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/* Copyright (c) 2000, 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_seek.cc
*/
#include "my_config.h"
#include <errno.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "my_sys.h"
#include "my_thread_local.h"
#include "mysys_err.h"
#if defined(_WIN32)
#include "mysys/mysys_priv.h"
#endif
/**
Seek to a position in a file. The my_seek function is a wrapper around
the system call lseek and repositions the offset of the file descriptor
fd to the argument offset according to the directive whence as follows:
SEEK_SET The offset is set to offset bytes.
SEEK_CUR The offset is set to its current location plus offset bytes
SEEK_END The offset is set to the size of the file plus offset bytes
@param fd The file descriptor
@param pos The expected position (absolute or relative)
@param whence A direction parameter and one of {SEEK_SET, SEEK_CUR, SEEK_END}
@param MyFlags flags to control error handling.
@retval newpos The new position in the file.
@retval MY_FILEPOS_ERROR An error was encountered while performing
the seek. my_errno is set to indicate the
actual error.
*/
my_off_t my_seek(File fd, my_off_t pos, int whence, myf MyFlags) {
DBUG_TRACE;
/*
Make sure we are using a valid file descriptor!
*/
assert(fd != -1);
const int64_t newpos =
#if defined(_WIN32)
my_win_lseek(fd, pos, whence);
#else
lseek(fd, pos, whence);
#endif
if (newpos == -1) {
set_my_errno(errno);
if (MyFlags & MY_WME) {
MyOsError(my_errno(), EE_CANT_SEEK, MYF(0), my_filename(fd));
}
return MY_FILEPOS_ERROR;
}
assert(newpos >= 0);
return newpos;
}
/* Tell current position of file */
my_off_t my_tell(File fd, myf MyFlags) {
DBUG_TRACE;
assert(fd >= 0);
const int64_t pos =
#if defined(HAVE_TELL) && !defined(_WIN32)
tell(fd);
#else
my_seek(fd, 0L, MY_SEEK_CUR, 0);
#endif
if (pos == -1) {
set_my_errno(errno);
if (MyFlags & MY_WME) {
MyOsError(my_errno(), EE_CANT_SEEK, MYF(0), my_filename(fd));
}
return MY_FILEPOS_ERROR;
}
assert(pos >= 0);
return pos;
}
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