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138 lines
4.5 KiB
138 lines
4.5 KiB
5 months ago
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/* 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_seek.cc
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*/
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#include "my_config.h"
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#include <errno.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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#if defined(_WIN32)
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#include "mysys/mysys_priv.h"
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#endif
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#if defined(_WIN32)
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typedef unsigned long long os_off_t;
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#else
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typedef off_t os_off_t;
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#endif
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/*
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Seek to a position in a file.
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ARGUMENTS
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File fd The file descriptor
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my_off_t pos The expected position (absolute or relative)
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int whence A direction parameter and one of
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{SEEK_SET, SEEK_CUR, SEEK_END}
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myf MyFlags MY_THREADSAFE must be set in case my_seek may be mixed
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with my_pread/my_pwrite calls and fd is shared among
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threads.
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DESCRIPTION
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The my_seek function is a wrapper around the system call lseek and
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repositions the offset of the file descriptor fd to the argument
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offset according to the directive whence as follows:
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SEEK_SET The offset is set to offset bytes.
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SEEK_CUR The offset is set to its current location plus offset bytes
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SEEK_END The offset is set to the size of the file plus offset bytes
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RETURN VALUE
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my_off_t newpos The new position in the file.
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MY_FILEPOS_ERROR An error was encountered while performing
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the seek. my_errno is set to indicate the
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actual error.
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*/
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my_off_t my_seek(File fd, my_off_t pos, int whence, myf MyFlags) {
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os_off_t newpos = -1;
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DBUG_TRACE;
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DBUG_PRINT("my", ("fd: %d Pos: %llu Whence: %d MyFlags: %d", fd,
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(ulonglong)pos, whence, MyFlags));
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/*
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Make sure we are using a valid file descriptor!
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*/
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DBUG_ASSERT(fd != -1);
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#if defined(_WIN32)
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newpos = my_win_lseek(fd, pos, whence);
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#else
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newpos = lseek(fd, pos, whence);
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#endif
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if (newpos == (os_off_t)-1) {
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set_my_errno(errno);
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if (MyFlags & MY_WME) {
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char errbuf[MYSYS_STRERROR_SIZE];
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my_error(EE_CANT_SEEK, MYF(0), my_filename(fd), my_errno(),
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my_strerror(errbuf, sizeof(errbuf), my_errno()));
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}
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DBUG_PRINT("error", ("lseek: %llu errno: %d", (ulonglong)newpos, errno));
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return MY_FILEPOS_ERROR;
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}
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if ((my_off_t)newpos != pos) {
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DBUG_PRINT("exit", ("pos: %llu", (ulonglong)newpos));
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}
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return (my_off_t)newpos;
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} /* my_seek */
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/* Tell current position of file */
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/* ARGSUSED */
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my_off_t my_tell(File fd, myf MyFlags) {
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os_off_t pos;
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DBUG_TRACE;
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DBUG_PRINT("my", ("fd: %d MyFlags: %d", fd, MyFlags));
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DBUG_ASSERT(fd >= 0);
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#if defined(HAVE_TELL) && !defined(_WIN32)
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pos = tell(fd);
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#else
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pos = my_seek(fd, 0L, MY_SEEK_CUR, 0);
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#endif
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if (pos == (os_off_t)-1) {
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set_my_errno(errno);
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if (MyFlags & MY_WME) {
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char errbuf[MYSYS_STRERROR_SIZE];
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my_error(EE_CANT_SEEK, MYF(0), my_filename(fd), my_errno(),
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my_strerror(errbuf, sizeof(errbuf), my_errno()));
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}
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DBUG_PRINT("error", ("tell: %llu errno: %d", (ulonglong)pos, my_errno()));
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}
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DBUG_PRINT("exit", ("pos: %llu", (ulonglong)pos));
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return (my_off_t)pos;
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} /* my_tell */
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