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 Library General Public License as
  5. published by the Free Software Foundation; either version 2 of the
  6. 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. Library General Public License for more details.
  11. You should have received a copy of the GNU Library General Public
  12. License along with the GNU C Library; see the file COPYING.LIB. If not,
  13. write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  14. Boston, MA 02111-1307, USA. */
  15. #include <errno.h>
  16. #include <termios.h>
  17. #include <sys/ioctl.h>
  18. #include <sys/types.h>
  19. #define __USE_XOPEN_EXTENDED
  20. #include <unistd.h>
  21. /* Return the session ID of FD. */
  22. pid_t tcgetsid (int fd)
  23. {
  24. pid_t pgrp;
  25. pid_t sid;
  26. #ifdef TIOCGSID
  27. static int tiocgsid_does_not_work;
  28. if (! tiocgsid_does_not_work)
  29. {
  30. int serrno = errno;
  31. int sid;
  32. if (ioctl (fd, TIOCGSID, &sid) < 0)
  33. {
  34. if (errno == EINVAL)
  35. {
  36. tiocgsid_does_not_work = 1;
  37. errno=serrno;
  38. }
  39. else
  40. return (pid_t) -1;
  41. }
  42. else
  43. return (pid_t) sid;
  44. }
  45. #endif
  46. pgrp = tcgetpgrp (fd);
  47. if (pgrp == -1)
  48. return (pid_t) -1;
  49. sid = getsid (pgrp);
  50. if (sid == -1 && errno == ESRCH)
  51. errno=ENOTTY;
  52. return sid;
  53. }