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/* Copyright (C) 1998-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
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
<http://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "pty-private.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, struct stat64 *stp)
{
int rv;
char *buf = *pts;
for (;;)
{
char *new_buf;
if (buf_len)
{
rv = __ptsname_internal (fd, buf, buf_len, stp);
if (rv != 0)
{
if (rv == ENOTTY)
/* ptsname_r returns with ENOTTY to indicate
a descriptor not referring to a pty master.
For this condition, grantpt must return EINVAL. */
rv = EINVAL;
errno = rv; /* Not necessarily set by __ptsname_r. */
break;
}
if (memchr (buf, '\0', buf_len))
/* 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 = (char *) realloc (buf, buf_len);
else
new_buf = (char *) 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;
}
/* Change the ownership and access permission of the slave pseudo
terminal associated with the master pseudo terminal specified
by FD. */
int
grantpt (int fd)
{
int retval = -1;
#ifdef PATH_MAX
char _buf[PATH_MAX];
#else
char _buf[512];
#endif
char *buf = _buf;
struct stat64 st;
if (__glibc_unlikely (pts_name (fd, &buf, sizeof (_buf), &st)))
{
int save_errno = errno;
/* Check, if the file descriptor is valid. pts_name returns the
wrong errno number, so we cannot use that. */
if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF)
return -1;
/* If the filedescriptor is no TTY, grantpt has to set errno
to EINVAL. */
if (save_errno == ENOTTY)
__set_errno (EINVAL);
else
__set_errno (save_errno);
return -1;
}
/* Make sure that we own the device. */
uid_t uid = __getuid ();
if (st.st_uid != uid)
{
if (__chown (buf, uid, st.st_gid) < 0)
goto helper;
}
static int tty_gid = -1;
if (__glibc_unlikely (tty_gid == -1))
{
char *grtmpbuf;
struct group grbuf;
size_t grbuflen = __sysconf (_SC_GETGR_R_SIZE_MAX);
struct group *p;
/* Get the group ID of the special `tty' group. */
if (grbuflen == (size_t) -1L)
/* `sysconf' does not support _SC_GETGR_R_SIZE_MAX.
Try a moderate value. */
grbuflen = 1024;
grtmpbuf = (char *) __alloca (grbuflen);
__getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p);
if (p != NULL)
tty_gid = p->gr_gid;
}
gid_t gid = tty_gid == -1 ? __getgid () : tty_gid;
/* Make sure the group of the device is that special group. */
if (st.st_gid != gid)
{
if (__chown (buf, uid, gid) < 0)
goto helper;
}
/* Make sure the permission mode is set to readable and writable by
the owner, and writable by the group. */
if ((st.st_mode & ACCESSPERMS) != (S_IRUSR|S_IWUSR|S_IWGRP))
{
if (__chmod (buf, S_IRUSR|S_IWUSR|S_IWGRP) < 0)
goto helper;
}
retval = 0;
goto cleanup;
/* We have to use the helper program if it is available. */
helper:;
#if HAVE_PT_CHOWN
pid_t pid = __fork ();
if (pid == -1)
goto cleanup;
else if (pid == 0)
{
/* Disable core dumps. */
struct rlimit rl = { 0, 0 };
__setrlimit (RLIMIT_CORE, &rl);
/* We pass the master pseudo terminal as file descriptor PTY_FILENO. */
if (fd != PTY_FILENO)
if (__dup2 (fd, PTY_FILENO) < 0)
_exit (FAIL_EBADF);
# ifdef CLOSE_ALL_FDS
CLOSE_ALL_FDS ();
# endif
execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL);
_exit (FAIL_EXEC);
}
else
{
int w;
if (__waitpid (pid, &w, 0) == -1)
goto cleanup;
if (!WIFEXITED (w))
__set_errno (ENOEXEC);
else
switch (WEXITSTATUS (w))
{
case 0:
retval = 0;
break;
case FAIL_EBADF:
__set_errno (EBADF);
break;
case FAIL_EINVAL:
__set_errno (EINVAL);
break;
case FAIL_EACCES:
__set_errno (EACCES);
break;
case FAIL_EXEC:
__set_errno (ENOEXEC);
break;
case FAIL_ENOMEM:
__set_errno (ENOMEM);
break;
default:
assert(! "grantpt: internal error: invalid exit code from pt_chown");
}
}
#endif
cleanup:
if (buf != _buf)
free (buf);
return retval;
}
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