ptsname.c 5.4 KB

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  1. /* Copyright (C) 1998 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Library General Public License as
  6. published by the Free Software Foundation; either version 2 of the
  7. License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Library General Public License for more details.
  12. You should have received a copy of the GNU Library General Public
  13. License along with the GNU C Library; see the file COPYING.LIB. If not,
  14. write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  15. Boston, MA 02111-1307, USA. */
  16. #define _ISOC99_SOURCE
  17. #include <stdio.h>
  18. #include <errno.h>
  19. #include <paths.h>
  20. #include <stdlib.h>
  21. #include <string.h>
  22. #include <sys/ioctl.h>
  23. #include <sys/stat.h>
  24. #include <sys/sysmacros.h>
  25. #include <termios.h>
  26. #include <unistd.h>
  27. #include <bits/uClibc_uintmaxtostr.h>
  28. #if !defined __UNIX98PTY_ONLY__
  29. /* Check if DEV corresponds to a master pseudo terminal device. */
  30. #define MASTER_P(Dev) \
  31. (major ((Dev)) == 2 \
  32. || (major ((Dev)) == 4 && minor ((Dev)) >= 128 && minor ((Dev)) < 192) \
  33. || (major ((Dev)) >= 128 && major ((Dev)) < 136))
  34. /* Check if DEV corresponds to a master pseudo terminal device. */
  35. #define SLAVE_P(Dev) \
  36. (major ((Dev)) == 3 \
  37. || (major ((Dev)) == 4 && minor ((Dev)) >= 192 && minor ((Dev)) < 256) \
  38. || (major ((Dev)) >= 136 && major ((Dev)) < 144))
  39. /* Note that major number 4 corresponds to the old BSD style pseudo
  40. terminal devices. As of Linux 2.1.115 these are no longer
  41. supported. They have been replaced by major numbers 2 (masters)
  42. and 3 (slaves). */
  43. /* The are declared in getpt.c. */
  44. extern const char _ptyname1[];
  45. extern const char _ptyname2[];
  46. #endif
  47. /* Directory where we can find the slave pty nodes. */
  48. #define _PATH_DEVPTS "/dev/pts/"
  49. /* Store at most BUFLEN characters of the pathname of the slave pseudo
  50. terminal associated with the master FD is open on in BUF.
  51. Return 0 on success, otherwise an error number. */
  52. int ptsname_r (int fd, char *buf, size_t buflen)
  53. {
  54. int save_errno = errno;
  55. #if !defined __UNIX98PTY_ONLY__
  56. struct stat st;
  57. #endif
  58. int ptyno;
  59. if (buf == NULL)
  60. {
  61. errno = EINVAL;
  62. return EINVAL;
  63. }
  64. #if !defined __UNIX98PTY_ONLY__
  65. if (!isatty (fd))
  66. {
  67. errno = ENOTTY;
  68. return ENOTTY;
  69. }
  70. #elif !defined TIOCGPTN
  71. # error "__UNIX98PTY_ONLY__ enabled but TIOCGPTN ioctl not supported by your kernel."
  72. #endif
  73. #ifdef TIOCGPTN
  74. if (ioctl (fd, TIOCGPTN, &ptyno) == 0)
  75. {
  76. /* Buffer we use to print the number in. */
  77. char numbuf[__BUFLEN_INT10TOSTR];
  78. static const char devpts[] = _PATH_DEVPTS;
  79. char *p;
  80. p = _int10tostr(&numbuf[sizeof numbuf - 1], ptyno);
  81. if (buflen < sizeof devpts + &numbuf[sizeof numbuf - 1] - p)
  82. {
  83. errno = ERANGE;
  84. return ERANGE;
  85. }
  86. strcpy (buf, devpts);
  87. strcat (buf, p);
  88. /* Note: Don't bother with stat on the slave name and checking the
  89. driver's major device number - the ioctl above succeeded so
  90. we know the fd was a Unix'98 master and the /dev/pts/ prefix
  91. is set by definition. If the name isn't really a slave PTY,
  92. the system is misconfigured anyway - something else will fail
  93. later.
  94. */
  95. errno = save_errno;
  96. return 0;
  97. }
  98. #endif
  99. #if defined __UNIX98PTY_ONLY__
  100. else
  101. {
  102. /* If the ioctl fails it wasn't a Unix 98 master PTY */
  103. errno = ENOTTY;
  104. return ENOTTY;
  105. }
  106. #else
  107. # if !defined TIOCGPTN
  108. else if (errno == EINVAL)
  109. # endif
  110. {
  111. char *p;
  112. if (buflen < strlen (_PATH_TTY) + 3)
  113. {
  114. errno = ERANGE;
  115. return ERANGE;
  116. }
  117. if (fstat (fd, &st) < 0)
  118. return errno;
  119. /* Check if FD really is a master pseudo terminal. */
  120. if (! MASTER_P (st.st_rdev))
  121. {
  122. errno = ENOTTY;
  123. return ENOTTY;
  124. }
  125. ptyno = minor (st.st_rdev);
  126. /* This is for the old BSD pseudo terminals. As of Linux
  127. 2.1.115 these are no longer supported. */
  128. if (major (st.st_rdev) == 4)
  129. ptyno -= 128;
  130. if (ptyno / 16 >= strlen (_ptyname1))
  131. {
  132. errno = ENOTTY;
  133. return ENOTTY;
  134. }
  135. strcpy (buf, _PATH_TTY);
  136. p = buf + strlen (buf);
  137. p[0] = _ptyname1[ptyno / 16];
  138. p[1] = _ptyname2[ptyno % 16];
  139. p[2] = '\0';
  140. }
  141. if (stat(buf, &st) < 0)
  142. return errno;
  143. /* Check if the name we're about to return really corresponds to a
  144. slave pseudo terminal. */
  145. if (! S_ISCHR (st.st_mode) || ! SLAVE_P (st.st_rdev))
  146. {
  147. /* This really is a configuration problem. */
  148. errno = ENOTTY;
  149. return ENOTTY;
  150. }
  151. #endif
  152. errno = save_errno;
  153. return 0;
  154. }
  155. /* Return the pathname of the pseudo terminal slave assoicated with
  156. the master FD is open on, or NULL on errors.
  157. The returned storage is good until the next call to this function. */
  158. char *
  159. ptsname (int fd)
  160. {
  161. static char buffer[sizeof (_PATH_DEVPTS) + 20];
  162. return ptsname_r (fd, buffer, sizeof (buffer)) != 0 ? NULL : buffer;
  163. }