pty: Fix signal handling (re: 1ca9286a)

This applies the OpenSUSE changes to pty.c from:
https://build.opensuse.org/package/view_file/shells/ksh/ksh93-builtin.dif

src/cmd/builtin/pty.c:
- Add a patch from OpenSUSE with a fix for signal handling.

src/cmd/ksh93/tests/pty.sh:
- Re-enable the process group exercise test.

Resolves: https://github.com/ksh93/ksh/issues/61

src/cmd/builtin/pty.c

@@ -215,28 +215,65 @@ mkpty(int* master, int* slave)
 #endif
 #if !_lib_openpty
 	char*		sname;
+#endif
+#ifdef __linux__
+	sigset_t blckttou, oldset;
+	(void)sigemptyset(&blckttou);
+	(void)sigaddset(&blckttou, SIGTTOU);
+	sigprocmask(SIG_BLOCK, &blckttou, &oldset);
 #endif
 	/*
 	 * some systems hang hard during the handshake
 	 * if you know why then please let us know
 	 */
 
-	alarm(4);
+	alarm(6);
-	if (tcgetattr(STDERR_FILENO, &tty) >= 0)
+	if (tcgetattr(sffileno(sfstderr), &tty) < 0)
-		ttyp = &tty;
-	else
 	{
+		if (errno != ENOTTY)
+			error(-1, "unable to get standard error terminal attributes");
+		cfmakeraw(&tty);
 		ttyp = 0;
-		error(-1, "unable to get standard error terminal attributes");
 	}
+	tty.c_lflag |= ICANON | IEXTEN | ISIG | ECHO|ECHOE|ECHOK|ECHOKE;
+	tty.c_oflag |= (ONLCR | OPOST);
+	tty.c_oflag &= ~(OCRNL | ONLRET);
+	tty.c_iflag |= BRKINT;
+	tty.c_iflag &= ~IGNBRK;
+	tty.c_lflag |= ISIG;
+	tty.c_cc[VTIME] = 0;
+	tty.c_cc[VMIN] = CMIN;
+#ifdef B115200
+	cfsetispeed(&tty, B115200);
+	cfsetospeed(&tty, B115200);
+#elif defined(B57600)
+	cfsetispeed(&tty, B57600);
+	cfsetospeed(&tty, B57600);
+#elif defined(B38400)
+	cfsetispeed(&tty, B38400);
+	cfsetospeed(&tty, B38400);
+#endif
+	ttyp = &tty;
 #ifdef TIOCGWINSZ
-	if (ioctl(STDERR_FILENO, TIOCGWINSZ, &win) >= 0)
+	if (ioctl(sffileno(sfstderr), TIOCGWINSZ, &win) < 0)
-		winp = &win;
-	else
 	{
+		if (errno != ENOTTY)
+			error(-1, "unable to get standard error window size");
+		win.ws_row = 0;
+		win.ws_col = 0;
 		winp = 0;
-		error(-1, "unable to get standard error window size");
 	}
+	if (win.ws_row < 24)
+		win.ws_row = 24;
+	if (win.ws_col < 80)
+		win.ws_col = 80;
+	winp = &win;
+#endif
+#ifdef __linux__
+# if !_lib_openpty
+#  undef  _lib_openpty
+#  define _lib_openpty 1
+# endif
 #endif
 #if _lib_openpty
 	if (openpty(master, slave, NULL, ttyp, winp) < 0)
@@ -278,6 +315,9 @@ mkpty(int* master, int* slave)
 	fcntl(*master, F_SETFD, FD_CLOEXEC);
 #if !O_cloexec
 	fcntl(*slave, F_SETFD, FD_CLOEXEC);
+#endif
+#ifdef __linux__
+	sigprocmask(SIG_SETMASK, &oldset, NULL);
 #endif
 	alarm(0);
 	return 0;
@@ -317,9 +357,13 @@ process(Sfio_t* mp, Sfio_t* lp, int delay, int timeout)
 	char*		s;
 	Sfio_t*		ip;
 	Sfio_t*		sps[2];
+	struct stat	dst;
+	struct stat	fst;
 
 	ip = sfstdin;
-	for (;;)
+	if (!fstat(sffileno(ip), &dst) && !stat("/dev/null", &fst) && dst.st_dev == fst.st_dev && dst.st_ino == fst.st_ino)
+		ip = 0;
+	do
 	{
 		i = 0;
 		t = timeout;
@@ -336,39 +380,39 @@ process(Sfio_t* mp, Sfio_t* lp, int delay, int timeout)
 		{
 			if (n < 0)
 				error(ERROR_SYSTEM|2, "poll failed");
-			if (t < 0)
+			break;
-				break;
 		}
-		else
+		for (i = t = 0; i < n; i++)
-			for (i = 0; i < n; i++)
+		{
+			if (!(sfvalue(sps[i]) & SF_READ))
+				/*skip*/;
+			else if (sps[i] == mp)
 			{
-				if (!(sfvalue(sps[i]) & SF_READ))
+				t++;
-					/*skip*/;
+				if (!(s = (char*)sfreserve(mp, SF_UNBOUND, -1)))
-				else if (sps[i] == mp)
 				{
-					if (!(s = (char*)sfreserve(mp, SF_UNBOUND, -1)))
+					sfclose(mp);
-					{
+					mp = 0;
-						sfclose(mp);
-						mp = 0;
-					}
-					else if ((r = sfvalue(mp)) > 0 && (sfwrite(sfstdout, s, r) != r || sfsync(sfstdout)))
-					{
-						error(ERROR_SYSTEM|2, "output write failed");
-						goto done;
-					}
 				}
-				else
+				else if ((r = sfvalue(mp)) > 0 && (sfwrite(sfstdout, s, r) != r || sfsync(sfstdout)))
 				{
-					if (!(s = sfgetr(ip, '\n', 1)))
+					error(ERROR_SYSTEM|2, "output write failed");
-						ip = 0;
+					goto done;
-					else if (sfputr(mp, s, '\r') < 0 || sfsync(mp))
-					{
-						error(ERROR_SYSTEM|2, "write failed");
-						goto done;
-					}
 				}
 			}
-	}
+			else
+			{
+				t++;
+				if (!(s = sfgetr(ip, '\n', 1)))
+					ip = 0;
+				else if (sfputr(mp, s, '\r') < 0 || sfsync(mp))
+				{
+					error(ERROR_SYSTEM|2, "write failed");
+					goto done;
+				}
+			}
+		}
+	} while (t);
  done:
 	if (mp)
 		sfclose(mp);

src/cmd/ksh93/tests/pty.sh

@@ -463,12 +463,7 @@ r echo repeat-3
 !
 fi
 
-# Following test is disabled because a bug in pty causes it to fail on too
+# err_exit #
-# many operating systems. Apparently pty doesn't handle SIGTSTP correctly:
-# https://github.com/att/ast/issues/375
-# TODO: fix pty and re-enable this test.
-: <<\end_disabled
-# err_(don't count me)_exit #
 whence -q less &&
 TERM=vt100 tst $LINENO <<"!"
 L process/terminal group exercise
@@ -480,7 +475,6 @@ r Stopped
 w fg
 u yes-yes
 !
-end_disabled
 
 # err_exit #
 # Test file name completion in vi mode