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/* Copyright (C) 1998-2025 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 <fcntl.h>
#include <limits.h>
#include <pty.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <shlib-compat.h>
/* Return the result of ptsname_r in the buffer pointed to by PTS,
which should be of length BUF_LEN. If it is too long to fit in
this buffer, a sufficiently long buffer is allocated using malloc,
and returned in PTS. 0 is returned upon success, -1 otherwise. */
static int
pts_name (int fd, char **pts, size_t buf_len)
{
int rv;
char *buf = *pts;
for (;;)
{
char *new_buf;
if (buf_len)
{
rv = __ptsname_r (fd, buf, buf_len);
if (rv != 0 || memchr (buf, '\0', buf_len))
/* We either got an error, or we succeeded and the
returned name fit in the buffer. */
break;
/* Try again with a longer buffer. */
buf_len += buf_len; /* Double it */
}
else
/* No initial buffer; start out by mallocing one. */
buf_len = 128; /* First time guess. */
if (buf != *pts)
/* We've already malloced another buffer at least once. */
new_buf = realloc (buf, buf_len);
else
new_buf = malloc (buf_len);
if (! new_buf)
{
rv = -1;
__set_errno (ENOMEM);
break;
}
buf = new_buf;
}
if (rv == 0)
*pts = buf; /* Return buffer to the user. */
else if (buf != *pts)
free (buf); /* Free what we malloced when returning an error. */
return rv;
}
/* Create pseudo tty multiplexer/terminal pair and set terminal attributes
according to TERMP and WINP. Return handles for both ends in
*PPTMX and *PTERMINAL, and return the name of the terminal end in NAME. */
int
__openpty (int *pptmx, int *pterminal, char *name,
const struct termios *termp, const struct winsize *winp)
{
#ifdef PATH_MAX
char _buf[PATH_MAX];
#else
char _buf[512];
#endif
char *buf = _buf;
int ptmx, ret = -1, terminal = -1;
*buf = '\0';
ptmx = __getpt ();
if (ptmx == -1)
return -1;
if (grantpt (ptmx))
goto on_error;
if (unlockpt (ptmx))
goto on_error;
#ifdef TIOCGPTPEER
/* Try to allocate terminal fd solely based on PTMX fd first. */
terminal = __ioctl (ptmx, TIOCGPTPEER, O_RDWR | O_NOCTTY);
#endif
if (terminal == -1)
{
/* Fallback to path-based terminal fd allocation in case kernel doesn't
* support TIOCGPTPEER.
*/
if (pts_name (ptmx, &buf, sizeof (_buf)))
goto on_error;
terminal = __open64 (buf, O_RDWR | O_NOCTTY);
if (terminal == -1)
goto on_error;
}
/* XXX Should we ignore errors here? */
if (termp)
__tcsetattr (terminal, TCSAFLUSH, termp);
#ifdef TIOCSWINSZ
if (winp)
__ioctl (terminal, TIOCSWINSZ, winp);
#endif
*pptmx = ptmx;
*pterminal = terminal;
if (name != NULL)
{
if (*buf == '\0')
if (pts_name (ptmx, &buf, sizeof (_buf)))
goto on_error;
strcpy (name, buf);
}
ret = 0;
on_error:
if (ret == -1) {
__close (ptmx);
if (terminal != -1)
__close (terminal);
}
if (buf != _buf)
free (buf);
return ret;
}
versioned_symbol (libc, __openpty, openpty, GLIBC_2_34);
libc_hidden_ver (__openpty, openpty)
#if OTHER_SHLIB_COMPAT (libutil, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libutil, __openpty, openpty, GLIBC_2_0);
#endif
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