Add ncurses 6.4

third_party/ncurses/lib_tstp.c

@@ -0,0 +1,428 @@
+/****************************************************************************
+ * Copyright 2020-2021,2022 Thomas E. Dickey                                *
+ * Copyright 1998-2014,2017 Free Software Foundation, Inc.                  *
+ *                                                                          *
+ * Permission is hereby granted, free of charge, to any person obtaining a  *
+ * copy of this software and associated documentation files (the            *
+ * "Software"), to deal in the Software without restriction, including      *
+ * without limitation the rights to use, copy, modify, merge, publish,      *
+ * distribute, distribute with modifications, sublicense, and/or sell       *
+ * copies of the Software, and to permit persons to whom the Software is    *
+ * furnished to do so, subject to the following conditions:                 *
+ *                                                                          *
+ * The above copyright notice and this permission notice shall be included  *
+ * in all copies or substantial portions of the Software.                   *
+ *                                                                          *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
+ * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
+ * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
+ *                                                                          *
+ * Except as contained in this notice, the name(s) of the above copyright   *
+ * holders shall not be used in advertising or otherwise to promote the     *
+ * sale, use or other dealings in this Software without prior written       *
+ * authorization.                                                           *
+ ****************************************************************************/
+
+/****************************************************************************
+ *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
+ *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
+ *     and: Thomas E. Dickey                        1995-on                 *
+ ****************************************************************************/
+
+/*
+**	lib_tstp.c
+**
+**	The routine _nc_signal_handler().
+**
+*/
+#include "curses.priv.h"
+
+#include "SigAction.h"
+
+MODULE_ID("$Id: lib_tstp.c,v 1.54 2022/12/24 22:22:10 tom Exp $")
+
+#if defined(SIGTSTP) && (HAVE_SIGACTION || HAVE_SIGVEC)
+#define USE_SIGTSTP 1
+#else
+#define USE_SIGTSTP 0
+#endif
+
+#ifdef TRACE
+static const char *
+signal_name(int sig)
+{
+    switch (sig) {
+#ifdef SIGALRM
+    case SIGALRM:
+	return "SIGALRM";
+#endif
+#ifdef SIGCONT
+    case SIGCONT:
+	return "SIGCONT";
+#endif
+    case SIGINT:
+	return "SIGINT";
+#ifdef SIGQUIT
+    case SIGQUIT:
+	return "SIGQUIT";
+#endif
+    case SIGTERM:
+	return "SIGTERM";
+#ifdef SIGTSTP
+    case SIGTSTP:
+	return "SIGTSTP";
+#endif
+#ifdef SIGTTOU
+    case SIGTTOU:
+	return "SIGTTOU";
+#endif
+#ifdef SIGWINCH
+    case SIGWINCH:
+	return "SIGWINCH";
+#endif
+    default:
+	return "unknown signal";
+    }
+}
+#endif
+
+/*
+ * Note: This code is fragile!  Its problem is that different OSs
+ * handle restart of system calls interrupted by signals differently.
+ * The ncurses code needs signal-call restart to happen -- otherwise,
+ * interrupted wgetch() calls will return FAIL, probably making the
+ * application think the input stream has ended and it should
+ * terminate.  In particular, you know you have this problem if, when
+ * you suspend an ncurses-using lynx with ^Z and resume, it dies
+ * immediately.
+ *
+ * Default behavior of POSIX sigaction(2) is not to restart
+ * interrupted system calls, but Linux's sigaction does it anyway (at
+ * least, on and after the 1.1.47 I (esr) use).  Thus this code works
+ * OK under Linux.  The 4.4BSD sigaction(2) supports a (non-portable)
+ * SA_RESTART flag that forces the right behavior.  Thus, this code
+ * should work OK under BSD/OS, NetBSD, and FreeBSD (let us know if it
+ * does not).
+ *
+ * Stock System Vs (and anything else using a strict-POSIX
+ * sigaction(2) without SA_RESTART) may have a problem.  Possible
+ * solutions:
+ *
+ *    sigvec      restarts by default (SV_INTERRUPT flag to not restart)
+ *    signal      restarts by default in SVr4 (assuming you link with -lucb)
+ *                and BSD, but not SVr3.
+ *    sigset      restarts, but is only available under SVr4/Solaris.
+ *
+ * The signal(3) call is mandated by the ANSI standard, and its
+ * interaction with sigaction(2) is described in the POSIX standard
+ * (3.3.4.2, page 72,line 934).  According to section 8.1, page 191,
+ * however, signal(3) itself is not required by POSIX.1.  And POSIX is
+ * silent on whether it is required to restart signals.
+ *
+ * So.  The present situation is, we use sigaction(2) with no
+ * guarantee of restart anywhere but on Linux and BSD.  We could
+ * switch to signal(3) and collar Linux, BSD, and SVr4.  Any way
+ * we slice it, System V UNIXes older than SVr4 will probably lose
+ * (this may include XENIX).
+ *
+ * This implementation will probably be changed to use signal(3) in
+ * the future.  If nothing else, it is simpler...
+ */
+
+#if USE_SIGTSTP
+static void
+handle_SIGTSTP(int dummy GCC_UNUSED)
+{
+    SCREEN *sp = CURRENT_SCREEN;
+    sigset_t mask, omask;
+    sigaction_t act, oact;
+
+#ifdef SIGTTOU
+    int sigttou_blocked;
+#endif
+
+    _nc_globals.have_sigtstp = 1;
+    T(("handle_SIGTSTP() called"));
+
+    /*
+     * The user may have changed the prog_mode tty bits, so save them.
+     *
+     * But first try to detect whether we still are in the foreground
+     * process group - if not, an interactive shell may already have
+     * taken ownership of the tty and modified the settings when our
+     * parent was stopped before us, and we would likely pick up the
+     * settings already modified by the shell.
+     *
+     * Don't do this if we're not in curses -
+     */
+    if (sp != 0 && (sp->_endwin == ewRunning))
+#if HAVE_TCGETPGRP
+	if (tcgetpgrp(STDIN_FILENO) == getpgrp())
+#endif
+	    NCURSES_SP_NAME(def_prog_mode) (NCURSES_SP_ARG);
+
+    /*
+     * Block window change and timer signals.  The latter
+     * is because applications use timers to decide when
+     * to repaint the screen.
+     */
+    (void) sigemptyset(&mask);
+#ifdef SIGALRM
+    (void) sigaddset(&mask, SIGALRM);
+#endif
+#if USE_SIGWINCH
+    (void) sigaddset(&mask, SIGWINCH);
+#endif
+    (void) sigprocmask(SIG_BLOCK, &mask, &omask);
+
+#ifdef SIGTTOU
+    sigttou_blocked = sigismember(&omask, SIGTTOU);
+    if (!sigttou_blocked) {
+	(void) sigemptyset(&mask);
+	(void) sigaddset(&mask, SIGTTOU);
+	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
+    }
+#endif
+
+    /*
+     * End window mode, which also resets the terminal state to the
+     * original (pre-curses) modes.
+     */
+    NCURSES_SP_NAME(endwin) (NCURSES_SP_ARG);
+
+    /* Unblock SIGTSTP. */
+    (void) sigemptyset(&mask);
+    (void) sigaddset(&mask, SIGTSTP);
+#ifdef SIGTTOU
+    if (!sigttou_blocked) {
+	/* Unblock this too if it wasn't blocked on entry */
+	(void) sigaddset(&mask, SIGTTOU);
+    }
+#endif
+    (void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
+
+    /* Now we want to resend SIGSTP to this process and suspend it */
+    act.sa_handler = SIG_DFL;
+    sigemptyset(&act.sa_mask);
+    act.sa_flags = 0;
+#ifdef SA_RESTART
+    act.sa_flags |= SA_RESTART;
+#endif /* SA_RESTART */
+    sigaction(SIGTSTP, &act, &oact);
+    kill(getpid(), SIGTSTP);
+
+    /* Process gets suspended...time passes...process resumes */
+
+    T(("SIGCONT received"));
+    sigaction(SIGTSTP, &oact, NULL);
+    NCURSES_SP_NAME(flushinp) (NCURSES_SP_ARG);
+
+    /*
+     * If the user modified the tty state while suspended, he wants
+     * those changes to stick.  So save the new "default" terminal state.
+     */
+    NCURSES_SP_NAME(def_shell_mode) (NCURSES_SP_ARG);
+
+    /*
+     * This relies on the fact that doupdate() will restore the
+     * program-mode tty state, and issue enter_ca_mode if need be.
+     */
+    NCURSES_SP_NAME(doupdate) (NCURSES_SP_ARG);
+
+    /* Reset the signals. */
+    (void) sigprocmask(SIG_SETMASK, &omask, NULL);
+}
+#endif /* USE_SIGTSTP */
+
+static void
+handle_SIGINT(int sig)
+{
+    SCREEN *sp = CURRENT_SCREEN;
+
+    /*
+     * Much of this is unsafe from a signal handler.  But we'll _try_ to clean
+     * up the screen and terminal settings on the way out.
+     *
+     * There are at least the following problems:
+     * 1) Walking the SCREEN list is unsafe, since all list management
+     *    is done without any signal blocking.
+     * 2) On systems which have REENTRANT turned on, set_term() uses
+     *    _nc_lock_global() which could deadlock or misbehave in other ways.
+     * 3) endwin() calls all sorts of stuff, many of which use stdio or
+     *    other library functions which are clearly unsafe.
+     */
+    if (!_nc_globals.cleanup_nested++
+	&& (sig == SIGINT || sig == SIGTERM)) {
+#if HAVE_SIGACTION || HAVE_SIGVEC
+	sigaction_t act;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	act.sa_handler = SIG_IGN;
+	if (sigaction(sig, &act, NULL) == 0)
+#else
+	if (signal(sig, SIG_IGN) != SIG_ERR)
+#endif
+	{
+	    SCREEN *scan;
+	    for (each_screen(scan)) {
+		if (scan->_ofp != 0
+		    && NC_ISATTY(fileno(scan->_ofp))) {
+		    scan->_outch = NCURSES_SP_NAME(_nc_outch);
+		}
+		set_term(scan);
+		NCURSES_SP_NAME(endwin) (NCURSES_SP_ARG);
+		if (sp)
+		    sp->_endwin = ewInitial;	/* in case of reuse */
+	    }
+	}
+    }
+    _exit(EXIT_FAILURE);
+}
+
+# ifndef _nc_set_read_thread
+NCURSES_EXPORT(void)
+_nc_set_read_thread(bool enable)
+{
+    _nc_lock_global(curses);
+    if (enable) {
+#  if USE_WEAK_SYMBOLS
+	if ((pthread_self) && (pthread_kill) && (pthread_equal))
+#  endif
+	    _nc_globals.read_thread = pthread_self();
+    } else {
+	_nc_globals.read_thread = 0;
+    }
+    _nc_unlock_global(curses);
+}
+# endif
+
+#if USE_SIGWINCH
+
+static void
+handle_SIGWINCH(int sig GCC_UNUSED)
+{
+    _nc_globals.have_sigwinch = 1;
+# if USE_PTHREADS_EINTR
+    if (_nc_globals.read_thread) {
+	if (!pthread_equal(pthread_self(), _nc_globals.read_thread))
+	    pthread_kill(_nc_globals.read_thread, SIGWINCH);
+	_nc_globals.read_thread = 0;
+    }
+# endif
+}
+#endif /* USE_SIGWINCH */
+
+/*
+ * If the given signal is still in its default state, set it to the given
+ * handler.
+ */
+static int
+CatchIfDefault(int sig, void (*handler) (int))
+{
+    int result;
+#if HAVE_SIGACTION || HAVE_SIGVEC
+    sigaction_t old_act;
+    sigaction_t new_act;
+
+    memset(&new_act, 0, sizeof(new_act));
+    sigemptyset(&new_act.sa_mask);
+#ifdef SA_RESTART
+#ifdef SIGWINCH
+    if (sig != SIGWINCH)
+#endif
+	new_act.sa_flags |= SA_RESTART;
+#endif /* SA_RESTART */
+    new_act.sa_handler = handler;
+
+    if (sigaction(sig, NULL, &old_act) == 0
+	&& (old_act.sa_handler == SIG_DFL
+	    || old_act.sa_handler == handler
+#if USE_SIGWINCH
+	    || (sig == SIGWINCH && old_act.sa_handler == SIG_IGN)
+#endif
+	)) {
+	(void) sigaction(sig, &new_act, NULL);
+	result = TRUE;
+    } else {
+	result = FALSE;
+    }
+#else /* !HAVE_SIGACTION */
+    void (*ohandler) (int);
+
+    ohandler = signal(sig, SIG_IGN);
+    if (ohandler == SIG_DFL
+	|| ohandler == handler
+#if USE_SIGWINCH
+	|| (sig == SIGWINCH && ohandler == SIG_IGN)
+#endif
+	) {
+	signal(sig, handler);
+	result = TRUE;
+    } else {
+	signal(sig, ohandler);
+	result = FALSE;
+    }
+#endif
+    T(("CatchIfDefault - will %scatch %s",
+       result ? "" : "not ", signal_name(sig)));
+    return result;
+}
+
+/*
+ * This is invoked once at the beginning (e.g., from 'initscr()'), to
+ * initialize the signal catchers, and thereafter when spawning a shell (and
+ * returning) to disable/enable the SIGTSTP (i.e., ^Z) catcher.
+ *
+ * If the application has already set one of the signals, we'll not modify it
+ * (during initialization).
+ *
+ * The XSI document implies that we shouldn't keep the SIGTSTP handler if
+ * the caller later changes its mind, but that doesn't seem correct.
+ */
+NCURSES_EXPORT(void)
+_nc_signal_handler(int enable)
+{
+    T((T_CALLED("_nc_signal_handler(%d)"), enable));
+#if USE_SIGTSTP			/* Xenix 2.x doesn't have SIGTSTP, for example */
+    {
+	static bool ignore_tstp = FALSE;
+
+	if (!ignore_tstp) {
+	    static sigaction_t new_sigaction, old_sigaction;
+
+	    if (!enable) {
+		new_sigaction.sa_handler = SIG_IGN;
+		sigaction(SIGTSTP, &new_sigaction, &old_sigaction);
+	    } else if (new_sigaction.sa_handler != SIG_DFL) {
+		sigaction(SIGTSTP, &old_sigaction, NULL);
+	    } else if (sigaction(SIGTSTP, NULL, &old_sigaction) == 0
+		       && (old_sigaction.sa_handler == SIG_DFL)) {
+		sigemptyset(&new_sigaction.sa_mask);
+#ifdef SA_RESTART
+		new_sigaction.sa_flags |= SA_RESTART;
+#endif /* SA_RESTART */
+		new_sigaction.sa_handler = handle_SIGTSTP;
+		(void) sigaction(SIGTSTP, &new_sigaction, NULL);
+	    } else {
+		ignore_tstp = TRUE;
+	    }
+	}
+    }
+#endif /* !USE_SIGTSTP */
+
+    if (!_nc_globals.init_signals) {
+	if (enable) {
+	    CatchIfDefault(SIGINT, handle_SIGINT);
+	    CatchIfDefault(SIGTERM, handle_SIGINT);
+#if USE_SIGWINCH
+	    CatchIfDefault(SIGWINCH, handle_SIGWINCH);
+#endif
+	    _nc_globals.init_signals = TRUE;
+	}
+    }
+    returnVoid;
+}