glibc/sysdeps/unix/sysv/linux/xmknodat.c

101 lines
2.7 KiB
C

/* Copyright (C) 2005-2013 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
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sysdep.h>
#include <kernel-features.h>
#include <sys/syscall.h>
#include <bp-checks.h>
/* Create a device file named PATH relative to FD, with permission and
special bits MODE and device number DEV (which can be constructed
from major and minor device numbers with the `makedev' macro above). */
int
__xmknodat (int vers, int fd, const char *file, mode_t mode, dev_t *dev)
{
if (vers != _MKNOD_VER)
{
__set_errno (EINVAL);
return -1;
}
/* We must convert the value to dev_t type used by the kernel. */
unsigned long long int k_dev = (*dev) & ((1ULL << 32) - 1);
if (k_dev != *dev)
{
__set_errno (EINVAL);
return -1;
}
#ifdef __NR_mknodat
# ifndef __ASSUME_ATFCTS
if (__have_atfcts >= 0)
# endif
{
int res = INLINE_SYSCALL (mknodat, 4, fd, file, mode,
(unsigned int) k_dev);
# ifndef __ASSUME_ATFCTS
if (res == -1 && errno == ENOSYS)
__have_atfcts = -1;
else
# endif
return res;
}
#endif
#ifndef __ASSUME_ATFCTS
char *buf = NULL;
if (fd != AT_FDCWD && file[0] != '/')
{
size_t filelen = strlen (file);
if (__builtin_expect (filelen == 0, 0))
{
__set_errno (ENOENT);
return -1;
}
static const char procfd[] = "/proc/self/fd/%d/%s";
/* Buffer for the path name we are going to use. It consists of
- the string /proc/self/fd/
- the file descriptor number
- the file name provided.
The final NUL is included in the sizeof. A bit of overhead
due to the format elements compensates for possible negative
numbers. */
size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
buf = alloca (buflen);
__snprintf (buf, buflen, procfd, fd, file);
file = buf;
}
return INLINE_SYSCALL (mknod, 3, CHECK_STRING (file), mode,
(unsigned int) k_dev);
#endif
}
libc_hidden_def (__xmknodat)