sysdeps/unix/bsd/getpt.c

   1 /* Copyright (C) 1998, 1999, 2000, 2001 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24
  25
  26 /* Prefix for master pseudo terminal nodes.  */
  27 #define _PATH_PTY "/dev/pty"
  28
  29
  30 /* Letters indicating a series of pseudo terminals.  */
  31 #ifndef PTYNAME1
  32 #define PTYNAME1 "pqrsPQRS"
  33 #endif
  34 const char __libc_ptyname1[] = PTYNAME1;
  35
  36 /* Letters indicating the position within a series.  */
  37 #ifndef PTYNAME2
  38 #define PTYNAME2 "0123456789abcdefghijklmnopqrstuv";
  39 #endif
  40 const char __libc_ptyname2[] = PTYNAME2;
  41
  42
  43 /* Open a master pseudo terminal and return its file descriptor.  */
  44 int
  45 __getpt (void)
  46 {
  47   char buf[sizeof (_PATH_PTY) + 2];
  48   const char *p, *q;
  49   char *s;
  50
  51   s = __mempcpy (buf, _PATH_PTY, sizeof (_PATH_PTY) - 1);
  52   /* s[0] and s[1] will be filled in the loop.  */
  53   s[2] = '\0';
  54
  55   for (p = __libc_ptyname1; *p != '\0'; ++p)
  56     {
  57       s[0] = *p;
  58
  59       for (q = __libc_ptyname2; *q != '\0'; ++q)
  60         {
  61           int fd;
  62
  63           s[1] = *q;
  64
  65           fd = __open (buf, O_RDWR);
  66           if (fd != -1)
  67             return fd;
  68
  69           if (errno == ENOENT)
  70             return -1;
  71         }
  72     }
  73
  74   __set_errno (ENOENT);
  75   return -1;
  76 }
  77
  78 #undef __getpt
  79 weak_alias (__getpt, getpt)
  80
  81 #ifndef HAVE_POSIX_OPENPT
  82 /* We cannot define posix_openpt in general for BSD systems.  */
  83 int
  84 __posix_openpt (int oflag)
  85 {
  86   __set_errno (ENOSYS);
  87   return -1;
  88 }
  89 weak_alias (__posix_openpt, posix_openpt)
  90
  91 stub_warning (posix_openpt)
  92 # include <stub-tag.h>
  93 #endif