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/* Copyright (C) 1991-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fd_to_filename.h>
#include "ttyname.h"
static int getttyname_r (char *buf, size_t buflen,
const struct stat64 *mytty, int save,
int *dostat);
static int
attribute_compat_text_section
getttyname_r (char *buf, size_t buflen, const struct stat64 *mytty,
int save, int *dostat)
{
struct stat64 st;
DIR *dirstream;
struct dirent64 *d;
size_t devlen = strlen (buf);
dirstream = __opendir (buf);
if (dirstream == NULL)
{
*dostat = -1;
return errno;
}
while ((d = __readdir64 (dirstream)) != NULL)
if ((d->d_fileno == mytty->st_ino || *dostat)
&& strcmp (d->d_name, "stdin")
&& strcmp (d->d_name, "stdout")
&& strcmp (d->d_name, "stderr"))
{
char *cp;
size_t needed = _D_EXACT_NAMLEN (d) + 1;
if (needed > buflen)
{
*dostat = -1;
(void) __closedir (dirstream);
__set_errno (ERANGE);
return ERANGE;
}
cp = __stpncpy (buf + devlen, d->d_name, needed);
cp[0] = '\0';
if (__stat64 (buf, &st) == 0
&& is_mytty (mytty, &st))
{
(void) __closedir (dirstream);
__set_errno (save);
return 0;
}
}
(void) __closedir (dirstream);
__set_errno (save);
/* It is not clear what to return in this case. `isatty' says FD
refers to a TTY but no entry in /dev has this inode. */
return ENOTTY;
}
/* Store at most BUFLEN character of the pathname of the terminal FD is
open on in BUF. Return 0 on success, otherwise an error number. */
int
__ttyname_r (int fd, char *buf, size_t buflen)
{
struct fd_to_filename filename;
struct stat64 st, st1;
int dostat = 0;
int doispty = 0;
int save = errno;
/* Test for the absolute minimal size. This makes life easier inside
the loop. */
if (!buf)
{
__set_errno (EINVAL);
return EINVAL;
}
if (buflen < sizeof ("/dev/pts/"))
{
__set_errno (ERANGE);
return ERANGE;
}
/* isatty check, tcgetattr is used because it sets the correct
errno (EBADF resp. ENOTTY) on error. */
struct termios term;
if (__glibc_unlikely (__tcgetattr (fd, &term) < 0))
return errno;
if (__fstat64 (fd, &st) < 0)
return errno;
/* We try using the /proc filesystem. */
ssize_t ret = __readlink (__fd_to_filename (fd, &filename), buf, buflen - 1);
if (__glibc_unlikely (ret == -1 && errno == ENAMETOOLONG))
{
__set_errno (ERANGE);
return ERANGE;
}
if (__glibc_likely (ret != -1))
{
#define UNREACHABLE_LEN strlen ("(unreachable)")
if (ret > UNREACHABLE_LEN
&& memcmp (buf, "(unreachable)", UNREACHABLE_LEN) == 0)
{
memmove (buf, buf + UNREACHABLE_LEN, ret - UNREACHABLE_LEN);
ret -= UNREACHABLE_LEN;
}
/* readlink need not terminate the string. */
buf[ret] = '\0';
/* Verify readlink result, fall back on iterating through devices. */
if (buf[0] == '/'
&& __stat64 (buf, &st1) == 0
&& is_mytty (&st, &st1))
return 0;
doispty = 1;
}
/* Prepare the result buffer. */
memcpy (buf, "/dev/pts/", sizeof ("/dev/pts/"));
buflen -= sizeof ("/dev/pts/") - 1;
if (__stat64 (buf, &st1) == 0 && S_ISDIR (st1.st_mode))
{
ret = getttyname_r (buf, buflen, &st, save,
&dostat);
}
else
{
__set_errno (save);
ret = ENOENT;
}
if (ret && dostat != -1)
{
buf[sizeof ("/dev/") - 1] = '\0';
buflen += sizeof ("pts/") - 1;
ret = getttyname_r (buf, buflen, &st, save,
&dostat);
}
if (ret && dostat != -1)
{
buf[sizeof ("/dev/") - 1] = '\0';
dostat = 1;
ret = getttyname_r (buf, buflen, &st,
save, &dostat);
}
if (ret && doispty && is_pty (&st))
{
/* We failed to figure out the TTY's name, but we can at least
signal that we did verify that it really is a PTY slave.
This happens when we have inherited the file descriptor from
a different mount namespace. */
__set_errno (ENODEV);
return ENODEV;
}
return ret;
}
libc_hidden_def (__ttyname_r)
weak_alias (__ttyname_r, ttyname_r)
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