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/* Copyright (c) 2001, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
Without limiting anything contained in the foregoing, this file,
which is part of C Driver for MySQL (Connector/C), is also subject to the
Universal FOSS Exception, version 1.0, a copy of which can be found at
http://oss.oracle.com/licenses/universal-foss-exception.
This program 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 General Public License, version 2.0, for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
/**
@file mysys/my_symlink.cc
*/
#include "my_config.h"
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "m_string.h"
#include "map_helpers.h"
#include "my_dbug.h"
#include "my_dir.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "my_sys.h"
#include "my_thread_local.h"
#include "mysys_err.h"
#ifndef _WIN32
#include <sys/stat.h>
#endif
/*
Reads the content of a symbolic link
If the file is not a symbolic link, return the original file name in to.
RETURN
0 If filename was a symlink, (to will be set to value of symlink)
1 If filename was a normal file (to will be set to filename)
-1 on error.
*/
int my_readlink(char *to, const char *filename, myf MyFlags) {
#ifdef _WIN32
(void)MyFlags; // maybe_unused
my_stpcpy(to, filename);
return 1;
#else
int result = 0;
int length;
DBUG_TRACE;
if ((length = readlink(filename, to, FN_REFLEN - 1)) < 0) {
/* Don't give an error if this wasn't a symlink */
set_my_errno(errno);
if (my_errno() == EINVAL) {
result = 1;
my_stpcpy(to, filename);
} else {
if (MyFlags & MY_WME) {
MyOsError(errno, EE_CANT_READLINK, MYF(0), filename);
}
result = -1;
}
} else
to[length] = 0;
DBUG_PRINT("exit", ("result: %d", result));
return result;
#endif /* !_WIN32 */
}
/* Create a symbolic link */
#ifndef _WIN32
int my_symlink(const char *content, const char *linkname, myf MyFlags) {
int result;
DBUG_TRACE;
DBUG_PRINT("enter", ("content: %s linkname: %s", content, linkname));
result = 0;
if (symlink(content, linkname)) {
result = -1;
set_my_errno(errno);
if (MyFlags & MY_WME) {
MyOsError(errno, EE_CANT_SYMLINK, MYF(0), linkname, content);
}
}
return result;
}
#endif /* !_WIN32 */
int my_is_symlink(const char *filename, ST_FILE_ID *file_id) {
#ifndef _WIN32
struct stat stat_buff;
int result = !lstat(filename, &stat_buff) && S_ISLNK(stat_buff.st_mode);
if (file_id && !result) {
file_id->st_dev = stat_buff.st_dev;
file_id->st_ino = stat_buff.st_ino;
}
return result;
#else
(void)file_id; // maybe_unused
DWORD dwAttr = GetFileAttributes(filename);
return (dwAttr != INVALID_FILE_ATTRIBUTES) &&
(dwAttr & FILE_ATTRIBUTE_REPARSE_POINT);
#endif
}
/*
Resolve all symbolic links in path
'to' may be equal to 'filename'
*/
int my_realpath(char *to, const char *filename, myf MyFlags) {
#ifndef _WIN32
int result = 0;
DBUG_TRACE;
DBUG_PRINT("info", ("executing realpath"));
unique_ptr_free<char> ptr(realpath(filename, nullptr));
if (ptr) {
strmake(to, ptr.get(), FN_REFLEN - 1);
} else {
/*
Realpath didn't work; Use my_load_path() which is a poor substitute
original name but will at least be able to resolve paths that starts
with '.'.
*/
DBUG_PRINT("error", ("realpath failed with errno: %d", errno));
set_my_errno(errno);
if (MyFlags & MY_WME) {
MyOsError(my_errno(), EE_REALPATH, MYF(0), filename);
}
my_load_path(to, filename, NullS);
result = -1;
}
return result;
#else
int ret = GetFullPathName(filename, FN_REFLEN, to, NULL);
if (ret == 0 || ret > FN_REFLEN) {
set_my_errno((ret > FN_REFLEN) ? ENAMETOOLONG : GetLastError());
if (MyFlags & MY_WME) {
MyOsError(my_errno(), EE_REALPATH, MYF(0), filename);
}
/*
GetFullPathName didn't work : use my_load_path() which is a poor
substitute original name but will at least be able to resolve
paths that starts with '.'.
*/
my_load_path(to, filename, NullS);
return -1;
}
return 0;
#endif
}
/**
Return non-zero if the file descriptor and a previously lstat-ed file
identified by file_id point to the same file.
*/
int my_is_same_file(File file, const ST_FILE_ID *file_id) {
MY_STAT stat_buf;
if (my_fstat(file, &stat_buf) == -1) {
set_my_errno(errno);
return 0;
}
return (stat_buf.st_dev == file_id->st_dev) &&
(stat_buf.st_ino == file_id->st_ino);
}
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