lib/ptsname_r.c

   1 /* Determine name of the slave side of a pseudo-terminal.
   2    Copyright (C) 1998, 2002, 2010-2020 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 #include <stdlib.h>
  20
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <string.h>
  24 #include <sys/stat.h>
  25 #include <unistd.h>
  26
  27 #ifdef _LIBC
  28 # include <paths.h>
  29 #else
  30 # ifndef _PATH_TTY
  31 #  define _PATH_TTY "/dev/tty"
  32 # endif
  33 # ifndef _PATH_DEV
  34 #  define _PATH_DEV "/dev/"
  35 # endif
  36
  37 # undef __set_errno
  38 # undef __stat
  39 # undef __ttyname_r
  40 # undef __ptsname_r
  41
  42 # define __set_errno(e) errno = (e)
  43 # define __isatty isatty
  44 # define __stat stat
  45 # define __ttyname_r ttyname_r
  46 # define __ptsname_r ptsname_r
  47
  48 #endif
  49
  50 /* Get the major, minor macros.  */
  51 #if MAJOR_IN_MKDEV
  52 # include <sys/mkdev.h>
  53 #endif
  54 #if MAJOR_IN_SYSMACROS
  55 # include <sys/sysmacros.h>
  56 #endif
  57
  58 #ifdef __sun
  59 /* Get ioctl() and 'struct strioctl'.  */
  60 # include <stropts.h>
  61 /* Get ISPTM.  */
  62 # include <sys/stream.h>
  63 # include <sys/ptms.h>
  64 # include <stdio.h>
  65 #endif
  66
  67 #if defined _AIX || defined __osf__
  68 /* Get ioctl(), ISPTM.  */
  69 # include <sys/ioctl.h>
  70 # include <stdio.h>
  71 #endif
  72
  73
  74 /* Store at most BUFLEN characters of the pathname of the slave pseudo
  75    terminal associated with the master FD is open on in BUF.
  76    Return 0 on success, otherwise an error number.  */
  77 int
  78 __ptsname_r (int fd, char *buf, size_t buflen)
  79 #undef ptsname_r
  80 {
  81 #if HAVE_ESSENTIALLY_WORKING_PTSNAME_R
  82   int ret = ptsname_r (fd, buf, buflen);
  83   if (ret == 0)
  84     return 0;
  85   else
  86     return errno;
  87 #else
  88   int save_errno = errno;
  89   struct stat st;
  90
  91   if (buf == NULL)
  92     {
  93       __set_errno (EINVAL);
  94       return EINVAL;
  95     }
  96
  97 # if defined __sun /* Solaris */
  98   if (fstat (fd, &st) < 0)
  99     return errno;
 100   if (!(S_ISCHR (st.st_mode) && major (st.st_rdev) == 0))
 101     {
 102       errno = ENOTTY;
 103       return errno;
 104     }
 105   {
 106     /* Master ptys can be recognized through a STREAMS ioctl.  See
 107        "STREAMS-based Pseudo-Terminal Subsystem"
 108        <https://docs.oracle.com/cd/E18752_01/html/816-4855/termsub15-44781.html>
 109        and "STREAMS ioctl commands"
 110        <https://docs.oracle.com/cd/E18752_01/html/816-5177/streamio-7i.html>
 111      */
 112     struct strioctl ioctl_arg;
 113     ioctl_arg.ic_cmd = ISPTM;
 114     ioctl_arg.ic_timout = 0;
 115     ioctl_arg.ic_len = 0;
 116     ioctl_arg.ic_dp = NULL;
 117
 118     if (ioctl (fd, I_STR, &ioctl_arg) < 0)
 119       {
 120         errno = ENOTTY;
 121         return errno;
 122       }
 123   }
 124   {
 125     char tmpbuf[9 + 10 + 1];
 126     int n = sprintf (tmpbuf, "/dev/pts/%u", minor (st.st_rdev));
 127     if (n >= buflen)
 128       {
 129         errno = ERANGE;
 130         return errno;
 131       }
 132     memcpy (buf, tmpbuf, n + 1);
 133   }
 134 # elif defined _AIX || defined __osf__ /* AIX, OSF/1 */
 135   /* This implementation returns /dev/pts/N, like ptsname() does.
 136      Whereas the generic implementation below returns /dev/ttypN.
 137      Both are correct, but let's be consistent with ptsname().  */
 138   if (fstat (fd, &st) < 0)
 139     return errno;
 140   if (!S_ISCHR (st.st_mode))
 141     {
 142       errno = ENOTTY;
 143       return errno;
 144     }
 145   {
 146     int ret;
 147     int dev;
 148     char tmpbuf[9 + 10 + 1];
 149     int n;
 150 #  ifdef _AIX
 151     ret = ioctl (fd, ISPTM, &dev);
 152 #  endif
 153 #  ifdef __osf__
 154     ret = ioctl (fd, ISPTM, NULL);
 155     dev = ret;
 156 #  endif
 157     if (ret < 0)
 158       {
 159         errno = ENOTTY;
 160         return errno;
 161       }
 162     n = sprintf (tmpbuf, "/dev/pts/%u", minor (dev));
 163     if (n >= buflen)
 164       {
 165         errno = ERANGE;
 166         return errno;
 167       }
 168     memcpy (buf, tmpbuf, n + 1);
 169   }
 170 # else
 171   if (!__isatty (fd))
 172     {
 173 #  if ISATTY_FAILS_WITHOUT_SETTING_ERRNO && defined F_GETFL /* IRIX, Solaris */
 174       /* Set errno.  */
 175       if (fcntl (fd, F_GETFL) != -1)
 176         errno = ENOTTY;
 177 #  else
 178       /* We rely on isatty to set errno properly (i.e. EBADF or ENOTTY).  */
 179 #  endif
 180       return errno;
 181     }
 182
 183   if (buflen < strlen (_PATH_TTY) + 3)
 184     {
 185       __set_errno (ERANGE);
 186       return ERANGE;
 187     }
 188
 189   int err = __ttyname_r (fd, buf, buflen);
 190   if (err != 0)
 191     {
 192       __set_errno (err);
 193       return errno;
 194     }
 195
 196   if (strncmp(buf, "/dev/pts/", strlen("/dev/pts/")) != 0)
 197     buf[sizeof (_PATH_DEV) - 1] = 't';
 198 # endif
 199
 200   if (__stat (buf, &st) < 0 && errno != EOVERFLOW)
 201     return errno;
 202
 203   __set_errno (save_errno);
 204   return 0;
 205 #endif
 206 }