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121 lines
3.2 KiB
C
121 lines
3.2 KiB
C
/* Copyright (C) 2005-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <stdio.h>
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#include <sysdep.h>
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#include <unistd.h>
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#include <kernel-features.h>
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/* Make a link to FROM named TO but relative paths in TO and FROM are
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interpreted relative to FROMFD and TOFD respectively. */
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int
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linkat (fromfd, from, tofd, to, flags)
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int fromfd;
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const char *from;
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int tofd;
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const char *to;
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int flags;
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{
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int result;
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#ifdef __NR_linkat
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# ifndef __ASSUME_ATFCTS
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if (__have_atfcts >= 0)
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# endif
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{
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result = INLINE_SYSCALL (linkat, 5, fromfd, from, tofd, to, flags);
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# ifndef __ASSUME_ATFCTS
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if (result == -1 && errno == ENOSYS)
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__have_atfcts = -1;
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else
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# endif
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return result;
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}
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#endif
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#ifndef __ASSUME_ATFCTS
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/* Without kernel support we cannot handle AT_SYMLINK_FOLLOW. */
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if (flags != 0)
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{
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__set_errno (EINVAL);
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return -1;
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}
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static const char procfd[] = "/proc/self/fd/%d/%s";
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char *buffrom = NULL;
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if (fromfd != AT_FDCWD && from[0] != '/')
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{
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size_t filelen = strlen (from);
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if (__glibc_unlikely (filelen == 0))
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{
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__set_errno (ENOENT);
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return -1;
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}
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/* Buffer for the path name we are going to use. It consists of
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- the string /proc/self/fd/
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- the file descriptor number
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- the file name provided.
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The final NUL is included in the sizeof. A bit of overhead
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due to the format elements compensates for possible negative
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numbers. */
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size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
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buffrom = alloca (buflen);
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__snprintf (buffrom, buflen, procfd, fromfd, from);
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from = buffrom;
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}
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char *bufto = NULL;
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if (tofd != AT_FDCWD && to[0] != '/')
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{
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size_t filelen = strlen (to);
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/* Buffer for the path name we are going to use. It consists of
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- the string /proc/self/fd/
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- the file descriptor number
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- the file name provided.
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The final NUL is included in the sizeof. A bit of overhead
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due to the format elements compensates for possible negative
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numbers. */
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size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
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bufto = alloca (buflen);
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__snprintf (bufto, buflen, procfd, tofd, to);
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to = bufto;
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}
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INTERNAL_SYSCALL_DECL (err);
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result = INTERNAL_SYSCALL (link, err, 2, from, to);
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if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
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{
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__atfct_seterrno_2 (INTERNAL_SYSCALL_ERRNO (result, err), tofd, bufto,
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fromfd, buffrom);
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result = -1;
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}
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return result;
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#endif
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}
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