sysdeps/unix/sysv/linux/ttyname.c

   1 /* Copyright (C) 1991,92,93,1996-2001,2002 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    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 #if 0
  32 /* Is this used anywhere?  It is not exported.  */
  33 char *__ttyname;
  34 #endif
  35
  36 static char *getttyname (const char *dev, dev_t mydev,
  37                          ino64_t myino, int save, int *dostat)
  38      internal_function;
  39
  40
  41 libc_freeres_ptr (static char *getttyname_name);
  42
  43 static char *
  44 internal_function
  45 getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
  46 {
  47   static size_t namelen;
  48   struct stat64 st;
  49   DIR *dirstream;
  50   struct dirent64 *d;
  51   size_t devlen = strlen (dev) + 1;
  52
  53   dirstream = __opendir (dev);
  54   if (dirstream == NULL)
  55     {
  56       *dostat = -1;
  57       return NULL;
  58     }
  59
  60   while ((d = __readdir64 (dirstream)) != NULL)
  61     if ((d->d_fileno == myino || *dostat)
  62         && strcmp (d->d_name, "stdin")
  63         && strcmp (d->d_name, "stdout")
  64         && strcmp (d->d_name, "stderr"))
  65       {
  66         size_t dlen = _D_ALLOC_NAMLEN (d);
  67         if (devlen + dlen > namelen)
  68           {
  69             free (getttyname_name);
  70             namelen = 2 * (devlen + dlen); /* Big enough.  */
  71             getttyname_name = malloc (namelen);
  72             if (! getttyname_name)
  73               {
  74                 *dostat = -1;
  75                 /* Perhaps it helps to free the directory stream buffer.  */
  76                 (void) __closedir (dirstream);
  77                 return NULL;
  78               }
  79             *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
  80           }
  81         memcpy (&getttyname_name[devlen], d->d_name, dlen);
  82         if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0
  83 #ifdef _STATBUF_ST_RDEV
  84             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  85 #else
  86             && d->d_fileno == myino && st.st_dev == mydev
  87 #endif
  88            )
  89           {
  90             (void) __closedir (dirstream);
  91 #if 0
  92             __ttyname = getttyname_name;
  93 #endif
  94             __set_errno (save);
  95             return getttyname_name;
  96           }
  97       }
  98
  99   (void) __closedir (dirstream);
 100   __set_errno (save);
 101   return NULL;
 102 }
 103
 104
 105 /* Static buffer in `ttyname'.  */
 106 libc_freeres_ptr (static char *ttyname_buf);
 107
 108
 109 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 110    The returned storage is good only until the next call to this function.  */
 111 char *
 112 ttyname (int fd)
 113 {
 114   static size_t buflen;
 115   char procname[30];
 116   struct stat64 st, st1;
 117   int dostat = 0;
 118   char *name;
 119   int save = errno;
 120   int len;
 121
 122   if (!__isatty (fd))
 123     return NULL;
 124
 125   /* We try using the /proc filesystem.  */
 126   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 127
 128   if (buflen == 0)
 129     {
 130       buflen = 4095;
 131       ttyname_buf = (char *) malloc (buflen + 1);
 132       if (ttyname_buf == NULL)
 133         {
 134           buflen = 0;
 135           return NULL;
 136         }
 137     }
 138
 139   len = __readlink (procname, ttyname_buf, buflen);
 140   if (len != -1
 141       /* This is for Linux 2.0.  */
 142       && ttyname_buf[0] != '[')
 143     {
 144       if ((size_t) len >= buflen)
 145         return NULL;
 146       /* readlink need not terminate the string.  */
 147       ttyname_buf[len] = '\0';
 148       return ttyname_buf;
 149     }
 150
 151   if (__fxstat64 (_STAT_VER, fd, &st) < 0)
 152     return NULL;
 153
 154   if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
 155     {
 156 #ifdef _STATBUF_ST_RDEV
 157       name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat);
 158 #else
 159       name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat);
 160 #endif
 161     }
 162   else
 163     {
 164       __set_errno (save);
 165       name = NULL;
 166     }
 167
 168   if (!name && dostat != -1)
 169     {
 170 #ifdef _STATBUF_ST_RDEV
 171       name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
 172 #else
 173       name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
 174 #endif
 175     }
 176
 177   if (!name && dostat != -1)
 178     {
 179       dostat = 1;
 180 #ifdef _STATBUF_ST_RDEV
 181       name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
 182 #else
 183       name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
 184 #endif
 185     }
 186
 187   return name;
 188 }