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/* Open a pseudoterminal.
Copyright (C) 2018-2021 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 <support/tty.h>
#include <support/check.h>
#include <support/support.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <unistd.h>
/* As ptsname, but allocates space for an appropriately-sized string
using malloc. */
static char *
xptsname (int fd)
{
int rv;
size_t buf_len = 128;
char *buf = xmalloc (buf_len);
for (;;)
{
rv = ptsname_r (fd, buf, buf_len);
if (rv)
FAIL_EXIT1 ("ptsname_r: %s", strerror (errno));
if (memchr (buf, '\0', buf_len))
return buf; /* ptsname succeeded and the buffer was not truncated */
buf_len *= 2;
buf = xrealloc (buf, buf_len);
}
}
void
support_openpty (int *a_outer, int *a_inner, char **a_name,
const struct termios *termp,
const struct winsize *winp)
{
int outer = -1, inner = -1;
char *namebuf = 0;
outer = posix_openpt (O_RDWR | O_NOCTTY);
if (outer == -1)
FAIL_EXIT1 ("posix_openpt: %s", strerror (errno));
if (grantpt (outer))
FAIL_EXIT1 ("grantpt: %s", strerror (errno));
if (unlockpt (outer))
FAIL_EXIT1 ("unlockpt: %s", strerror (errno));
#ifdef TIOCGPTPEER
inner = ioctl (outer, TIOCGPTPEER, O_RDWR | O_NOCTTY);
#endif
if (inner == -1)
{
/* The kernel might not support TIOCGPTPEER, fall back to open
by name. */
namebuf = xptsname (outer);
inner = open (namebuf, O_RDWR | O_NOCTTY);
if (inner == -1)
FAIL_EXIT1 ("%s: %s", namebuf, strerror (errno));
}
if (termp)
{
if (tcsetattr (inner, TCSAFLUSH, termp))
FAIL_EXIT1 ("tcsetattr: %s", strerror (errno));
}
#ifdef TIOCSWINSZ
if (winp)
{
if (ioctl (inner, TIOCSWINSZ, winp))
FAIL_EXIT1 ("TIOCSWINSZ: %s", strerror (errno));
}
#endif
if (a_name)
{
if (!namebuf)
namebuf = xptsname (outer);
*a_name = namebuf;
}
else
free (namebuf);
*a_outer = outer;
*a_inner = inner;
}
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