libc/stdlib/bsd_getpt.c

   1 /* Copyright (C) 1998, 1999, 2000, 2001, 2002 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 #if defined __USE_BSD
  25
  26 /* Prefix for master pseudo terminal nodes.  */
  27 #define _PATH_PTY "/dev/pty"
  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 /* Open a master pseudo terminal and return its file descriptor.  */
  42 static __inline__ int
  43 __getpt (void)
  44 {
  45   char buf[sizeof (_PATH_PTY) + 2];
  46   const char *p, *q;
  47   char *s;
  48
  49   s = mempcpy (buf, _PATH_PTY, sizeof (_PATH_PTY) - 1);
  50   /* s[0] and s[1] will be filled in the loop.  */
  51   s[2] = '\0';
  52
  53   for (p = __libc_ptyname1; *p != '\0'; ++p)
  54     {
  55       s[0] = *p;
  56
  57       for (q = __libc_ptyname2; *q != '\0'; ++q)
  58         {
  59           int fd;
  60
  61           s[1] = *q;
  62
  63           fd = open (buf, O_RDWR);
  64           if (fd != -1)
  65             return fd;
  66
  67           if (errno == ENOENT)
  68             return -1;
  69         }
  70     }
  71
  72   __set_errno (ENOENT);
  73   return -1;
  74 }
  75 #endif /* __USE_BSD */