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/* Copyright (C) 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David Bartley <dtbartle@csclub.uwaterloo.ca>.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <unistd.h>
#include <streams/stropts.h>
#include <sys/ptms.h>
#include <grp.h>
#include <stddef.h>
#include <memory.h>
#include <errno.h>
#define INIT_GROUP_LEN 0x0100
#define MAX_GROUP_LEN 0x8000
int
grantpt (int fd)
{
pt_own_t pto;
pto.pto_ruid = getuid ();
pto.pto_rgid = -1;
/* Keep calling getgrnam with a bigger buffer. */
size_t len = INIT_GROUP_LEN;
char *buf = NULL;
struct group gr, *gro;
do
{
buf = realloc (buf, len);
if (!buf)
{
/* If we can't allocate 64 KB something is wrong. */
free(buf);
return -1;
}
gro = NULL;
int result = getgrnam_r ("tty", &gr, buf, len, &gro);
if(result == 0)
{
/* No entry found. */
if(gro == NULL)
break;
pto.pto_rgid = gro->gr_gid;
}
else if (errno != EINTR && errno != ERANGE && errno != ENOMEM)
{
/* Unknown error - assume failure. */
break;
}
len <<= 1;
}
while (len < MAX_GROUP_LEN);
free (buf);
/* If getgrnam fails we use the user's gid. */
if (pto.pto_rgid == -1)
pto.pto_rgid = getgid ();
/* Send OWNERPT down. */
struct strioctl si;
si.ic_cmd = OWNERPT;
si.ic_timout = 0;
si.ic_len = sizeof (pt_own_t);
si.ic_dp = (char *)&pto;
int res = (ioctl (fd, I_STR, &si) < 0) ? -1 : 0;
if (res != 0 && errno == ENOTTY)
__set_errno (EINVAL);
return res;
}
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