sysdeps/unix/bsd/getpt.c

   1 /* Copyright (C) 1998-2014 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
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23
  24
  25 /* Prefix for master pseudo terminal nodes.  */
  26 #define _PATH_PTY "/dev/pty"
  27
  28
  29 /* Letters indicating a series of pseudo terminals.  */
  30 #ifndef PTYNAME1
  31 #define PTYNAME1 "pqrsPQRS"
  32 #endif
  33 const char __libc_ptyname1[] attribute_hidden = PTYNAME1;
  34
  35 /* Letters indicating the position within a series.  */
  36 #ifndef PTYNAME2
  37 #define PTYNAME2 "0123456789abcdefghijklmnopqrstuv";
  38 #endif
  39 const char __libc_ptyname2[] attribute_hidden = PTYNAME2;
  40
  41
  42 /* Open a master pseudo terminal and return its file descriptor.  */
  43 int
  44 __getpt (void)
  45 {
  46   char buf[sizeof (_PATH_PTY) + 2];
  47   const char *p, *q;
  48   char *s;
  49
  50   s = __mempcpy (buf, _PATH_PTY, sizeof (_PATH_PTY) - 1);
  51   /* s[0] and s[1] will be filled in the loop.  */
  52   s[2] = '\0';
  53
  54   for (p = __libc_ptyname1; *p != '\0'; ++p)
  55     {
  56       s[0] = *p;
  57
  58       for (q = __libc_ptyname2; *q != '\0'; ++q)
  59         {
  60           int fd;
  61
  62           s[1] = *q;
  63
  64           fd = __open (buf, O_RDWR);
  65           if (fd != -1)
  66             return fd;
  67
  68           if (errno == ENOENT)
  69             return -1;
  70         }
  71     }
  72
  73   __set_errno (ENOENT);
  74   return -1;
  75 }
  76
  77 #undef __getpt
  78 weak_alias (__getpt, getpt)
  79
  80 #ifndef HAVE_POSIX_OPENPT
  81 /* We cannot define posix_openpt in general for BSD systems.  */
  82 int
  83 __posix_openpt (int oflag)
  84 {
  85   __set_errno (ENOSYS);
  86   return -1;
  87 }
  88 weak_alias (__posix_openpt, posix_openpt)
  89
  90 stub_warning (posix_openpt)
  91 #endif