subject: [PATCH] gdb/remote-fileio.c: Eliminate custom SIGINT signal handler ... 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 * 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. --- gdb/ChangeLog | 15 +++++++++ gdb/remote-fileio.c | 80 ++++++++++++--------------------------------- 2 files changed, 35 insertions(+), 60 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9d08c67888..18261a785b 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,18 @@ +2016-06-01 Pedro Alves + + * 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 * common/common-utils.c (xmalloc_failed): New function. Provided diff --git a/gdb/remote-fileio.c b/gdb/remote-fileio.c index 29c5ca3589..93121aaa42 100644 --- a/gdb/remote-fileio.c +++ b/gdb/remote-fileio.c @@ -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; } -- 2.34.1