63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
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/* Copyright (C) 1997-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <termios.h>
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#include <sys/ioctl.h>
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#include <sys/types.h>
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#include <unistd.h>
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/* Return the session ID of FD. */
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pid_t
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tcgetsid (int fd)
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{
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pid_t pgrp;
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pid_t sid;
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#ifdef TIOCGSID
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static int tiocgsid_does_not_work;
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if (! tiocgsid_does_not_work)
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{
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int serrno = errno;
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int sid;
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if (__ioctl (fd, TIOCGSID, &sid) < 0)
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{
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if (errno == EINVAL)
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{
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tiocgsid_does_not_work = 1;
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__set_errno (serrno);
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}
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else
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return (pid_t) -1;
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}
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else
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return (pid_t) sid;
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}
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#endif
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pgrp = tcgetpgrp (fd);
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if (pgrp == -1)
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return (pid_t) -1;
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sid = getsid (pgrp);
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if (sid == -1 && errno == ESRCH)
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__set_errno (ENOTTY);
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return sid;
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}
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