From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id mqxFGwvJx2AYUQAAWB0awg (envelope-from ) for ; Mon, 14 Jun 2021 17:24:27 -0400 Received: by simark.ca (Postfix, from userid 112) id 638D11F163; Mon, 14 Jun 2021 17:24:27 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-0.6 required=5.0 tests=MAILING_LIST_MULTI, RDNS_DYNAMIC,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (ip-8-43-85-97.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 792951E54D for ; Mon, 14 Jun 2021 17:24:25 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 0A98C3973065 for ; Mon, 14 Jun 2021 21:24:25 +0000 (GMT) Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com [209.85.128.50]) by sourceware.org (Postfix) with ESMTPS id C5E863857010 for ; Mon, 14 Jun 2021 21:24:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org C5E863857010 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=palves.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-wm1-f50.google.com with SMTP id l9so12902782wms.1 for ; Mon, 14 Jun 2021 14:24:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=4i1ZPOlk3p7kZ++3YKq/A9XrxdCk27cAklAmWYXQ8OQ=; b=syB1obKUWFlrRhBL8lK+Knttz1KsMZHn0uQZV1l293IjPwmblMYmBUNpW8daPT7diw 09gfwEBEWNpS8lmhF6yv/89A4ZzL2Vbu5Gw5nwBG2hE50MlYuiqqK3pMdHynxnNGGsHf 5B7cKHh7ygK2hxWfsb0JzRhJHvwHMdDpF/8KA/yChogRIQ+9ftmn7wkUfVCXpelPnQ4v /SPTugGcdP2Ar9sY5kcuPKwLtgOPXAUjygRQ4OTXSqJodMRjKvo26ZBhA5E9EbQiQ7co p2MpA0l6Nj273mjWBsUaSuJGXtwuUl/NIVbjyUN+0l2dC9p26CmCjxh5C35PzNWNo2NO qtPQ== X-Gm-Message-State: AOAM532NnBbFP2DpmZZPmgGfwtR/MAjDF22o+NcfiEHlvRnsjN69wBNF U/LiQWbWXxIEQ4WQfMyzifugUuMl+UWd2g== X-Google-Smtp-Source: ABdhPJwIB3yzMw7vVOcLIPwkdG8i5HGiLhXGDZNY/zPq9qm2BgS9lUnTUhIeO3Z8tQjuaYe/M7N9dA== X-Received: by 2002:a05:600c:214c:: with SMTP id v12mr302738wml.33.1623705852077; Mon, 14 Jun 2021 14:24:12 -0700 (PDT) Received: from localhost ([2001:8a0:f932:6a00:6b6e:c7b6:c5a7:aac3]) by smtp.gmail.com with ESMTPSA id r4sm18188025wre.84.2021.06.14.14.24.10 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 14 Jun 2021 14:24:11 -0700 (PDT) From: Pedro Alves To: gdb-patches@sourceware.org Subject: [PATCH v2 00/16] Interrupting programs that block/ignore SIGINT Date: Mon, 14 Jun 2021 22:23:54 +0100 Message-Id: <20210614212410.1612666-1-pedro@palves.net> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" New in v2: - run + detach no longer results in the detached process dying with SIGHUP. GDB no longer queries about it on detach. - the testsuite gets fewer "tty /dev/tty" as a result. - documentation updated accordingly. - documentation now explicitly mentions that you can use "signal SIGINT" after Ctrl-C. - Added missing "@noindent" per Eli's review. - the gdb.base/annota1.exp patch has been meanwhile merged For review convenience, I've put this in the users/palves/ctrl-c branch. Currently, on GNU/Linux, it is not possible to interrupt with Ctrl-C programs that block or ignore SIGINT, with e.g., sigprocmask or signal(SIGINT, SIG_IGN). You type Ctrl-C, but nothing happens. Similarly, if a program uses sigwait to wait for SIGINT, and the program receives a SIGINT, the SIGINT is _not_ intercepted by ptrace, it goes straight to the inferior. These problems have been known for years, and recorded in gdb/9425, gdb/14559. This is a consequence of how GDB implements interrupting programs with Ctrl-C -- when GDB spawns a new process, it makes the process use the same terminal as GDB, and then makes the process's process group be the foreground process group in GDB's terminal. This means that when the process is running in the foreground, after e.g. "continue", when the user types Ctrl-C, the kernel sends a SIGINT to the foreground process group, which is the inferior. GDB then intercepts the SIGINT via ptrace, the same way it intercepts any other signal, stops all the other threads of the inferior if in all-stop, and presents the "Program received SIGINT" stop to the user. This series address the problem by turning Ctrl-C handling around such that the SIGINT always reaches GDB first, not the inferior. That is done by making GDB put inferiors in their own terminal/session created by GDB. I.e., GDB creates a pseudo-terminal master/slave pair, makes the inferior run with the slave as its terminal, and pumps output/input on the master end. Because the inferior is run with its own session/terminal, GDB is free to remain as the foreground process in its own terminal, which means that the Ctrl-C SIGINT always reaches GDB first, instead of reaching the inferior first, and then GDB reacting to the ptrace-intercepted SIGINT. Because GDB gets the SIGINT first, GDB is then free to handle it by interrupting the program any way it sees fit. The series will then make GDB interrupt the program with SIGSTOP instead of SIGINT, which always works even if the inferior blocks/ignores SIGINT -- SIGSTOP can't be ignored. (In the future GDB may even switch to PTRACE_INTERRUPT, though that's a project of its own.) Having the inferior in its own terminal also means that GDB is in control of when inferior output is flushed to the screen. When debugging with the CLI, this means that inferior output is now never interpersed with GDB's output in an unreadable fashion. This will also allow fixing the problem of inferior output really messing up the screen in the TUI, forcing users to Ctrl-L to refresh the screen. This series does not address the TUI part, but it shouldn't be too hard -- I wrote a quick&dirty prototype patch doing that a few years back, so I know it works. Tested on GNU/Linux native, gdbserver and gdbserver + "maint target set-non-stop on". Also build-tested on mingw32-w64, Solaris 11, and OpenBSD. More details in each of the patches in the series. The first patch adds tests that fail currently, but will pass at the end of the series. The main GDB changes are in patches #12 and #15. Patch #1-#5, #9-#11, #13-#14 could go in without the main changes. All documentation (manual, NEWS) is in the last patch -- patch #16. Pedro Alves (16): Test interrupting programs that block SIGINT [gdb/9425, gdb/14559] prefork_hook: Remove 'args' parameter Make gdb.base/long-inferior-output.exp fail fast Fix gdb.multi/multi-term-settings.exp race Don't check parent pid in gdb.threads/{ia64-sigill,siginfo-threads,watchthreads-reorder}.c Special-case "set inferior-tty /dev/tty" Make inferior/GDB share terminal in tests expecting output after detach Make inferior/GDB share terminal in tests that exercise GDB/inferior reading same input gdb.mi/mi-logging.exp, don't send input to GDB while the inferior is running target_terminal::ours_for_output before printing signal received Move scoped_ignore_sigttou to gdbsupport/ Always put inferiors in their own terminal/session [gdb/9425, gdb/14559] exists_non_stop_target: Avoid flushing frames convert previous_inferior_ptid to strong reference to thread_info GNU/Linux: Interrupt/Ctrl-C with SIGSTOP instead of SIGINT [PR gdb/9425, PR gdb/14559] Document pseudo-terminal and interrupting changes gdb/doc/gdb.texinfo | 117 ++- gdb/NEWS | 23 + gdb/Makefile.in | 1 - gdb/event-top.c | 10 +- gdb/fork-child.c | 10 +- gdb/inf-ptrace.c | 24 +- gdb/inf-ptrace.h | 8 + gdb/infcmd.c | 39 +- gdb/inferior.h | 4 + gdb/inflow.c | 719 +++++++++++++++--- gdb/infrun.c | 179 ++++- gdb/infrun.h | 16 + gdb/linux-nat.c | 115 ++- gdb/linux-nat.h | 2 + gdb/nat/fork-inferior.c | 120 ++- gdb/nat/fork-inferior.h | 30 +- gdb/procfs.c | 1 - gdb/ser-unix.c | 2 +- gdb/target.c | 40 +- gdb/terminal.h | 3 + .../gdb.base/annota-input-while-running.exp | 4 + gdb/testsuite/gdb.base/annota1.exp | 3 +- .../gdb.base/bp-cmds-continue-ctrl-c.exp | 3 + .../gdb.base/continue-all-already-running.exp | 3 + gdb/testsuite/gdb.base/infcall-input.exp | 12 +- .../gdb.base/interrupt-daemon-attach.exp | 2 +- gdb/testsuite/gdb.base/interrupt-daemon.exp | 4 +- gdb/testsuite/gdb.base/interrupt-noterm.exp | 2 +- gdb/testsuite/gdb.base/interrupt.exp | 4 +- .../gdb.base/long-inferior-output.exp | 31 +- gdb/testsuite/gdb.base/random-signal.exp | 3 +- gdb/testsuite/gdb.base/range-stepping.exp | 2 +- gdb/testsuite/gdb.base/sigint-masked-out.c | 43 ++ gdb/testsuite/gdb.base/sigint-masked-out.exp | 109 +++ gdb/testsuite/gdb.base/sigint-sigwait.c | 80 ++ gdb/testsuite/gdb.base/sigint-sigwait.exp | 113 +++ gdb/testsuite/gdb.gdb/selftest.exp | 4 +- gdb/testsuite/gdb.mi/mi-logging.exp | 94 ++- gdb/testsuite/gdb.mi/new-ui-mi-sync.exp | 2 +- .../gdb.multi/multi-target-interrupt.exp | 2 +- .../gdb.multi/multi-target-no-resumed.exp | 2 +- .../gdb.multi/multi-term-settings.exp | 92 ++- gdb/testsuite/gdb.server/reconnect-ctrl-c.exp | 4 +- gdb/testsuite/gdb.threads/async.exp | 2 +- .../gdb.threads/continue-pending-status.exp | 2 +- gdb/testsuite/gdb.threads/ia64-sigill.c | 5 - gdb/testsuite/gdb.threads/leader-exit.exp | 2 +- gdb/testsuite/gdb.threads/manythreads.exp | 4 +- .../process-dies-while-detaching.exp | 3 + gdb/testsuite/gdb.threads/pthreads.exp | 2 +- gdb/testsuite/gdb.threads/schedlock.exp | 11 +- gdb/testsuite/gdb.threads/siginfo-threads.c | 5 - gdb/testsuite/gdb.threads/sigthread.exp | 2 +- .../gdb.threads/watchthreads-reorder.c | 5 - gdb/testsuite/lib/gdb.exp | 19 + gdb/tui/tui-win.c | 3 + gdbserver/fork-child.cc | 15 +- gdbsupport/Makefile.am | 1 + gdbsupport/Makefile.in | 15 +- gdbsupport/managed-tty.cc | 22 + gdbsupport/managed-tty.h | 42 + .../scoped_ignore_sigttou.h | 8 +- 62 files changed, 1994 insertions(+), 255 deletions(-) create mode 100644 gdb/testsuite/gdb.base/sigint-masked-out.c create mode 100644 gdb/testsuite/gdb.base/sigint-masked-out.exp create mode 100644 gdb/testsuite/gdb.base/sigint-sigwait.c create mode 100644 gdb/testsuite/gdb.base/sigint-sigwait.exp create mode 100644 gdbsupport/managed-tty.cc create mode 100644 gdbsupport/managed-tty.h rename gdb/inflow.h => gdbsupport/scoped_ignore_sigttou.h (90%) base-commit: c9923e71ff57ce6e824833560aae59057c6f5783 -- 2.26.2