| /* Copyright (C) 1997-2018 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 Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #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 (int fd) |
| { |
| pid_t pgrp; |
| pid_t sid; |
| #ifdef TIOCGSID |
| static int tiocgsid_does_not_work; |
| |
| if (! tiocgsid_does_not_work) |
| { |
| int serrno = errno; |
| int sid; |
| |
| if (__ioctl (fd, TIOCGSID, &sid) < 0) |
| { |
| if (errno == EINVAL) |
| { |
| tiocgsid_does_not_work = 1; |
| __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; |
| } |