(init_subshell): use openpty() to open master/slave devices for subshell.

Thanks Jesse R. Gorzinski <jgorzins@us.ibm.com> for the original patch.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

m4.include/mc-subshell.m4

@@ -24,6 +24,15 @@ AC_DEFUN([mc_SUBSHELL], [
 
     if test "x$result" != xno; then
         AC_DEFINE(ENABLE_SUBSHELL, 1, [Define to enable subshell support])
+
+        dnl openpty() can simplify opening of master/slave devices for subshell
+        AC_CHECK_HEADERS([pty.h libutil.h util.h])
+        AC_CHECK_FUNCS(openpty,,
+            AC_CHECK_LIB(util,openpty,
+                [AC_DEFINE(HAVE_OPENPTY)
+                    LIBS="$LIBS -lutil"]
+            )
+        )
     fi
 
     AC_MSG_RESULT([$result])

src/subshell/common.c

@@ -74,6 +74,20 @@
 #include <stropts.h>            /* For I_PUSH */
 #endif /* HAVE_STROPTS_H */
 
+#ifdef HAVE_OPENPTY
+/* includes for openpty() */
+#if HAVE_PTY_H
+#include <pty.h>
+#endif
+#if HAVE_UTIL_H
+#include <util.h>
+#endif
+/* <sys/types.h> is a prerequisite of <libutil.h> on FreeBSD 8.0.  */
+#if HAVE_LIBUTIL_H
+#include <libutil.h>
+#endif
+#endif /* HAVE_OPENPTY */
+
 #include "lib/global.h"
 
 #include "lib/unixcompat.h"
@@ -1026,6 +1040,15 @@ init_subshell (void)
 
         /* FIXME: We may need to open a fresh pty each time on SVR4 */
 
+#ifdef HAVE_OPENPTY
+        if (openpty (&mc_global.tty.subshell_pty, &subshell_pty_slave, NULL, NULL, NULL))
+        {
+            fprintf (stderr, "Cannot open master and slave sides of pty: %s\n",
+                     unix_error_string (errno));
+            mc_global.tty.use_subshell = FALSE;
+            return;
+        }
+#else
         mc_global.tty.subshell_pty = pty_open_master (pty_name);
         if (mc_global.tty.subshell_pty == -1)
         {
@@ -1041,6 +1064,7 @@ init_subshell (void)
             mc_global.tty.use_subshell = FALSE;
             return;
         }
+#endif /* HAVE_OPENPTY */
 
         /* Create a pipe for receiving the subshell's CWD */