91 lines
2.4 KiB
C
91 lines
2.4 KiB
C
/* Copyright (C) 1991, 1992, 1993, 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include <limits.h>
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#include <stddef.h>
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#include <dirent.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdlib.h>
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char *__ttyname = NULL;
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/* Return the pathname of the terminal FD is open on, or NULL on errors.
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The returned storage is good only until the next call to this function. */
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char *
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ttyname (fd)
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int fd;
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{
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static const char dev[] = "/dev";
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static char *name;
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static size_t namelen = 0;
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struct stat st;
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dev_t mydev;
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ino_t myino;
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DIR *dirstream;
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struct dirent *d;
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int save = errno;
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if (!__isatty (fd))
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return NULL;
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if (fstat (fd, &st) < 0)
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return NULL;
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mydev = st.st_dev;
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myino = st.st_ino;
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dirstream = opendir (dev);
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if (dirstream == NULL)
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return NULL;
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while ((d = readdir (dirstream)) != NULL)
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if ((ino_t) d->d_fileno == myino)
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{
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size_t dlen = _D_ALLOC_NAMLEN (d);
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if (sizeof (dev) + dlen > namelen)
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{
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free (name);
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namelen = 2 * (sizeof (dev) + dlen); /* Big enough. */
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name = malloc (namelen);
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if (! name)
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{
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/* Perhaps it helps to free the directory stream buffer. */
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(void) closedir (dirstream);
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return NULL;
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}
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(void) memcpy (name, dev, sizeof (dev) - 1);
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name[sizeof (dev) - 1] = '/';
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}
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(void) memcpy (&name[sizeof (dev)], d->d_name, dlen);
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if (stat (name, &st) == 0 && st.st_dev == mydev)
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{
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(void) closedir (dirstream);
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__ttyname = name;
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__set_errno (save);
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return name;
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}
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}
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(void) closedir (dirstream);
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__set_errno (save);
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return NULL;
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}
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