sysdeps/unix/sysv/linux/ttyname_r.c

   1 /* Copyright (C) 1991, 92, 93, 95, 96, 97, 98 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <dirent.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <unistd.h>
  26 #include <string.h>
  27 #include <stdlib.h>
  28
  29 #include <stdio-common/_itoa.h>
  30
  31 static int getttyname_r __P ((int fd, char *buf, size_t buflen,
  32                               dev_t mydev, ino_t myino, int save,
  33                               int *dostat)) internal_function;
  34
  35 static int
  36 internal_function
  37 getttyname_r (fd, buf, buflen, mydev, myino, save, dostat)
  38      int fd;
  39      char *buf;
  40      size_t buflen;
  41      dev_t mydev;
  42      ino_t myino;
  43      int save;
  44      int *dostat;
  45 {
  46   struct stat st;
  47   DIR *dirstream;
  48   struct dirent *d;
  49   size_t devlen = strlen (buf);
  50
  51   dirstream = __opendir (buf);
  52   if (dirstream == NULL)
  53     {
  54       *dostat = -1;
  55       return errno;
  56     }
  57
  58   while ((d = __readdir (dirstream)) != NULL)
  59     if (((ino_t) d->d_fileno == myino || *dostat)
  60         && strcmp (d->d_name, "stdin")
  61         && strcmp (d->d_name, "stdout")
  62         && strcmp (d->d_name, "stderr"))
  63       {
  64         char *cp;
  65         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  66
  67         if (needed > buflen)
  68           {
  69             *dostat = -1;
  70             (void) __closedir (dirstream);
  71             __set_errno (ERANGE);
  72             return ERANGE;
  73           }
  74
  75         cp = __stpncpy (buf + devlen, d->d_name, needed);
  76         cp[0] = '\0';
  77
  78         if (stat (buf, &st) == 0
  79 #ifdef _STATBUF_ST_RDEV
  80             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  81 #else
  82             && (ino_t) d->d_fileno == myino && st.st_dev == mydev
  83 #endif
  84            )
  85           {
  86             (void) __closedir (dirstream);
  87             __set_errno (save);
  88             return 0;
  89           }
  90       }
  91
  92   (void) __closedir (dirstream);
  93   __set_errno (save);
  94   /* It is not clear what to return in this case.  `isatty' says FD
  95      refers to a TTY but no entry in /dev has this inode.  */
  96   return ENOTTY;
  97 }
  98
  99 /* Store at most BUFLEN character of the pathname of the terminal FD is
 100    open on in BUF.  Return 0 on success,  otherwise an error number.  */
 101 int
 102 __ttyname_r (fd, buf, buflen)
 103      int fd;
 104      char *buf;
 105      size_t buflen;
 106 {
 107   char procname[30];
 108   struct stat st, st1;
 109   int dostat = 0;
 110   int save = errno;
 111   int ret;
 112
 113   /* Test for the absolute minimal size.  This makes life easier inside
 114      the loop.  */
 115   if (!buf)
 116     {
 117       __set_errno (EINVAL);
 118       return EINVAL;
 119     }
 120
 121   if (buflen < sizeof ("/dev/pts/"))
 122     {
 123       __set_errno (ERANGE);
 124       return ERANGE;
 125     }
 126
 127   if (!__isatty (fd))
 128     {
 129       __set_errno (ENOTTY);
 130       return ENOTTY;
 131     }
 132
 133   /* We try using the /proc filesystem.  */
 134   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 135
 136   ret = __readlink (procname, buf, buflen - 1);
 137   if (ret != -1 && buf[0] != '[')
 138     return 0;
 139   if (ret == -1 && errno == ENAMETOOLONG)
 140     {
 141       __set_errno (ERANGE);
 142       return ERANGE;
 143     }
 144
 145   if (fstat (fd, &st) < 0)
 146     return errno;
 147
 148   /* Prepare the result buffer.  */
 149   memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
 150   buflen -= sizeof ("/dev/pts/") - 1;
 151
 152   if (stat (buf, &st1) == 0 && S_ISDIR (st1.st_mode))
 153     {
 154 #ifdef _STATBUF_ST_RDEV
 155       ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino, save,
 156                           &dostat);
 157 #else
 158       ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino, save,
 159                           &dostat);
 160 #endif
 161     }
 162   else
 163     {
 164       __set_errno (save);
 165       ret = ENOENT;
 166     }
 167
 168   if (ret && dostat != -1)
 169     {
 170       buf[sizeof ("/dev/") - 1] = '\0';
 171       buflen += sizeof ("pts/") - 1;
 172 #ifdef _STATBUF_ST_RDEV
 173       ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino, save,
 174                           &dostat);
 175 #else
 176       ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino, save,
 177                           &dostat);
 178 #endif
 179     }
 180
 181   if (ret && dostat != -1)
 182     {
 183       buf[sizeof ("/dev/") - 1] = '\0';
 184       dostat = 1;
 185 #ifdef _STATBUF_ST_RDEV
 186       ret = getttyname_r (fd, buf, buflen, st.st_rdev, st.st_ino,
 187                           save, &dostat);
 188 #else
 189       ret = getttyname_r (fd, buf, buflen, st.st_dev, st.st_ino,
 190                           save, &dostat);
 191 #endif
 192     }
 193
 194   return ret;
 195 }
 196
 197 weak_alias (__ttyname_r, ttyname_r)