sysdeps/unix/sysv/linux/ttyname_r.c

   1 /* Copyright (C) 1991,92,93,1995-2001,2003,2006 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 static int getttyname_r (char *buf, size_t buflen,
  34                          dev_t mydev, ino64_t myino, int save,
  35                          int *dostat) internal_function;
  36
  37 static int
  38 internal_function attribute_compat_text_section
  39 getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
  40               int save, int *dostat)
  41 {
  42   struct stat64 st;
  43   DIR *dirstream;
  44   struct dirent64 *d;
  45   size_t devlen = strlen (buf);
  46
  47   dirstream = __opendir (buf);
  48   if (dirstream == NULL)
  49     {
  50       *dostat = -1;
  51       return errno;
  52     }
  53
  54   while ((d = __readdir64 (dirstream)) != NULL)
  55     if ((d->d_fileno == myino || *dostat)
  56         && strcmp (d->d_name, "stdin")
  57         && strcmp (d->d_name, "stdout")
  58         && strcmp (d->d_name, "stderr"))
  59       {
  60         char *cp;
  61         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  62
  63         if (needed > buflen)
  64           {
  65             *dostat = -1;
  66             (void) __closedir (dirstream);
  67             __set_errno (ERANGE);
  68             return ERANGE;
  69           }
  70
  71         cp = __stpncpy (buf + devlen, d->d_name, needed);
  72         cp[0] = '\0';
  73
  74         if (__xstat64 (_STAT_VER, buf, &st) == 0
  75 #ifdef _STATBUF_ST_RDEV
  76             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  77 #else
  78             && d->d_fileno == myino && st.st_dev == mydev
  79 #endif
  80            )
  81           {
  82             (void) __closedir (dirstream);
  83             __set_errno (save);
  84             return 0;
  85           }
  86       }
  87
  88   (void) __closedir (dirstream);
  89   __set_errno (save);
  90   /* It is not clear what to return in this case.  `isatty' says FD
  91      refers to a TTY but no entry in /dev has this inode.  */
  92   return ENOTTY;
  93 }
  94
  95 /* Store at most BUFLEN character of the pathname of the terminal FD is
  96    open on in BUF.  Return 0 on success,  otherwise an error number.  */
  97 int
  98 __ttyname_r (int fd, char *buf, size_t buflen)
  99 {
 100   char procname[30];
 101   struct stat64 st, st1;
 102   int dostat = 0;
 103   int save = errno;
 104
 105   /* Test for the absolute minimal size.  This makes life easier inside
 106      the loop.  */
 107   if (!buf)
 108     {
 109       __set_errno (EINVAL);
 110       return EINVAL;
 111     }
 112
 113   if (buflen < sizeof ("/dev/pts/"))
 114     {
 115       __set_errno (ERANGE);
 116       return ERANGE;
 117     }
 118
 119   /* isatty check, tcgetattr is used because it sets the correct
 120      errno (EBADF resp. ENOTTY) on error.  */
 121   struct termios term;
 122   if (__builtin_expect (__tcgetattr (fd, &term) < 0, 0))
 123     return errno;
 124
 125   /* We try using the /proc filesystem.  */
 126   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 127
 128   ssize_t ret = __readlink (procname, buf, buflen - 1);
 129   if (__builtin_expect (ret == -1 && errno == ENOENT, 0))
 130     {
 131       __set_errno (EBADF);
 132       return EBADF;
 133     }
 134
 135   if (__builtin_expect (ret == -1 && errno == ENAMETOOLONG, 0))
 136     {
 137       __set_errno (ERANGE);
 138       return ERANGE;
 139     }
 140
 141   if (__builtin_expect (ret != -1
 142 #ifndef __ASSUME_PROC_SELF_FD_SYMLINK
 143                         /* This is for Linux 2.0.  */
 144                         && buf[0] != '['
 145 #endif
 146                         , 1))
 147     {
 148       buf[ret] = '\0';
 149       return 0;
 150     }
 151
 152   if (__fxstat64 (_STAT_VER, fd, &st) < 0)
 153     return errno;
 154
 155   /* Prepare the result buffer.  */
 156   memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
 157   buflen -= sizeof ("/dev/pts/") - 1;
 158
 159   if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
 160     {
 161 #ifdef _STATBUF_ST_RDEV
 162       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 163                           &dostat);
 164 #else
 165       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 166                           &dostat);
 167 #endif
 168     }
 169   else
 170     {
 171       __set_errno (save);
 172       ret = ENOENT;
 173     }
 174
 175   if (ret && dostat != -1)
 176     {
 177       buf[sizeof ("/dev/") - 1] = '\0';
 178       buflen += sizeof ("pts/") - 1;
 179 #ifdef _STATBUF_ST_RDEV
 180       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 181                           &dostat);
 182 #else
 183       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 184                           &dostat);
 185 #endif
 186     }
 187
 188   if (ret && dostat != -1)
 189     {
 190       buf[sizeof ("/dev/") - 1] = '\0';
 191       dostat = 1;
 192 #ifdef _STATBUF_ST_RDEV
 193       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
 194                           save, &dostat);
 195 #else
 196       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
 197                           save, &dostat);
 198 #endif
 199     }
 200
 201   return ret;
 202 }
 203
 204 weak_alias (__ttyname_r, ttyname_r)