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 <unistd.h>
  26 #include <string.h>
  27 #include <stdlib.h>
  28
  29 #include <stdio-common/_itoa.h>
  30 #include <kernel-features.h>
  31
  32 static int getttyname_r (char *buf, size_t buflen,
  33                          dev_t mydev, ino64_t myino, int save,
  34                          int *dostat) internal_function;
  35
  36 static int
  37 internal_function attribute_compat_text_section
  38 getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
  39               int save, int *dostat)
  40 {
  41   struct stat64 st;
  42   DIR *dirstream;
  43   struct dirent64 *d;
  44   size_t devlen = strlen (buf);
  45
  46   dirstream = __opendir (buf);
  47   if (dirstream == NULL)
  48     {
  49       *dostat = -1;
  50       return errno;
  51     }
  52
  53   while ((d = __readdir64 (dirstream)) != NULL)
  54     if ((d->d_fileno == myino || *dostat)
  55         && strcmp (d->d_name, "stdin")
  56         && strcmp (d->d_name, "stdout")
  57         && strcmp (d->d_name, "stderr"))
  58       {
  59         char *cp;
  60         size_t needed = _D_EXACT_NAMLEN (d) + 1;
  61
  62         if (needed > buflen)
  63           {
  64             *dostat = -1;
  65             (void) __closedir (dirstream);
  66             __set_errno (ERANGE);
  67             return ERANGE;
  68           }
  69
  70         cp = __stpncpy (buf + devlen, d->d_name, needed);
  71         cp[0] = '\0';
  72
  73         if (__xstat64 (_STAT_VER, buf, &st) == 0
  74 #ifdef _STATBUF_ST_RDEV
  75             && S_ISCHR (st.st_mode) && st.st_rdev == mydev
  76 #else
  77             && d->d_fileno == myino && st.st_dev == mydev
  78 #endif
  79            )
  80           {
  81             (void) __closedir (dirstream);
  82             __set_errno (save);
  83             return 0;
  84           }
  85       }
  86
  87   (void) __closedir (dirstream);
  88   __set_errno (save);
  89   /* It is not clear what to return in this case.  `isatty' says FD
  90      refers to a TTY but no entry in /dev has this inode.  */
  91   return ENOTTY;
  92 }
  93
  94 /* Store at most BUFLEN character of the pathname of the terminal FD is
  95    open on in BUF.  Return 0 on success,  otherwise an error number.  */
  96 int
  97 __ttyname_r (int fd, char *buf, size_t buflen)
  98 {
  99   char procname[30];
 100   struct stat64 st, st1;
 101   int dostat = 0;
 102   int save = errno;
 103
 104   /* Test for the absolute minimal size.  This makes life easier inside
 105      the loop.  */
 106   if (!buf)
 107     {
 108       __set_errno (EINVAL);
 109       return EINVAL;
 110     }
 111
 112   if (buflen < sizeof ("/dev/pts/"))
 113     {
 114       __set_errno (ERANGE);
 115       return ERANGE;
 116     }
 117
 118   if (__builtin_expect (!__isatty (fd), 0))
 119     {
 120       __set_errno (ENOTTY);
 121       return ENOTTY;
 122     }
 123
 124   /* We try using the /proc filesystem.  */
 125   *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
 126
 127   ssize_t ret = __readlink (procname, buf, buflen - 1);
 128   if (__builtin_expect (ret == -1 && errno == ENOENT, 0))
 129     {
 130       __set_errno (EBADF);
 131       return EBADF;
 132     }
 133
 134   if (__builtin_expect (ret == -1 && errno == ENAMETOOLONG, 0))
 135     {
 136       __set_errno (ERANGE);
 137       return ERANGE;
 138     }
 139
 140   if (__builtin_expect (ret != -1
 141 #ifndef __ASSUME_PROC_SELF_FD_SYMLINK
 142                         /* This is for Linux 2.0.  */
 143                         && buf[0] != '['
 144 #endif
 145                         , 1))
 146     {
 147       buf[ret] = '\0';
 148       return 0;
 149     }
 150
 151   if (__fxstat64 (_STAT_VER, fd, &st) < 0)
 152     return errno;
 153
 154   /* Prepare the result buffer.  */
 155   memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
 156   buflen -= sizeof ("/dev/pts/") - 1;
 157
 158   if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
 159     {
 160 #ifdef _STATBUF_ST_RDEV
 161       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 162                           &dostat);
 163 #else
 164       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 165                           &dostat);
 166 #endif
 167     }
 168   else
 169     {
 170       __set_errno (save);
 171       ret = ENOENT;
 172     }
 173
 174   if (ret && dostat != -1)
 175     {
 176       buf[sizeof ("/dev/") - 1] = '\0';
 177       buflen += sizeof ("pts/") - 1;
 178 #ifdef _STATBUF_ST_RDEV
 179       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
 180                           &dostat);
 181 #else
 182       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
 183                           &dostat);
 184 #endif
 185     }
 186
 187   if (ret && dostat != -1)
 188     {
 189       buf[sizeof ("/dev/") - 1] = '\0';
 190       dostat = 1;
 191 #ifdef _STATBUF_ST_RDEV
 192       ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
 193                           save, &dostat);
 194 #else
 195       ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
 196                           save, &dostat);
 197 #endif
 198     }
 199
 200   return ret;
 201 }
 202
 203 weak_alias (__ttyname_r, ttyname_r)