sysdeps/unix/sysv/linux/ttyname.c

   1 /* Copyright (C) 1991,92,93,1996-2002,2006 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 <termios.h>
  26 #include <unistd.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29
  30 #include <stdio-common/_itoa.h>
  31 #include <kernel-features.h>
  32
  33 #if 0
  34 /* Is this used anywhere?  It is not exported.  */
  35 char *__ttyname;
  36 #endif
  37
  38 static char *getttyname (const char *dev, dev_t mydev,
  39                          ino64_t myino, int save, int *dostat)
  40      internal_function;
  41
  42
  43 libc_freeres_ptr (static char *getttyname_name);
  44
  45 static char *
  46 internal_function attribute_compat_text_section
  47 getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
  48 {
  49   static size_t namelen;
  50   struct stat64 st;
  51   DIR *dirstream;
  52   struct dirent64 *d;
  53   size_t devlen = strlen (dev) + 1;
  54
  55   dirstream = __opendir (dev);
  56   if (dirstream == NULL)
  57     {
  58       *dostat = -1;
  59       return NULL;
  60     }
  61
  62   while ((d = __readdir64 (dirstream)) != NULL)
  63     if ((d->d_fileno == myino || *dostat)
  64         && strcmp (d->d_name, "stdin")
  65         && strcmp (d->d_name, "stdout")
  66         && strcmp (d->d_name, "stderr"))
  67       {
  68         size_t dlen = _D_ALLOC_NAMLEN (d);
  69         if (devlen + dlen > namelen)
  70           {
  71             free (getttyname_name);
  72             namelen = 2 * (devlen + dlen); /* Big enough.  */
  73             getttyname_name = malloc (namelen);
  74             if (! getttyname_name)
  75               {
  76                 *dostat = -1;
  77                 /* Perhaps it helps to free the directory stream buffer.  */
  78                 (void) __closedir (dirstream);
  79                 return NULL;
  80               }
  81             *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
  82           }
  83         memcpy (&getttyname_name[devlen], d->d_name, dlen);
  84         if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0
  85 #ifdef _STATBUF_ST_RDEV
  86             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  87 #else
  88             && d->d_fileno == myino && st.st_dev == mydev
  89 #endif
  90            )
  91           {
  92             (void) __closedir (dirstream);
  93 #if 0
  94             __ttyname = getttyname_name;
  95 #endif
  96             __set_errno (save);
  97             return getttyname_name;
  98           }
  99       }
 100
 101   (void) __closedir (dirstream);
 102   __set_errno (save);
 103   return NULL;
 104 }
 105
 106
 107 /* Static buffer in `ttyname'.  */
 108 libc_freeres_ptr (static char *ttyname_buf);
 109
 110
 111 /* Return the pathname of the terminal FD is open on, or NULL on errors.
 112    The returned storage is good only until the next call to this function.  */
 113 char *
 114 ttyname (int fd)
 115 {
 116   static size_t buflen;
 117   char procname[30];
 118   struct stat64 st, st1;
 119   int dostat = 0;
 120   char *name;
 121   int save = errno;
 122   struct termios term;
 123
 124   /* isatty check, tcgetattr is used because it sets the correct
 125      errno (EBADF resp. ENOTTY) on error.  */
 126   if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
 127     return NULL;
 128
 129   /* We try using the /proc filesystem.  */
 130   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 131
 132   if (buflen == 0)
 133     {
 134       buflen = 4095;
 135       ttyname_buf = (char *) malloc (buflen + 1);
 136       if (ttyname_buf == NULL)
 137         {
 138           buflen = 0;
 139           return NULL;
 140         }
 141     }
 142
 143   ssize_t len = __readlink (procname, ttyname_buf, buflen);
 144   if (__builtin_expect (len == -1 && errno == ENOENT, 0))
 145     {
 146       __set_errno (EBADF);
 147       return NULL;
 148     }
 149
 150   if (__builtin_expect (len != -1
 151 #ifndef __ASSUME_PROC_SELF_FD_SYMLINK
 152                         /* This is for Linux 2.0.  */
 153                         && ttyname_buf[0] != '['
 154 #endif
 155                         , 1))
 156     {
 157       if ((size_t) len >= buflen)
 158         return NULL;
 159       /* readlink need not terminate the string.  */
 160       ttyname_buf[len] = '\0';
 161       return ttyname_buf;
 162     }
 163
 164   if (__fxstat64 (_STAT_VER, fd, &st) < 0)
 165     return NULL;
 166
 167   if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
 168     {
 169 #ifdef _STATBUF_ST_RDEV
 170       name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat);
 171 #else
 172       name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat);
 173 #endif
 174     }
 175   else
 176     {
 177       __set_errno (save);
 178       name = NULL;
 179     }
 180
 181   if (!name && dostat != -1)
 182     {
 183 #ifdef _STATBUF_ST_RDEV
 184       name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
 185 #else
 186       name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
 187 #endif
 188     }
 189
 190   if (!name && dostat != -1)
 191     {
 192       dostat = 1;
 193 #ifdef _STATBUF_ST_RDEV
 194       name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
 195 #else
 196       name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
 197 #endif
 198     }
 199
 200   return name;
 201 }