libutil/openpty.c

   1 /* Copyright (C) 1998, 1999, 2004 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 <limits.h>
  22 #include <pty.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <termios.h>
  26 #include <unistd.h>
  27 #include <sys/types.h>
  28
  29 /* BCS: the following function is, IMO, overkill */
  30 #if 0
  31 /* Return the result of ptsname_r in the buffer pointed to by PTS,
  32    which should be of length BUF_LEN.  If it is too long to fit in
  33    this buffer, a sufficiently long buffer is allocated using malloc,
  34    and returned in PTS.  0 is returned upon success, -1 otherwise.  */
  35 static int
  36 pts_name (int fd, char **pts, size_t buf_len)
  37 {
  38   int rv;
  39   char *buf = *pts;
  40
  41   for (;;)
  42     {
  43       char *new_buf;
  44
  45       if (buf_len)
  46         {
  47           rv = ptsname_r (fd, buf, buf_len);
  48
  49           if (rv != 0 || memchr (buf, '\0', buf_len))
  50             /* We either got an error, or we succeeded and the
  51                returned name fit in the buffer.  */
  52             break;
  53
  54           /* Try again with a longer buffer.  */
  55           buf_len += buf_len;   /* Double it */
  56         }
  57       else
  58         /* No initial buffer; start out by mallocing one.  */
  59         buf_len = 128;          /* First time guess.  */
  60
  61       if (buf != *pts)
  62         /* We've already malloced another buffer at least once.  */
  63         new_buf = realloc (buf, buf_len);
  64       else
  65         new_buf = malloc (buf_len);
  66       if (! new_buf)
  67         {
  68           rv = -1;
  69           __set_errno (ENOMEM);
  70           break;
  71         }
  72       buf = new_buf;
  73     }
  74
  75   if (rv == 0)
  76     *pts = buf;         /* Return buffer to the user.  */
  77   else if (buf != *pts)
  78     free (buf);         /* Free what we malloced when returning an error.  */
  79
  80   return rv;
  81 }
  82 #endif
  83
  84 /* Create pseudo tty master slave pair and set terminal attributes
  85    according to TERMP and WINP.  Return handles for both ends in
  86    AMASTER and ASLAVE, and return the name of the slave end in NAME.  */
  87 int
  88 openpty (int *amaster, int *aslave, char *name, struct termios *termp,
  89          struct winsize *winp)
  90 {
  91 #if 0
  92 #ifdef PATH_MAX
  93   char _buf[PATH_MAX];
  94 #else
  95   char _buf[512];
  96 #endif
  97   char *buf = _buf;
  98 #else
  99 #ifdef PATH_MAX
 100   char buf[PATH_MAX];
 101 #else
 102   char buf[512];
 103 #endif
 104 #endif
 105   int master, slave;
 106
 107   master = posix_openpt (O_RDWR);
 108   if (master == -1)
 109     return -1;
 110
 111   if (grantpt (master))
 112     goto fail;
 113
 114   if (unlockpt (master))
 115     goto fail;
 116
 117 #if 0
 118   if (pts_name (master, &buf, sizeof (_buf)))
 119 #else
 120   if (ptsname_r (master, buf, sizeof buf))
 121 #endif
 122     goto fail;
 123
 124   slave = open (buf, O_RDWR | O_NOCTTY);
 125   if (slave == -1)
 126     {
 127 #if 0
 128       if (buf != _buf)
 129         free (buf);
 130 #endif
 131       goto fail;
 132     }
 133
 134   /* XXX Should we ignore errors here?  */
 135   if(termp)
 136     tcsetattr (slave, TCSAFLUSH, termp);
 137   if (winp)
 138     ioctl (slave, TIOCSWINSZ, winp);
 139
 140   *amaster = master;
 141   *aslave = slave;
 142   if (name != NULL)
 143     strcpy (name, buf);
 144
 145 #if 0
 146   if (buf != _buf)
 147     free (buf);
 148 #endif
 149   return 0;
 150
 151  fail:
 152   close (master);
 153   return -1;
 154 }
 155 libutil_hidden_def(openpty)