| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* Copyright (C) 1997, 1999 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | |
| 4 | The GNU C Library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Lesser General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2.1 of the License, or (at your option) any later version. |
| 8 | |
| 9 | The GNU C Library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public |
| 15 | License along with the GNU C Library; if not, write to the Free |
| 16 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 17 | 02111-1307 USA. */ |
| 18 | |
| 19 | #include <errno.h> |
| 20 | #include <termios.h> |
| 21 | #include <sys/ioctl.h> |
| 22 | #include <sys/types.h> |
| 23 | #include <unistd.h> |
| 24 | |
| 25 | |
| 26 | /* Return the session ID of FD. */ |
| 27 | pid_t |
| 28 | tcgetsid (int fd) |
| 29 | { |
| 30 | pid_t pgrp; |
| 31 | pid_t sid; |
| 32 | #ifdef TIOCGSID |
| 33 | static smallint tiocgsid_does_not_work; |
| 34 | |
| 35 | if (! tiocgsid_does_not_work) |
| 36 | { |
| 37 | int serrno = errno; |
| 38 | |
| 39 | if (ioctl (fd, TIOCGSID, &sid) < 0) |
| 40 | { |
| 41 | if (errno == EINVAL) |
| 42 | { |
| 43 | tiocgsid_does_not_work = 1; |
| 44 | __set_errno (serrno); |
| 45 | } |
| 46 | else |
| 47 | return (pid_t) -1; |
| 48 | } |
| 49 | else |
| 50 | return (pid_t) sid; |
| 51 | } |
| 52 | #endif |
| 53 | |
| 54 | pgrp = tcgetpgrp (fd); |
| 55 | if (pgrp == -1) |
| 56 | return (pid_t) -1; |
| 57 | |
| 58 | sid = getsid (pgrp); |
| 59 | if (sid == -1 && errno == ESRCH) |
| 60 | __set_errno (ENOTTY); |
| 61 | |
| 62 | return sid; |
| 63 | } |