lib/ptsname_r.c

   1 /* Determine name of the slave side of a pseudo-terminal.
   2    Copyright (C) 1998, 2002, 2010-2025 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    This file 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 Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <stdlib.h>
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <string.h>
  25 #include <sys/stat.h>
  26 #include <unistd.h>
  27
  28 #ifndef _PATH_TTY
  29 # define _PATH_TTY "/dev/tty"
  30 #endif
  31 #ifndef _PATH_DEV
  32 # define _PATH_DEV "/dev/"
  33 #endif
  34
  35 /* Get the major, minor macros.  */
  36 #if MAJOR_IN_MKDEV
  37 # include <sys/mkdev.h>
  38 #endif
  39 #if MAJOR_IN_SYSMACROS
  40 # include <sys/sysmacros.h>
  41 #endif
  42
  43 #ifdef __sun
  44 /* Get ioctl() and 'struct strioctl'.  */
  45 # include <stropts.h>
  46 /* Get ISPTM.  */
  47 # include <sys/stream.h>
  48 # include <sys/ptms.h>
  49 # include <stdio.h>
  50 #endif
  51
  52 #if defined _AIX || defined __osf__
  53 /* Get ioctl(), ISPTM.  */
  54 # include <sys/ioctl.h>
  55 # include <stdio.h>
  56 #endif
  57
  58 #if defined __DragonFly__
  59 /* Get fdevname_r().  */
  60 # include <stdlib.h>
  61 #endif
  62
  63 /* Store at most BUFLEN characters of the pathname of the slave pseudo
  64    terminal associated with the master FD is open on in BUF.
  65    Return 0 on success, otherwise an error number.  */
  66 int
  67 ptsname_r (int fd, char *buf, size_t buflen)
  68 #undef ptsname_r
  69 {
  70 #if HAVE_ESSENTIALLY_WORKING_PTSNAME_R
  71 # if defined __NetBSD__ || defined __sun
  72   char tmpbuf[32];
  73   if (buf == NULL)
  74     return EINVAL;
  75   if (buflen >= sizeof (tmpbuf))
  76     /* ERANGE should not happen in this case.  */
  77     return ptsname_r (fd, buf, buflen);
  78   else
  79     {
  80       int ret = ptsname_r (fd, tmpbuf, sizeof (tmpbuf));
  81       if (ret != 0)
  82         return ret;
  83       else
  84         {
  85           size_t len = strlen (tmpbuf);
  86           if (len >= buflen)
  87             return ERANGE;
  88           memcpy (buf, tmpbuf, len + 1);
  89           return 0;
  90         }
  91     }
  92 # else
  93   int ret = ptsname_r (fd, buf, buflen);
  94   if (ret == 0)
  95     return 0;
  96   else
  97     return errno;
  98 # endif
  99 #elif defined __DragonFly__
 100   int saved_errno = errno;
 101   char tmpbuf[5 + 4 + 10 + 1];
 102   int ret;
 103   int n;
 104   if (buf == NULL)
 105     {
 106       errno = EINVAL;
 107       return errno;
 108     }
 109   /* The result of fdevname_r is typically of the form ptm/N.  */
 110   ret = fdevname_r (fd, tmpbuf + 5, sizeof (tmpbuf) - 5);
 111   if (ret < 0 || strncmp (tmpbuf + 5, "ptm/", 4) != 0)
 112     {
 113       errno = ENOTTY;
 114       return errno;
 115     }
 116   /* Turn it into /dev/pts/N.  */
 117   memcpy (tmpbuf, "/dev/pts/", 5 + 4);
 118   n = strlen (tmpbuf);
 119   if (n >= buflen)
 120     {
 121       errno = ERANGE;
 122       return errno;
 123     }
 124   memcpy (buf, tmpbuf, n + 1);
 125   /* Don't do a final stat(), since the file name /dev/pts/N does not actually
 126      exist.  */
 127   errno = saved_errno;
 128   return 0;
 129 #else
 130   int saved_errno = errno;
 131   struct stat st;
 132
 133   if (buf == NULL)
 134     {
 135       errno = EINVAL;
 136       return errno;
 137     }
 138
 139 # if defined __sun /* Solaris */
 140   if (fstat (fd, &st) < 0)
 141     return errno;
 142   if (!S_ISCHR (st.st_mode))
 143     {
 144       errno = ENOTTY;
 145       return errno;
 146     }
 147   {
 148     /* Master ptys can be recognized through a STREAMS ioctl.  See
 149        "STREAMS-based Pseudo-Terminal Subsystem"
 150        <https://docs.oracle.com/cd/E18752_01/html/816-4855/termsub15-44781.html>
 151        and "STREAMS ioctl commands"
 152        <https://docs.oracle.com/cd/E18752_01/html/816-5177/streamio-7i.html>
 153      */
 154     struct strioctl ioctl_arg;
 155     ioctl_arg.ic_cmd = ISPTM;
 156     ioctl_arg.ic_timout = 0;
 157     ioctl_arg.ic_len = 0;
 158     ioctl_arg.ic_dp = NULL;
 159
 160     if (ioctl (fd, I_STR, &ioctl_arg) < 0)
 161       {
 162         errno = ENOTTY;
 163         return errno;
 164       }
 165   }
 166   {
 167     char tmpbuf[9 + 10 + 1];
 168     int n = sprintf (tmpbuf, "/dev/pts/%u", minor (st.st_rdev));
 169     if (n >= buflen)
 170       {
 171         errno = ERANGE;
 172         return errno;
 173       }
 174     memcpy (buf, tmpbuf, n + 1);
 175   }
 176 # elif defined _AIX || defined __osf__ /* AIX, OSF/1 */
 177   /* This implementation returns /dev/pts/N, like ptsname() does.
 178      Whereas the generic implementation below returns /dev/ttypN.
 179      Both are correct, but let's be consistent with ptsname().  */
 180   if (fstat (fd, &st) < 0)
 181     return errno;
 182   if (!S_ISCHR (st.st_mode))
 183     {
 184       errno = ENOTTY;
 185       return errno;
 186     }
 187   {
 188     int ret;
 189     int dev;
 190     char tmpbuf[9 + 10 + 1];
 191     int n;
 192 #  ifdef _AIX
 193     ret = ioctl (fd, ISPTM, &dev);
 194 #  endif
 195 #  ifdef __osf__
 196     ret = ioctl (fd, ISPTM, NULL);
 197     dev = ret;
 198 #  endif
 199     if (ret < 0)
 200       {
 201         errno = ENOTTY;
 202         return errno;
 203       }
 204     n = sprintf (tmpbuf, "/dev/pts/%u", minor (dev));
 205     if (n >= buflen)
 206       {
 207         errno = ERANGE;
 208         return errno;
 209       }
 210     memcpy (buf, tmpbuf, n + 1);
 211   }
 212 # else
 213   if (!isatty (fd))
 214     {
 215 #  if ISATTY_FAILS_WITHOUT_SETTING_ERRNO && defined F_GETFL /* IRIX, Solaris */
 216       /* Set errno.  */
 217       if (fcntl (fd, F_GETFL) != -1)
 218         errno = ENOTTY;
 219 #  else
 220       /* We rely on isatty to set errno properly (i.e. EBADF or ENOTTY).  */
 221 #  endif
 222       return errno;
 223     }
 224
 225   if (buflen < strlen (_PATH_TTY) + 3)
 226     {
 227       errno = ERANGE;
 228       return errno;
 229     }
 230
 231   int err = ttyname_r (fd, buf, buflen);
 232   if (err != 0)
 233     {
 234       errno = err;
 235       return errno;
 236     }
 237
 238   if (strncmp(buf, "/dev/pts/", strlen("/dev/pts/")) != 0)
 239     buf[sizeof (_PATH_DEV) - 1] = 't';
 240 # endif
 241
 242   if (stat (buf, &st) < 0 && errno != EOVERFLOW)
 243     return errno;
 244
 245   errno = saved_errno;
 246   return 0;
 247 #endif
 248 }