lib/ttyname_r.c

   1 /* Determine name of a terminal.
   2
   3    Copyright (C) 2010-2018 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Bruno Haible <bruno@clisp.org>, 2010.  */
  19
  20 #include <config.h>
  21
  22 #include <unistd.h>
  23
  24 #include <errno.h>
  25 #include <limits.h>
  26 #include <string.h>
  27
  28 int
  29 ttyname_r (int fd, char *buf, size_t buflen)
  30 #undef ttyname_r
  31 {
  32   /* When ttyname_r exists, use it.  */
  33 #if HAVE_TTYNAME_R
  34   /* This code is multithread-safe.  */
  35   /* On Solaris, ttyname_r always fails if buflen < 128.  On OSF/1 5.1,
  36      ttyname_r ignores the buffer size and assumes the buffer is large enough.
  37      So provide a buffer that is large enough.  */
  38   char largerbuf[512];
  39 # if HAVE_POSIXDECL_TTYNAME_R
  40   int err =
  41     (buflen < sizeof (largerbuf)
  42      ? ttyname_r (fd, largerbuf, sizeof (largerbuf))
  43      : ttyname_r (fd, buf, buflen <= INT_MAX ? buflen : INT_MAX));
  44   if (err != 0)
  45     return err;
  46   if (buflen < sizeof (largerbuf))
  47     {
  48       size_t namelen = strlen (largerbuf) + 1;
  49       if (namelen > buflen)
  50         return ERANGE;
  51       memcpy (buf, largerbuf, namelen);
  52     }
  53 # else
  54   char *name =
  55     (buflen < sizeof (largerbuf)
  56      ? ttyname_r (fd, largerbuf, sizeof (largerbuf))
  57      : ttyname_r (fd, buf, buflen <= INT_MAX ? buflen : INT_MAX));
  58   if (name == NULL)
  59     return errno;
  60   if (name != buf)
  61     {
  62       size_t namelen = strlen (name) + 1;
  63       if (namelen > buflen)
  64         return ERANGE;
  65       memmove (buf, name, namelen);
  66     }
  67 # endif
  68   return 0;
  69 #elif HAVE_TTYNAME
  70   /* Note: This is not multithread-safe.  */
  71   char *name;
  72   size_t namelen;
  73
  74   name = ttyname (fd);
  75   if (name == NULL)
  76     return errno;
  77   namelen = strlen (name) + 1;
  78   if (namelen > buflen)
  79     return ERANGE;
  80   memcpy (buf, name, namelen);
  81   return 0;
  82 #else
  83   /* Platforms like mingw: no ttys exist at all.  */
  84   return ENOTTY;
  85 #endif
  86 }