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215 lines
6.7 KiB
215 lines
6.7 KiB
/* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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Without limiting anything contained in the foregoing, this file,
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which is part of C Driver for MySQL (Connector/C), is also subject to the
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Universal FOSS Exception, version 1.0, a copy of which can be found at
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http://oss.oracle.com/licenses/universal-foss-exception.
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This program 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
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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/**
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@file mysys/my_symlink2.cc
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Advanced symlink handling.
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This is used in MyISAM to let users symlinks tables to different disk.
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The main idea with these functions is to automaticly create, delete and
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rename files and symlinks like they would be one unit.
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*/
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#include "my_config.h"
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#include <errno.h>
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#include <string.h>
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#include "m_string.h"
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include "my_dbug.h"
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#include "my_inttypes.h"
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#include "my_io.h"
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#include "my_sys.h"
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#include "my_thread_local.h"
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#include "mysys_err.h"
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File my_create_with_symlink(const char *linkname, const char *filename,
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int createflags, int access_flags, myf MyFlags) {
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#ifdef _WIN32
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if (linkname) filename = linkname;
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if (!(MyFlags & MY_DELETE_OLD)) {
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if (!access(filename, F_OK)) {
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char errbuf[MYSYS_STRERROR_SIZE];
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errno = EEXIST;
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set_my_errno(EEXIST);
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my_error(EE_CANTCREATEFILE, MYF(0), filename, EEXIST,
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my_strerror(errbuf, sizeof(errbuf), EEXIST));
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return -1;
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}
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}
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return my_create(filename, createflags, access_flags, MyFlags);
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#else
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File file;
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int tmp_errno;
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/* Test if we should create a link */
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int create_link;
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char abs_linkname[FN_REFLEN];
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DBUG_TRACE;
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DBUG_PRINT("enter",
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("linkname: %s filename: %s", linkname ? linkname : "(null)",
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filename ? filename : "(null)"));
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if (!my_enable_symlinks) {
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DBUG_PRINT("info", ("Symlinks disabled"));
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/* Create only the file, not the link and file */
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create_link = 0;
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if (linkname) filename = linkname;
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} else {
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if (linkname) my_realpath(abs_linkname, linkname, MYF(0));
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create_link = (linkname && strcmp(abs_linkname, filename));
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}
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if (!(MyFlags & MY_DELETE_OLD)) {
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if (!access(filename, F_OK)) {
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char errbuf[MYSYS_STRERROR_SIZE];
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errno = EEXIST;
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set_my_errno(EEXIST);
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my_error(EE_CANTCREATEFILE, MYF(0), filename, EEXIST,
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my_strerror(errbuf, sizeof(errbuf), EEXIST));
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return -1;
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}
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if (create_link && !access(linkname, F_OK)) {
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char errbuf[MYSYS_STRERROR_SIZE];
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errno = EEXIST;
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set_my_errno(EEXIST);
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my_error(EE_CANTCREATEFILE, MYF(0), linkname, EEXIST,
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my_strerror(errbuf, sizeof(errbuf), EEXIST));
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return -1;
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}
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}
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if ((file = my_create(filename, createflags, access_flags, MyFlags)) >= 0) {
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if (create_link) {
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/* Delete old link/file */
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if (MyFlags & MY_DELETE_OLD) my_delete(linkname, MYF(0));
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/* Create link */
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if (my_symlink(filename, linkname, MyFlags)) {
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/* Fail, remove everything we have done */
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tmp_errno = my_errno();
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my_close(file, MYF(0));
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my_delete(filename, MYF(0));
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file = -1;
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set_my_errno(tmp_errno);
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}
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}
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}
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return file;
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#endif // !_WIN32
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}
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/*
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If the file was a symlink, delete both symlink and the file which the
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symlink pointed to.
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*/
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int my_delete_with_symlink(const char *name, myf MyFlags) {
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#ifdef _WIN32
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return my_delete(name, MyFlags);
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#else
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char link_name[FN_REFLEN];
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int was_symlink =
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(my_enable_symlinks && !my_readlink(link_name, name, MYF(0)));
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int result;
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DBUG_TRACE;
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if (!(result = my_delete(name, MyFlags))) {
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if (was_symlink) result = my_delete(link_name, MyFlags);
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}
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return result;
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#endif // _WIN32
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}
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/*
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If the file is a normal file, just rename it.
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If the file is a symlink:
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- Create a new file with the name 'to' that points at
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symlink_dir/basename(to)
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- Rename the symlinked file to symlink_dir/basename(to)
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- Delete 'from'
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If something goes wrong, restore everything.
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*/
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int my_rename_with_symlink(const char *from, const char *to, myf MyFlags) {
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#ifdef _WIN32
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return my_rename(from, to, MyFlags);
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#else
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char link_name[FN_REFLEN], tmp_name[FN_REFLEN];
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int was_symlink =
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(my_enable_symlinks && !my_readlink(link_name, from, MYF(0)));
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int result = 0;
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int name_is_different;
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DBUG_TRACE;
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if (!was_symlink) return my_rename(from, to, MyFlags);
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/* Change filename that symlink pointed to */
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my_stpcpy(tmp_name, to);
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fn_same(tmp_name, link_name, 1); /* Copy dir */
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name_is_different = strcmp(link_name, tmp_name);
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if (name_is_different && !access(tmp_name, F_OK)) {
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set_my_errno(EEXIST);
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if (MyFlags & MY_WME) {
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char errbuf[MYSYS_STRERROR_SIZE];
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my_error(EE_CANTCREATEFILE, MYF(0), tmp_name, EEXIST,
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my_strerror(errbuf, sizeof(errbuf), EEXIST));
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}
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return 1;
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}
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/* Create new symlink */
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if (my_symlink(tmp_name, to, MyFlags)) return 1;
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/*
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Rename symlinked file if the base name didn't change.
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This can happen if you use this function where 'from' and 'to' has
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the same basename and different directories.
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*/
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if (name_is_different && my_rename(link_name, tmp_name, MyFlags)) {
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int save_errno = my_errno();
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my_delete(to, MyFlags); /* Remove created symlink */
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set_my_errno(save_errno);
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return 1;
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}
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/* Remove original symlink */
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if (my_delete(from, MyFlags)) {
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int save_errno = my_errno();
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/* Remove created link */
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my_delete(to, MyFlags);
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/* Rename file back */
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if (strcmp(link_name, tmp_name))
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(void)my_rename(tmp_name, link_name, MyFlags);
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set_my_errno(save_errno);
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result = 1;
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}
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return result;
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#endif /* !_WIN32 */
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}
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