1 files changed, 64 insertions, 0 deletions
diff --git a/termios/tcgetsid.c b/termios/tcgetsid.c
new file mode 100644
index 0000000000..b83858f420
--- /dev/null
+++ b/termios/tcgetsid.c
@@ -0,0 +1,64 @@
+/* Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <errno.h>
+#include <termios.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/* Return the session ID of FD.  */
+pid_t
+tcgetsid (fd)
+     int fd;
+{
+  pid_t pgrp;
+  pid_t sid;
+#ifdef TIOCGSID
+  static int tiocgsid_works = 1;
+
+  if (tiocgsid_works)
+    {
+      int serrno = errno;
+      int sid;
+
+      if (__ioctl (fd, TIOCGSID, &sid) < 0)
+	{
+	  if (errno == EINVAL)
+	    {
+	      tiocgsid_works = 0;
+	      __set_errno (serrno);
+	    }
+	  else
+	    return (pid_t) -1;
+	}
+      else
+	return (pid_t) sid;
+    }
+#endif
+
+  pgrp = tcgetpgrp (fd);
+  if (pgrp == -1)
+    return (pid_t) -1;
+
+  sid = getsid (pgrp);
+  if (sid == -1 && errno == ESRCH)
+    __set_errno (ENOTTY);
+
+  return sid;
+}