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/* $OpenBSD: posix_pty.c,v 1.3 2019/01/25 00:19:25 millert Exp $ */
/*
* Copyright (c) 2012 Todd C. Miller <millert@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/tty.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int
posix_openpt(int oflag)
{
struct ptmget ptm;
int fd, mfd = -1;
/* User must specify O_RDWR in oflag. */
if ((oflag & O_ACCMODE) != O_RDWR ||
(oflag & ~(O_ACCMODE | O_NOCTTY)) != 0) {
errno = EINVAL;
return -1;
}
/* Get pty master and slave (this API only uses the master). */
fd = open(PATH_PTMDEV, O_RDWR);
if (fd != -1) {
if (ioctl(fd, PTMGET, &ptm) != -1) {
close(ptm.sfd);
mfd = ptm.cfd;
}
close(fd);
}
return mfd;
}
/*
* Look up the name of the specified pty master fd.
* Note that the name returned does *not* include the /dev/ prefix.
* Returns the name on success and NULL on error, setting errno.
*/
static const char *
ptmname(int mfd)
{
struct stat sb;
const char *name;
/* Make sure it is a pty master. */
if (fstat(mfd, &sb) != 0)
return NULL;
if (!S_ISCHR(sb.st_mode)) {
errno = EINVAL;
return NULL;
}
name = devname(sb.st_rdev, S_IFCHR);
if (strncmp(name, "pty", 3) != 0) {
errno = EINVAL;
return NULL;
}
return name;
}
/*
* The PTMGET ioctl handles the mode and owner for us.
*/
int
grantpt(int mfd)
{
return ptmname(mfd) ? 0 : -1;
}
/*
* The PTMGET ioctl unlocks the pty master and slave for us.
*/
int
unlockpt(int mfd)
{
return ptmname(mfd) ? 0 : -1;
}
/*
* Look up the path of the slave pty that corresponds to the master fd.
* Returns the path if successful or NULL on error.
*/
char *
ptsname(int mfd)
{
const char *master;
static char slave[sizeof(((struct ptmget *)NULL)->sn)];
if ((master = ptmname(mfd)) == NULL)
return NULL;
/* Add /dev/ prefix and convert "pty" to "tty". */
strlcpy(slave, _PATH_DEV, sizeof(slave));
strlcat(slave, master, sizeof(slave));
slave[sizeof(_PATH_DEV) - 1] = 't';
return slave;
}
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