tcgetsid.c 1.6 KB

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